Virtual Service

31 minute read

Configuration affecting traffic routing. Here are a few terms useful to define in the context of traffic routing.

Service a unit of application behavior bound to a unique name in a service registry. Services consist of multiple network endpoints implemented by workload instances running on pods, containers, VMs etc.

Service versions (a.k.a. subsets) - In a continuous deployment scenario, for a given service, there can be distinct subsets of instances running different variants of the application binary. These variants are not necessarily different API versions. They could be iterative changes to the same service, deployed in different environments (prod, staging, dev, etc.). Common scenarios where this occurs include A/B testing, canary rollouts, etc. The choice of a particular version can be decided based on various criterion (headers, url, etc.) and/or by weights assigned to each version. Each service has a default version consisting of all its instances.

Source - A downstream client calling a service.

Host - The address used by a client when attempting to connect to a service.

Access model - Applications address only the destination service (Host) without knowledge of individual service versions (subsets). The actual choice of the version is determined by the proxy/sidecar, enabling the application code to decouple itself from the evolution of dependent services.

A VirtualService defines a set of traffic routing rules to apply when a host is addressed. Each routing rule defines matching criteria for traffic of a specific protocol. If the traffic is matched, then it is sent to a named destination service (or subset/version of it) defined in the registry.

The source of traffic can also be matched in a routing rule. This allows routing to be customized for specific client contexts.

The following example on Kubernetes, routes all HTTP traffic by default to pods of the reviews service with label “version: v1”. In addition, HTTP requests with path starting with /wpcatalog/ or /consumercatalog/ will be rewritten to /newcatalog and sent to pods with label “version: v2”.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews-route
spec:
  hosts:
  - reviews.prod.svc.cluster.local
  http:
  - name: "reviews-v2-routes"
    match:
    - uri:
        prefix: "/wpcatalog"
    - uri:
        prefix: "/consumercatalog"
    rewrite:
      uri: "/newcatalog"
    route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v2
  - name: "reviews-v1-route"
    route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v1

A subset/version of a route destination is identified with a reference to a named service subset which must be declared in a corresponding DestinationRule.

apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
  name: reviews-destination
spec:
  host: reviews.prod.svc.cluster.local
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2

VirtualService

Configuration affecting traffic routing.

Field	Type	Description	Required
`hosts`	`string[]`	The destination hosts to which traffic is being sent. Could be a DNS name with wildcard prefix or an IP address. Depending on the platform, short-names can also be used instead of a FQDN (i.e. has no dots in the name). In such a scenario, the FQDN of the host would be derived based on the underlying platform. A single VirtualService can be used to describe all the traffic properties of the corresponding hosts, including those for multiple HTTP and TCP ports. Alternatively, the traffic properties of a host can be defined using more than one VirtualService, with certain caveats. Refer to the Operations Guide for details. Note for Kubernetes users: When short names are used (e.g. “reviews” instead of “reviews.default.svc.cluster.local”), Istio will interpret the short name based on the namespace of the rule, not the service. A rule in the “default” namespace containing a host “reviews” will be interpreted as “reviews.default.svc.cluster.local”, irrespective of the actual namespace associated with the reviews service. To avoid potential misconfigurations, it is recommended to always use fully qualified domain names over short names. The hosts field applies to both HTTP and TCP services. Service inside the mesh, i.e., those found in the service registry, must always be referred to using their alphanumeric names. IP addresses are allowed only for services defined via the Gateway. Note: It must be empty for a delegate VirtualService.	No
`gateways`	`string[]`	The names of gateways and sidecars that should apply these routes. Gateways in other namespaces may be referred to by `<gateway namespace>/<gateway name>`; specifying a gateway with no namespace qualifier is the same as specifying the VirtualService’s namespace. A single VirtualService is used for sidecars inside the mesh as well as for one or more gateways. The selection condition imposed by this field can be overridden using the source field in the match conditions of protocol-specific routes. The reserved word `mesh` is used to imply all the sidecars in the mesh. When this field is omitted, the default gateway (`mesh`) will be used, which would apply the rule to all sidecars in the mesh. If a list of gateway names is provided, the rules will apply only to the gateways. To apply the rules to both gateways and sidecars, specify `mesh` as one of the gateway names.	No
`http`	`HTTPRoute[]`	An ordered list of route rules for HTTP traffic. HTTP routes will be applied to platform service ports using HTTP/HTTP2/GRPC protocols, gateway ports with protocol HTTP/HTTP2/GRPC/TLS-terminated-HTTPS and service entry ports using HTTP/HTTP2/GRPC protocols. The first rule matching an incoming request is used.	No
`tls`	`TLSRoute[]`	An ordered list of route rule for non-terminated TLS & HTTPS traffic. Routing is typically performed using the SNI value presented by the ClientHello message. TLS routes will be applied to platform service ports named ‘https-’, ’tls-’, unterminated gateway ports using HTTPS/TLS protocols (i.e. with “passthrough” TLS mode) and service entry ports using HTTPS/TLS protocols. The first rule matching an incoming request is used. NOTE: Traffic ‘https-’ or ’tls-’ ports without associated virtual service will be treated as opaque TCP traffic.	No
`tcp`	`TCPRoute[]`	An ordered list of route rules for opaque TCP traffic. TCP routes will be applied to any port that is not a HTTP or TLS port. The first rule matching an incoming request is used.	No
`exportTo`	`string[]`	A list of namespaces to which this virtual service is exported. Exporting a virtual service allows it to be used by sidecars and gateways defined in other namespaces. This feature provides a mechanism for service owners and mesh administrators to control the visibility of virtual services across namespace boundaries. If no namespaces are specified then the virtual service is exported to all namespaces by default. The value “.” is reserved and defines an export to the same namespace that the virtual service is declared in. Similarly the value “*” is reserved and defines an export to all namespaces.	No

Destination

Destination indicates the network addressable service to which the request/connection will be sent after processing a routing rule. The destination.host should unambiguously refer to a service in the service registry. Istio’s service registry is composed of all the services found in the platform’s service registry (e.g., Kubernetes services, Consul services), as well as services declared through the ServiceEntry resource.

Note for Kubernetes users: When short names are used (e.g. “reviews” instead of “reviews.default.svc.cluster.local”), Istio will interpret the short name based on the namespace of the rule, not the service. A rule in the “default” namespace containing a host “reviews” will be interpreted as “reviews.default.svc.cluster.local”, irrespective of the actual namespace associated with the reviews service. To avoid potential misconfigurations, it is recommended to always use fully qualified domain names over short names.

The following Kubernetes example routes all traffic by default to pods of the reviews service with label “version: v1” (i.e., subset v1), and some to subset v2, in a Kubernetes environment.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews-route
  namespace: foo
spec:
  hosts:
  - reviews # interpreted as reviews.foo.svc.cluster.local
  http:
  - match:
    - uri:
        prefix: "/wpcatalog"
    - uri:
        prefix: "/consumercatalog"
    rewrite:
      uri: "/newcatalog"
    route:
    - destination:
        host: reviews # interpreted as reviews.foo.svc.cluster.local
        subset: v2
  - route:
    - destination:
        host: reviews # interpreted as reviews.foo.svc.cluster.local
        subset: v1

And the associated DestinationRule

apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
  name: reviews-destination
  namespace: foo
spec:
  host: reviews # interpreted as reviews.foo.svc.cluster.local
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2

The following VirtualService sets a timeout of 5s for all calls to productpage.prod.svc.cluster.local service in Kubernetes. Notice that there are no subsets defined in this rule. Istio will fetch all instances of productpage.prod.svc.cluster.local service from the service registry and populate the sidecar’s load balancing pool. Also, notice that this rule is set in the istio-system namespace but uses the fully qualified domain name of the productpage service, productpage.prod.svc.cluster.local. Therefore the rule’s namespace does not have an impact in resolving the name of the productpage service.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: my-productpage-rule
  namespace: istio-system
spec:
  hosts:
  - productpage.prod.svc.cluster.local # ignores rule namespace
  http:
  - timeout: 5s
    route:
    - destination:
        host: productpage.prod.svc.cluster.local

To control routing for traffic bound to services outside the mesh, external services must first be added to Istio’s internal service registry using the ServiceEntry resource. VirtualServices can then be defined to control traffic bound to these external services. For example, the following rules define a Service for wikipedia.org and set a timeout of 5s for HTTP requests.

apiVersion: networking.istio.io/v1
kind: ServiceEntry
metadata:
  name: external-svc-wikipedia
spec:
  hosts:
  - wikipedia.org
  location: MESH_EXTERNAL
  ports:
  - number: 80
    name: example-http
    protocol: HTTP
  resolution: DNS
---
apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: my-wiki-rule
spec:
  hosts:
  - wikipedia.org
  http:
  - timeout: 5s
    route:
    - destination:
        host: wikipedia.org

Field Type Description Required

Field	Type	Description	Required
`host`	`string`	The name of a service from the service registry. Service names are looked up from the platform’s service registry (e.g., Kubernetes services, Consul services, etc.) and from the hosts declared by ServiceEntry. Traffic forwarded to destinations that are not found in either of the two, will be dropped. Note for Kubernetes users: When short names are used (e.g. “reviews” instead of “reviews.default.svc.cluster.local”), Istio will interpret the short name based on the namespace of the rule, not the service. A rule in the “default” namespace containing a host “reviews” will be interpreted as “reviews.default.svc.cluster.local”, irrespective of the actual namespace associated with the reviews service. To avoid potential misconfiguration, it is recommended to always use fully qualified domain names over short names.	Yes
`subset`	`string`	The name of a subset within the service. Applicable only to services within the mesh. The subset must be defined in a corresponding DestinationRule.	No
`port`	`PortSelector`	Specifies the port on the host that is being addressed. If a service exposes only a single port it is not required to explicitly select the port.	No

host

string

The name of a service from the service registry. Service names are looked up from the platform’s service registry (e.g., Kubernetes services, Consul services, etc.) and from the hosts declared by ServiceEntry. Traffic forwarded to destinations that are not found in either of the two, will be dropped.

Note for Kubernetes users: When short names are used (e.g. “reviews” instead of “reviews.default.svc.cluster.local”), Istio will interpret the short name based on the namespace of the rule, not the service. A rule in the “default” namespace containing a host “reviews” will be interpreted as “reviews.default.svc.cluster.local”, irrespective of the actual namespace associated with the reviews service. To avoid potential misconfiguration, it is recommended to always use fully qualified domain names over short names.

Yes

subset

string

The name of a subset within the service. Applicable only to services within the mesh. The subset must be defined in a corresponding DestinationRule.

port

PortSelector

Specifies the port on the host that is being addressed. If a service exposes only a single port it is not required to explicitly select the port.

HTTPRoute

Describes match conditions and actions for routing HTTP/1.1, HTTP2, and gRPC traffic. See VirtualService for usage examples.

Field	Type	Description	Required
`name`	`string`	The name assigned to the route for debugging purposes. The route’s name will be concatenated with the match’s name and will be logged in the access logs for requests matching this route/match.	No
`match`	`HTTPMatchRequest[]`	Match conditions to be satisfied for the rule to be activated. All conditions inside a single match block have AND semantics, while the list of match blocks have OR semantics. The rule is matched if any one of the match blocks succeed.	No
`route`	`HTTPRouteDestination[]`	A HTTP rule can either return a direct_response, redirect or forward (default) traffic. The forwarding target can be one of several versions of a service (see glossary in beginning of document). Weights associated with the service version determine the proportion of traffic it receives.	No
`redirect`	`HTTPRedirect`	A HTTP rule can either return a direct_response, redirect or forward (default) traffic. If traffic passthrough option is specified in the rule, route/redirect will be ignored. The redirect primitive can be used to send a HTTP 301 redirect to a different URI or Authority.	No
`directResponse`	`HTTPDirectResponse`	A HTTP rule can either return a direct_response, redirect or forward (default) traffic. Direct Response is used to specify a fixed response that should be sent to clients. It can be set only when `Route` and `Redirect` are empty.	No
`delegate`	`Delegate`	Delegate is used to specify the particular VirtualService which can be used to define delegate HTTPRoute. It can be set only when `Route` and `Redirect` are empty, and the route rules of the delegate VirtualService will be merged with that in the current one. NOTE: Only one level delegation is supported. The delegate’s HTTPMatchRequest must be a strict subset of the root’s, otherwise there is a conflict and the HTTPRoute will not take effect.	No
`rewrite`	`HTTPRewrite`	Rewrite HTTP URIs and Authority headers. Rewrite cannot be used with Redirect primitive. Rewrite will be performed before forwarding.	No
`timeout`	`Duration`	Timeout for HTTP requests, default is disabled.	No
`retries`	`HTTPRetry`	Retry policy for HTTP requests. Note: the default cluster-wide retry policy, if not specified, is: `attempts: 2 retryOn: "connect-failure,refused-stream,unavailable,cancelled,503"` This can be customized in `Mesh Config` `defaultHttpRetryPolicy`.	No
`fault`	`HTTPFaultInjection`	Fault injection policy to apply on HTTP traffic at the client side. Note that timeouts or retries will not be enabled when faults are enabled on the client side.	No
`mirror`	`Destination`	Mirror HTTP traffic to a another destination in addition to forwarding the requests to the intended destination. Mirrored traffic is on a best effort basis where the sidecar/gateway will not wait for the mirrored cluster to respond before returning the response from the original destination. Statistics will be generated for the mirrored destination.	No
`mirrors`	`HTTPMirrorPolicy[]`	Specifies the destinations to mirror HTTP traffic in addition to the original destination. Mirrored traffic is on a best effort basis where the sidecar/gateway will not wait for the mirrored destinations to respond before returning the response from the original destination. Statistics will be generated for the mirrored destination.	No
`mirrorPercentage`	`Percent`	Percentage of the traffic to be mirrored by the `mirror` field. If this field is absent, all the traffic (100%) will be mirrored. Max value is 100.	No
`corsPolicy`	`CorsPolicy`	Cross-Origin Resource Sharing policy (CORS). Refer to CORS for further details about cross origin resource sharing.	No
`headers`	`Headers`	Header manipulation rules	No

Delegate

Describes the delegate VirtualService. The following routing rules forward the traffic to /productpage by a delegate VirtualService named productpage, forward the traffic to /reviews by a delegate VirtualService named reviews.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: bookinfo
spec:
  hosts:
  - "bookinfo.com"
  gateways:
  - mygateway
  http:
  - match:
    - uri:
        prefix: "/productpage"
    delegate:
       name: productpage
       namespace: nsA
  - match:
    - uri:
        prefix: "/reviews"
    delegate:
        name: reviews
        namespace: nsB

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: productpage
  namespace: nsA
spec:
  http:
  - match:
     - uri:
        prefix: "/productpage/v1/"
    route:
    - destination:
        host: productpage-v1.nsA.svc.cluster.local
  - route:
    - destination:
        host: productpage.nsA.svc.cluster.local

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews
  namespace: nsB
spec:
  http:
  - route:
    - destination:
        host: reviews.nsB.svc.cluster.local

Field	Type	Description	Required
`name`	`string`	Name specifies the name of the delegate VirtualService.	No
`namespace`	`string`	Namespace specifies the namespace where the delegate VirtualService resides. By default, it is same to the root’s.	No

Headers

Message headers can be manipulated when Envoy forwards requests to, or responses from, a destination service. Header manipulation rules can be specified for a specific route destination or for all destinations. The following VirtualService adds a test header with the value true to requests that are routed to any reviews service destination. It also removes the foo response header, but only from responses coming from the v1 subset (version) of the reviews service.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews-route
spec:
  hosts:
  - reviews.prod.svc.cluster.local
  http:
  - headers:
      request:
        set:
          test: "true"
    route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v2
      weight: 25
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v1
      headers:
        response:
          remove:
          - foo
      weight: 75

Field	Type	Description	Required
`request`	`HeaderOperations`	Header manipulation rules to apply before forwarding a request to the destination service	No
`response`	`HeaderOperations`	Header manipulation rules to apply before returning a response to the caller	No

TLSRoute

Describes match conditions and actions for routing unterminated TLS traffic (TLS/HTTPS) The following routing rule forwards unterminated TLS traffic arriving at port 443 of gateway called “mygateway” to internal services in the mesh based on the SNI value.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: bookinfo-sni
spec:
  hosts:
  - "*.bookinfo.com"
  gateways:
  - mygateway
  tls:
  - match:
    - port: 443
      sniHosts:
      - login.bookinfo.com
    route:
    - destination:
        host: login.prod.svc.cluster.local
  - match:
    - port: 443
      sniHosts:
      - reviews.bookinfo.com
    route:
    - destination:
        host: reviews.prod.svc.cluster.local

Field	Type	Description	Required
`match`	`TLSMatchAttributes[]`	Match conditions to be satisfied for the rule to be activated. All conditions inside a single match block have AND semantics, while the list of match blocks have OR semantics. The rule is matched if any one of the match blocks succeed.	Yes
`route`	`RouteDestination[]`	The destination to which the connection should be forwarded to.	No

TCPRoute

Describes match conditions and actions for routing TCP traffic. The following routing rule forwards traffic arriving at port 27017 for mongo.prod.svc.cluster.local to another Mongo server on port 5555.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: bookinfo-mongo
spec:
  hosts:
  - mongo.prod.svc.cluster.local
  tcp:
  - match:
    - port: 27017
    route:
    - destination:
        host: mongo.backup.svc.cluster.local
        port:
          number: 5555

Field	Type	Description	Required
`match`	`L4MatchAttributes[]`	Match conditions to be satisfied for the rule to be activated. All conditions inside a single match block have AND semantics, while the list of match blocks have OR semantics. The rule is matched if any one of the match blocks succeed.	No
`route`	`RouteDestination[]`	The destination to which the connection should be forwarded to.	No

HTTPMatchRequest

HttpMatchRequest specifies a set of criteria to be met in order for the rule to be applied to the HTTP request. For example, the following restricts the rule to match only requests where the URL path starts with /ratings/v2/ and the request contains a custom end-user header with value jason.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - match:
    - headers:
        end-user:
          exact: jason
      uri:
        prefix: "/ratings/v2/"
      ignoreUriCase: true
    route:
    - destination:
        host: ratings.prod.svc.cluster.local

HTTPMatchRequest CANNOT be empty. Note:

If a root VirtualService have matched any property (path, header etc.) by regex, delegate VirtualServices should not have any other matches on the same property.
If a delegate VirtualService have matched any property (path, header etc.) by regex, root VirtualServices should not have any other matches on the same property.

Field	Type	Description	Required
`name`	`string`	The name assigned to a match. The match’s name will be concatenated with the parent route’s name and will be logged in the access logs for requests matching this route.	No
`uri`	`StringMatch`	URI to match values are case-sensitive and formatted as follows: `exact: "value"` for exact string match `prefix: "value"` for prefix-based match `regex: "value"` for RE2 style regex-based match. Note: Case-insensitive matching could be enabled via the `ignoreUriCase` flag.	No
`scheme`	`StringMatch`	URI Scheme values are case-sensitive and formatted as follows: `exact: "value"` for exact string match `prefix: "value"` for prefix-based match `regex: "value"` for RE2 style regex-based match.	No
`method`	`StringMatch`	HTTP Method values are case-sensitive and formatted as follows: `exact: "value"` for exact string match `prefix: "value"` for prefix-based match `regex: "value"` for RE2 style regex-based match.	No
`authority`	`StringMatch`	HTTP Authority values are case-sensitive and formatted as follows: `exact: "value"` for exact string match `prefix: "value"` for prefix-based match `regex: "value"` for RE2 style regex-based match.	No
`headers`	`map<string, StringMatch>`	The header keys must be lowercase and use hyphen as the separator, e.g. x-request-id. Header values are case-sensitive and formatted as follows: `exact: "value"` for exact string match `prefix: "value"` for prefix-based match `regex: "value"` for RE2 style regex-based match. If the value is empty and only the name of header is specified, presence of the header is checked. To provide an empty value, use `{}`, for example: `- match: - headers: myheader: {}` Note: The keys `uri`, `scheme`, `method`, and `authority` will be ignored.	No
`port`	`uint32`	Specifies the ports on the host that is being addressed. Many services only expose a single port or label ports with the protocols they support, in these cases it is not required to explicitly select the port.	No
`sourceLabels`	`map<string, string>`	One or more labels that constrain the applicability of a rule to source (client) workloads with the given labels. If the VirtualService has a list of gateways specified in the top-level `gateways` field, it must include the reserved gateway `mesh` for this field to be applicable.	No
`gateways`	`string[]`	Names of gateways where the rule should be applied. Gateway names in the top-level `gateways` field of the VirtualService (if any) are overridden. The gateway match is independent of sourceLabels.	No
`queryParams`	`map<string, StringMatch>`	Query parameters for matching. Ex: For a query parameter like “?key=true”, the map key would be “key” and the string match could be defined as `exact: "true"`. For a query parameter like “?key”, the map key would be “key” and the string match could be defined as `exact: ""`. For a query parameter like “?key=abc” or “?key=abx”, the map key would be “key” and the string match could be defined as `prefix: "ab"`. For a query parameter like “?key=123”, the map key would be “key” and the string match could be defined as `regex: "\d+$"`. Note that this configuration will only match values like “123” but not “a123” or “123a”.	No
`ignoreUriCase`	`bool`	Flag to specify whether the URI matching should be case-insensitive. Note: The case will be ignored only in the case of `exact` and `prefix` URI matches.	No
`withoutHeaders`	`map<string, StringMatch>`	withoutHeader has the same syntax with the header, but has opposite meaning. If a header is matched with a matching rule among withoutHeader, the traffic becomes not matched one.	No
`sourceNamespace`	`string`	Source namespace constraining the applicability of a rule to workloads in that namespace. If the VirtualService has a list of gateways specified in the top-level `gateways` field, it must include the reserved gateway `mesh` for this field to be applicable.	No
`statPrefix`	`string`	The human readable prefix to use when emitting statistics for this route. The statistics are generated with prefix route.<stat_prefix>. This should be set for highly critical routes that one wishes to get “per-route” statistics on. This prefix is only for proxy-level statistics (envoy_) and not service-level (istio_) statistics. Refer to https://www.envoyproxy.io/docs/envoy/latest/api-v3/config/route/v3/route_components.proto#envoy-v3-api-field-config-route-v3-route-stat-prefix for statistics that are generated when this is configured.	No

HTTPRouteDestination

Each routing rule is associated with one or more service versions (see glossary in beginning of document). Weights associated with the version determine the proportion of traffic it receives. For example, the following rule will route 25% of traffic for the “reviews” service to instances with the “v2” tag and the remaining traffic (i.e., 75%) to “v1”.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews-route
spec:
  hosts:
  - reviews.prod.svc.cluster.local
  http:
  - route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v2
      weight: 25
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v1
      weight: 75

And the associated DestinationRule

apiVersion: networking.istio.io/v1
kind: DestinationRule
metadata:
  name: reviews-destination
spec:
  host: reviews.prod.svc.cluster.local
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2

Traffic can also be split across two entirely different services without having to define new subsets. For example, the following rule forwards 25% of traffic to reviews.com to dev.reviews.com

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews-route-two-domains
spec:
  hosts:
  - reviews.com
  http:
  - route:
    - destination:
        host: dev.reviews.com
      weight: 25
    - destination:
        host: reviews.com
      weight: 75

Field	Type	Description	Required
`destination`	`Destination`	Destination uniquely identifies the instances of a service to which the request/connection should be forwarded to.	Yes
`weight`	`int32`	Weight specifies the relative proportion of traffic to be forwarded to the destination. A destination will receive `weight/(sum of all weights)` requests. If there is only one destination in a rule, it will receive all traffic. Otherwise, if weight is `0`, the destination will not receive any traffic.	No
`headers`	`Headers`	Header manipulation rules	No

RouteDestination

L4 routing rule weighted destination.

Field	Type	Description	Required
`destination`	`Destination`	Destination uniquely identifies the instances of a service to which the request/connection should be forwarded to.	Yes
`weight`	`int32`	Weight specifies the relative proportion of traffic to be forwarded to the destination. A destination will receive `weight/(sum of all weights)` requests. If there is only one destination in a rule, it will receive all traffic. Otherwise, if weight is `0`, the destination will not receive any traffic.	No

L4MatchAttributes

L4 connection match attributes. Note that L4 connection matching support is incomplete.

Field	Type	Description	Required
`destinationSubnets`	`string[]`	IPv4 or IPv6 ip addresses of destination with optional subnet. E.g., a.b.c.d/xx form or just a.b.c.d.	No
`port`	`uint32`	Specifies the port on the host that is being addressed. Many services only expose a single port or label ports with the protocols they support, in these cases it is not required to explicitly select the port.	No
`sourceLabels`	`map<string, string>`	One or more labels that constrain the applicability of a rule to workloads with the given labels. If the VirtualService has a list of gateways specified in the top-level `gateways` field, it should include the reserved gateway `mesh` in order for this field to be applicable.	No
`gateways`	`string[]`	Names of gateways where the rule should be applied. Gateway names in the top-level `gateways` field of the VirtualService (if any) are overridden. The gateway match is independent of sourceLabels.	No
`sourceNamespace`	`string`	Source namespace constraining the applicability of a rule to workloads in that namespace. If the VirtualService has a list of gateways specified in the top-level `gateways` field, it must include the reserved gateway `mesh` for this field to be applicable.	No

TLSMatchAttributes

TLS connection match attributes.

Field	Type	Description	Required
`sniHosts`	`string[]`	SNI (server name indicator) to match on. Wildcard prefixes can be used in the SNI value, e.g., *.com will match foo.example.com as well as example.com. An SNI value must be a subset (i.e., fall within the domain) of the corresponding virtual service’s hosts.	Yes
`destinationSubnets`	`string[]`	IPv4 or IPv6 ip addresses of destination with optional subnet. E.g., a.b.c.d/xx form or just a.b.c.d.	No
`port`	`uint32`	Specifies the port on the host that is being addressed. Many services only expose a single port or label ports with the protocols they support, in these cases it is not required to explicitly select the port.	No
`sourceLabels`	`map<string, string>`	One or more labels that constrain the applicability of a rule to workloads with the given labels. If the VirtualService has a list of gateways specified in the top-level `gateways` field, it should include the reserved gateway `mesh` in order for this field to be applicable.	No
`gateways`	`string[]`	Names of gateways where the rule should be applied. Gateway names in the top-level `gateways` field of the VirtualService (if any) are overridden. The gateway match is independent of sourceLabels.	No
`sourceNamespace`	`string`	Source namespace constraining the applicability of a rule to workloads in that namespace. If the VirtualService has a list of gateways specified in the top-level `gateways` field, it must include the reserved gateway `mesh` for this field to be applicable.	No

HTTPRedirect

HTTPRedirect can be used to send a 301 redirect response to the caller, where the Authority/Host and the URI in the response can be swapped with the specified values. For example, the following rule redirects requests for /v1/getProductRatings API on the ratings service to /v1/bookRatings provided by the bookratings service.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - match:
    - uri:
        exact: /v1/getProductRatings
    redirect:
      uri: /v1/bookRatings
      authority: newratings.default.svc.cluster.local
  ...

Field	Type	Description	Required
`uri`	`string`	On a redirect, overwrite the Path portion of the URL with this value. Note that the entire path will be replaced, irrespective of the request URI being matched as an exact path or prefix.	No
`authority`	`string`	On a redirect, overwrite the Authority/Host portion of the URL with this value.	No
`port`	`uint32 (oneof)`	On a redirect, overwrite the port portion of the URL with this value.	No
`derivePort`	`RedirectPortSelection (oneof)`	On a redirect, dynamically set the port: FROM_PROTOCOL_DEFAULT: automatically set to 80 for HTTP and 443 for HTTPS. FROM_REQUEST_PORT: automatically use the port of the request.	No
`scheme`	`string`	On a redirect, overwrite the scheme portion of the URL with this value. For example, `http` or `https`. If unset, the original scheme will be used. If `derivePort` is set to `FROM_PROTOCOL_DEFAULT`, this will impact the port used as well	No
`redirectCode`	`uint32`	On a redirect, Specifies the HTTP status code to use in the redirect response. The default response code is MOVED_PERMANENTLY (301).	No

HTTPDirectResponse

HTTPDirectResponse can be used to send a fixed response to clients. For example, the following rule returns a fixed 503 status with a body to requests for /v1/getProductRatings API.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - match:
    - uri:
        exact: /v1/getProductRatings
    directResponse:
      status: 503
      body:
        string: "unknown error"
  ...

It is also possible to specify a binary response body. This is mostly useful for non text-based protocols such as gRPC.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - match:
    - uri:
        exact: /v1/getProductRatings
    directResponse:
      status: 503
      body:
        bytes: "dW5rbm93biBlcnJvcg==" # "unknown error" in base64
  ...

It is good practice to add headers in the HTTPRoute as well as the direct_response, for example to specify the returned Content-Type.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - match:
    - uri:
        exact: /v1/getProductRatings
    directResponse:
      status: 503
      body:
        string: "{\"error\": \"unknown error\"}"
    headers:
      response:
        set:
          content-type: "text/plain"
  ...

Field	Type	Description	Required
`status`	`uint32`	Specifies the HTTP response status to be returned.	Yes
`body`	`HTTPBody`	Specifies the content of the response body. If this setting is omitted, no body is included in the generated response.	No

HTTPBody

Field	Type	Description	Required
`string`	`string (oneof)`	response body as a string	No
`bytes`	`bytes (oneof)`	response body as base64 encoded bytes.	No

HTTPRewrite

HTTPRewrite can be used to rewrite specific parts of a HTTP request before forwarding the request to the destination. Rewrite primitive can be used only with HTTPRouteDestination. The following example demonstrates how to rewrite the URL prefix for api call (/ratings) to ratings service before making the actual API call.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - match:
    - uri:
        prefix: /ratings
    rewrite:
      uri: /v1/bookRatings
    route:
    - destination:
        host: ratings.prod.svc.cluster.local
        subset: v1

Field	Type	Description	Required
`uri`	`string`	rewrite the path (or the prefix) portion of the URI with this value. If the original URI was matched based on prefix, the value provided in this field will replace the corresponding matched prefix.	No
`authority`	`string`	rewrite the Authority/Host header with this value.	No
`uriRegexRewrite`	`RegexRewrite`	rewrite the path portion of the URI with the specified regex.	No

RegexRewrite

Field Type Description Required

Field	Type	Description	Required
`match`	`string`	RE2 style regex-based match.	No
`rewrite`	`string`	The string that should replace into matching portions of original URI. Capture groups in the pattern can be referenced in the new URI. Examples: Example 1: rewrite with capture groups Path pattern “/service/update/v1/api” with match “^/service/([^/]+)(/.*)$” and rewrite string of “/customprefix/\2/\1” would transform into “/customprefix/v1/api/update”. Example 2: case insensitive rewrite Path pattern “/aaa/XxX/bbb” with match “(?i)/xxx/” and a rewrite string of /yyy/ would do a case-insensitive match and transform the path to “/aaa/yyy/bbb”.	No

match

string

RE2 style regex-based match.

rewrite

string

The string that should replace into matching portions of original URI. Capture groups in the pattern can be referenced in the new URI. Examples:

Example 1: rewrite with capture groups Path pattern “/service/update/v1/api” with match “^/service/([^/]+)(/.*)$” and rewrite string of “/customprefix/\2/\1” would transform into “/customprefix/v1/api/update”.

Example 2: case insensitive rewrite Path pattern “/aaa/XxX/bbb” with match “(?i)/xxx/” and a rewrite string of /yyy/ would do a case-insensitive match and transform the path to “/aaa/yyy/bbb”.

StringMatch

Describes how to match a given string in HTTP headers. exact and prefix matching is case-sensitive. regex matching supports case-insensitive matches.

Field Type Description Required

Field	Type	Description	Required
`exact`	`string (oneof)`	exact string match	No
`prefix`	`string (oneof)`	prefix-based match	No
`regex`	`string (oneof)`	RE2 style regex-based match. Example: `(?i)^aaa$` can be used to case-insensitive match a string consisting of three a’s.	No

exact

string (oneof)

exact string match

prefix

string (oneof)

prefix-based match

regex

string (oneof)

RE2 style regex-based match.

Example: (?i)^aaa$ can be used to case-insensitive match a string consisting of three a’s.

HTTPRetry

Describes the retry policy to use when a HTTP request fails. For example, the following rule sets the maximum number of retries to 3 when calling ratings:v1 service, with a 2s timeout per retry attempt. A retry will be attempted if there is a connect-failure, refused_stream or when the upstream server responds with Service Unavailable(503).

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - route:
    - destination:
        host: ratings.prod.svc.cluster.local
        subset: v1
    retries:
      attempts: 3
      perTryTimeout: 2s
      retryOn: gateway-error,connect-failure,refused-stream

Field	Type	Description	Required
`attempts`	`int32`	Number of retries to be allowed for a given request. The interval between retries will be determined automatically (25ms+). When request `timeout` of the HTTP route or `per_try_timeout` is configured, the actual number of retries attempted also depends on the specified request `timeout` and `per_try_timeout` values. MUST BE >= 0. If `0`, retries will be disabled. The maximum possible number of requests made will be 1 + `attempts`.	No
`perTryTimeout`	`Duration`	Timeout per attempt for a given request, including the initial call and any retries. Format: 1h/1m/1s/1ms. MUST BE >=1ms. Default is same value as request `timeout` of the HTTP route, which means no timeout.	No
`retryOn`	`string`	Specifies the conditions under which retry takes place. One or more policies can be specified using a ‘,’ delimited list. See the retry policies and gRPC retry policies for more details. In addition to the policies specified above, a list of HTTP status codes can be passed, such as `retryOn: "503,reset"`. Note these status codes refer to the actual responses received from the destination. For example, if a connection is reset, Istio will translate this to 503 for it’s response. However, the destination did not return a 503 error, so this would not match `"503"` (it would, however, match `"reset"`). If not specified, this defaults to `connect-failure,refused-stream,unavailable,cancelled,503`.	No
`retryRemoteLocalities`	`BoolValue`	Flag to specify whether the retries should retry to other localities. See the retry plugin configuration for more details.	No

CorsPolicy

Describes the Cross-Origin Resource Sharing (CORS) policy, for a given service. Refer to CORS for further details about cross origin resource sharing. For example, the following rule restricts cross origin requests to those originating from example.com domain using HTTP POST/GET, and sets the Access-Control-Allow-Credentials header to false. In addition, it only exposes X-Foo-bar header and sets an expiry period of 1 day.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - route:
    - destination:
        host: ratings.prod.svc.cluster.local
        subset: v1
    corsPolicy:
      allowOrigins:
      - exact: https://example.com
      allowMethods:
      - POST
      - GET
      allowCredentials: false
      allowHeaders:
      - X-Foo-Bar
      maxAge: "24h"

Field	Type	Description	Required
`allowOrigins`	`StringMatch[]`	String patterns that match allowed origins. An origin is allowed if any of the string matchers match. If a match is found, then the outgoing Access-Control-Allow-Origin would be set to the origin as provided by the client.	No
`allowMethods`	`string[]`	List of HTTP methods allowed to access the resource. The content will be serialized into the Access-Control-Allow-Methods header.	No
`allowHeaders`	`string[]`	List of HTTP headers that can be used when requesting the resource. Serialized to Access-Control-Allow-Headers header.	No
`exposeHeaders`	`string[]`	A list of HTTP headers that the browsers are allowed to access. Serialized into Access-Control-Expose-Headers header.	No
`maxAge`	`Duration`	Specifies how long the results of a preflight request can be cached. Translates to the `Access-Control-Max-Age` header.	No
`allowCredentials`	`BoolValue`	Indicates whether the caller is allowed to send the actual request (not the preflight) using credentials. Translates to `Access-Control-Allow-Credentials` header.	No
`unmatchedPreflights`	`UnmatchedPreflights`	Indicates whether preflight requests not matching the configured allowed origin shouldn’t be forwarded to the upstream. Default is forward to upstream.	No

HTTPFaultInjection

HTTPFaultInjection can be used to specify one or more faults to inject while forwarding HTTP requests to the destination specified in a route. Fault specification is part of a VirtualService rule. Faults include aborting the Http request from downstream service, and/or delaying proxying of requests. A fault rule MUST HAVE delay or abort or both.

Note: Delay and abort faults are independent of one another, even if both are specified simultaneously.

Field	Type	Description	Required
`delay`	`Delay`	Delay requests before forwarding, emulating various failures such as network issues, overloaded upstream service, etc.	No
`abort`	`Abort`	Abort Http request attempts and return error codes back to downstream service, giving the impression that the upstream service is faulty.	No

HTTPMirrorPolicy

HTTPMirrorPolicy can be used to specify the destinations to mirror HTTP traffic in addition to the original destination. Mirrored traffic is on a best effort basis where the sidecar/gateway will not wait for the mirrored destinations to respond before returning the response from the original destination. Statistics will be generated for the mirrored destination.

Field	Type	Description	Required
`destination`	`Destination`	Destination specifies the target of the mirror operation.	Yes
`percentage`	`Percent`	Percentage of the traffic to be mirrored by the `destination` field. If this field is absent, all the traffic (100%) will be mirrored. Max value is 100.	No

PortSelector

PortSelector specifies the number of a port to be used for matching or selection for final routing.

Field	Type	Description	Required
`number`	`uint32`	Valid port number	No

Percent

Percent specifies a percentage in the range of [0.0, 100.0].

Field	Type	Description	Required
`value`	`double`		No

Headers.HeaderOperations

HeaderOperations Describes the header manipulations to apply

Field	Type	Description	Required
`set`	`map<string, string>`	Overwrite the headers specified by key with the given values	No
`add`	`map<string, string>`	Append the given values to the headers specified by keys (will create a comma-separated list of values)	No
`remove`	`string[]`	Remove the specified headers	No

HTTPFaultInjection.Delay

Delay specification is used to inject latency into the request forwarding path. The following example will introduce a 5 second delay in 1 out of every 1000 requests to the “v1” version of the “reviews” service from all pods with label env: prod

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: reviews-route
spec:
  hosts:
  - reviews.prod.svc.cluster.local
  http:
  - match:
    - sourceLabels:
        env: prod
    route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v1
    fault:
      delay:
        percentage:
          value: 0.1
        fixedDelay: 5s

The fixedDelay field is used to indicate the amount of delay in seconds. The optional percentage field can be used to only delay a certain percentage of requests. If left unspecified, no request will be delayed.

Field	Type	Description	Required
`fixedDelay`	`Duration (oneof)`	Add a fixed delay before forwarding the request. Format: 1h/1m/1s/1ms. MUST be >=1ms.	No
`percentage`	`Percent`	Percentage of requests on which the delay will be injected. If left unspecified, no request will be delayed.	No
`percent`	`int32`	Percentage of requests on which the delay will be injected (0-100). Use of integer `percent` value is deprecated. Use the double `percentage` field instead.	No

HTTPFaultInjection.Abort

Abort specification is used to prematurely abort a request with a pre-specified error code. The following example will return an HTTP 400 error code for 1 out of every 1000 requests to the “ratings” service “v1”.

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: ratings-route
spec:
  hosts:
  - ratings.prod.svc.cluster.local
  http:
  - route:
    - destination:
        host: ratings.prod.svc.cluster.local
        subset: v1
    fault:
      abort:
        percentage:
          value: 0.1
        httpStatus: 400

The httpStatus field is used to indicate the HTTP status code to return to the caller. The optional percentage field can be used to only abort a certain percentage of requests. If not specified, no request will be aborted.

Field	Type	Description	Required
`httpStatus`	`int32 (oneof)`	HTTP status code to use to abort the Http request.	No
`grpcStatus`	`string (oneof)`	GRPC status code to use to abort the request. The supported codes are documented in https://github.com/grpc/grpc/blob/master/doc/statuscodes.md Note: If you want to return the status “Unavailable”, then you should specify the code as `UNAVAILABLE`(all caps), but not `14`.	No
`percentage`	`Percent`	Percentage of requests to be aborted with the error code provided. If not specified, no request will be aborted.	No

google.protobuf.UInt32Value

Wrapper message for uint32.

The JSON representation for UInt32Value is JSON number.

Field	Type	Description	Required
`value`	`uint32`	The uint32 value.	No

HTTPRedirect.RedirectPortSelection

Name	Description
`FROM_PROTOCOL_DEFAULT`
`FROM_REQUEST_PORT`

CorsPolicy.UnmatchedPreflights

Name	Description
`UNSPECIFIED`	Default to FORWARD
`FORWARD`	Preflight requests not matching the configured allowed origin will be forwarded to the upstream.
`IGNORE`	Preflight requests not matching the configured allowed origin will not be forwarded to the upstream.