Egress Gateways with TLS Origination (SDS)

The TLS Origination for Egress Traffic example shows how to configure Istio to perform TLS origination for traffic to an external service. The Configure an Egress Gateway example shows how to configure Istio to direct egress traffic through a dedicated egress gateway service. This example combines the previous two by describing how to configure an egress gateway to perform TLS origination for traffic to external services.

The TLS required private key, server certificate, and root certificate, are configured using the Secret Discovery Service (SDS).

Before you begin

  • Setup Istio by following the instructions in the Installation guide.

  • Start the sleep sample which will be used as a test source for external calls.

    If you have enabled automatic sidecar injection, do

    Zip
    $ kubectl apply -f @samples/sleep/sleep.yaml@
    

    otherwise, you have to manually inject the sidecar before deploying the sleep application:

    Zip
    $ kubectl apply -f <(istioctl kube-inject -f @samples/sleep/sleep.yaml@)
    

    Note that any pod that you can exec and curl from would do.

  • For macOS users, verify that you are using openssl version 1.1 or later:

    $ openssl version -a | grep OpenSSL
    OpenSSL 1.1.1g  21 Apr 2020
    

    If the previous command outputs a version 1.1 or later, as shown, your openssl command should work correctly with the instructions in this task. Otherwise, upgrade your openssl or try a different implementation of openssl, for example on a Linux machine.

  • Deploy an Istio egress gateway.

  • Enable Envoy’s access logging.

Perform TLS origination with an egress gateway using SDS

This section describes how to perform the same TLS origination as in the TLS Origination for Egress Traffic example, only this time using an egress gateway. Note that in this case the TLS origination will be done by the egress gateway, as opposed to by the sidecar in the previous example. The egress gateway will use SDS instead of the file-mount to provision client certificates.

Generate CA and server certificates and keys

For this task you can use your favorite tool to generate certificates and keys. The commands below use openssl.

  1. Create a root certificate and private key to sign the certificate for your services:

    $ openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -subj '/O=example Inc./CN=example.com' -keyout example.com.key -out example.com.crt
    
  2. Create a certificate and a private key for my-nginx.mesh-external.svc.cluster.local:

    $ openssl req -out my-nginx.mesh-external.svc.cluster.local.csr -newkey rsa:2048 -nodes -keyout my-nginx.mesh-external.svc.cluster.local.key -subj "/CN=my-nginx.mesh-external.svc.cluster.local/O=some organization"
    $ openssl x509 -req -days 365 -CA example.com.crt -CAkey example.com.key -set_serial 0 -in my-nginx.mesh-external.svc.cluster.local.csr -out my-nginx.mesh-external.svc.cluster.local.crt
    

Deploy a simple TLS server

To simulate an actual external service that supports the simple TLS protocol, deploy an NGINX server in your Kubernetes cluster, but running outside of the Istio service mesh, i.e., in a namespace without Istio sidecar proxy injection enabled.

  1. Create a namespace to represent services outside the Istio mesh, namely mesh-external. Note that the sidecar proxy will not be automatically injected into the pods in this namespace since the automatic sidecar injection was not enabled on it.

    $ kubectl create namespace mesh-external
    
  2. Create Kubernetes Secrets to hold the server’s and CA certificates.

    $ kubectl create -n mesh-external secret tls nginx-server-certs --key my-nginx.mesh-external.svc.cluster.local.key --cert my-nginx.mesh-external.svc.cluster.local.crt
    $ kubectl create -n mesh-external secret generic nginx-ca-certs --from-file=example.com.crt
    
  3. Create a configuration file for the NGINX server:

    $ cat <<\EOF > ./nginx.conf
    events {
    }
    
    http {
      log_format main '$remote_addr - $remote_user [$time_local]  $status '
      '"$request" $body_bytes_sent "$http_referer" '
      '"$http_user_agent" "$http_x_forwarded_for"';
      access_log /var/log/nginx/access.log main;
      error_log  /var/log/nginx/error.log;
    
      server {
        listen 443 ssl;
    
        root /usr/share/nginx/html;
        index index.html;
    
        server_name my-nginx.mesh-external.svc.cluster.local;
        ssl_certificate /etc/nginx-server-certs/tls.crt;
        ssl_certificate_key /etc/nginx-server-certs/tls.key;
        ssl_client_certificate /etc/nginx-ca-certs/example.com.crt;
        ssl_verify_client off; # In simple TLS, server doesn't verify client's certificate
      }
    }
    EOF
    
  4. Create a Kubernetes ConfigMap to hold the configuration of the NGINX server:

    $ kubectl create configmap nginx-configmap -n mesh-external --from-file=nginx.conf=./nginx.conf
    
  5. Deploy the NGINX server:

    $ kubectl apply -f - <<EOF
    apiVersion: v1
    kind: Service
    metadata:
      name: my-nginx
      namespace: mesh-external
      labels:
        run: my-nginx
    spec:
      ports:
      - port: 443
        protocol: TCP
      selector:
        run: my-nginx
    ---
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: my-nginx
      namespace: mesh-external
    spec:
      selector:
        matchLabels:
          run: my-nginx
      replicas: 1
      template:
        metadata:
          labels:
            run: my-nginx
        spec:
          containers:
          - name: my-nginx
            image: nginx
            ports:
            - containerPort: 443
            volumeMounts:
            - name: nginx-config
              mountPath: /etc/nginx
              readOnly: true
            - name: nginx-server-certs
              mountPath: /etc/nginx-server-certs
              readOnly: true
            - name: nginx-ca-certs
              mountPath: /etc/nginx-ca-certs
              readOnly: true
          volumes:
          - name: nginx-config
            configMap:
              name: nginx-configmap
          - name: nginx-server-certs
            secret:
              secretName: nginx-server-certs
          - name: nginx-ca-certs
            secret:
              secretName: nginx-ca-certs
    EOF
    

Configure simple TLS origination for egress traffic

  1. Create a Kubernetes Secret to hold the CA certificate used by egress gateway to originate TLS connections:

    $ kubectl create secret generic client-credential-cacert --from-file=ca.crt=example.com.crt -n istio-system
    

    Note that the secret name for an Istio CA-only certificate must end with -cacert and the secret must be created in the same namespace as Istio is deployed in, istio-system in this case.

  2. Create an egress Gateway for my-nginx.mesh-external.svc.cluster.local, port 443, and destination rules and virtual services to direct the traffic through the egress gateway and from the egress gateway to the external service.

    $ kubectl apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: istio-egressgateway
    spec:
      selector:
        istio: egressgateway
      servers:
      - port:
          number: 443
          name: https
          protocol: HTTPS
        hosts:
        - my-nginx.mesh-external.svc.cluster.local
        tls:
          mode: ISTIO_MUTUAL
    ---
    apiVersion: networking.istio.io/v1alpha3
    kind: DestinationRule
    metadata:
      name: egressgateway-for-nginx
    spec:
      host: istio-egressgateway.istio-system.svc.cluster.local
      subsets:
      - name: nginx
        trafficPolicy:
          loadBalancer:
            simple: ROUND_ROBIN
          portLevelSettings:
          - port:
              number: 443
            tls:
              mode: ISTIO_MUTUAL
              sni: my-nginx.mesh-external.svc.cluster.local
    EOF
    
  3. Define a VirtualService to direct the traffic through the egress gateway:

    $ kubectl apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: VirtualService
    metadata:
      name: direct-nginx-through-egress-gateway
    spec:
      hosts:
      - my-nginx.mesh-external.svc.cluster.local
      gateways:
      - istio-egressgateway
      - mesh
      http:
      - match:
        - gateways:
          - mesh
          port: 80
        route:
        - destination:
            host: istio-egressgateway.istio-system.svc.cluster.local
            subset: nginx
            port:
              number: 443
          weight: 100
      - match:
        - gateways:
          - istio-egressgateway
          port: 443
        route:
        - destination:
            host: my-nginx.mesh-external.svc.cluster.local
            port:
              number: 443
          weight: 100
    EOF
    
  4. Add a DestinationRule to perform simple TLS origination

    $ kubectl apply -n istio-system -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: DestinationRule
    metadata:
      name: originate-tls-for-nginx
    spec:
      host: my-nginx.mesh-external.svc.cluster.local
      trafficPolicy:
        loadBalancer:
          simple: ROUND_ROBIN
        portLevelSettings:
        - port:
            number: 443
          tls:
            mode: SIMPLE
            credentialName: client-credential # this must match the secret created earlier without the "-cacert" suffix
            sni: my-nginx.mesh-external.svc.cluster.local
    EOF
    
  5. Send an HTTP request to http://my-nginx.mesh-external.svc.cluster.local:

    $ kubectl exec "$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})" -c sleep -- curl -s http://my-nginx.mesh-external.svc.cluster.local
    <!DOCTYPE html>
    <html>
    <head>
    <title>Welcome to nginx!</title>
    ...
    
  6. Check the log of the istio-egressgateway pod for a line corresponding to our request. If Istio is deployed in the istio-system namespace, the command to print the log is:

    $ kubectl logs -l istio=egressgateway -n istio-system | grep 'my-nginx.mesh-external.svc.cluster.local' | grep HTTP
    

    You should see a line similar to the following:

    [2018-08-19T18:20:40.096Z] "GET / HTTP/1.1" 200 - 0 612 7 5 "172.30.146.114" "curl/7.35.0" "b942b587-fac2-9756-8ec6-303561356204" "my-nginx.mesh-external.svc.cluster.local" "172.21.72.197:443"
    

Cleanup the TLS origination example

  1. Remove the Istio configuration items you created:

    $ kubectl delete destinationrule originate-tls-for-nginx
    $ kubectl delete virtualservice direct-nginx-through-egress-gateway
    $ kubectl delete destinationrule egressgateway-for-nginx
    $ kubectl delete gateway istio-egressgateway
    $ kubectl delete secret client-credential-cacert -n istio-system
    $ kubectl delete service my-nginx -n mesh-external
    $ kubectl delete deployment my-nginx -n mesh-external
    $ kubectl delete configmap nginx-configmap -n mesh-external
    $ kubectl delete secret nginx-server-certs nginx-ca-certs -n mesh-external
    $ kubectl delete namespace mesh-external
    
  2. Delete the certificates and private keys:

    $ rm example.com.crt example.com.key my-nginx.mesh-external.svc.cluster.local.crt my-nginx.mesh-external.svc.cluster.local.key my-nginx.mesh-external.svc.cluster.local.csr
    
  3. Delete the generated configuration files used in this example:

    $ rm ./nginx.conf
    

Perform mutual TLS origination with an egress gateway

Similar to the previous section, this section describes how to configure an egress gateway to perform TLS origination for an external service, only this time using a service that requires mutual TLS.

Egress Gateway will use SDS instead of the file-mount to provision client certificates.

Generate client and server certificates and keys

For this task you can use your favorite tool to generate certificates and keys. The commands below use openssl.

  1. Create a root certificate and private key to sign the certificate for your services:

    $ openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -subj '/O=example Inc./CN=example.com' -keyout example.com.key -out example.com.crt
    
  2. Create a certificate and a private key for my-nginx.mesh-external.svc.cluster.local:

    $ openssl req -out my-nginx.mesh-external.svc.cluster.local.csr -newkey rsa:2048 -nodes -keyout my-nginx.mesh-external.svc.cluster.local.key -subj "/CN=my-nginx.mesh-external.svc.cluster.local/O=some organization"
    $ openssl x509 -req -days 365 -CA example.com.crt -CAkey example.com.key -set_serial 0 -in my-nginx.mesh-external.svc.cluster.local.csr -out my-nginx.mesh-external.svc.cluster.local.crt
    
  3. Generate client certificate and private key:

    $ openssl req -out client.example.com.csr -newkey rsa:2048 -nodes -keyout client.example.com.key -subj "/CN=client.example.com/O=client organization"
    $ openssl x509 -req -days 365 -CA example.com.crt -CAkey example.com.key -set_serial 1 -in client.example.com.csr -out client.example.com.crt
    

Deploy a mutual TLS server

To simulate an actual external service that supports the mutual TLS protocol, deploy an NGINX server in your Kubernetes cluster, but running outside of the Istio service mesh, i.e., in a namespace without Istio sidecar proxy injection enabled.

  1. Create a namespace to represent services outside the Istio mesh, namely mesh-external. Note that the sidecar proxy will not be automatically injected into the pods in this namespace since the automatic sidecar injection was not enabled on it.

    $ kubectl create namespace mesh-external
    
  2. Create Kubernetes Secrets to hold the server’s certificates.

    $ kubectl create -n mesh-external secret tls nginx-server-certs --key my-nginx.mesh-external.svc.cluster.local.key --cert my-nginx.mesh-external.svc.cluster.local.crt
    $ kubectl create -n mesh-external secret generic nginx-ca-certs --from-file=example.com.crt
    
  3. Create a configuration file for the NGINX server:

    $ cat <<\EOF > ./nginx.conf
    events {
    }
    
    http {
      log_format main '$remote_addr - $remote_user [$time_local]  $status '
      '"$request" $body_bytes_sent "$http_referer" '
      '"$http_user_agent" "$http_x_forwarded_for"';
      access_log /var/log/nginx/access.log main;
      error_log  /var/log/nginx/error.log;
    
      server {
        listen 443 ssl;
    
        root /usr/share/nginx/html;
        index index.html;
    
        server_name my-nginx.mesh-external.svc.cluster.local;
        ssl_certificate /etc/nginx-server-certs/tls.crt;
        ssl_certificate_key /etc/nginx-server-certs/tls.key;
        ssl_client_certificate /etc/nginx-ca-certs/example.com.crt;
        ssl_verify_client on; # In mutual TLS, server verifies client's certificate
      }
    }
    EOF
    
  4. Create a Kubernetes ConfigMap to hold the configuration of the NGINX server:

    $ kubectl create configmap nginx-configmap -n mesh-external --from-file=nginx.conf=./nginx.conf
    
  5. Deploy the NGINX server:

    $ kubectl apply -f - <<EOF
    apiVersion: v1
    kind: Service
    metadata:
      name: my-nginx
      namespace: mesh-external
      labels:
        run: my-nginx
    spec:
      ports:
      - port: 443
        protocol: TCP
      selector:
        run: my-nginx
    ---
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: my-nginx
      namespace: mesh-external
    spec:
      selector:
        matchLabels:
          run: my-nginx
      replicas: 1
      template:
        metadata:
          labels:
            run: my-nginx
        spec:
          containers:
          - name: my-nginx
            image: nginx
            ports:
            - containerPort: 443
            volumeMounts:
            - name: nginx-config
              mountPath: /etc/nginx
              readOnly: true
            - name: nginx-server-certs
              mountPath: /etc/nginx-server-certs
              readOnly: true
            - name: nginx-ca-certs
              mountPath: /etc/nginx-ca-certs
              readOnly: true
          volumes:
          - name: nginx-config
            configMap:
              name: nginx-configmap
          - name: nginx-server-certs
            secret:
              secretName: nginx-server-certs
          - name: nginx-ca-certs
            secret:
              secretName: nginx-ca-certs
    EOF
    

Configure mutual TLS origination for egress traffic using SDS

  1. Create Kubernetes Secrets to hold the client’s certificates:

    $ kubectl create secret -n istio-system generic client-credential --from-file=tls.key=client.example.com.key \
      --from-file=tls.crt=client.example.com.crt --from-file=ca.crt=example.com.crt
    

    The secret must be created in the same namespace as Istio is deployed in, istio-system in this case.

    To support integration with various tools, Istio supports a few different Secret formats.

    In this example. a single generic Secret with keys tls.key, tls.crt, and ca.crt is used.

  2. Create an egress Gateway for my-nginx.mesh-external.svc.cluster.local, port 443, and destination rules and virtual services to direct the traffic through the egress gateway and from the egress gateway to the external service.

    $ kubectl apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: Gateway
    metadata:
      name: istio-egressgateway
    spec:
      selector:
        istio: egressgateway
      servers:
      - port:
          number: 443
          name: https
          protocol: HTTPS
        hosts:
        - my-nginx.mesh-external.svc.cluster.local
        tls:
          mode: ISTIO_MUTUAL
    ---
    apiVersion: networking.istio.io/v1alpha3
    kind: DestinationRule
    metadata:
      name: egressgateway-for-nginx
    spec:
      host: istio-egressgateway.istio-system.svc.cluster.local
      subsets:
      - name: nginx
        trafficPolicy:
          loadBalancer:
            simple: ROUND_ROBIN
          portLevelSettings:
          - port:
              number: 443
            tls:
              mode: ISTIO_MUTUAL
              sni: my-nginx.mesh-external.svc.cluster.local
    EOF
    
  3. Define a VirtualService to direct the traffic through the egress gateway:

    $ kubectl apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: VirtualService
    metadata:
      name: direct-nginx-through-egress-gateway
    spec:
      hosts:
      - my-nginx.mesh-external.svc.cluster.local
      gateways:
      - istio-egressgateway
      - mesh
      http:
      - match:
        - gateways:
          - mesh
          port: 80
        route:
        - destination:
            host: istio-egressgateway.istio-system.svc.cluster.local
            subset: nginx
            port:
              number: 443
          weight: 100
      - match:
        - gateways:
          - istio-egressgateway
          port: 443
        route:
        - destination:
            host: my-nginx.mesh-external.svc.cluster.local
            port:
              number: 443
          weight: 100
    EOF
    
  4. Add a DestinationRule to perform mutual TLS origination

    $ kubectl apply -n istio-system -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: DestinationRule
    metadata:
      name: originate-mtls-for-nginx
    spec:
      host: my-nginx.mesh-external.svc.cluster.local
      trafficPolicy:
        loadBalancer:
          simple: ROUND_ROBIN
        portLevelSettings:
        - port:
            number: 443
          tls:
            mode: MUTUAL
            credentialName: client-credential # this must match the secret created earlier to hold client certs
            sni: my-nginx.mesh-external.svc.cluster.local
    EOF
    
  5. Send an HTTP request to http://my-nginx.mesh-external.svc.cluster.local:

    $ kubectl exec "$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})" -c sleep -- curl -s http://my-nginx.mesh-external.svc.cluster.local
    <!DOCTYPE html>
    <html>
    <head>
    <title>Welcome to nginx!</title>
    ...
    
  6. Check the log of the istio-egressgateway pod for a line corresponding to our request. If Istio is deployed in the istio-system namespace, the command to print the log is:

    $ kubectl logs -l istio=egressgateway -n istio-system | grep 'my-nginx.mesh-external.svc.cluster.local' | grep HTTP
    

    You should see a line similar to the following:

    [2018-08-19T18:20:40.096Z] "GET / HTTP/1.1" 200 - 0 612 7 5 "172.30.146.114" "curl/7.35.0" "b942b587-fac2-9756-8ec6-303561356204" "my-nginx.mesh-external.svc.cluster.local" "172.21.72.197:443"
    

Cleanup the mutual TLS origination example

  1. Remove created Kubernetes resources:

    $ kubectl delete secret nginx-server-certs nginx-ca-certs -n mesh-external
    $ kubectl delete secret client-credential -n istio-system
    $ kubectl delete configmap nginx-configmap -n mesh-external
    $ kubectl delete service my-nginx -n mesh-external
    $ kubectl delete deployment my-nginx -n mesh-external
    $ kubectl delete namespace mesh-external
    $ kubectl delete gateway istio-egressgateway
    $ kubectl delete virtualservice direct-nginx-through-egress-gateway
    $ kubectl delete destinationrule -n istio-system originate-mtls-for-nginx
    $ kubectl delete destinationrule egressgateway-for-nginx
    
  2. Delete the certificates and private keys:

    $ rm example.com.crt example.com.key my-nginx.mesh-external.svc.cluster.local.crt my-nginx.mesh-external.svc.cluster.local.key my-nginx.mesh-external.svc.cluster.local.csr client.example.com.crt client.example.com.csr client.example.com.key
    
  3. Delete the generated configuration files used in this example:

    $ rm ./nginx.conf
    $ rm ./gateway-patch.json
    

Cleanup

Delete the sleep service and deployment:

$ kubectl delete service sleep
$ kubectl delete deployment sleep
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