Upgrade Steps

Follow this flow to upgrade an existing Istio deployment, including both the control plane and the sidecar proxies, to a new release of Istio. The upgrade process may install new binaries and may change configuration and API schemas. The upgrade process may result in service downtime. To minimize downtime, please ensure your Istio control plane components and your applications are highly available with multiple replicas.

This flow assumes that the Istio components are installed and upgraded in the istio-system namespace.

Upgrade steps

Download the new Istio release and change directory to the new release directory.

Control plane upgrade

The Istio control plane components include: Citadel, Ingress gateway, Egress gateway, Pilot, Galley, Policy, Telemetry and Sidecar injector. Choose one of the following two mutually exclusive options to update the control plane:

You can use Kubernetes’ rolling update mechanism to upgrade the control plane components. This is suitable for cases where kubectl apply was used to deploy the Istio components, including configurations generated using helm template.

  1. Use kubectl apply to upgrade all the Istio’s CRDs. Wait a few seconds for the Kubernetes API server to receive the upgraded CRDs:

    $ for i in install/kubernetes/helm/istio-init/files/crd*yaml; do kubectl apply -f $i; done
    
  2. Add Istio’s core components to a Kubernetes manifest file, for example.

    $ helm template install/kubernetes/helm/istio --name istio \
    --namespace istio-system > $HOME/istio.yaml
    

    If you want to enable global mutual TLS, set global.mtls.enabled and global.controlPlaneSecurityEnabled to true for the last command:

    $ helm template install/kubernetes/helm/istio --name istio --namespace istio-system \
    --set global.mtls.enabled=true --set global.controlPlaneSecurityEnabled=true > $HOME/istio-auth.yaml
    

    If using Kubernetes versions prior to 1.9, you should add --set sidecarInjectorWebhook.enabled=false.

  3. Upgrade the Istio control plane components via the manifest, for example:

    $ kubectl apply -f $HOME/istio.yaml
    

    or

    $ kubectl apply -f $HOME/istio-auth.yaml
    

The rolling update process will upgrade all deployments and configmaps to the new version. After this process finishes, your Istio control plane should be updated to the new version. Your existing application should continue to work without any change. If there is any critical issue with the new control plane, you can rollback the changes by applying the yaml files from the old version.

Sidecar upgrade

After the control plane upgrade, the applications already running Istio will still be using an older sidecar. To upgrade the sidecar, you will need to re-inject it.

If you’re using automatic sidecar injection, you can upgrade the sidecar by doing a rolling update for all the pods, so that the new version of the sidecar will be automatically re-injected. There are some tricks to reload all pods. E.g. There is a sample bash script which triggers the rolling update by patching the grace termination period.

If you’re using manual injection, you can upgrade the sidecar by executing:

$ kubectl apply -f <(istioctl kube-inject -f $ORIGINAL_DEPLOYMENT_YAML)

If the sidecar was previously injected with some customized inject configuration files, you will need to change the version tag in the configuration files to the new version and re-inject the sidecar as follows:

$ kubectl apply -f <(istioctl kube-inject \
     --injectConfigFile inject-config.yaml \
     --filename $ORIGINAL_DEPLOYMENT_YAML)

Migrating per-service mutual TLS enablement via annotations to authentication policy

If you use service annotations to override global mutual TLS enablement for a service, you need to replace it with authentication policy and destination rules.

For example, if you install Istio with mutual TLS enabled, and disable it for service foo using a service annotation like below:

kind: Service
metadata:
  name: foo
  namespace: bar
  annotations:
    auth.istio.io/8000: NONE

You need to replace this with this authentication policy and destination rule (deleting the old annotation is optional)

apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "disable-mTLS-foo"
  namespace: bar
spec:
  targets:
  - name: foo
    ports:
    - number: 8000
  peers:
---
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "disable-mTLS-foo"
  namespace: "bar"
spec:
  host: "foo"
  trafficPolicy:
    tls:
      mode: ISTIO_MUTUAL
    portLevelSettings:
    - port:
        number: 8000
      tls:
        mode: DISABLE

If you already have destination rules for foo, you must edit that rule instead of creating a new one. When create a new destination rule, make sure to include other settings, i.e load balancer, connection pool and outlier detection if necessary. Finally, If foo doesn’t have sidecar, you can skip authentication policy, but still need to add destination rule.

If 8000 is the only port that service foo provides (or you want to disable mutual TLS for all ports), the policies can be simplified as:

apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
  name: "disable-mTLS-foo"
    namespace: bar
  spec:
    targets:
    - name: foo
    peers:
---
apiVersion: "networking.istio.io/v1alpha3"
kind: "DestinationRule"
metadata:
  name: "disable-mTLS-foo"
  namespace: "bar"
spec:
  host: "foo"
trafficPolicy:
  tls:
    mode: DISABLE

Migrating the mtls_excluded_services configuration to destination rules

If you installed Istio with mutual TLS enabled, and used the mesh configuration option mtls_excluded_services to disable mutual TLS when connecting to these services (e.g Kubernetes API server), you need to replace this by adding a destination rule. For example:

apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: "kubernetes-master"
  namespace: "default"
spec:
  host: "kubernetes.default.svc.cluster.local"
  trafficPolicy:
    tls:
      mode: DISABLE

Migrating from RbacConfig to ClusterRbacConfig

The RbacConfig is deprecated due to a bug. You must migrate to ClusterRbacConfig if you are currently using RbacConfig. The bug reduces the scope of the object to be namespace-scoped in some cases. The ClusterRbacConfig follows the exact same specification as the RbacConfig but with the correct cluster scope implementation.

To automate the migration, we developed the convert_RbacConfig_to_ClusterRbacConfig.sh script. The script is included in the Istio installation package.

Download and run the script with the following command:

$ curl -L https://raw.githubusercontent.com/istio/istio/master/tools/convert_RbacConfig_to_ClusterRbacConfig.sh | sh -

The script automates the following operations:

  1. The script creates the cluster RBAC configuration with same specification as the existing RBAC configuration because Kubernetes doesn’t allow the value of kind: in a custom resource to change after it’s created.

    For example, if you have the following RBAC configuration:

    apiVersion: "rbac.istio.io/v1alpha1"
    kind: RbacConfig
    metadata:
      name: default
    spec:
      mode: 'ON_WITH_INCLUSION'
      inclusion:
        namespaces: ["default"]
    

    The script creates the following cluster RBAC configuration:

    apiVersion: "rbac.istio.io/v1alpha1"
    kind: ClusterRbacConfig
    metadata:
      name: default
    spec:
      mode: 'ON_WITH_INCLUSION'
      inclusion:
        namespaces: ["default"]
    
  2. The script applies the configuration and waits for a few seconds to let the configuration to take effect.

  3. The script deletes the previous RBAC configuration custom resource after applying the cluster RBAC configuration successfully.