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Chapter 3. Sidecar injection
To use Istio’s capabilities within a service mesh, each pod needs a sidecar proxy, configured and managed by the Istio control plane.
3.1. About sidecar injection Copiar o linkLink copiado para a área de transferência!
Sidecar injection is enabled using labels at the namespace or pod level. These labels also indicate the specific control plane managing the proxy. When you apply a valid injection label to the pod template defined in a deployment, any new pods created by that deployment automatically receive a sidecar. Similarly, applying a pod injection label at the namespace level ensures any new pods in that namespace include a sidecar.
Injection happens at pod creation through an admission controller, so changes appear on individual pods rather than the deployment resources. To confirm sidecar injection, check the pod details directly using oc describe, where you can see the injected Istio proxy container.
3.2. Identifying the revision name Copiar o linkLink copiado para a área de transferência!
The label required to enable sidecar injection is determined by the specific control plane instance, known as a revision. Each revision is managed by an IstioRevision resource, which is automatically created and managed by the Istio resource, so manual creation or modification of IstioRevision resources is generally unnecessary.
The naming of an IstioRevision depends on the spec.updateStrategy.type setting in the Istio resource. If set to InPlace, the revision shares the Istio resource name. If set to RevisionBased, the revision name follows the format <Istio resource name>-v<version>. Typically, each Istio resource corresponds to a single IstioRevision. However, during a revision-based upgrade, multiple IstioRevision resources may exist, each representing a distinct control plane instance.
To see available revision names, use the following command:
oc get istiorevisions
$ oc get istiorevisions
You should see output similar to the following example:
Example output
NAME READY STATUS IN USE VERSION AGE my-mesh-v1-23-0 True Healthy False v1.23.0 114s
NAME READY STATUS IN USE VERSION AGE
my-mesh-v1-23-0 True Healthy False v1.23.0 114s
3.2.1. Enabling sidecar injection with default revision Copiar o linkLink copiado para a área de transferência!
When the service mesh’s IstioRevision name is default, it’s possible to use the following labels on a namespace or a pod to enable sidecar injection:
| Resource | Label | Enabled value | Disabled value |
|---|---|---|---|
| Namespace |
|
|
|
| Pod |
|
|
|
You can also enable injection by setting the istio.io/rev: default label in the namespace or pod.
3.2.2. Enabling sidecar injection with other revisions Copiar o linkLink copiado para a área de transferência!
When the IstioRevision name is not default, use the specific IstioRevision name with the istio.io/rev label to map the pod to the desired control plane and enable sidecar injection. To enable injection, set the istio.io/rev: default label in either the namespace or the pod, as adding it to both is not required.
For example, with the revision shown above, the following labels would enable sidecar injection:
| Resource | Enabled label | Disabled label |
|---|---|---|
| Namespace |
|
|
| Pod |
|
|
When both istio-injection and istio.io/rev labels are applied, the istio-injection label takes precedence and treats the namespace as part of the default revision.
3.3. Enabling sidecar injection Copiar o linkLink copiado para a área de transferência!
To demonstrate different approaches for configuring sidecar injection, the following procedures use the Bookinfo application.
Prerequisites
-
You have installed the Red Hat OpenShift Service Mesh Operator, created an
Istioresource, and the Operator has deployed Istio. -
You have created the
IstioCNIresource, and the Operator has deployed the necessaryIstioCNIpods. - You have created the namespaces that are to be part of the mesh, and they are discoverable by the Istio control plane.
-
Optional: You have deployed the workloads to be included in the mesh. In the following examples, the Bookinfo has been deployed to the
bookinfonamespace, but sidecar injection (step 5) has not been configured. For more information, see "Deploying the Bookinfo application".
3.3.1. Enabling sidecar injection with namespace labels Copiar o linkLink copiado para a área de transferência!
In this example, all workloads within a namespace receive a sidecar proxy injection, making it the best approach when the majority of workloads in the namespace should be included in the mesh.
Procedure
Verify the revision name of the Istio control plane using the following command:
oc get istiorevisions
$ oc get istiorevisionsCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
NAME TYPE READY STATUS IN USE VERSION AGE default Local True Healthy False v1.23.0 4m57s
NAME TYPE READY STATUS IN USE VERSION AGE default Local True Healthy False v1.23.0 4m57sCopy to Clipboard Copied! Toggle word wrap Toggle overflow Since the revision name is default, you can use the default injection labels without referencing the exact revision name.
Verify that workloads already running in the desired namespace show
1/1containers asREADYby using the following command. This confirms that the pods are running without sidecars.oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow To apply the injection label to the
bookinfonamespace, run the following command at the CLI:oc label namespace bookinfo istio-injection=enabled
$ oc label namespace bookinfo istio-injection=enabled namespace/bookinfo labeledCopy to Clipboard Copied! Toggle word wrap Toggle overflow To ensure sidecar injection is applied, redeploy the existing workloads in the
bookinfonamespace. Use the following command to perform a rolling update of all workloads:oc -n bookinfo rollout restart deployments
$ oc -n bookinfo rollout restart deploymentsCopy to Clipboard Copied! Toggle word wrap Toggle overflow
Verification
Verify the rollout by checking that the new pods display
2/2containers asREADY, confirming successful sidecar injection by running the following command:oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow
3.3.2. Exclude a workload from the mesh Copiar o linkLink copiado para a área de transferência!
You can exclude specific workloads from sidecar injection within a namespace where injection is enabled for all workloads.
This example is for demonstration purposes only. The bookinfo application requires all workloads to be part of the mesh for proper functionality.
Procedure
-
Open the application’s
Deploymentresource in an editor. In this case, exclude theratings-v1service. Modify the
spec.template.metadata.labelssection of yourDeploymentresource to include the labelsidecar.istio.io/inject: falseto disable sidecar injection.Copy to Clipboard Copied! Toggle word wrap Toggle overflow NoteAdding the label to the top-level
labelssection of theDeploymentdoes not affect sidecar injection.Updating the deployment triggers a rollout, creating a new ReplicaSet with updated pod(s).
Verification
Verify that the updated pod(s) do not contain a sidecar container and show
1/1containers asRunningby running the following command:oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow
3.3.3. Enabling sidecar injection with pod labels Copiar o linkLink copiado para a área de transferência!
This approach allows you to include individual workloads for sidecar injection instead of applying it to all workloads within a namespace, making it ideal for scenarios where only a few workloads need to be part of a service mesh. This example also demonstrates the use of a revision label for sidecar injection, where the Istio resource is created with the name my-mesh. A unique Istio resource name is required when multiple Istio control planes are present in the same cluster or during a revision-based control plane upgrade.
Procedure
Verify the revision name of the Istio control plane by running the following command:
oc get istiorevisions
$ oc get istiorevisionsCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
NAME TYPE READY STATUS IN USE VERSION AGE my-mesh Local True Healthy False v1.23.0 47s
NAME TYPE READY STATUS IN USE VERSION AGE my-mesh Local True Healthy False v1.23.0 47sCopy to Clipboard Copied! Toggle word wrap Toggle overflow Since the revision name is
my-mesh, use the revision labelistio.io/rev=my-meshto enable sidecar injection.Verify that workloads already running show
1/1containers asREADY, indicating that the pods are running without sidecars by running the following command:oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow -
Open the application’s
Deploymentresource in an editor. In this case, update theratings-v1service. Update the
spec.template.metadata.labelssection of yourDeploymentto include the appropriate pod injection or revision label. In this case,istio.io/rev: my-mesh:Copy to Clipboard Copied! Toggle word wrap Toggle overflow NoteAdding the label to the top-level
labelssection of theDeploymentresource does not impact sidecar injection.Updating the deployment triggers a rollout, creating a new ReplicaSet with the updated pod(s).
Verification
Verify that only the ratings-v1 pod now shows
2/2containersREADY, indicating that the sidecar has been successfully injected by running the following command:oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow You should see output similar to the following example:
Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow - Repeat for other workloads that you wish to include in the mesh.
3.4. Enabling sidecar injection with namespace labels and an IstioRevisionTag resource Copiar o linkLink copiado para a área de transferência!
To use the istio-injection=enabled label when your revision name is not default, you must create an IstioRevisionTag resource with the name default that references your Istio resource.
Prerequisites
-
You have installed the Red Hat OpenShift Service Mesh Operator, created an
Istioresource, and the Operator has deployed Istio. -
You have created the
IstioCNIresource, and the Operator has deployed the necessaryIstioCNIpods. - You have created the namespaces that are to be part of the mesh, and they are discoverable by the Istio control plane.
-
Optional: You have deployed the workloads to be included in the mesh. In the following examples, the Bookinfo has been deployed to the
bookinfonamespace, but sidecar injection (step 5 in "Deploying the Bookinfo application" procedure) has not been configured. For more information, see "Deploying the Bookinfo application".
Procedure
Find the name of your
Istioresource by running the following command:oc get istio
$ oc get istioCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
NAME REVISIONS READY IN USE ACTIVE REVISION STATUS VERSION AGE default 1 1 1 default-v1-24-3 Healthy v1.24.3 11s
NAME REVISIONS READY IN USE ACTIVE REVISION STATUS VERSION AGE default 1 1 1 default-v1-24-3 Healthy v1.24.3 11sCopy to Clipboard Copied! Toggle word wrap Toggle overflow In this example, the
Istioresource has the namedefault, but the underlying revision is calleddefault-v1-24-3.Create the
IstioRevisionTagresource in a YAML file:Example
IstioRevistionTagresource YAML fileCopy to Clipboard Copied! Toggle word wrap Toggle overflow Apply the
IstioRevisionTagresource by running the following command:oc apply -f istioRevisionTag.yaml
$ oc apply -f istioRevisionTag.yamlCopy to Clipboard Copied! Toggle word wrap Toggle overflow Verify that the
IstioRevisionTagresource has been created successfully by running the following command:oc get istiorevisiontags.sailoperator.io
$ oc get istiorevisiontags.sailoperator.ioCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
NAME STATUS IN USE REVISION AGE default Healthy True default-v1-24-3 4m23s
NAME STATUS IN USE REVISION AGE default Healthy True default-v1-24-3 4m23sCopy to Clipboard Copied! Toggle word wrap Toggle overflow In this example, the new tag is referencing your active revision,
default-v1-24-3. Now you can use theistio-injection=enabledlabel as if your revision was calleddefault.Confirm that the pods are running without sidecars by running the following command. Any workloads that are already running in the desired namespace should show
1/1containers in theREADYcolumn.oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Apply the injection label to the
bookinfonamespace by running the following command:oc label namespace bookinfo istio-injection=enabled \ namespace/bookinfo labeled
$ oc label namespace bookinfo istio-injection=enabled \ namespace/bookinfo labeledCopy to Clipboard Copied! Toggle word wrap Toggle overflow To ensure sidecar injection is applied, redeploy the workloads in the
bookinfonamespace by running the following command:oc -n bookinfo rollout restart deployments
$ oc -n bookinfo rollout restart deploymentsCopy to Clipboard Copied! Toggle word wrap Toggle overflow
Verification
Verify the rollout by running the following command and confirming that the new pods display
2/2containers in theREADYcolumn:oc get pods -n bookinfo
$ oc get pods -n bookinfoCopy to Clipboard Copied! Toggle word wrap Toggle overflow Example output
Copy to Clipboard Copied! Toggle word wrap Toggle overflow