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Instana AutoTrace webhook

The Instana AutoTrace webhook is a Kubernetes admission controller mutating webhook that automatically configures the Instana tracing on Node.js, .NET Core, Ruby and Pyhton applications as well as ingress-nginx ingress controllers running across the entire Kubernetes cluster.

Requirements

  • Kubernetes 1.16+ OR OpenShift 4.5+
  • kubectl 1.16+
  • Helm 3.2+ (some automation relies on Helm lookup functionality)

Setup

Replace <download_key> in the following script with valid Instana download key and run it with administrator priviledges for your cluster:

helm install --create-namespace --namespace instana-autotrace-webhook instana-autotrace-webhook \
  --repo https://agents.instana.io/helm instana-autotrace-webhook \
  --set webhook.imagePullCredentials.password=<download_key>

Alternative to providing the <download_key>, it's possible to provide the imagePullSecret by modifying the values.yaml file, specifying the secret under webhook.imagePullSecrets and passing the file to the helm install command with flag -f values.yaml. The imagePullSecret name can also be provided through the helm flag --set webhook.imagePullSecrets[0].name=my-secret.

Important: When installing on OpenShift, you must set additionally --set openshift.enabled=true.

Verify it works

First of all, ensure the instana-autotrace-webhook in the instana-autotrace-webhook namespace is running as expected:

$ kubectl get pods -n instana-autotrace-webhook
NAME                                         READY   STATUS    RESTARTS   AGE
instana-autotrace-webhook-7c5d5bf6df-82w7c   1/1     Running   0          12m

Then time to try it out. Deploy a Node.js pod. When it comes up, you will see the following when checking the labels of the pod:

$ kubectl get pod test-nodejs -n test-apps -o=jsonpath='{.metadata.labels.instana-autotrace-applied}'
true

Assuming that you also installed the Instana host agent, e.g., using the instana/agent helm chart, the Node.js process will soon appear in your Instana dashboard. For more information, refer to the Installing the Host Agent on Kubernetes documentation.

If, on the other hand, you do not see the instana-autotrace-applied labels appear on your containers, consult the Troubleshooting section.

Updates

The Instana AutoTrace webhook does not currently have an automated way of upgrading the instrumentation that it will install. The instrumentation is delivered over the instana/instrumentation image (icr.io/instana/instrumentation). The instana-autotrace-webhook Helm chart will be regularly updated to use the newest instana/instrumentation image; so, to update the instrumentation to the latest and greatest version, you can upgrade the deployment with:

helm upgrade --namespace instana-autotrace-webhook instana-autotrace-webhook \
  --repo https://agents.instana.io/helm instana-autotrace-webhook \
  --reuse-values

You can find out which version of the AutoTrace webhook has been applied to which of your resources by looking up the instana-autotrace-version label. The instana-autotrace-version label will be applied to the Pods, ReplicaSets, StatefulStes, Deployments and DeploymentConfigs.

Gotchas

  • The Instana AutoTrace webhook will take effect on new Kubernetes resources. That is, you may need to delete your Pods, ReplicaSets, StatefulStes, Deployments and DeploymentConfigs and create them anew, for the Instana AutoTrace webhook to do its magic.
  • Only linux/amd64 Kubernetes nodes are currently supported.
  • In your Kubernetes setup, updating the webhook via Helm doesn't automatically pull the latest image, leading to potential mismatches between new code and old images. To address this, uninstalling and reinstalling the webhook can ensure it uses the latest default values and images, but previously deployed workloads may still require redeployment to apply the updated instrumentation.

Configuration

Enable ingress-nginx tracing

To enable the automatic instrumentation of ingress-nginx objects in your kubernetes cluster, please set the value of autotrace.ingress_nginx.enabled to true:

--set autotrace.ingress_nginx.enabled=true

Note: Changes to already existing objects are only done whenever the objects are either modified or recreated.

Role-based Access Control

In order to deploy the AutoTrace webhook into a ServiceAccount guarded by a ClusterRole and matching ClusterRoleBinding, set the rbac.enabled=true flag when deploying the Helm chart.

In addition to the RBAC, if you use Pod Security Policies, add rbac.psp.enabled=true to the Helm arguments.

Container port

In order to be reachable from Kubernetes' API server, the AutoTrace webhook pod must be hosted on the host network, and the deployment is configured to achieve that transparently. By default, the container will be bound to port 42650. If something else on your nodes already uses port 42650, causing the AutoTrace webhook to go in a crash loop because it finds its port already bound, you can change the port using the webhook.port property.

Opt-in or opt-out

In purely Instana fashion, the AutoTrace webhook will instrument all containers in all pods. However, you may want to have more control over which resources are instrumented and which not. By setting the autotrace.opt_in=true value when deploying the Helm chart, the AutoTrace webhook will only modify pods, replica sets, stateful sets, daemon sets and deployments that carry the instana-autotrace: "true" label.

Irrespective of the value of the autotrace.opt_in, the AutoTrace webhook will not touch pods that carry the instana-autotrace: "false" label.

The instana-autotrace: "false" label is respected in metadata of DaemonSets, Deployments, DeploymentConfigs, ReplicaSets, and StatefulSets, as well as in nested Pod templates and in standalone Pods.

Ignoring namespaces

Using the autotrace.exclude.namespaces configuration, you can exclude entire namespaces from being auto-instrumented. Helm is... quaint... around list-like data structures when passing values from the command line with --set, so you will need to do something like the following:

helm upgrade instana-autotrace-webhook ... --set autotrace.exclude.namespaces[0]=ignore_this_namespace

The [0] in the list above is the positional argument in the list of ignored namespaces, which is in this case a list of one element (list indexes start from 0 in Helm).

If you want to ignore multiple namespaces, you will need to do the following:

helm upgrade instana-autotrace-webhook ... --set autotrace.exclude.namespaces[0]=ignore_this_namespace --set autotrace.exclude.namespaces[1]=ignore_this_other_namespace_too

Notice that, even when using --reuse-values, you will still need to specify the whole list of excluded namespaces (Helm does not support appending to lists), which is not convenient. In case of wanting to exclude namespaces, the suggested approach is to use a values.yaml file instead.

Built-in ignored namespaces

The Helm chart has a built-in list of excluded namespacesm, like kube-* and openshift-*. Due to the lack of list-append capability of Helm, they are stored in a separate list called autotrace.exclude.builtin_namespaces. It is strongly advised not to change that list. We are likely to grow that list over time, and if you modify it, your modifications may be wiped in the next helm upgrade.

Ignored namespaces and opt-in resources

Resources that have the instana-autotrace: "true" label, will be instrumented regardless of namespace exclusion.

The instana-autotrace label is respected in metadata of DaemonSets, Deployments, DeploymentConfigs, ReplicaSets, StatefulSets, and Namespaces as well as in nested Pod templates and in standalone Pods.

Ignoring resources

Resources that have the instana-autotrace: "false" label, will be ignored regardless other settings.

The instana-autotrace label is respected in metadata of DaemonSets, Deployments, DeploymentConfigs, ReplicaSets, StatefulSets, and Namespaces as well as in nested Pod templates and in standalone Pods.

Minimize required ephemeral storage

The webhook mutates the pod and adds the initContainer which pulls the image that has instrumentation files for all technologies that are supported (Node.js, .NET Core, Ruby, Python and NGINX) and copies all these files to the pod by the default. The files are stored in the emptyDir volume instana-instrumentation-volume under volume mount path /opt/instana/instrumentation/. As emptyDir volumes are stored on the local filesystem of the node, this is taking up pod's ephemeral storage usage. The total size of the instrumentation files is around 300MB:

  • libinstana_init 5M - required for all technologies
  • ibmmq 17M
  • ruby 151M
  • ibmace 9M
  • netcore 4M
  • nginx 66M
  • nodejs 32M
  • python 20M

It's possible to limit the ephemeral storage required and specify webhook to only copy files for some techonologies. This can be done globally for the whole cluster by specifying the helm chart flags or modifying the values file (--set autotrace.instrumentation.manual.<technology>=true, where technology can be nodejs, netcore, python, ruby or nginx).

Alternatively, it is possible to configure it per deployment or pod. For this approach, ensure to set the environment variable in the spec INSTANA_INSTRUMENT_<technology>=true, where where technology can be NODEJS, NETCORE, PYTHON, RUBY or NGINX.

It is possible to specify more than one flag and include instrumentation files for two or more technologies. For more details on the environment variables or helm chart flags, please check the helm values section.

Troubleshooting

If you do not see the Instana AutoTrace webhook have effect on your new Kubernetes resources, the steps to troubleshoot are the following.

Ensure the Instana AutoTrace webhook is receiving requests

Check the logs of the instana-autotrace-webhook pod. Using kubectl, you can launch the following command:

kubectl logs -l app.kubernetes.io/name=instana-autotrace-webhook -n instana-autotrace-webhook

In a functioning installation, you will see logs like the following:

14:41:37.590 INFO  |- [AdmissionReview 48556a1a-7d55-497b-aa9c-23634b089cd1] Applied transformation DefaultDeploymentTransformation to the Deployment 'test-netcore-glibc/test-apps'
14:41:37.588 INFO  |- [AdmissionReview 1d5877cf-7153-4a95-9bfb-de0af8351195] Applied transformation DefaultDeploymentTransformation to the Deployment 'test-nodejs-12/test-apps'

If you do not see logs like these, then very likely there is a problem with the Kubernetes setup, see the following section.

Check the Kube ApiServer logs

The logs of your kube-apiserver will report on whether the Instana AutoTrace webhook is being invoked and, if so, what is the outcome.

(Not so) common issues

No network connectivity between kube-apiserver and the instana-autotrace-webhook pods

The most common issue is that the kube-apiserver cannot reach the worker nodes running the instana-autotrace-webhook pods due to security policies, which prevents the Instana AutoTrace webhook to work. In this case, the solution is to change your network settings so that the kube-apiserver will be able to reach the instana-autotrace-webhook pods. How to achieve that is entirely dependent on your setup, so we cannot provided guidance on how to solve this case.

kube-apiserver and the instana-autotrace-webhook pods cannot negotiate a TLS session

Another issue we have sporadically seen is that cryptography restrictions in terms of which algorithms can be used for TLS prevent kube-apiserver from negotiations a TLS session with the instana-autotrace-webhook pod. In this case, please open a ticket and tell us which cryptography algorithms your clusters support.

Helm Values

The most important helm values and the environment variables they map to (which are used in the mutating webhook itself) are the ones related to the instrumentation image. You can find a table with an explanation and the respective environment variable below.

Helm Value Environment variable Explanation
.Values.webhook.imagePullSecrets[x].name NA Alternative to providing the <download_key> as plaintext flag, it's possible to provide the already created imagePullSecret name directly.
.Values.autotrace.exclude.builtin_namespaces .Values.autotrace.exclude.namespaces INSTANA_AUTOTRACE_IGNORED_NAMESPACES List of kubernetes namespaces to be ignored for autotracing. This includes a list of builtin that are always ignored such as the ones starting with instana- or kube-
.Values.autotrace.exclude.selector List of kubernetes namespaces that will be ignored at the configuration-level, resources in this namespace will not be sent to the webhook, resources in namespaces specified in the other exclude fields will be sent through the webhook, but will be ignored at runtime
.Values.autotrace.instrumentation.image INSTANA_INSTRUMENTATION_INIT_CONTAINER_IMAGE Name and tag of the instrumentation image
.Values.autotrace.instrumentation.imagePullPolicy INSTANA_INSTRUMENTATION_INIT_CONTAINER_IMAGE_PULL_POLICY Instrumentation image pull policy (Default IfNotPresent)
.Values.autotrace.instrumentation.imagePullSecret INSTANA_INSTRUMENTATION_INIT_CONTAINER_IMAGE_PULL_SECRET Instrumentation image pull secret (If .Values.autotrace.instrumentation.image comes from a private regitry)
.Values.autotrace.opt_in INSTANA_AUTOTRACE_OPT_IN When set to "true", only those pods with the label instana-autotrace=true, are going to be autotraced. By default is false, and in this case all pods will be autotraced except those the label instana-autotrace=false
.Values.autotrace.nodejs.enabled INSTANA_AUTOTRACE_NODEJS Whether to autotrace Node.js pods. Default true.
.Values.autotrace.nodejs.application_type INSTANA_AUTOTRACE_NODEJS_APPLICATION_TYPE How the Customers Node.js app loads its modules. The default is commonjs. If you opt for ESM loading and your Node.js version is 18.19.0 or higher, select module_v2. For Node.js versions lower than 18.19.0, use module_v1.
.Values.autotrace.nodejs.esm INSTANA_AUTOTRACE_NODEJS_ESM This variable is deprecated and will be removed in future updates. It determines whether the Node.js application is utilizing ESM or not. This setting is relevant only for Node.js versions below 18.19.0, with the default being false. We recommend using INSTANA_AUTOTRACE_NODEJS_APPLICATION_TYPE instead.
.Values.autotrace.netcore.enabled INSTANA_AUTOTRACE_NETCORE Whether to autotrace NET Core pods. Default true.
.Values.autotrace.ruby.enabled INSTANA_AUTOTRACE_RUBY Whether to autotrace Ruby pods. Default true.
.Values.autotrace.python.enabled INSTANA_AUTOTRACE_PYTHON Whether to autotrace Python pods. Default true.
.Values.autotrace.ingress_nginx.enabled INSTANA_AUTOTRACE_INGRESS_NGINX Whether to autotrace Ingress NGINX pods. Default false.
.Values.autotrace.ingress_nginx.status_enabled INSTANA_AUTOTRACE_INGRESS_NGINX_STATUS When autotrace is enabled for Ingress NGINX, also add an status endpoint. Default false.
.Values.autotrace.ingress_nginx.status_allow INSTANA_AUTOTRACE_INGRESS_NGINX_STATUS_ALLOW IP address or CIDR mask of the agent to restrict the access to the status endpoint. Default all.
.Values.autotrace.libinstana_init.enabled INSTANA_AUTOTRACE_USE_LIB_INSTANA_INIT Whether to use libinstana_init library. Default true.
.Values.autotrace.initContainer.memoryLimit INSTANA_AUTOTRACE_INIT_MEMORY_LIMIT Memory limit of the init container. Defaults to 128Mi.
.Values.autotrace.initContainer.cpuLimit INSTANA_AUTOTRACE_INIT_CPU_LIMIT CPU limit of the init container. Defaults to 250m.
.Values.awseksfargate.enabled INSTANA_ENVIRONMENT_AWSEKSFARGATE Makes the webhook set the INSTANA_TRACER_ENVIRONMENT to an EKS Fargate specific value, which enables the EKS Fargate support in the in-process tracer.
.Values.awseksfargate.instanaEndpointURL INSTANA_ENDPOINT_URL Specifys the endpoint URL of the serverless agent for the in-process the tracer.
.Values.awseksfargate.instanaAgentKey INSTANA_AGENT_KEY Specifys the agent key for the in-process tracer, which is used for authentication on the endpoint URL.
.Values.autotrace.instrumentation.manual.nodejs INSTANA_INSTRUMENT_NODEJS Flag to explicitely copy files for NodeJS applications. The files for other technologies will be omitted unless manually set with similar flags for other technologies. Helm chart flag sets the configuration globally for the cluster.
.Values.autotrace.instrumentation.manual.netcore INSTANA_INSTRUMENT_NETCORE Flag to explicitely copy files for .NET core applications. The files for other technologies will be omitted unless manually set with similar flags for other technologies. Helm chart flag sets the configuration globally for the cluster.
.Values.autotrace.instrumentation.manual.nginx INSTANA_INSTRUMENT_NGINX Flag to explicitely copy files for nginx. The files for other technologies will be omitted unless manually set with similar flags for other technologies. Helm chart flag sets the configuration globally for the cluster.
.Values.autotrace.instrumentation.manual.ruby INSTANA_INSTRUMENT_RUBY Flag to explicitely copy files for Ruby applications. The files for other technologies will be omitted unless manually set with similar flags for other technologies. Helm chart flag sets the configuration globally for the cluster.
.Values.autotrace.instrumentation.manual.python INSTANA_INSTRUMENT_PYTHON Flag to explicitely copy files for Python applications. The files for other technologies will be omitted unless manually set with similar flags for other technologies. Helm chart flag sets the configuration globally for the cluster.
.Values.autotrace.instrumentation.imagePullCredentials.registry NA The initContainer image can be pulled from private registry by customizing the deployment. This flag can be used to specify the registry for creating the pull secret.
.Values.autotrace.instrumentation.imagePullCredentials.username NA The initContainer image can be pulled from private registry by customizing the deployment. This flag can be used to specify the username for creating the pull secret.
.Values.autotrace.instrumentation.imagePullCredentials.password NA The initContainer image can be pulled from private registry by customizing the deployment. This flag can be used to specify the password for creating the pull secret.