Fine-Tune Your Tracing Data

Istio provides some additional configuration options that you may find useful to fine-tune your telemetry data. These include options to set the service name reported with the telemetry data and the ability to add custom attributes to the span data.

Configure the Service Name

The default configuration for Istio sets the service name on the telemetry data to APP_LABEL_AND_NAMESPACE. If there is no app label on the workload it will use istio-proxy instead. The two value are concatenated with a period (ex. my-app.my-namespace). If this is not your preferred naming scheme, Istio provides the following options for you to choose from:

Value	Description
`APP_LABEL_AND_NAMESPACE`	Default. Uses the `app` label and workload namespace to construct the service name. If the `app` label does not exist `istio-proxy` is used.
`CANONICAL_NAME_ONLY`	Uses the canonical name for the workload without the namespace
`CANONICAL_NAME_AND_NAMESPACE`	Uses the canonical name with the namespace

This setting is managed in the defaultConfig section of the mesh config in the Istio ConfigMap. Here is an example:

apiVersion: v1
kind: ConfigMap
metadata:
  name: istio
  namespace: istio-system
  annotations:
    meta.helm.sh/release-name: istiod
    meta.helm.sh/release-namespace: istio-system
  labels:
    app.kubernetes.io/managed-by: Helm
    install.operator.istio.io/owning-resource: unknown
    istio.io/rev: default
    operator.istio.io/component: Pilot
    release: istiod
data:
  meshNetworks: |-
        networks: {}

  mesh: |-
    defaultConfig:
      discoveryAddress: istiod.istio-system.svc:15012
      # use only the canonical name to generate the services names
      tracingServiceName: CANONICAL_NAME_ONLY
    defaultProviders:
      tracing:
        - opentelemetry
    extensionProviders:
      - name: "opentelemetry"
        opentelemetry:
          service: "opentelemetry-collector.istio-system.svc.cluster.local"
          port: 4317
    enablePrometheusMerge: true
    rootNamespace: null
    trustDomain: cluster.local

After updating this configuration, apply the changes to your cluster:

kubectl apply -f istio-telemetry.yaml -n istio-system

Don’t forget to restart your workloads so the changes get applied to the sidecars.

Once you have restarted your workloads, load or refresh the Bookinfo product page again and review the traces in Cloud Observability. You should see the service names have been updated like so:

Updated Service Names

Add Custom Attributes

You can configure Istio telemetry to add tags/attributes to the spans that are generated by the sidecar proxies. This is helpful when you want to add additional context to the spans in order to better understand that state of the requests and/or support specific queries. You have three options to set the value for these attributes: get the value from an environment variable, extract the value from the request headers or hard code the value.

You can configure these attributes by modifying the Telemetry resource that you created in the Configure Istio Telemetry section above. Here is an example with comments:

apiVersion: telemetry.istio.io/v1alpha1
kind: Telemetry
metadata:
  name: mesh-default
  namespace: istio-system
spec:
  accessLogging:
    - providers:
        - name: opentelemetry
  metrics:
    - providers:
        - name: opentelemetry
  tracing:
    - providers:
        - name: opentelemetry
      # This section defines the custom attributes that will be
      # added to the spans generated by the Istio sidecars
      customTags:
        my-attr.hard-coded: # this value will be the attribute key
          literal: # use "literal" when hard coding the attribute value
            value: "this is the value of my hard coded custom attribute"
        my-attr.from-env-var: # this value will be the attribute key
          environment: # use "environment" when getting the attribute value from an environment variable
            name: my-env-var # the name of the environment variable to get the value from
            defaultValue: "this is the default value" # default value to use when the environment variable is not found
        my-attr.from-header: # this value will be the attribute key
          header: # use "header" when getting the attribute value from the request headers
            name: my-header # the name of the header to get the value from
            defaultValue: "this is the default value" # default value to use when the header is not found
      randomSamplingPercentage: 100

Once you have these configured deploy the changes to your cluster:

kubectl apply -f istio-telemetry.yaml -n istio-system

Again, don’t forget to restart your workloads so the changes get applied to the sidecars.

After you restart your workloads, load or refresh the Bookinfo product page again and review the traces in Cloud Observability. Notice the custom attributes now appear on your spans.

Custom Attributes

And that brings us to the end of this workshop. Before wrapping it up, let’s recap what you completed and discuss some next steps to further enhance observability with Istio.

next: Conclusion