[AKS][Istio][meshConfig.defaultConfig] Tracing should be configurable

[herrBez]

Type of issue

Other (describe below)

Feedback

First of all, I want to thank you for the detailed documentation. I would like to give feedback on the tracing setup, which took me longer than necessary to got :).

According to the documentation configuring tracing in managed istio is supported https://learn.microsoft.com/en-us/azure/aks/istio-meshconfig#proxyconfig-meshconfigdefaultconfig.

When I try to modify tracing (e.g., to set sampling rate to a higher value than 1.0 or by changing the address of the tracing backend), the changes never have effect. This is because the standard configuration already specify tracing:

apiVersion: v1
data:
  mesh: |-
    defaultConfig:
      discoveryAddress: istiod-asm-1-20.aks-istio-system.svc:15012
      gatewayTopology:
        numTrustedProxies: 1
      image:
        imageType: distroless
      # <--- THIS IS ALREADY SPECIFIED IN DEFAULT . Why --->
      tracing:
        zipkin:
          address: zipkin.aks-istio-system:9411
    defaultProviders:
      metrics:
      - prometheus
    enablePrometheusMerge: true
    rootNamespace: aks-istio-system
    trustDomain: cluster.local
  meshNetworks: 'networks: {}'

So, when I modify the mesh.DefaultConfig via istio-shared-configmap-asm-1-20. The changes are accepted but are then overwritten by default configuration (as documented):

apiVersion: v1
kind: ConfigMap
metadata:
  name: istio-shared-configmap-asm-1-20
  namespace: aks-istio-system
data:
  mesh: |-
    accessLogFile: /dev/stdout
    defaultConfig:
      holdApplicationUntilProxyStarts: true
      # <-- THIS SETTINGS ARE ACCEPTED BUT OVERWRITTEN BY THE DEFAULT -->
      tracing:
        sampling: 100.0
        zipkin:
          address: opentelemetry-collector.observability:9411

This does not have effect.

I have a couple of questions:

• Is it expected that by default the istio-asm-1-20 specifies tracing property 🤔 ?
• If that's expected, does it really make sense to mark tracing a supported setting?
• Are there any plans to modify the behavior to actually allow configuration of tracing? In particular:
  • Would it be possible to at least specify a sampling value?
  • Would it be possible to change the address?
  • Would it be possible to change the tracing backend (instead of zipkin, using another backend like jaeger or otel)?

Page URL

https://learn.microsoft.com/en-us/azure/aks/istio-meshconfig

Content source URL

https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/aks/istio-meshconfig.md

Author

@shashankbarsin

Document Id

5ab04aa2-6477-6a34-d600-8408e533eb9a

---

Document Details

⚠ Do not edit this section. It is required for learn.microsoft.com ➟ GitHub issue linking.

• ID: be0b50ba-1be7-5ab9-5f1e-5f03eacb49be
• Version Independent ID: 5ab04aa2-6477-6a34-d600-8408e533eb9a
• Content: Configure Istio-based service mesh add-on for Azure Kubernetes Service - Azure Kubernetes Service
• Content Source: articles/aks/istio-meshconfig.md
• Service: azure-kubernetes-service
• GitHub Login: @shashankbarsin
• Microsoft Alias: shasb

[TPavanBalaji]

@herrBez
Thanks for your feedback! We will investigate and update as appropriate.

[SaibabaBalapur-MSFT]

@herrBez
I'm going to assign this to the document author so they can take a look at it accordingly.

@shashankbarsin
please review it.