Startup probe failed

Question

Hi, for my container app I have not configured the health probes but I do have set up a dashboard to check if the container is healthy using this query-

Question is that I have not setup any health probes then why am I getting the error? None of the probes are configured from my end how to handle this?

This is the query for dashboard , can you also please share the reference to "ReplicaUnhealthy". I believe it is configurable for our end. Please help me know. Thanks

Also,any suggested methods to reduce/avoid these kind of errors will be helpful.

ContainerAppSystemLogs_CL
| where Reason_s == "ReplicaUnhealthy"
| summarize cnt = count() by Reason_s, ContainerAppName_s, dt=bin(TimeGenerated, 30m)
| project ContainerAppName_s, Reason_s, cnt, dt
| render timechart 

Answer 1

Hello Mansi Gusain,

Welcome to the Microsoft Q&A and thank you for posting your questions here.

I understand that you are having Startup probe failed error for your container app.

Yes, Even though you haven’t explicitly configured any health probes. Azure Container Apps automatically adds default health probes if none are configured. This includes startup, liveness, and readiness probes - https://learn.microsoft.com/en-us/azure/container-apps/health-probes

Also, the startup probe checks if your application has successfully started. If it fails, the container is killed and restarted according to the pod’s restart policy - https://kubebyexample.com/learning-paths/application-development-kubernetes/lesson-4-customize-deployments-application-2

However, your SQL query for the dashboard looks good for monitoring unhealthy replicas:

ContainerAppSystemLogs_CL
| where Reason_s == "ReplicaUnhealthy"
| summarize cnt = count() by Reason_s, ContainerAppName_s, dt=bin(TimeGenerated, 30m)
| project ContainerAppName_s, Reason_s, cnt, dt
| render timechart

So, to reduce or avoid errors you will need to configure custom health probes that match your application’s startup and runtime characteristics. This can prevent premature restarts, and you should use detailed logging and monitoring to understand why probes are failing. This can help you fine-tune the probe configurations. Then, make sure your container has sufficient resources (CPU, memory) to start and run properly. For an example on how you might configure a startup probe in your container app:

{
  "containers": [
    {
      "image": "your-image",
      "name": "your-container",
      "probes": [
        {
          "type": "startup",
          "httpGet": {
            "path": "/startup",
            "port": 8080
          },
          "initialDelaySeconds": 10,
          "periodSeconds": 5,
          "failureThreshold": 30
        }
      ]
    }
  ]
}

I hope this is helpful! Do not hesitate to let me know if you have any other questions.

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