Skip to content

04 - Logging, Monitoring, and Observability

This tutorial step shows how to inspect console logs, query Log Analytics, and add Application Insights-based observability for production operations.

Infrastructure Context

Service: Container Apps (Consumption) | Network: VNet integrated | VNet: ✅

This tutorial assumes a production-ready Container Apps deployment with a custom VNet, ACR with managed identity pull, and private endpoints for backend services.

flowchart TD
    INET[Internet] -->|HTTPS| CA["Container App\nConsumption\nLinux Node 18 LTS"]

    subgraph VNET["VNet 10.0.0.0/16"]
        subgraph ENV_SUB["Environment Subnet 10.0.0.0/23\nDelegation: Microsoft.App/environments"]
            CAE[Container Apps Environment]
            CA
        end
        subgraph PE_SUB["Private Endpoint Subnet 10.0.2.0/24"]
            PE_ACR[PE: ACR]
            PE_KV[PE: Key Vault]
            PE_ST[PE: Storage]
        end
    end

    PE_ACR --> ACR[Azure Container Registry]
    PE_KV --> KV[Key Vault]
    PE_ST --> ST[Storage Account]

    subgraph DNS[Private DNS Zones]
        DNS_ACR[privatelink.azurecr.io]
        DNS_KV[privatelink.vaultcore.azure.net]
        DNS_ST[privatelink.blob.core.windows.net]
    end

    PE_ACR -.-> DNS_ACR
    PE_KV -.-> DNS_KV
    PE_ST -.-> DNS_ST

    CA -.->|System-Assigned MI| ENTRA[Microsoft Entra ID]
    CAE --> LOG[Log Analytics]
    CA --> AI[Application Insights]

    style CA fill:#107c10,color:#fff
    style VNET fill:#E8F5E9,stroke:#4CAF50
    style DNS fill:#E3F2FD

How Observability Works in Container Apps

flowchart LR
    APP[App container stdout/stderr] --> CONSOLE[Console logs]
    DAPR[Dapr sidecar stdout/stderr] --> CONSOLE
    PLATFORM[Platform/revision/auth events] --> SYSTEM[System logs]
    CONSOLE --> LAW[Log Analytics workspace]
    SYSTEM --> LAW
    OTEL[App instrumentation<br/>Application Insights SDK] --> AI[Application Insights]
    AZMON[Azure Monitor] --> METRICS[Metrics: requests, CPU, memory, replicas]

Prerequisites

Step-by-step

  1. Set standard variables

    RG="rg-nodejs-guide"
APP_NAME=$(az containerapp list --resource-group "$RG" --query "[0].name" --output tsv)

  2. Stream console logs

    az containerapp logs show \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --follow
    Expected output 
    {"timestamp":"2026-04-05T11:00:00.000Z","level":"INFO","message":"Server started on port 8000"}
{"timestamp":"2026-04-05T11:01:00.000Z","level":"INFO","method":"GET","url":"/health","status":200}

    Note

    Use Ctrl+C to stop following logs.

  3. Check system logs for startup or image issues

    az containerapp logs show \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --type system
    Expected output 
    {"TimeStamp":"2026-04-05T11:00:00Z","Type":"Normal","ContainerAppName":"<your-app-name>","Reason":"ConnectedToEventsServer","Msg":"Successfully connected to events server"}

  4. Query logs via CLI (recommended for automation)

    Get your Log Analytics workspace ID and run KQL queries directly from the command line:

    # Get the workspace ID
WORKSPACE_ID=$(az monitor log-analytics workspace list \
  --resource-group "$RG" \
  --query "[0].customerId" \
  --output tsv)

# Query console logs (use your actual app name from $APP_NAME)
az monitor log-analytics query \
  --workspace $WORKSPACE_ID \
  --analytics-query "ContainerAppConsoleLogs_CL | where ContainerAppName_s == '$APP_NAME' | project TimeGenerated, ContainerAppName_s, Log_s | take 5" \
  --output table
    Expected output 
    ContainerAppName_s    Log_s                                                                                          TimeGenerated
--------------------  ---------------------------------------------------------------------------------------------  ----------------------------
<your-app-name>       {"timestamp":"2026-04-04T16:10:50.376Z","level":"INFO","message":"Server started on port 8000"}  2026-04-04T16:10:51.723Z
<your-app-name>       {"timestamp":"2026-04-04T16:11:58.005Z","level":"INFO","method":"GET","path":"/health",...}      2026-04-04T16:11:58.474Z

  5. Query for errors via CLI

    az monitor log-analytics query \
  --workspace $WORKSPACE_ID \
  --analytics-query "ContainerAppConsoleLogs_CL | where ContainerAppName_s == '$APP_NAME' | where Log_s has_any ('error', 'exception', 'failed') | project TimeGenerated, Log_s | take 10" \
  --output table
    Expected output

    If no errors exist, the query returns an empty result set:

    TableName
-------------
PrimaryResult

    If errors exist, they appear with timestamps:

    TimeGenerated                 Log_s
----------------------------  -------------------------------------------------------
2026-04-05T11:05:00.000Z      {"level":"ERROR","message":"Database connection failed"}

  6. Enable Application Insights (OpenTelemetry)

    The reference app includes the applicationinsights SDK. To enable it, provide the connection string:

    # Get connection string from your App Insights resource
CONNECTION_STRING="InstrumentationKey=...;IngestionEndpoint=..."

az containerapp update \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --set-env-vars "APPLICATIONINSIGHTS_CONNECTION_STRING=$CONNECTION_STRING"

    The app will automatically start collecting: - HTTP request metrics (latency, throughput) - Exception traces - Console log redirection to App Insights - Dependency tracking (outbound HTTP calls)

Node.js Structured Logging

The reference app uses a custom middleware to emit JSON logs. This ensures logs are easily searchable in Log Analytics.

// src/middleware/logging.js
const jsonLogger = (req, res, next) => {
  res.on('finish', () => {
    console.log(JSON.stringify({
      timestamp: new Date().toISOString(),
      level: 'INFO',
      method: req.method,
      url: req.url,
      status: res.statusCode
    }));
  });
  next();
};

Advanced Topics

  • Use the winston or pino libraries for more advanced logging features like log levels and multiple transports.
  • Configure custom metrics in Application Insights to track business-specific KPIs.
  • Use Service Map in Application Insights to visualize dependencies between your microservices.

See Also

Sources