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04 - Logging, Monitoring, and Observability

This tutorial step shows how to inspect console logs, query Log Analytics, and add OpenTelemetry-based observability for production .NET applications on Azure Container Apps.

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 .NET 8"]

    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/>OpenTelemetry SDK] --> AI[Application Insights]
    AZMON[Azure Monitor] --> METRICS[Metrics: requests, CPU, memory, replicas]

Prerequisites

Step-by-step

  1. Set standard variables
RG="rg-dotnet-guide"
DEPLOYMENT_NAME="main"

APP_NAME=$(az deployment group show \
  --name "$DEPLOYMENT_NAME" \
  --resource-group "$RG" \
  --query "properties.outputs.containerAppName.value" \
  --output tsv)
  1. Stream console logs

ASP.NET Core logs to stdout by default. You can stream these directly to your terminal.

az containerapp logs show \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --follow

???+ example "Expected output" 

{"TimeStamp":"2026-04-04T16:15:01","Log":"Connecting to the container 'app'..."}
{"TimeStamp":"2026-04-04T16:15:01","Log":"Successfully Connected to container: 'app'"}
{"TimeStamp":"2026-04-04T16:15:02Z","Log":"info: Microsoft.Hosting.Lifetime[14]\n      Now listening on: http://0.0.0.0:8000"}
{"TimeStamp":"2026-04-04T16:15:02Z","Log":"info: Microsoft.Hosting.Lifetime[0]\n      Application started. Press Ctrl+C to shut down."}

  1. Check system logs for platform events

System logs capture events like container crashes, scaling activities, and health probe failures.

az containerapp logs show \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --type system

???+ example "Expected output" 

{"TimeStamp":"2026-04-04T16:15:00Z","Type":"Normal","Msg":"Successfully connected to events server","Reason":"ConnectedToEventsServer"}

  1. 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

???+ example "Expected output" 

ContainerAppName_s    Log_s                                                                                           TimeGenerated
--------------------  ----------------------------------------------------------------------------------------------  ----------------------------
<your-app-name>       {"LogLevel":"Information","Message":"Now listening on: http://0.0.0.0:8000"...}                  2026-04-04T16:13:17.631Z
<your-app-name>       {"LogLevel":"Information","Message":"Application started. Press Ctrl+C to shut down."...}        2026-04-04T16:13:17.632Z
<your-app-name>       {"LogLevel":"Information","Message":"Application is shutting down..."...}                         2026-04-04T16:12:33.373Z

  1. Query for .NET Exceptions via CLI
az monitor log-analytics query \
  --workspace $WORKSPACE_ID \
  --analytics-query "ContainerAppConsoleLogs_CL | where ContainerAppName_s == '$APP_NAME' | where Log_s has 'Exception' or Log_s has 'Error' | project TimeGenerated, Log_s | take 10" \
  --output table

???+ example "Expected output" | TimeGenerated | Log_s | |---|---| | 2026-04-04T16:20:00Z | fail: Microsoft.AspNetCore.Server.Kestrel[13] Connection id "0HN2..." ... |

  1. Enable OpenTelemetry with Azure Monitor

The reference app uses the Azure.Monitor.OpenTelemetry.AspNetCore NuGet package.

// In Program.cs
if (!string.IsNullOrEmpty(Environment.GetEnvironmentVariable("APPLICATIONINSIGHTS_CONNECTION_STRING")))
{
    builder.Services.AddOpenTelemetry().UseAzureMonitor();
}

To enable this in your Container App:

AI_CONNECTION_STRING="InstrumentationKey=...;IngestionEndpoint=..."

az containerapp update \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --set-env-vars "APPLICATIONINSIGHTS_CONNECTION_STRING=$AI_CONNECTION_STRING"
  1. View Metrics in Azure Monitor

Navigate to the Metrics tab of your Container App to visualize: - Requests: Total number of HTTP requests. - CPU/Memory Usage: Resource consumption per replica. - Replica Count: Current number of running instances (scaled by KEDA).

Observability Best Practices for .NET

  • Structured Logging: Use ILogger to emit logs. Container Apps captures the output and indexes it in Log Analytics.
  • Correlation IDs: ASP.NET Core automatically propagates TraceId in HTTP headers, which OpenTelemetry uses to correlate traces across services.
  • Health Checks: Use the ASP.NET Core Health Checks middleware (/health) to provide the platform with accurate liveness/readiness signals.

Advanced Topics

  • Custom Metrics: Use System.Diagnostics.Metrics to emit custom business metrics like orders-processed.
  • Live Metrics: Use Application Insights Live Metrics Stream for real-time monitoring of your .NET app.
  • Log Scopes: Use logger.BeginScope to add contextual metadata (like UserId) to every log entry.

See Also

Sources