04 - Logging and Monitoring (Dedicated)¶

Enable production-grade observability with Application Insights, structured logs, and baseline alerting for Java handlers.

Prerequisites¶

Tool	Version	Purpose
JDK	17+	Compile and run Java functions locally
Maven	3.6+	Build and package Java artifacts
Azure Functions Core Tools	v4	Start local host and publish artifacts
Azure CLI	2.61+	Provision Azure resources and inspect app state

Dedicated plan basics

Dedicated (App Service Plan) runs functions on standard App Service infrastructure with predictable pricing. B1 provides 1 vCPU, 1.75 GB memory. It supports Always On, manual/auto-scale, deployment slots, and VNet integration.

What You'll Build¶

You will verify Application Insights connectivity, query structured logs from the deployed function app, configure streaming logs, and set up a baseline alert rule for failure detection.

flowchart TD
    A[ExecutionContext logger] --> B[FunctionAppLogs]
    B --> C[Application Insights]
    C --> D[Dashboards and alerts]

Steps¶

Step 1 - Emit structured logs in handler methods¶

The reference app's Health.java uses ExecutionContext.getLogger():

@FunctionName("health")
public HttpResponseMessage health(
    @HttpTrigger(name = "req", methods = {HttpMethod.GET},
        authLevel = AuthorizationLevel.ANONYMOUS, route = "health")
    HttpRequestMessage<Optional<String>> request,
    final ExecutionContext context) {

    context.getLogger().info("event=health-check status=started invocationId="
        + context.getInvocationId());

    return request.createResponseBuilder(HttpStatus.OK)
        .header("Content-Type", "application/json")
        .body("{\"status\":\"healthy\"}")
        .build();
}

Step 2 - Confirm Application Insights connection¶

Application Insights is auto-created with the function app. Verify the connection string is set:

az functionapp config appsettings list \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --query "[?name=='APPLICATIONINSIGHTS_CONNECTION_STRING'].value" \
  --output tsv

CLI element	Explanation
Command(s)	`az functionapp config appsettings list`
Key flags	`--name`, `--resource-group`, `--query`, `--output`
Variables	`$APP_NAME`, `$RG`
Expected result	Azure CLI applies the configuration change; confirm the returned JSON or follow-up query shows the expected value.

Step 3 - Trigger requests and wait for telemetry ingestion¶

# Generate traffic
curl --request GET "https://$APP_NAME.azurewebsites.net/api/health"
curl --request GET "https://$APP_NAME.azurewebsites.net/api/hello/Monitoring"
curl --request GET "https://$APP_NAME.azurewebsites.net/api/loglevels"

# Wait for telemetry ingestion (2-5 minutes for new App Insights)
sleep 180

Telemetry ingestion delay

Application Insights typically takes 2-5 minutes to ingest and index new telemetry, especially for newly created instances. If queries return empty results, wait and retry.

Step 4 - Query recent traces¶

az monitor app-insights query \
  --apps "$APP_NAME" \
  --resource-group "$RG" \
  --analytics-query "traces | where timestamp > ago(30m) | project timestamp, message, severityLevel | order by timestamp desc | take 10"

CLI element	Explanation
Command(s)	`az monitor app-insights query`
Key flags	`--apps`, `--resource-group`, `--analytics-query`
Variables	`$APP_NAME`, `$RG`
Expected result	Azure CLI returns the requested resource data; verify names, IDs, status fields, or metric values match the scenario.

Step 5 - Query request performance¶

az monitor app-insights query \
  --apps "$APP_NAME" \
  --resource-group "$RG" \
  --analytics-query "requests | where timestamp > ago(30m) | project timestamp, name, resultCode, duration | order by timestamp desc | take 10"

CLI element	Explanation
Command(s)	`az monitor app-insights query`
Key flags	`--apps`, `--resource-group`, `--analytics-query`
Variables	`$APP_NAME`, `$RG`
Expected result	Azure CLI returns the requested resource data; verify names, IDs, status fields, or metric values match the scenario.

Step 6 - View streaming logs¶

az webapp log tail \
  --name "$APP_NAME" \
  --resource-group "$RG"

CLI element	Explanation
Command(s)	`az webapp log tail`
Key flags	`--name`, `--resource-group`
Variables	`$APP_NAME`, `$RG`
Expected result	Azure CLI completes successfully and returns JSON, table, or no output depending on the command; verify the next documented check before continuing.

Expected output:

Welcome, you are now connected to log-streaming service.
Starting Log Tail -n 10 of existing logs ----
/appsvctmp/volatile/logs/runtime/container.log
2026-04-09T17:26:00.465Z Hosting environment: Production
2026-04-09T17:26:00.465Z Content root path: /azure-functions-host
2026-04-09T17:26:00.465Z Now listening on: http://[::]:80
2026-04-09T17:26:00.465Z Application started. Press Ctrl+C to shut down.

az functionapp log tail does not exist

As of Azure CLI 2.83.0, az functionapp log tail is not a valid command. Use az webapp log tail instead — it works for function apps on all plans.

Step 7 - Add an alert for HTTP 5xx spikes¶

FUNCTION_APP_ID=$(az functionapp show \
  --name "$APP_NAME" \
  --resource-group "$RG" \
  --query "id" \
  --output tsv)

az monitor metrics alert create \
  --name "func-java-http5xx" \
  --resource-group "$RG" \
  --scopes "$FUNCTION_APP_ID" \
  --condition "total Http5xx > 5" \
  --window-size 5m \
  --evaluation-frequency 1m

CLI element	Explanation
Command(s)	`az functionapp show`, `az monitor metrics alert create`
Key flags	`--name`, `--resource-group`, `--query`, `--output`, `--scopes`, `--condition`, `--window-size`, `--evaluation-frequency`
Variables	`$APP_NAME`, `$RG`, `$FUNCTION_APP_ID`
Expected result	Azure CLI returns provisioning details; confirm the resource name and successful provisioning state before continuing.

Verification¶

Streaming logs output:

Hosting environment: Production
Content root path: /azure-functions-host
Now listening on: http://[::]:80
Application started. Press Ctrl+C to shut down.

Dedicated Always On keeps logs flowing

Like Premium, Dedicated enables Always On by default. The function app remains warm, and streaming logs will always have an active connection.

Next Steps¶

Next: 05 - Infrastructure as Code