Stream Azure Spring Apps application console logs in real time

Use the following steps to stream logs in the Azure portal:

1. Go to the Overview page for your Azure Spring Apps service instance and then select Apps in the navigation pane.

2. Find your target app and select the context menu.

3. In the pop-up context menu, select View log stream.

   

By default, logs start streaming for a randomly selected app instance. You can select yours afterwards.

For convenience, there are many entry points to stream logs. You can find them in the following panes:

• The App list pane
• The Deployment list pane
• The App instance list pane

This section provides examples of using the Azure CLI to produce tail logs. To avoid repeatedly specifying your resource group and service instance name, use the following commands to set your default resource group name and cluster name:

az config set defaults.group=<service-group-name>
az config set defaults.spring=<service-instance-name>

The resource group and service name are omitted in the following examples.

View the tail log for an app with a single instance

If an app named auth-service has only one instance, you can view the log of the app instance with the following command:

az spring app logs --name <application-name>

The command returns logs similar to the following examples, where auth-service is the application name.

...
2020-01-15 01:54:40.481  INFO [auth-service,,,] 1 --- [main] o.apache.catalina.core.StandardService  : Starting service [Tomcat]
2020-01-15 01:54:40.482  INFO [auth-service,,,] 1 --- [main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.22]
2020-01-15 01:54:40.760  INFO [auth-service,,,] 1 --- [main] o.a.c.c.C.[Tomcat].[localhost].[/uaa]  : Initializing Spring embedded WebApplicationContext
2020-01-15 01:54:40.760  INFO [auth-service,,,] 1 --- [main] o.s.web.context.ContextLoader  : Root WebApplicationContext: initialization completed in 7203 ms

...

View the tail log for an app with multiple instances

If multiple instances exist for the app named auth-service, you can view the instance log by using the -i/--instance option.

First, run the following command to get the app instance names:

az spring app show --name auth-service --query properties.activeDeployment.properties.instances --output table

The command produces results similar to the following output:

Name                                         Status    DiscoveryStatus
-------------------------------------------  --------  -----------------
auth-service-default-12-75cc4577fc-pw7hb  Running   UP
auth-service-default-12-75cc4577fc-8nt4m  Running   UP
auth-service-default-12-75cc4577fc-n25mh  Running   UP

Then, you can stream logs of an app instance using the -i/--instance option, as follows:

az spring app logs --name auth-service --instance auth-service-default-12-75cc4577fc-pw7hb

You can also get details of app instances from the Azure portal. After selecting Apps in the left navigation pane of your Azure Spring Apps service, select App Instances.

Continuously stream new logs

By default, az spring app logs prints only existing logs streamed to the app console and then exits. If you want to stream new logs, add the -f/--follow argument, as shown in the following example:

az spring app logs --name auth-service --follow

When you use the --follow argument to tail instant logs, the Azure Spring Apps log streaming service sends heartbeat logs to the client every minute unless your application is writing logs constantly. Heartbeat log messages use the following format: 2020-01-15 04:27:13.473: No log from server.

Use the following command to check all the logging options that are supported:

az spring app logs --help

Format JSON structured logs

Structured application logs are displayed in JSON format, which can be difficult to read. You can use the --format-json argument to format logs in JSON format into a more readable format. For more information, see Structured application log for Azure Spring Apps.

The following example shows how to use the --format-json argument:

# Raw JSON log
$ az spring app logs --name auth-service
{"timestamp":"2021-05-26T03:35:27.533Z","logger":"com.netflix.discovery.DiscoveryClient","level":"INFO","thread":"main","mdc":{},"message":"Disable delta property : false"}
{"timestamp":"2021-05-26T03:35:27.533Z","logger":"com.netflix.discovery.DiscoveryClient","level":"INFO","thread":"main","mdc":{},"message":"Single vip registry refresh property : null"}

# Formatted JSON log
$ az spring app logs --name auth-service --format-json
2021-05-26T03:35:27.533Z  INFO [           main] com.netflix.discovery.DiscoveryClient   : Disable delta property : false
2021-05-26T03:35:27.533Z  INFO [           main] com.netflix.discovery.DiscoveryClient   : Single vip registry refresh property : null

The --format-json argument also accepts an optional customized format using format string syntax. For more information, see Format String Syntax.

The following example shows how to use format string syntax:

# Custom format
$ az spring app logs --name auth-service --format-json="{message}{n}"
Disable delta property : false
Single vip registry refresh property : null

The default format being used is:

{timestamp} {level:>5} [{thread:>15.15}] {logger{39}:<40.40}: {message}{n}{stackTrace}

Use the following steps to enable a log streaming endpoint on the public network:

1. Select the Azure Spring Apps service instance deployed in your virtual network and then select Networking in the navigation menu.

2. Select the Vnet injection tab.

3. Switch the status of Dataplane resources on public network to enable to enable a log streaming endpoint on the public network. This process takes a few minutes.

   

Use the following command to enable the log stream public endpoint:

az spring update \
    --resource-group <resource-group-name> \
    --service <service-instance-name> \
    --enable-dataplane-public-endpoint true