Elastic Container Instance:Collect logs by using environment variables

Background information

Simple Log Service is a one-stop service for log data. It lets you quickly collect, consume, ship, query, and analyze log data without writing code. For more information, see What is Simple Log Service?.

Prerequisites

Ensure that Simple Log Service is activated. If the service is not activated, you will be prompted to activate it when you log on to the Simple Log Service console. Follow the on-screen instructions to complete the activation.

Usage notes

• Log-related environment variables take effect only at instance creation. Variables set during instance updates are ignored.

• Delete unused custom projects and Logtail configurations to avoid charges.

• Renaming an environment variable does not delete the original configuration. Manually delete it to avoid charges.

Configuration

Log-related environment variables must be prefixed with aliyun_logs_{key}. The following table describes the available environment variables.

Configuration example

1. Connect to the cluster.

2. Create an application.

   Set log configurations as environment variables for the container. The following YAML file provides an example Deployment.

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     labels:
       app: sls
     name: eci-sls-demo
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: sls
     template:
       metadata:
         labels:
           app: sls
           alibabacloud.com/eci: "true" 
       spec:
         containers:
         - image: registry-vpc.cn-beijing.aliyuncs.com/eci_open/alpine:3.5
           imagePullPolicy: Always
           args:
           - -c
           - mkdir -p /log;while true; do echo hello world; date; echo hello sls >> /log/alpine.log; sleep 1;done
           command:
           - /bin/sh
           name: alpine
           env:
           # Specify a project. You can omit this to use the default project.
           - name: aliyun_logs_test-stdout_project
             value: k8s-log-c21492
           - name: aliyun_logs_test-file_project
             value: k8s-log-c21492
           # Specify a machine group. You can omit this to use the default machine group.
           - name: aliyun_logs_test-stdout_machinegroup
             value: k8s-group-app-alpine
           - name: aliyun_logs_test-file_machinegroup
             value: k8s-group-app-alpine
           # Collect stdout logs to a Logstore named test-stdout.
           - name: aliyun_logs_test-stdout
             value: stdout
           # Collect logs from the /log/*.log files to a Logstore named test-file.
           - name: aliyun_logs_test-file
             value: /log/*.log
           # Set the log retention period. This setting applies only to the test-stdout Logstore.
           - name: aliyun_logs_test-stdout_ttl
             value: "7"
           # Set the number of shards. This setting applies only to the test-stdout Logstore.
           - name: aliyun_logs_test-stdout_shard
             value: "2"
           # Mount an emptyDir volume. This is required for collecting logs from custom file paths.
           volumeMounts:
           - name: volume-sls
             mountPath: /log
         volumes:
         - name: volume-sls
           emptyDir: {}

   Save the preceding YAML content to a file named test-sls-env.yaml and run the following command to create the application.

   kubectl create -f test-sls-env.yaml

3. Check the application status.

   kubectl get pod

   Expected output:

   NAME                             READY   STATUS    RESTARTS   AGE
   eci-sls-demo-b97bbd7d6-z9twz     1/1     Running   0          2m45s

4. View the logs.

   1. Log on to the Log Service console.

   2. Click the name of the target project.

   3. Find the target Logstore and click its name to view the logs.

      • stdout logs

        In the test-stdout Logstore, you can view the collected stdout logs. The log fields include _container_name_: alpine, _image_name_: registry-vpc.cn-beijing.aliyuncs.com/eci_open/alpine:3.5, _namespace_: default, and _source_: stdout. An example log content is hello world.

      • File logs

        In the Log Service console, select the test-file Logstore from the left navigation pane. Then, click the test-file tab and click Raw in the toolbar to view the raw logs. The query result shows the collected container logs. Each log entry includes metadata tag fields, such as __tag__:__container_name__:alpine, __tag__:__namespace__:default, __tag__:__container_ip__, __tag__:__pod_name__, __tag__:__pod_uid__, and __tag__:__eci_id__, and the log content content:hello sls.