Container Service for Kubernetes:Collect application logs by using pod environment variables

Image

1. Log on to the ACK console. In the left navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want to manage and click its name. In the left navigation pane, choose Workloads > Deployments.

3. In the upper part of the Deployments page, select the namespace where you want to create an application from the Namespace drop-down list. Then, click Create from Image in the upper-right corner of the page.

   1. In the Basic Information step, set the Name, Replicas, and Type parameters. Then, click Next.

   2. In the Container step, set the parameters in the Log Service section.

      Note

      The following table describes only the parameters related to Simple Log Service. For more information about other parameters, see Create a Deployment.

      The following figure is an example.

      Parameter	Description
      Collection Configuration After modifying a collection configuration, you must manually delete the previous version to avoid duplicate data collection.	Click Collection Configuration. Set Logstore and Log Path in Container (Can be set to stdout). Logstore: the name of the Logstore that you want to use. The name can contain only lowercase letters, digits, and hyphens (-). You can use this parameter to specify the Logstore that stores the collected logs. If the specified Logstore does not exist, the system automatically creates a Logstore in the Simple Log Service project that is associated with the cluster. Log Path in Container (Can be set to stdout): the path from which you want to collect logs. A value of /usr/local/tomcat/logs/catalina.*.log indicates that the log files of a Tomcat application are collected. Note If you set the value to stdout, stdout and stderr are collected. All settings are added as configuration entries to the corresponding Logstore. By default, logs are collected in simple mode (by row). If you want to use other methods to collect logs, log on to the Simple Log Service console and modify the log collection configurations of the project and Logstore. By default, the project uses the k8s-log prefix.
      Custom Tag	Click Custom Tag. Set Tag Key and Tag Value. Each tag is a key-value pair that is appended to the collected log data. You can use custom tags to mark log data. For example, you can use a tag to denote the application version.

   3. After you configure the parameters, click Next to configure advanced settings. For more information about the subsequent steps, see Create a Deployment.

YAML template

1. Log on to the ACK console. In the left navigation pane, click Clusters.

2. On the Clusters page, find the cluster you want to manage and click its name. In the left navigation pane, choose Workloads > Deployments.

3. In the upper part of the Deployments page, select the namespace where you want to create an application from the Namespace drop-down list. Then, click Create from YAML in the upper-right corner of the page.

4. On the Create page, select a template from the Sample Template drop-down list and modify the template content in the Template code editor based on your requirements. Then, click Create.

   YAML templates comply with the Kubernetes syntax. You can use env to define log collection configurations and custom tags. You must also set the volumeMounts and volumes parameters. Sample pod YAML template:

   apiVersion: v1
   kind: Pod
   metadata:
     name: my-demo
   spec:
     containers:
     - name: my-demo-app
       image: 'registry.cn-hangzhou.aliyuncs.com/log-service/docker-log-test:latest'
       args:
       - -c
       - mkdir -p /log;while true; do echo hello world; date; echo hello sls >> /var/log/test.log; sleep 1;done
       command:
       - /bin/sh
       env:
       ######### Specify environment variables ###########
       - name: aliyun_logs_log-stdout
         value: stdout
       - name: aliyun_logs_log-varlog
         value: /var/log/*.log
       - name: aliyun_logs_mytag1_tags
         value: tag1=v1
       ######### Specify volume mounting parameters. ###########
       volumeMounts:
       - name: volumn-sls-mydemo
         mountPath: /var/log
     volumes:
     - name: volumn-sls-mydemo
       emptyDir: {}

   You can add the following configurations based on your requirements:

   Note

   If you have other requirements on log collection, see Step 2: Configure advanced settings in the env field.

   1. Add log collection configurations and custom tags by using environment variables. All environment variables related to log collection must use aliyun_logs_ as the prefix.

      1. Add log collection configurations in the following format:

         - name: aliyun_logs_log-stdout
           value: stdout
         - name: aliyun_logs_log-varlog
           value: /var/log/*.log

         In the preceding example, two environment variables in the following format are added to the log collection configuration: aliyun_logs_{key}. The {keys} of the environment variables are log-stdout and log-varlog.

         • The aliyun_logs_log-stdout environment variable indicates that a Logstore named log-stdout is created to store the stdout collected from containers. The name of the collection configuration is log-stdout. This way, the stdout of containers is collected to the Logstore named log-stdout.

         • The aliyun_logs_log-varlog environment variable indicates that a Logstore named log-varlog is created to store the collected log files from the /var/log/*.log path. The name of the collection configuration is log-varlog. This way, the log files in the /var/log/*.log path are collected to the Logstore named log-varlog.

      2. Add custom tags in the following format:

         - name: aliyun_logs_mytag1_tags
           value: tag1=v1

         After a tag is added, the tag is automatically appended to the log data that is collected from the container. The value of mytag1 can contain only lowercase letters, digits, and hyphens (-).

   2. If you specify a log path to collect log files other than stdout, you must set the volumeMounts parameter. In the preceding YAML template, the mountPath field in volumeMounts is set to /var/log. This allows Logtail to collect log data from the /var/log/*.log file.