Collect log files from containers by using Log Service

Step 1: Install Logtail

When you create a cluster, select Enable Log service to install Logtail. You can also install Logtail for an existing cluster.

Install Logtail when you create a cluster:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. In the upper-right corner of the Clusters page, click Create Kubernetes Cluster.
   In this example, only the steps to enable Log Service are described. For more information about how to create an ACK cluster, see Create a managed Kubernetes cluster.
4. In the Component Configurations step, select Enable Log Service to install Logtail for the Kubernetes cluster to be created.

   When the Enable Log Service check box is selected, the system prompts you to create a Log Service project. For more information about how log files are managed in Log Service, see Projects). Select one of the following methods to specify a project in one of the following ways:

   • You can select an existing project to manage the collected log files.
   • You can click Create Project. Then, a project named k8s-log-{ClusterID} is automatically created to manage the collected log files. ClusterID indicates the unique ID of the cluster to be created.
5. After you set the parameters, click Create Cluster in the lower-right corner. In the message that appears, click OK.
   After the ACK cluster is created, you can find the cluster that has Logtail enabled on the Clusters page.

Install Logtail for an existing cluster:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, find the cluster that you want to manage and click the name of the cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the details page, choose Operations > Add-ons. In the Logs and Monitoring section, find logtail-ds.
5. Click Install next to logtail-ds.
6. In the Note message, click OK.

If an earlier version of Logtail is installed, click Upgrade next to logtail-ds.

Step 2: Configure Log Service when you create an application

You can configure Log Service to collect log files from containers when you create an application. You can use the wizard in the console or YAML templates to create applications.

Use the wizard in the console to create an application and configure Log Service

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, find the cluster that you want to manage and click the name of the cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the details page, choose Workloads > Deployments.
5. On the Deployments page, select a namespace from the Namespace drop-down list. Then, click Create from Image in the upper-right corner of the page.
6. In the Basic Information step, specify Name, Replicas, and Type. Then, click Next to go to the Container step.
   The following steps describe how to configure Log Service. For more information about other configuration items, see Use a Deployment to create a stateless application.
7. In the Log section, click the plus sign (+) to add a Logstore. You must specify Logstore and Log Path in Container (Can be set to stdout).
   • Logstore: specifies the Logstore that stores collected log files. If the specified Logstore does not exist, the system automatically creates a Logstore in the Log Service project that is associated with the cluster.
     Note The name of the Logstore cannot contain underscores (_). You can use hyphens (-) instead.
   • Log Path in Container (Can be set to stdout): specifies the path from which you want to collect log files. For example, /usr/local/tomcat/logs/catalina.*.log indicates that log files from the Tomcat application are collected.
     Note If you set the value to stdout, standard outputs and error messages are collected.

     After you add a configuration entry, the system automatically creates a Logstore. By default, logtail-ds collects log files in simple mode. In this mode, log files are collected by line. To use more log collection methods, go to the Log Service console and modify the log collection configurations of the project and Logstore. By default, the project uses k8s-log as the prefix.

   
8. Add Custom Tag.
   Click the plus sign (+) to add custom tags. Each tag is a key-value pair that is appended to the collected log files. You can use custom tags to mark log data. For example, you can use a tag to denote the application version.
9. After you set the other parameters, click Next to set advanced settings. For more information about advanced settings, see Use a Deployment to create a stateless application.

Create an application by using a YAML template

1. In the left-side navigation pane of the cluster details page, click Workloads.
2. On the Deployments page, select a namespace from the Namespace drop-down list. Then, click Create from YAML in the upper-right corner of the page.
3. The syntax of the YAML template is the same as that of Kubernetes. You can use env to define collection configurations and custom tags. You must also configure volumeMounts and volumes. The following is an example of a pod for collecting log files:

   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'
       env:
       ######### Configure 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
       ###############################
       ######### Configure volume mounting ###########
       volumeMounts:
       - name: volumn-sls-mydemo
         mountPath: /var/log
     volumes:
     - name: volumn-sls-mydemo
       emptyDir: {}
     ###############################

   Perform the following steps in sequence based on your needs:

   Note If you have more requirements for log collection, see Step 3: Configure advanced parameters in the env field.

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

        - name: aliyun_logs_{Logstore name}
          value: {Log file path}                            

        In the preceding YAML template, two environment variables are added to the log collection configuration. Environment variable aliyun_logs_log-stdout indicates that a Logstore named log-stdout is created to store the stdout files collected from containers.

        Note The name of the Logstore cannot contain underscores (_). You can use hyphens (-) instead.
      • Custom tags must be specified in the following format:

        - name: aliyun_logs_{Tag name without underscores (_)}_tags
          value: {Tag name }={Tag value}                            

        After a tag is added, the tag is automatically appended to the collected log files when logtail-ds collects the container logs.
   2. If you specify a log path to collect log files that are not standard outputs, you must configure volumeMounts.

      In the preceding YAML template, the mountPath field in volumeMounts is set to /var/log. This allows logtail-ds to collect log files from the /var/log/*.log directory.

4. After you modify the YAML template, click Create to submit the configurations.

Step 3: Configure advanced parameters in the env field

- name: aliyun_logs_catalina_tags

   app=catalina

- name: aliyun_logs_catalina_project

   my-k8s-project

- name: aliyun_logs_catalina_logstore

   my-logstore

- name: aliyun_logs_catalina_shard

   4

- name: aliyun_logs_catalina_ttl

   3650

- name: aliyun_logs_catalina_machinegroup

   my-machine-group

• Scenario 1: Collect log files from multiple applications and store them in the same Logstore

  In this scenario, set the aliyun_logs_{key}_logstore parameter. The following example shows how to collect standard outputs from two applications and store the outputs in stdout-logstore.

  Configure the following environment variables for Application 1:

  ######### Configure environment variables ###########
      - name: aliyun_logs_app1-stdout
        value: stdout
      - name: aliyun_logs_app1-stdout_logstore
        value: stdout-logstore

  Configure the following environment variables for Application 2:

  ######### Configure environment variables ###########
      - name: aliyun_logs_app2-stdout
        value: stdout
      - name: aliyun_logs_app2-stdout_logstore
        value: stdout-logstore

• Scenario 2: Collect log files from different applications and store them in different projects
  In this scenario, perform the following steps:

  1. Create a machine group in each project and set the machine group ID in the following format: k8s-group-{cluster-id}, where {cluster-id} is the ID of the cluster. You can customize the machine group name.
  2. Specify the project, Logstore, and machine group in the environment variables for each application.

     ######### Configure environment variables ###########
         - name: aliyun_logs_app1-stdout
           value: stdout
         - name: aliyun_logs_app1-stdout_project
           value: app1-project
         - name: aliyun_logs_app1-stdout_logstore
           value: app1-logstore
         - name: aliyun_logs_app1-stdout_machinegroup
           value: app1-machine-group

Step 4: View log files

The following example shows how to view log files of the Tomcat application created by using the wizard in the console. Log files from the Tomcat application are stored in Log Service. You can log on to the Log Service console to view log files collected from the containers. Perform the following steps to view log files:

1. Log on to the Log Service console.
2. In the Projects section, click the project that is associated with the Kubernetes cluster to go to the Logstores tab. By default, the project name is in the format of k8s-log-{Kubernetes cluster ID}.
3. In the Logstores list, find the Logstore that is specified when you configure log collection. Move the pointer over the Logstore name and click the icon. Then, click Search & Analysis.
4. In this example, you can view standard outputs of the Tomcat application and text log files of containers. You can also find that custom tags are appended to the collected log files.

   

After Log Service is enabled for the application, you can view log files of containers in the ACK console. Perform the following steps to view log files of containers:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, find the cluster that you want to manage and click the name of the cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the details page, choose Operations > Event Center.
5. On the Log Center page, click the Application Logs tab and specify the filter conditions. Then, click Select Logstore to view log files of containers.

More information

1. By default, Log Service collects log files by line and does not parse the log files. If you want to change the log collection mode and parse the log files, modify the log collection configurations in the Log Service console. For more information, see the following topics:
   • Use the console to collect Kubernetes text log files in DaemonSet mode
   • Use the console to collect Kubernetes stdout and stderr outputs in DaemonSet mode
2. You can also use CustomResourceDefinitions (CRDs) to collect log files from Kubernetes clusters
3. For more information about troubleshooting, see Troubleshoot collection errors.