Use Log Service to collect container logs

Step 1: Activate Logtail

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

Activate Logtail when you create a cluster:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, click Create Kubernetes Cluster in the upper-right corner. For more information, see Create a cluster.
4. In the Select Cluster Template dialog box, select a template.
5. In the Component Configurations step, select the Log Service check box to install Logtail for the newly created Kubernetes cluster.
6. After you select the Enable Log Servicecheck box, specify a project to manage log data. For more information about projects, see Projects.
   • You can select an existing project.
   • Create a project to manage logs. By default, the system names the project in the format of k8s-log-{ClusterID}, where ClusterID is the unique identifier of the Kubernetes cluster to be created.
7. After you set the parameters, click Create Cluster in the upper-right corner. In the dialog box that appears, click OK to create the cluster.
   You can find the created cluster 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, click the name of a cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane of the Cluster Information page, choose Operations > Add-ons, and find logtail-ds in the System Add-ons section.
5. On the right of logtail-ds, click Install.
   
6. In the Confirm message, click Confirm.

If you have installed Logtail of an earlier version, you can upgrade it in the System Add-ons section.

Step 2: Configure Log Service when you create an application

You can configure Log Service to collect container logs when you create an application. You can use the wizard in the console or YAML templates to create applications.

Use the wizard to create an application:

1. Log on to the ACK console.
2. In the left-side navigation pane, click Clusters.
3. On the Clusters page, click the name of a cluster or click Details in the Actions column. The details page of the cluster appears.
4. In the left-side navigation pane, click Workload.
5. Select a Namespace and click the Deployments tab. 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 on to the Container step.
   
7. On the Container page, specify the image. In this example, NGINX is selected.
   The following text describes configurations about Log Service only. For information about other configuration items, see Use an image to create a stateless application.
8. In the Log section, click the plus sign (+) to create collection configuration entries, each of which consists of a Logstore name and a log path.
   • Logstore name: specifies the Logstore that stores logs. 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 Logstore name cannot contain underscores (_). Use hyphens (-) instead.
   • Log path: specifies the path of the logs that you want to collect. For example, /usr/local/tomcat/logs/catalina. *.log indicates Tomcat log files.
     Note If you set the log path to stdout, standard output logs and standard error logs (stderr) are collected.

     Each configuration entry is automatically used as the configuration entry of the specified Logstore. By default, the system collects logs by line. If you need more collection methods, log on to the Log Service console to modify the log collection configurations of the related project and Logstore. By default, the project uses k8s-log as the prefix.

   
9. Custom tags.
   Click the plus sign (+) to create custom tags. Each tag is a key-value pair that will be appended to the collected logs. You can add custom tags to log data. For example, you can use a tag to denote the log version.
10. After you set all parameters, click Next to configure advanced settings. For more information about advanced settings, see Use an image to create a stateless application.

Use a YAML template to create an application

1. In the left-side navigation pane, click Workload.
2. Select a Namespace and click the Deployments tab. Click Create from Template in the upper-right corner of the page.
3. YAML templates follow the Kubernetes syntax. You can use the env field to add collection configurations and custom tags. You also need to create volumeMounts and volumes. The following example shows how to configure Log Service in a pod:

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

   Perform the following steps based on your needs:

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

   1. Use environment variables to add collection configurations and custom tags. All environment variables related to log collection must use aliyun_logs_ as the prefix.
      • Collection configurations must be in the following format:

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

        In the preceding example, two environment variables are used to configure log collection. The environment variable aliyun_logs_log-stdout instructs the system to create a Logstore named log-stdout. This Logstore collects stdout logs of the container.

        Note A Logstore name cannot contain underscores (_). 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 custom tag is specified, it is automatically appended to log fields when the Logstore collects logs from the container.
   2. If you specify a log path to collect log files other than standard outputs, you must add the volumeMounts field.

      In the preceding example, the volumeMounts field is added and set to /var/log. This allows the specified Logstore to collect /var/log/*.log files.

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

Optional. 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_tags

   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 logs 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 output logs from two applications and store them in stdout-logstore.

  Set the following environment variables for Application 1:

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

  Set the following environment variables for Application 2:

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

• Scenario 2: Collect logs 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.

     ######### Specify 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 logs

The following example shows how to view logs of the Tomcat application created in the console. Tomcat application logs are stored in Log Service. Perform the following steps to view logs:

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 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 container logs. You can also find custom tags that are appended to log fields.

   

More information

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