Log4j is an open-source project of Apache, which consists of three important components: log level, log output destination, and log output format. By configuring Log4jAppender, you can set the log output destination to console, file, GUI component, socket server, NT event recorder, or UNIX Syslog daemon.

This document introduces how to configure a YAML file to output Alibaba Cloud Container Service Kubernetes cluster logs to Alibaba Cloud Log Service, without modifying the application codes. In this document, deploy a sample API application in the Kubernetes cluster for demonstration.

Prerequisites

  • You have activated Container Service and created a Kubernetes cluster.

    In this example, create a Kubernetes cluster in the region of China East 1 (Hangzhou).

  • Enable AccessKey or Resource Access Management (RAM). Make sure you have sufficient access permissions. Use the AccessKey in this example.

Step 1 Configure Log4jAppender in Alibaba Cloud Log Service

  1. Log on to theLog Service console.
  2. On the Project List page, click Create Project in the upper-right corner. Complete the configurations and then click Confirm to create the project.

    In this example, create a project named k8s-log4j and select the same region (China East 1 (Hangzhou)) as the Kubernetes cluster.

    Note Generally, create a Log Service project in the same region as the Kubernetes cluster. When the Kubernetes cluster and Log Service project are in the same region, log data is transmitted by using the intranet, which saves the Internet bandwidth cost and time of data transmission because of different regions, and implements the best practice of real-time collection and quick query.


  3. After being created, the project k8s-log4j is displayed on the Project List page. Click the project name.
  4. The Logstore List page appears. Click Create in the upper-right corner.


  5. Complete the configurations and then click Confirm.
    In this example, create a Logstore named k8s-logstore.


  6. Then, a dialog box asking you to use the data import wizard appears.


  7. Click Data Import Wizard. In the Select Data Source step, select log4jAppender under Other Sources and then complete the configurations as instructed on the page.
    Use the default configurations in this example. Configure the settings according to the specific scenarios of log data.


Step 2 Configure Log4jAppender in the Kubernetes cluster

In this example, use the sample YAML files demo-deployment and demo-service for demonstration.

  1. Connect to your Kubernetes cluster.

    For more information, see Access Kubernetes clusters by using SSH or Connect to a Kubernetes cluster by using kubectl.

  2. Obtain the demo-deployment.yaml file and configure the environment variable JAVA_OPTS to collect logs from the Kubernetes cluster.

    The sample orchestration of the demo-deployment.yaml file is as follows: 

    apiVersion: apps/v1beta2
kind: Deployment
metadata:
  name: log4j-appender-demo-spring-boot
  labels:
    app: log4j-appender
spec:
  replicas: 1
  selector:
    matchLabels:
      app: log4j-appender
  template:
    metadata:
    labels:
      app: log4j-appender
  spec:
    containers:
    - name: log4j-appender-demo-spring-boot
      image: registry.cn-hangzhou.aliyuncs.com/jaegertracing/log4j-appender-demo-spring-boot:0.0.2
      env:
      - name: JAVA_OPTS ##Note
        value: "-Dproject={your_project} -Dlogstore={your_logstore} -Dendpoint={your_endpoint} -Daccess_key_id={your_access_key_id} -Daccess_key={your_access_key_secret}"
      ports:
      - containerPort: 8080

    Wherein:

    • -Dproject: The name of the used Alibaba Cloud Log Service project. In this example, it is k8s-log4j.
    • -Dlogstore: The name of the used Alibaba Cloud Log Service Logstore. In this example, it is k8s-logstore.
    • -Dendpoint: The service endpoint of Log Service. You must configure your service endpoint according to the region where the Log Service project resides. For more information, see Service endpoint. In this example, it is cn-hangzhou.log.aliyuncs.com.
    • -Daccess_key_id: Your AccessKey ID.
    • -Daccess_key: Your AccessKey Secret.
  3. Run the following command in the command line to create the deployment: 
    kubectl create -f demo-deployment.yaml
  4. Obtain the demo-service.yaml file and run the following command to create the service.

    No need to modify the configurations in the demo-service.yaml file. 

    kubectl create -f demo-service.yaml

Step 3 Test to generate Kubernetes cluster logs

You can run the kubectl get command to view the deployment status of the resource object. Wait until the deployment and the service are successfully deployed. Then, run the kubectl get svc command to view the external access IP of the service, that is, the EXTERNAL-IP. 

$ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
log4j-appender-demo-spring-boot-svc LoadBalancer 172.21. XX.XX 120.55. XXX.XXX 8080:30398/TCP 1h

In this example, test to generate Kubernetes cluster logs by running the login command, wherein, K8S_SERVICE_IP is the EXTERNAL-IP.

Note See GitHub log4j-appender-demo to view the complete collection of APIs. 
curl http://${K8S_SERVICE_IP}:8080/login? name=bruce

Step 4 View logs in Alibaba Cloud Log Service

Log on to the Log Service console.

Click the project name and click Search at the right of the Logstore k8s-logstore to view the output logs of the Kubernetes cluster.


The output content of the log corresponds to the preceding command. This example demonstrates how to output the logs of the sample application to Alibaba Cloud Log Service. By completing the preceding steps, you can configure Log4JAppender in Alibaba Cloud and implement advanced functions such as collecting logs in real time, filtering data, and querying logs by using Alibaba Cloud Log Service.