Serverless App Engine:Diagnose applications with a webshell

Routine checks

You can diagnose an SAE application by performing routine checks, such as verifying the process, threads, and Java Virtual Machine (JVM) health for a Java application.

• Run the following command to check whether the application's Java process exists.

  ps -ef | grep java

  Note

  A container typically uses its main process to start an application. If the application stops, the container also exits. SAE then automatically restarts the exited container to prevent service interruptions.

  • If the process does not exist, run the dmesg | grep -i kill command to check for out-of-memory (OOM) logs.

  • If such logs exist, it indicates that the application's process was stopped. You need to check the hs_err_pid{PID}.log file in the working directory to identify the root cause.

• For online analysis of Java applications, you can also use Arthas, an open-source tool from Alibaba. We recommend integrating the Arthas tool into your test image for routine diagnostics. Arthas can display Java class loading status in real time, making it easy to observe method input and output parameters, environment variables, and more.

  1. Connect to the internet.

     For more information, see Configure a NAT gateway to allow an SAE application to access the internet.

  2. Run the following command to download Arthas.

     sudo wget https://alibaba.github.io/arthas/arthas-boot.jar

  3. Run the following command to start Arthas.

     sudo java -jar arthas-boot.jar

Upload and download logs

If routine checks are insufficient, upload the logs from the container to the cloud and then download them to your local machine for analysis.

• For files up to 10 MB, use the webshell's built-in file transfer features. For more information, see Use a webshell to upload and download files.

• For files larger than 10 MB: You can use Alibaba Cloud OSS. The OSS service is accessible from all Alibaba Cloud network environments, so you can use it to upload and download logs. Follow these steps:

1. Install the OSS command-line tool (ossutil) inside the container. For more information, see Install the OSS command-line tool.

   This topic uses a 64-bit CentOS system as an example. If your container does not have internet access, you can download the file to your local machine, upload it to OSS, and then obtain the VPC-internal endpoint of OSS to download the file from within the container.

   1. Run the following command to download ossutil.

      sudo wget http://gosspublic.alicdn.com/ossutil/1.5.0/ossutil64

   2. Run the following command to change the file permissions.

      sudo chmod 755 ossutil64

2. Configure the OSS command-line tool with the endpoint for the VPC in the current region and the AccessKey of the account that will receive the uploaded files. Then, check an existing bucket to verify that the OSS service is available.

   Note

   • Ensure that OSS is activated for an Alibaba Cloud account, which does not need to be the current one.

   • Create a bucket. For more information, see Create a bucket in the console.

   1. Run the following command to create a configuration file to store OSS access information.

      Follow the prompts to configure your AccessKey and endpoint information. You do not need to enter an STS token.

      ./ossutil64 config  

   2. Run the following command to list all buckets.

      Check whether the account is available. If an error is reported, the configuration is incorrect.

      ./ossutil64 ls

      Example output:

      CreationTime                                 Region    StorageClass    BucketName
      2021-12-08 18:53:46 +0800 CST       oss-cn-hangzhou        Standard    oss://test-bucket

   3. Run the following command to create a sample log file named sae-app.log.

      echo "Hello" > sae-app.log

   4. Run the following command to upload the log file to the specified bucket.

      ./ossutil64 cp sae-app.log {bucket-address}                                       

      Example:

      ./ossutil64 cp sae-app.log oss://test-bucket

3. Verify the result.

   • Method 1: Run the following command to view the uploaded sample file.

     ./ossutil64 ls oss://test-bucket

     Example output:

     LastModifiedTime                   Size(B)  StorageClass   ETAG                                  ObjectName
     2021-12-08 19:26:18 +0800 CST            6      Standard   09F7E02F1290BE211DA707A266F1****      oss://cri-55md3gmii09m****-chart/sae-app.log
     Object Number is: 1
     0.047758(s) elapsed

   • Method 2: Find your log file in the OSS console or other tools, download it to your local machine, and then use your preferred tools for analysis.