docker permission denied

What's going wrong?

docker permission denied when use child_process.exec('docker restart xxx')

How could we reproduce this issue?

Supporting information

At first, deployer user is not in root:docker, so added.
then 'node app.js' is ok, but start with 'pm2 start app.js' still wrong

Error: Command failed: docker restart offlinechinamap_tileserver_1
Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Post "http://%2Fvar%2Frun%2Fdocker.sock/v1.39/containers/offlinechinamap_tileserver_1/restart": dial unix /var/run/docker.sock: connect: permission denied
at ChildProcess.exithandler (node:child_process:412:12)
at ChildProcess.emit (node:events:513:28)
at maybeClose (node:internal/child_process:1091:16)
at ChildProcess._handle.onexit (node:internal/child_process:302:5) {
code: 1,
killed: false,
signal: null,
cmd: 'docker restart offlinechinamap_tileserver_1'
}

Start by comparing the environment for node app.js with the one used by pm2 start app.js, focusing on the child_process.exec('docker restart xxx') entry point and access to /var/run/docker.sock. Confirm that the Docker restart command works under PM2 with the deployer user; the issue provides no project file or test to run.