I have a NodeJs microservice. Doing yarn start normally works perfectly fine. When I try to use pm2 to start this as a background service, facing the below issue:

复制 1/Users/sairamk/.pm2/logs/api-error-21.log last 15 lines:
 221|api     | /usr/local/Cellar/yarn/0.27.5_1/bin/yarn:2
 321|api     | PREFIX="/usr/local" exec "/usr/local/Cellar/yarn/0.27.5_1/libexec/bin/yarn.js" "$@"
 421|api     |                     ^^^^
 521|api     |
 621|api     | SyntaxError: Unexpected identifier
 721|api     |     at createScript (vm.js:74:10)
 821|api     |     at Object.runInThisContext (vm.js:116:10)
 921|api     |     at Module._compile (module.js:533:28)
1021|api     |     at Object.Module._extensions..js (module.js:580:10)
1121|api     |     at Module.load (module.js:503:32)
1221|api     |     at tryModuleLoad (module.js:466:12)
1321|api     |     at Function.Module._load (module.js:458:3)
1421|api     |     at Object.<anonymous> (/usr/local/lib/node_modules/pm2/lib/ProcessContainerFork.js:70:21)
1521|api     |     at Module._compile (module.js:569:30)
1621|api     |     at Object.Module._extensions..js (module.js:580:10)

PM2 command that I use:

复制 1pm2 start yarn --name api -- start

while npm start for the same, works fine with below command :

复制 1pm2 start npm --name api -- start

Tried exploring many possibilities. What am I doing wrong ?

1

The error you’re getting is because a bash script (yarn) is being executed with node…

pm2’s default interpreter is set to node.

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To run yarn (bash script) correctly, you’ll have to set pm2’s interpreter to bash:

shell:

复制 1pm2 start yarn --interpreter bash --name api -- start

or when you are using the ecosystem.config.js:

复制 1module.exports = {
 2  apps : [{
 3    name      : 'yarn',
 4    script    : 'yarn',
 5    args      : 'start',
 6    interpreter: '/bin/bash',
 7    env: {
 8      NODE_ENV: 'development'
 9    }
10  }]
11};

 

Your yarn command is pointing to a bash script /usr/local/Cellar/yarn/0.27.5_1/bin/yarn and not the yarn.js in the same folder. By manually running something like

复制 1pm2 start /usr/local/Cellar/yarn/0.27.5_1/bin/yarn.js --name api -- start

it should work as expected. Just adapt the path to the current location. In my case it was /usr/share/yarn/bin/yarn.js.

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As a sidenote: executing yarn like this takes up almost double the memory than compared to npm. I don’t know the exact reason, but I’ll stick to npm for pm2 since it should not make any difference, in theory…