Unitech
declare app dependencies inside ecosystem
Supporting information
I has json file like this:
"apps": [
{
"name": "app1"
"scripe" : "app.js"
"cwd": "/app1/"
"wait_ready": true
},
{
"name": "app2"
"scripe" : "app.js"
"cwd": "/app2/"
"wait_ready": true
}
]
Can pm2 start /app2/app.js after App name 'app1' status is online?
PM2 version: 2.4.4
Node version: 6.9.4
Linux
We should add a option to be able to declare dependencies between app like docker-compose do.
This would be a really good idea as this is a common scenario in production. Any update on this?
This would be useful for having startup parity between k8s, docker, and others. K8s provides "init-containers", and docker compose allows you to declare depends_on - both allow you to do things before your app runs. This includes (but is not limited to):
- Waiting for databases to be running and accepting connections
- Running database migrations
- Provisioning users for both the database and application
- Ensuring network drives are mounted
- Starting system-level services (smtp, et al)
- Anything else required for the app to run with determinism
These tasks are required for the app to run, but are not the concern of application code. Many of these processes need to run with special admin/root privileges and should run separately (sandboxed) from the app. I know we can wrap pm2 in our own scripts to do all of this, but it would be much cleaner to make it declarative inside pm2 configs. This would allow pm2 configs to mirror k8s and docker.
