Docker: Running two services with one Dockerfile

Question

I am working on telegram group for premium members in which I have two services, one is monitoring all the joinee and other one is monitoring if any member has expired premium plan so It would kick out that user from the channel. I am very very new to Docker and deployment things. So I am very confused that, to run two processes simultaneously with one Dockerfile. I have tried like this.

here is the file structure:

start.sh

#!/bin/bash
cd  TelegramChannelMonitor

pm2 start services/kickNonPremium.js --name  KICK_NONPREMIUM

pm2 start services/monitorTelegramJoinee.js --name  MONITOR_JOINEE

Dockerfile

FROM node:12-alpine
WORKDIR ./TelegramChannelMonitor
COPY package*.json ./

RUN npm install
COPY . .

EXPOSE 8080
ENTRYPOINT ["/start.sh"]

What should I do to achieve this?

Answer 1

A Docker container only runs one process. On the other hand, you can run arbitrarily many containers off of a single image, each with a different command. So the approach I'd take here is to build a single image; as you've shown it, except without the ENTRYPOINT line.

FROM node:12-alpine
# Note that the Dockerfile already puts us in the right directory
WORKDIR /TelegramChannelMonitor
...
# Important: no ENTRYPOINT
# (There can be a default CMD if you think one path is more likely)

Then when you want to run this application, run two containers, and in each, make the main container command run a different script.

docker build -t telegram-channel-monitor .
docker run -d -p 8080:8080 --name kick-non-premium \
  telegram-channel-monitor \
  node services/kickNonPremium.js
docker run -d -p 8081:8080 --name monitor-joined \
  telegram-channel-monitor \
  node services/monitorTelegramJoinee.js

You can have a similar setup using Docker Compose. Set all of the containers to build: ., but set a different command: for each.

(The reason to avoid ENTRYPOINT here is because the syntax to override the command gets very clumsy: you need --entrypoint node before the image name, but then the rest of the arguments after it. I've also used plain node instead of pm2 since a Docker container provides most of the functionality of a process supervisor; see also what is the point of using pm2 and docker together?.)

Answer 2

Try pm2 ecosystem for apps(i.e services) declaration and run pm2 in non-backrgound mode or pm2-runtime

https://pm2.keymetrics.io/docs/usage/application-declaration/ https://pm2.keymetrics.io/docs/usage/docker-pm2-nodejs/