Precious Container

POC: One Docker container should be able to run many NestJS applications simultaneously.

Requirements

You need PM2 in order to run the two applications at once. This requires creating ecosystem.config.js in one directory level above the applications.

It should look something like this:

module.exports = {
  apps: [
    {
      name: "rest-api",
      script: "./api/dist/main.js",
    },
    {
      name: "users-service",
      script: "./users/dist/main.js",
    },
  ],
};

Once it is configured, you can use the following commands to test it locally:

Start all applications:

pm2 start ecosystem.config.js

Stop all applications:

pm2 stop ecosystem.config.js

Dockerization Steps:

1. Create Dockerfile one directory level above the application.

2. Configure the Dockerfile to build the application in the respective directory and remove the source.

3. Install PM2 globally inside the image.

4. Set the entrypoint in Dockerfile to use PM2.

5. Set CMD in Dockerfile to use ecosystem.config.js.

Once done, the Dockerfile should look something like this:

FROM node:alpine3.14

# REST API ----------------------- Start

WORKDIR /server

COPY ./api ./api

WORKDIR /server/api

RUN npm ci

RUN npm run build

RUN rm -rf ./api/src

# REST API ----------------------- End

# Users Service ------------------ Start

WORKDIR /server

COPY ./users ./users

WORKDIR /server/users

RUN npm ci

RUN npm run build

RUN rm -rf ./users/src

# Users Service ------------------ End

# Run Ecosystem using PM2 -------- Start

RUN npm install -g pm2

WORKDIR /server

COPY ./ecosystem.config.js ./ecosystem.config.js

EXPOSE 3000

EXPOSE 3001

ENTRYPOINT ["pm2", "--no-daemon", "start"]

CMD [ "ecosystem.config.js" ]

# Run Ecosystem using PM2 -------- End

Demo

You can create a docker-compose.yml file in order to easily run this POC. After running docker-compose up, go to http://localhost:3000 where the REST API is exposed in this demo.