docker-compose entrypoint with multiple or multiline commands

I figured out how!

Steps:

1. In docker-compose.yml, say for service: gvhservice, add below lines of code

  gvhservice:
    entrypoint:
      - "/bin/sh"
      - -ecx
      - |
          yarn install
          yarn build
          sleep infinity

2. optionally, add all these commands to a file say - entrypoint.sh

Where in entrypoint.sh, add below lines of code:

#!/bin/sh

set -ex

yarn install
yarn build
sleep infinity

where in docker-compose.yml, add below lines of code:

  gvhservice:
    entrypoint: entrypoint.sh

3. By using combination of a docker ENTRYPOINT instruction within the container and command instruction and operator | configuration option in docker-compose.yml (suitable for a variable number of commands to be passed during runtime)

build you container with instruction: COPY entrypoint.sh . and

where contents of entrypoint.sh is:

#!/bin/sh

set -ex

exec "$@"

where in docker-compose.yml, add below lines of code

  gvhservice:
    entrypoint: entrypoint.sh
    command:
      - "/bin/sh"
      - -ecx
      - |
          yarn install
          yarn build
          sleep infinity