Running gulp in Docker compose - does not create files - node.js

Question

I have issues where gulp is not making any files. It says finished, but no file is being created.
If I log in to my docker instance using:
docker exec -t -i myservice-service /bin/bash
and if I run the gulp command, then it creates it properly
Then all the files defined in the gulpfile.js are created. In other words, public/dist/ is populated with the main.js and other css files.
This is my Dockerfile.
FROM node:9
RUN mkdir -p /usr/src/app
RUN mkdir -p /usr/src/logs
WORKDIR /usr/src/app
# GULP Installation
RUN npm install -g gulp
RUN npm install gulp
COPY package*.json /usr/src/app/
COPY .npmrc /usr/src/app/
RUN cd /usr/src/app/ && npm install && npm install -g nodemon
COPY . /usr/src/app
RUN chown -R node:node /usr/src/app && chown -R node:node /usr/src/logs
USER node
EXPOSE 3000
RUN gulp
CMD ["npm", "run-script", "start" ]
And this is my composer file (development):
version: "3"
services:
myservice-service:
build: .
image: myservice-service
container_name: myservice-service
volumes:
- .:/usr/src/app
- /usr/src/app/node_modules
environment:
- NODE_ENV=dev
ports:
- 3000:3000
command: nodemon --delay 2 ./bin/www
I run it as:
docker-compose -f docker-compose.development.yml up --build
When I run it like that, it does not create any files. I get the same output on the screen, when I run the command manually.
I have spent hours trying to make it work, I tried with setting permissions and what not, but it just does not work.
My expectation was to have public/dist/ populated with files.
Any help is appreciated.
UPDATE. It works, but I have doubts:
I manage to make it work by using command inside the composerfile itself.
So in my case:
command: bash -c "gulp && nodemon --delay 2 ./bin/www"
In my reasoning, gulp should be done inside the Dockerfile itself, not on the composer files. But then again, it is out of my scope of knowledge.

Answer 1

The Dockerfile is run at build time and will COPY all the files in your local directory into the container, then run gulp and create any files.
You then mount the local folder over the docker containers file system, pretty much overwriting what was done in the docker file with the original files, as gulp ran on the files in the container, it did not effect the original files so you are undoing the changes.
The solutions are either to do as as you have mentioned in your question (add it to the command in docker-compose.yml or run it via docker-compose exec) or write a custom entrypoint script that will run gulp and then the command, something like:
bin/entrypoint.sh
#!/bin/sh
gulp
exec "$#"
Dockerfile
FROM node:9
COPY bin/entrypoint.sh /entrypoint.sh
RUN chmod 755 /entrypoint.sh
RUN mkdir -p /usr/src/app
RUN mkdir -p /usr/src/logs
WORKDIR /usr/src/app
# GULP Installation
RUN npm install -g gulp
RUN npm install gulp
COPY package*.json /usr/src/app/
COPY .npmrc /usr/src/app/
RUN cd /usr/src/app/ && npm install && npm install -g nodemon
COPY . /usr/src/app
RUN chown -R node:node /usr/src/app && chown -R node:node /usr/src/logs
USER node
EXPOSE 3000
ENTRYPOINT ["/entrypoint.sh"]
CMD ["npm", "run-script", "start" ]
This will make your build a little less predictable though as it will run gulp each time the container starts (e.g. after every deployment) if you use the same Dockerfile in dev and production.