yarn: install local package from monorepo and use it inside docker image with offline cache

Question

My folder structure looks like this (monorepo):

project
|
+--- /api
|    |
|    +--- /.offline-cache
|    +--- /src
|    |    +--- index.js
|    |    +--- ...
|    |
|    +--- Dockerfile
|    +--- package.json
|    +--- yarn.lock
|
+--- /common
|    |
|    +--- /src
|    |    +--- index.js
|    |
|    +--- package.json
|
+--- /ui
|    |
|    +--- /.offline-cache
|    +--- /src
|    |    +--- index.js
|    |    +--- ...
|    |
|    +--- Dockerfile
|    +--- package.json
|    +--- yarn.lock
|
+--- docker-compose.yml

The offline-cache and building the docker-images for every 'service' (ui, api) are working.

Now I want to access/install the common module inside api and ui as well.
Running yarn add ./../common inside /api works and installs the module inside the api folder and adds it to package.json and yarn.lock file. But when I try to rebuild the docker-image I get an error telling me

error Package "" refers to a non-existing file '"/common"'.

That's because there is no common folder inside the docker container and the installed package isn't added to the offline-mirror :(

I can't copy the common folder to the docker-image because it is outside the build context and I don't want to publish to NPM. What else can I do to get this working?

Answer 1

You can specify a context in your docker-compose.yml, which does not need to be the same directory as your Dockerfile.

So you can create something like this:

version: '3.5'

services:
  ui:
    build:
      context: .
      dockerfile: ui/Dockerfile
    ports:
      - 'xxxx:xxxx'

  api:
    build:
      context: .
      dockerfile: api/Dockerfile
    ports:
      - 'xxxx:xxxx'

The same thing can be done with docker build as well, by adding the -f option, while running the command from the root directory.

docker build -f ui/Dockerfile xxxxxx/ui .

docker build -f api/Dockerfile xxxxxx/api .

You need to be aware, that you have to modify your Dockerfile slightly as well, to match the file structure of the project (using WORKDIR).

FROM node:18-alpine

# switch to root and copy all relevant files
WORKDIR /app
COPY ./ui/ ./ui/
COPY ./common/ ./common/

# switch to relevant path (in this case ui)
WORKDIR /app/ui
RUN yarn && yarn build

CMD ["yarn", "start"]