Docker compose build fails in git submodule

[czeni]

Hello,

when connector is added to another repo as a submodule, docker compose build fails.

$ git submodule add [email protected]:Prometheus-X-association/dataspace-connector.git connector
$ git submodule update --init
$ cd connector
$ cp .env.sample .env && cp .env.sample .env.development
$ docker compose build
WARN[0000] /home/czentye/projects/PTX-edge-computing/dataspace/connector/docker-compose.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion 
Compose now can delegate build to bake for better performances
Just set COMPOSE_BAKE=true
[+] Building 0.7s (17/23)                                                                                                                                                                           docker:default
 => [mongodb internal] load build definition from Dockerfile                                                                                                                                                  0.0s
 => => transferring dockerfile: 230B                                                                                                                                                                          0.0s
 => [dataspace-connector internal] load build definition from Dockerfile                                                                                                                                      0.0s
 => => transferring dockerfile: 584B                                                                                                                                                                          0.0s
 => [dataspace-connector internal] load metadata for docker.io/library/node:lts                                                                                                                               0.4s
 => [mongodb internal] load metadata for docker.io/library/mongo:latest                                                                                                                                       0.4s
 => [mongodb internal] load .dockerignore                                                                                                                                                                     0.0s
 => => transferring context: 57B                                                                                                                                                                              0.0s
 => [dataspace-connector internal] load .dockerignore                                                                                                                                                         0.0s
 => => transferring context: 57B                                                                                                                                                                              0.0s
 => CACHED [mongodb 1/1] FROM docker.io/library/mongo:latest@sha256:f6164e498dbaee3966031c1ced1bfa0fd1c4961151b38a770fa6994f4b0dcae7                                                                          0.0s
 => [mongodb] exporting to image                                                                                                                                                                              0.0s
 => => exporting layers                                                                                                                                                                                       0.0s
 => => writing image sha256:2338ebd94aae89efb924773f45e2d116b9d504049ae69f1a9a1c3497e253ac2c                                                                                                                  0.0s
 => => naming to docker.io/library/connector-mongodb                                                                                                                                                          0.0s
 => [dataspace-connector  1/13] FROM docker.io/library/node:lts@sha256:f6b9c31ace05502dd98ef777aaa20464362435dcc5e312b0e213121dcf7d8b95                                                                       0.0s
 => [dataspace-connector internal] load build context                                                                                                                                                         0.1s
 => => transferring context: 2.20MB                                                                                                                                                                           0.1s
 => [mongodb] resolving provenance for metadata file                                                                                                                                                          0.0s
 => CACHED [dataspace-connector  2/13] RUN npm install -g pnpm                                                                                                                                                0.0s
 => CACHED [dataspace-connector  3/13] RUN mkdir -p /usr/src/app                                                                                                                                              0.0s
 => CACHED [dataspace-connector  4/13] WORKDIR /usr/src/app                                                                                                                                                   0.0s
 => CACHED [dataspace-connector  5/13] COPY package.json .                                                                                                                                                    0.0s
 => CACHED [dataspace-connector  6/13] RUN git init                                                                                                                                                           0.0s
 => ERROR [dataspace-connector  7/13] COPY . .                                                                                                                                                                0.0s
------
 > [dataspace-connector  7/13] COPY . .:
------
failed to solve: cannot replace to directory /var/lib/docker/overlay2/5l6keyp2r6gxd7bqp4xaeqwq4/merged/usr/src/app/.git with file

This is only an issue within a submodule.
The main problem is that the line RUN git init in Dockerfile creates a .git folder, which is later to be overwritten with the local .git folder within the line COPY . ..

Temporal solution:

echo .git >>.dockerignore

This solves the build issue and the connector seems runnable whether it is built from a submodule or a regular repo.

However, I am uncertain why RUN git init is necessary in the first place and leaving out the local .git folder is a good solution without side effects.

[nuthub]

I need to echo "\n.git" >> .dockerignore, since .dockerignore doesn't have a newline at the end.