How to change context for Dockerfile using docker composer?

user_70600 0
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I'm developing a CMake project that uses Docker to build on Linux. It's 2 libraries and one executable. One of the libraries is made available in source format only and for which I must provide the CMakeLists.txt file myself.

I can't move or copy that directory to my project folder tree on the root of which is my Dockerfile so I need to find a way to reliably ADD that directory to my container every time I build my project. A solution Google returned is to use docker composer to do so, but I can't get it to work.

This is my docker-composer.yml:

version: '3.8'
services:
  dlstreamer:
    build:
      context: ../
      dockerfile: ./PrivacyContainer/Dockerfile

As context shows, the sources I want are in a directory at the same level as my project directory.

And yet, when I open my folder in a container using Visual Studio code that folder is never copied. What should I be looking for?

docker-compose docker cmake linux
3 Answers

The docker build documentation page indicates the following :

The context is limited to the current directory (and its children) for security reasons, and to ensure repeatable builds on remote Docker hosts.

This could explain why setting ../ as context doesn't work.

So I think you should launch the docker build command from within your parent directory containing your sources (../), specify the path of your dockerFile using -f and indicate the context Path as . like this :

docker build -f PrivacyContainer/Dockerfile .

This way, your context includes the directory you want and you'll have access to the files you need for COPY etc.

user_36084830

The folder in your build context will not default be in final image, you should explicitly specify COPY in Dockerfile.

Let's suppose next folder structure to simulate your scenario:

$ tree trial
trial
├── OneLibrary
│   └── main.c
└── PrivacyContainer
    ├── CMakeLists.txt
    ├── docker-compose.yaml
    └── Dockerfile

So, I think your aim is to see both main.c & CMakeLists.txt in final image, then you could do next:

Option 1: Just with Dockerfile:

Dockerfile:

FROM debian
COPY OneLibrary /tmp
COPY PrivacyContainer/CMakeLists.txt /tmp
RUN ls /tmp

Execute next command from the directory of PrivacyContainer:

pie@pie:~/trial/PrivacyContainer$ docker build -t abc:1 -f Dockerfile .. --no-cache
Sending build context to Docker daemon   5.12kB
Step 1/4 : FROM debian
 ---> 5890f8ba95f6
Step 2/4 : COPY OneLibrary /tmp
 ---> 9200efffeba0
Step 3/4 : COPY PrivacyContainer/CMakeLists.txt /tmp
 ---> 33874c7e6be1
Step 4/4 : RUN ls /tmp
 ---> Running in ff9dde40251c
CMakeLists.txt
main.c
Removing intermediate container ff9dde40251c
 ---> d7640c75b197
Successfully built d7640c75b197
Successfully tagged abc:1

You could see both main.c & CMakeLists.txt in the image now.

Option 2: With compose + Above Dockerfile:

docker-compose.yaml:

version: '3'
services:
  dlstreamer:
    build:
      context: ../
      dockerfile: ./PrivacyContainer/Dockerfile

Execute next command from the directory of PrivacyContainer:

pie@pie:~/trial/PrivacyContainer$ docker-compose build --no-cache
Building dlstreamer
Step 1/4 : FROM debian
 ---> 5890f8ba95f6
Step 2/4 : COPY OneLibrary /tmp
 ---> f100c69d7e87
Step 3/4 : COPY PrivacyContainer/CMakeLists.txt /tmp
 ---> fffafba2ceaf
Step 4/4 : RUN ls /tmp
 ---> Running in 139cfb9be5f9
CMakeLists.txt
main.c
Removing intermediate container 139cfb9be5f9
 ---> 0aba679e4e33
Successfully built 0aba679e4e33
Successfully tagged privacycontainer_dlstreamer:latest

You could also see both main.c & CMakeLists.txt in the image now.

user_63947220

Best would be to create repository for the library and get it with git clone in the container. This way you will have control over what had entered in the build

Further more, if your project is already in a git repository, you can use git submodule to include it in the place in the project where you want to build it and fetch the whole project from repository during build and initialize the submodules (which will fetch the library)

user_28167030
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