Docker Configuration for docker/docker-credential-helpers

Building the Docker Credential Helpers

The Docker credential helpers facilitate managing Docker credentials for different environments. This documentation outlines how to set up a development environment using the Dockerfile and Makefile provided.

Step 1: Setting Up Your Development Environment

Clone the Repository: Begin by cloning the docker-credential-helpers repository. You can do this using the following command:
```
git clone https://github.com/docker/docker-credential-helpers.git
cd docker-credential-helpers
```
Install Prerequisites: Make sure you have Docker and Go installed on your machine, as the project relies on both tools.
Review the Dockerfile: The provided Dockerfile handles various aspects of building the project, including cross-compilation and dependency installation.

Step 2: Understanding the Dockerfile

The Dockerfile consists of several stages. Each stage addresses a specific task:

Base Image:
```
FROM golang:${GO_VERSION}-${DEBIAN_VERSION} AS gobase
```
The base image leverages the specified Go and Debian versions.

Dependencies Installation: Dependencies necessary for building the binaries are installed.

RUN apt-get update && apt-get install -y --no-install-recommends clang dpkg-dev file git lld llvm make pkg-config rsync

Building for Different Platforms: Several build stages are defined for different operating systems (Linux, Darwin, Windows). For example:

FROM base AS build-linux
RUN make build-pass build-secretservice PACKAGE=$PACKAGE VERSION=$(cat /tmp/.version) REVISION=$(cat /tmp/.revision) DESTDIR=/out

Step 3: Build and Test Locally

Building the Project: Use the Makefile to build the credential helpers. The general command to initiate the build process is:
```
make build-linux
```
This will create the necessary binaries for Linux.
Running Tests: To ensure the integrity of the code, run the tests defined in the Makefile:
```
make test
```

Step 4: Understanding the Makefile

The Makefile defines several important functions:

Testing: The test function will execute tests across the project:
```
test:
    # Commands to run tests
```
Building Specific Targets: Build targets for different OS platforms can be initiated using:
```
build-linux:
build-osxkeychain:
build-wincred:
```
Cross Compilation: The capability to cross-compile for different platforms is also integrated, which requires environment configuration in the Makefile.

Step 5: Additional Configuration

Environment Variables: Configure any necessary environment variables required for the credential helpers.
Customizing the Build: You may change the versioning or add additional packages by modifying the build arguments in the Dockerfile.
Testing in a Local Docker Environment: To test the built credential helpers, run the following command:
```
docker run --rm -v ~/.docker:/root/.docker <your-image-name> <commands>
```

This facilitates interaction with the constructed Docker credential helpers in a local testing environment.

Conclusion

By following the outlined steps, expert developers can efficiently set up and manage their development environments for Docker credential helpers. This framework not only supports building and testing but also encourages healthy collaboration across various platforms.

Sources: Dockerfile, Makefile.