dockbuild

Compiling environments in Docker images.

Features

• Commands in the container are run as the calling user, so that any created files have the expected ownership, (i.e. not root).
• Make variables (CC, CXX etc) are set to point to the appropriate tools in the container.
• Recent CMake and ninja are precompiled.
• Conan.io can be used as a package manager.
• Current directory is mounted as the container's workdir, /work.
• Works with the Docker for Mac and Docker for Windows.
• Support using alternative container executor by setting OCI_EXE environment variable. By default, it searches for docker and podman executable.

In addition to the devtools, all images include:

• cmake 3.22.1
• curl with TLS 1.2 support
• git 2.34.1 (with git config --global advice.detachedHead false)
• python 3.9.10
• ninja 1.1.10 with GNU make jobserver client and Fortran support

What is the difference between dockcross and dockbuild ?

The key difference is that dockbuild images use the same method to conveniently isolate the build environment as dockcross but they do NOT provide a toolchain file.

Compiling environments

dockbuild/centos7-devtoolset4-gcc5:latest, dockbuild/centos7:latest

Centos7 based image including the devtools-4.

dockbuild/centos7-devtoolset7-gcc7:latest

Centos7 based image including the devtools-7.

dockbuild/ubuntu1804-gcc7:latest, dockbuild/ubuntu1804:latest

Ubuntu 18.04 based image.

dockbuild/ubuntu2004-gcc9:latest, dockbuild/ubuntu2004:latest

Ubuntu 20.04 based image.

dockbuild/ubuntu2104-gcc11:latest, dockbuild/ubuntu2104:latest

Ubuntu 21.04 based image.

Deprecated build environments

Deprecated build environments are not built/tested/deployed using continuous integration and corresponding Dockerfile have been removed.

dockbuild/centos5-devtoolset2-gcc4:latest, dockbuild/centos5:latest

Centos5 based image including the devtools-2.

dockbuild/centos6-devtoolset2-gcc4:latest, dockbuild/centos6:latest

Centos6 based image including the devtools-2.

dockbuild/ubuntu1004-gcc4:latest, dockbuild/ubuntu1004:latest

Ubuntu 10.04 based image.

dockbuild/ubuntu1604-gcc5:latest, dockbuild/ubuntu1604:latest

Ubuntu 16.04 based image.

dockbuild/ubuntu1904-gcc8:latest, dockbuild/ubuntu1904:latest

Ubuntu 19.04 based image.

dockbuild/ubuntu2010-gcc10:latest, dockbuild/ubuntu2010:latest

Ubuntu 20.10 based image.

Installation

This image does not need to be run manually. Instead, there is a helper script to execute build commands on source code existing on the local host filesystem. This script is bundled with the image.

To install the helper script, run one of the images with no arguments, and redirect the output to a file:

docker run --rm IMAGE_NAME > ./dockbuild
chmod +x ./dockbuild
mv ./dockbuild ~/bin/

Where IMAGE_NAME is the name of the compiling environment Docker instance, e.g. dockbuild/centos5-devtoolset2-gcc4.

Only 64-bit images are provided; a 64-bit host system is required.

Usage

For the impatient, here's how to compile a hello world on centos5-devtoolset2-gcc4:

cd ~/src/dockbuild
docker run --rm dockbuild/centos5-devtoolset2-gcc4 > ./dockbuild-centos5-devtoolset2-gcc4
chmod +x ./dockbuild-centos5-devtoolset2-gcc4
./dockbuild-centos5-devtoolset2-gcc4 bash -c '$CC test/C/hello.c -o hello_centos5'

Note how invoking any build command (make, gcc, etc.) is just a matter of prepending the dockbuild script on the commandline:

./dockbuild-centos5-devtoolset2-gcc4 [command] [args...]

The dockbuild script will execute the given command-line inside the container, along with all arguments passed after the command. Commands that evaluate environmental variables in the image, like $CC above, should be executed in bash -c. The present working directory is mounted within the image, which can be used to make source code available in the Docker container.

Built-in update commands

A special update command can be executed that will update the source cross-compiler Docker image or the dockbuild script itself.

• dockbuild [--] command [args...]: Forces a command to run inside the container (in case of a name clash with a built-in command), use -- before the command.
• dockbuild update-image: Fetch the latest version of the docker image.
• dockbuild update-script: Update the installed dockbuild script with the one bundled in the image.
• dockbuild update: Update both the docker image, and the dockbuild script.

Download all images

To easily download all images, the convenience target display_images could be used:

curl https://raw.githubusercontent.com/dockbuild/dockbuild/master/Makefile -o dockbuild-Makefile
for image in $(make -f dockbuild-Makefile display_images); do
  echo "Pulling dockbuild/$image"
  docker pull dockbuild/$image
done

Install all dockbuild scripts

To automatically install in ~/bin the dockbuild scripts for each images already downloaded, the convenience target display_images could be used:

curl https://raw.githubusercontent.com/dockbuild/dockbuild/master/Makefile -o dockbuild-Makefile
for image in $(make -f dockbuild-Makefile display_images); do
  if [[ $(docker images -q dockbuild/$image) == "" ]]; then
    echo "~/bin/dockbuild-$image skipping: image not found locally"
    continue
  fi
  echo "~/bin/dockbuild-$image ok"
  docker run dockbuild/$image > ~/bin/dockbuild-$image && \
  chmod u+x  ~/bin/dockbuild-$image
done

Dockbuild configuration

TBD

Per-project dockbuild configuration

TBD

How to extend Dockbuild images

TBD

maintainers

Updating CMake version

1. Set CMake version X.Y.Z corresponding to an existing tag. For example:

CMAKE_VERSION=3.22.1

2. Update CMake version, and create a Pull Request

# Get current version
git clone git@github.com:dockbuilb/dockbuild && \
cd $_ && \
PREVIOUS_CMAKE_VERSION=$(cat README.rst | grep "^\* cmake" | cut -d" " -f3) && \
echo "PREVIOUS_CMAKE_VERSION [${PREVIOUS_CMAKE_VERSION}]"

# Update version
git checkout -b update-cmake-from-v${PREVIOUS_CMAKE_VERSION}-to-v${CMAKE_VERSION} && \
\
for file in $(find . -name Dockerfile) README.rst; do
  sed -i "s/${PREVIOUS_CMAKE_VERSION}/${CMAKE_VERSION}/g" $file
done && \
\
git add $(find . -name Dockerfile) README.rst && \
\
git commit -m "Update CMake from v${PREVIOUS_CMAKE_VERSION} to v${CMAKE_VERSION}"

# Inspect changes
git diff HEAD^

# Publish branch
git push origin update-cmake-from-v${PREVIOUS_CMAKE_VERSION}-to-v${CMAKE_VERSION}
git pull-request

3. Check CircleCI and merge Pull Request if tests pass.

Note

• Command sed -i may not be available on all unix systems.
• Command git pull-request is available after install hub

Articles

• How to build distributable C++ executables for Linux with Docker

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Credits go to sdt/docker-raspberry-pi-cross-compiler, who invented the base of the dockcross script.