buildock

Reproducible build environments for local builds using Docker

Do you need to make your builds (e.g. using make and cmake) or software (e.g. using node or python3) to reliably work on a wide range of different host systems, but you still want to keep your actual application's files locally on the host system?

buildock creates a new docker container from an image and mounts the current working directory ($(pwd)) to /app in the container. This enables reliable builds (e.g. using make and cmake) or the use of specific versions of software (e.g. using node or python3) working on a wide range of host systems, but keeps your actual files locally on the host system.

What does it do?

buildock provides two sets of tools:

• A shell function buildock that wraps docker to facilitate easy local builds
• Several pre-built docker images that have software like make and gcc. These images are just for convenience!

How to install

If you just want to try it out:

git clone https://github.com/ulikoehler/buildock
source buildock/buildock.sh

Permanent installation:

For bash:

curl -fsSLhttps://raw.githubusercontent.com/ulikoehler/buildock/master/buildock.sh >> ~/.bashrc

For zsh:

curl -fsSL https://raw.githubusercontent.com/ulikoehler/buildock/master/buildock.sh >> ~/.zshrc
sed -i -e 's/export -f buildock/#export -f buildock/g' ~/.zshrc

This will add a buildock function to your ~/.bashrc or ~/.zshrc.

This function will be automatically loaded once you restart your shell. To load buildock in already active shells, run source ~/.bashrc or source ~/.zshrc, else you'll see command not found: buildock

One-liner to activate in the current shell (not persistent!)

source /dev/stdin < <(curl -fsSL https://techoverflow.net/install-buildock.sh)

How to use

Usage:

buildock [docker run argument(s)] <image name> <command(s)>

Example: To compile a C++ application using make:

buildock ulikoehler/ubuntu-gcc-make make

cmake This command is mostly equivalent to just running make locally, however using the docker-based approach you don't have to deal with different compiler/make versions on different host systems producing.

By default, buildock does not enable interactive mode (docker run --interactive/-i) or allocate a pseudo-TTY (docker run --tty/-t) to facilitate easy automated builds in non-TTY environments like Gitlab runners. In case you need to run in interactive mode (e.g. if you need to interact with the program being run), use this syntax:

buildock -it ulikoehler/ubuntu-gcc-make make

Tips, tricks & limitation:

npm install fails

buildock ulikoehler/ubuntu-opencascade-node:12 npm install

This fails with

npm ERR! path /.npm
npm ERR! code EACCES
npm ERR! errno -13
npm ERR! syscall mkdir
npm ERR! Error: EACCES: permission denied, mkdir '/.npm'
npm ERR!  [Error: EACCES: permission denied, mkdir '/.npm'] {
npm ERR!   stack: "Error: EACCES: permission denied, mkdir '/.npm'",
npm ERR!   errno: -13,
npm ERR!   code: 'EACCES',
npm ERR!   syscall: 'mkdir',
npm ERR!   path: '/.npm'
npm ERR! }
npm ERR! 
npm ERR! The operation was rejected by your operating system.
npm ERR! It is likely you do not have the permissions to access this file as the current user
npm ERR! 
npm ERR! If you believe this might be a permissions issue, please double-check the
npm ERR! permissions of the file and its containing directories, or try running
npm ERR! the command again as root/Administrator (though this is not recommended).

The reason for this is that the current user's ID does not have a home directory on the container and therefore npm tries to access /.npm for its cache, which it can't create.

Workaround: Use -e HOME=/tmp to define a home dir or update buildock since this is the default in more recent versions.

How does it work`

buildock creates a new container using the given imamage an mounts the current working directory ($(pwd)) to /app on said container. It then runs the user-defined command on the container (e.g. make). Additionally it ensures that the docker container runs under the current user using --user $(id -u):$(id -g). This prevents the output files (if any) to be created as root user, instead they will be created with the user and group running buildock.

How to make custom buildock images

Easy: Just use any docker container with the software you need installed. The only requirement is that /app is not used for anything relevant in the image, since /app is where buildock will mount the current directory to.

More reading

• The post that started it all: Towards a docker-based build of C/C++ applications