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Simple wrappers around Docker etc. for fully isolated build environments

Project description

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Project- and build-oriented tool for working with Docker images and containers

What’s the point of this tool?

Docker is great for building isolated environments for builds or applications. For my tastes, however, there are a few usability issues associated with it:

  • The commands are fiddly to use and difficult to remember
  • Docker containers run as root by default resulting in files created on the host as the root user, instead of the current user
  • It’s too easy to leave intermediate images and containers lying around

Note that this is a very personal list of perceived shortcomings. If these aren’t issues for you, then don’t use this tool!

IBT makes Docker images and containers more development- and project-focused. It encourages the following workflows:

  • Editing of source files is carried out predominantly on the host machine
  • Building, running and debugging of targets is always carried out within the Docker container
  • Source code will typically be under the control of a VCS such as Git
  • Source files should not be copied en masse into the container
  • Output files from builds etc. should be exposed directly to the host

You’ll notice that the commands strongly resemble those of Vagrant. This is not completely accidental. The workflows described above strongly resemble Vagrant workflows where up, destroy, run correspond closely to up, destroy and ssh.

Installation

Ensure you have a working Python 2.7 installation:

pip install --user ibt

You can also clone from this repository and perform a dev install:

git clone https://github.com/rcook/ibt.git
cd ibt
pip install --user -e .

Note that Pip installs scripts to $HOME/.local/bin by default (varies based on platform), so make sure that this path is available on the system search path (via the PATH environment variable). You can do this by appending this in your .bashrc or other shell configuration script:

echo 'export PATH=$HOME/.local/bin:$PATH' >> ~/.bashrc

Standard commands

  • destroy: destroys the project’s Docker image
  • help: display help
  • info: shows system and project information
  • run: runs a command inside a Docker container
  • script: runs a script inside a Docker container
  • shell: runs an interactive shell inside a Docker container
  • up: creates Docker image for the project after optionally building base Docker image

All commands have available to them the following environment variables:

  • IBTALIASARGS: additional arguments passed on the command line to aliases
  • IBTPROJECTDIR: the current project directory in the container
  • IBTUSER and USER: the user name

Ibtfile settings

Configuration for any given project is driven by the contents of the Ibtfile settings file which should be placed in the root directory of the project. Alternatively, an .ibtprojects file placed in the user’s home directory can be used to specify the location of the Ibtfile for zero or more project root directories for situations where the IBT configuration must be kept out of the source tree.

  • aliases: (optional) one or more project-specific command aliases
  • docker: specifies base Docker image information for project including
  • env_vars: (optional) one or more environment variables to define inside container image and build
  • ports: (optional) one or more host port-container port pairs to
  • container-project-dir: (optional) specifies directory to which project directory is mapped in container configure port forwarding
  • volumes: (optional) one or more additional volumes to mount inside container

Environment variable settings

The environment section contain multiple environment variables to be set in the container. The key represents the environment variable to be created. The value contains either the value or a reference to a substitution. A Substitution value starts with a $ and is resolved against the environment variable map. If the variable is not found, the environment variable is looked up on the host.

env_vars:
    ARTIFACTORY_APIKEY: $ARTIFACTORY_APIKEY
    ARTIFACTORY_USER: BOB_THE_BUILDER
    COMPOSITE_KEY: $ARTIFACTORY_USER@$HOST

Volumes settings

The volume section contains multiple keys and values. The key refers to a path on the host and the value contains the path in the container.

volumes:
   host-path: container-path

Key and values support variable expansion like the environment variables.

volumes:
   $HOME/.kube: /home/$USER/.kube
   $HOME/.aws: /home/$USER/.aws

Sample project

Create Docker images

All build commands will run inside a fully isolated Debian-based Docker container as specified by the project configuration in Ibtfile. First, create the base Docker images:

cd docker
pushd debian-gcc
make build
popd
pushd debian-gcc-python
make build
popd
pushd debian-gcc6
make build
popd
docker images

This creates debian-gcc which contains basic build tools, CMake and gdb and debian-gcc-python which extends this with the addition of Python 2.7. debian-gcc6 includes the GCC 6 toolchain. The last command will list locally available Docker images which will now include ibt/debian-gcc and ibt/debian-gcc-python etc.

Aliases

Once this is done, the following commands (configured as aliases in Ibtfile) can be run to configure/make/run the project code:

  • ibt cmake: generates CMake build directory
  • ibt make: runs make inside CMake build directory
  • ibt exec: runs target binary
  • ibt debug: starts gdb and loads target binary

Example workflow

See contents of example subdirectory.

$ cd example/
$ ibt up
Building Docker image ibt-789dbc504a0690d786ddd43474dfbcc5
$ ibt cmake
-- The C compiler identification is GNU 6.3.0
-- The CXX compiler identification is GNU 6.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/g++
-- Check for working CXX compiler: /usr/bin/g++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /example/build
$ ibt make
Scanning dependencies of target hello-world
[ 50%] Building CXX object CMakeFiles/hello-world.dir/hello-world.cpp.o
[100%] Linking CXX executable hello-world
[100%] Built target hello-world
$ ibt exec first second third
Hello world
argc=4
argv[0] = ./hello-world
argv[1] = first
argv[2] = second
argv[3] = third
$ ibt info
IBT: Isolated Build Tool
https://github.com/rcook/ibt

System information:
  Docker:              installed

Context information:
  Working directory:   /home/user/src/ibt/example
  User:                user (1002)
  Group:               group (1003)

Project information:
  Project directory:   /home/user/src/ibt/example
  Project ID:          789dbc504a0690d786ddd43474dfbcc5
  Configuration file:  /home/user/src/ibt/example/Ibtfile
  Temporary directory: /home/user/src/ibt/example/.ibt

Project user information:
  User:                user (1002)
  Group:               group (1003)

Docker container information:
  Docker image ID:     ibt-789dbc504a0690d786ddd43474dfbcc5
  Project directory:   /example
  Temporary directory: /example/.ibt
  Docker base image:   ibt/debian-gcc6

IBT status:
  Temporary directory: exists
  Docker image:        built

Project aliases:
  cmake = run 'cd $IBTPROJECTDIR && mkdir -p build && cd build && cmake -DCMAKE_BUILD_TYPE=Debug ..'
  debug = shell /bin/sh -c 'cd $IBTPROJECTDIR/build && gdb ./hello-world'
  exec = run 'cd $IBTPROJECTDIR/build && ./hello-world'
  make:
  - cd $IBTPROJECTDIR/build
  - make
$ ibt destroy
Destroying Docker image ibt-789dbc504a0690d786ddd43474dfbcc5

Developer guide

See developer guide

Licence

Released under MIT License

Copyright © 2016, Richard Cook. All rights reserved.

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