source-to-image (sti)

Source-to-image (sti) is a tool for building reproducible docker images. sti produces ready-to-run images by injecting source code into a docker image and assembling a new docker image which incorporates the builder image and built source, and is ready to use with docker run. sti supports incremental builds which re-use previously downloaded dependencies, previously built artifacts, etc.

Interested in learning more? Read on!

Want to just get started now? Check out the instructions.

Philosophy

1. Simplify the process of application source + builder image -> usable image for most use cases (the 80%)
2. Define and implement a workflow for incremental build that eventually uses only docker primitives
3. Develop tooling that can assist in verifying that two different builder images result in the same "docker run" outcome for the same input
4. Use native docker primitives to accomplish this - map out useful improvements to docker that benefit all image builders

Anatomy of a builder image

Creating builder images is easy. sti expects you to supply the following scripts to use with an image:

1. assemble - this script builds and/or deploys the source
2. run- this script runs the deployed source
3. save-artifacts (optional) - this script saves the build context for an incremental build
4. usage (optional) - this script displays builder image usage information

Additionally for the best user experience and optimized sti operation we suggest image to have /bin/sh and tar command inside.

For detailed description of the requirements and the scripts along with examples see builder_image.md

Build workflow

sti build workflow is:

1. sti creates a container based on the build image and passes it a tar file that contains:
   1. The application source in src
   2. The build artifacts in artifacts (if applicable - see incremental builds)
2. sti starts the container and runs its assemble script
3. sti waits for the container to finish
4. sti commits the container, setting the CMD for the output image to be the run script and tagging the image with the name provided.

Incremental builds

sti automatically detects:

• Whether a builder image is compatible with incremental building
• Whether a previous image exists, with the same name as the output name for this build

If a save-artifacts script exists, a prior image already exists, and the --clean option is not used, the workflow is as follows:

1. sti creates a new docker container from the prior build image
2. sti runs save-artifacts in this container - this script is responsible for streaming out a tar of the artifacts to stdout
3. sti builds the new output image:
   1. The artifacts from the previous build will be in the artifacts directory of the tar passed to the build
   2. The build image's assemble script is responsible for detecting and using the build artifacts

NOTE: The save-artifacts script is responsible for streaming out dependencies in a tar file.

Dependencies

1. Docker
2. Go

Installation

Assuming go and docker are installed and configured, execute the following commands:

$ go get github.com/openshift/source-to-image
$ cd ${GOPATH}/src/github.com/openshift/source-to-image
$ export PATH=$PATH:${GOPATH}/src/github.com/openshift/source-to-image/_output/local/go/bin/
$ hack/build-go.sh

Getting Started

You can start using sti right away with the following test sources and publicly available images:

$ sti build git://github.com/pmorie/simple-ruby openshift/ruby-20-centos test-ruby-app
$ docker run -rm -i -p :9292 -t test-ruby-app

$ sti build git://github.com/bparees/openshift-jee-sample openshift/wildfly-8-centos test-jee-app
$ docker run -rm -i -p :8080 -t test-jee-app

Interested in more advanced sti usage? See cli.md for detailed CLI description with examples.