Build Reference

How to build REX-Ray

Build with Go

The following one-line command is the quickest, simplest, and most deterministic approach to building REX-Ray:

$ go get

The above command will download the REX-Ray sources and build the binary at $GOPATH/bin/rexray.


Using go get to download and install REX-Ray is simple, but it also produces a binary without the correct semantic version. To create the version information use go generate:

$ go generate

To download and build REX-Ray in one line with the correct version information please use the following command:

$ go get -d && \
  go generate && \
  go install

Build Tags

A REX-Ray build can be influenced through the use of Go build tags. For example, the following command builds REX-Ray with only the EBS driver:

go build -tags ebs -o rexray

The table below includes the tags that can be used to determine what type of REX-Ray binary is produced.

Tag Description
agent Builds an agent-only REX-Ray binary
client Builds a client-only REX-Ray binary
controller Builds a controller-only REX-Ray binary

Additionally, each of the directories in ./libstorage/storage/drivers can be used as a build tag to produce a REX-Ray binary with specific drivers.

If no build tags are provided then REX-Ray is built with all drivers and the binary includes the client, agent, and controller modes.

Go Build Requirements

Building REX-Ray with Go has the following requirements:

Requirement Version
Operating System Linux, OS X
Go >=1.6
Git >= 1.7

Build with Docker

Docker can be used to build REX-Ray binaries that have checksums which match the same binaries produced by REX-Ray's official builds on Travis-CI. Simply clone the REX-Ray repository (or fork) and checkout the desired reference. Then use the following command to build REX-Ray:

$ && \
  docker run -it \
  -e SRC -e GOOS -e GOARCH \
  -v "$(pwd)":/go/src/$SRC golang:1.8.3 \
  bash -c "cd src/$SRC && \
  go build -o rexray"

Additionally, if Docker is detected and running on the local host the following command will also use Docker to build REX-Ray:

$ make

Docker Build Requirements

This project has very few build requirements, but there are still one or two items of which to be aware. Also, please note these are the requirements to build REX-Ray, not run it.

Requirement Version
Operating System Linux, OS X
Docker >=17.05

Docker Plug-ins

This section describes how to build and create Docker plug-ins and as such requires Docker.

Creating Docker Plug-ins

The first step to creating a new Docker plug-in is creating its directory and skeleton files. With $DRIVER being the storage platform for which the plug-in is being created, execute the following command:

$ mkdir -p .docker/plugins/$DRIVER

The next step is to create the and config.json files that will be placed in the new directory. Please use this gist as a starting point for creating those files.

Building Docker Plug-ins

To build a Docker plug-in it is first necessary to create the REX-Ray binary that the plug-in will use:


The above command will create a binary named rexray that embeds only the driver specified as the environment variable DRIVER. The next step is to create the Docker plug-in itself:

$ DRIVER=$DRIVER make build-docker-plugin

Version File

There is a file at the root of the project named VERSION. The file contains a single line with the target version of the project in the file. The version follows the format:


For example, during active development of version 0.1.0 the file would contain the version 0.1.0. When it's time to create 0.1.0's first release candidate the version in the file will be changed to 0.1.0-rc1. And when it's time to release 0.1.0 the version is changed back to 0.1.0.

So what's the point of the file if it's basically duplicating the utility of a tag? Well, the VERSION file in fact has two purposes:

  1. First and foremost updating the VERSION file with the same value as that of the tag used to create a release provides a single, contextual reason to push a commit and tag. Otherwise some random commit off of master would be tagged as a release candidate or release. Always using the commit that is related to updating the VERSION file is much cleaner.

  2. The contents of the VERSION file are also used during the build process as a means of overriding the output of a git describe. This enables the semantic version injected into the produced binary to be created using the targeted version of the next release and not just the value of the last, tagged commit.