Building Syncthing

Note

You probably only need to go through the build process if you are going to do development on Syncthing or if you need to do a special packaging of it. For all other purposes we recommend using the the official binary releases instead.

Note

If you’re on Linux and want the quickest possible start, check out Building with Docker. Otherwise follow the guide below to set up the development environment on your computer.

Branches and Tags

You should base your work on the master branch when doing your development. This branch is usually what will be going into the next release and always what pull requests should be based on.

If you’re looking to build and package a release of Syncthing you should instead use the latest tag (vX.Y.Z) as the contents of master may be unstable and unsuitable for general consumption.

Prerequisites

  • Go 1.3 or higher

  • Git

If you’re not a Go developer since before, the easiest way to get going is to download the latest version of Go as instructed in http://golang.org/doc/install and export GOPATH=~.

Note

You need to set GOPATH correctly and the source must be checked out into $GOPATH/src/github.com/syncthing/syncthing. The instructions below accomplish this correctly.

Building (Unix)

  • Install the prerequisites.

  • Open a terminal.

# This should output "go version go1.3" or higher.
$ go version

# Go is particular about file locations; use this path unless you know very
# well what you're doing.
$ mkdir -p ~/src/github.com/syncthing
$ cd ~/src/github.com/syncthing
# Note that if you are building from a source code archive, you need to
# rename the directory from syncthing-XX.YY.ZZ to syncthing
$ git clone https://github.com/syncthing/syncthing

# Now we have the source. Time to build!
$ cd syncthing

# You should be inside ~/src/github.com/syncthing/syncthing right now.
$ go run build.go

Unless something goes wrong, you will have a syncthing binary built and ready in ~/src/github.com/syncthing/syncthing/bin.

Building (Windows)

  • Install the prerequisites.

  • Open a cmd Window:

    # This should output "go version go1.3" or higher.
> go version

# Go is particular about file locations; use this path unless you know very
# well what you're doing.
> mkdir c:\src\github.com\syncthing
> cd c:\src\github.com\syncthing
# Note that if you are building from a source code archive, you need to
# rename the directory from syncthing-XX.YY.ZZ to syncthing
> git clone https://github.com/syncthing/syncthing

# Now we have the source. Time to build!
> cd syncthing
> go run build.go

Unless something goes wrong, you will have a syncthing.exe binary built and ready in c:\src\github.com\syncthing\syncthing\bin.

Subcommands and Options

The following build.go subcommands and options exist.

  • go run build.go install – installs binaries in ./bin (default command, this is what happens when build.go is run without any commands or parameters).

  • go run build.go build – forces a rebuild of the binary to the current directory; similar to install but slower.

  • go run build.go clean – remove build artefacts, guaranteeing a complete rebuild. Use this when switching between normal builds and noupgrade builds.

  • go run build.go test – run the tests.

  • go run build.go tar – create a Syncthing tar.gz dist file in the current directory. Assumes a Unixy build.

  • go run build.go zip – create a Syncthing zip dist file in the current directory. Assumes a Windows build.

  • go run build.go  assets – rebuild the compiled-in GUI assets.

  • go run build.go  deps – update the in-repo dependencies.

  • go run build.go  xdr – regenerate the XDR en/decoders. Only necessary when the protocol has changed.

The options -no-upgrade, -goos and -goarch can be given to influence install, build, tar and zip. Examples:

  • go run build.go -goos linux -goarch 386 tar – build a tar.gz distribution of Syncthing for linux-386.

  • go run build.go -goos windows -no-upgrade zip – build a zip distribution of Syncthing for Windows (current architecture) with upgrading disabled.

Note

Building for a different operating system or architecture than your native one requires Go having been set up for cross compilation. The easiest way to get this right is to use the official Docker image, described below.

Building without Git

Syncthing can be built perfectly fine from a source tarball of course. If the tarball is from our build server it contains a file called RELEASE that informs the build system of the version being built. If you’re building from a different source package, for example one automatically generated by Github, you must instead pass the -version flag to build.go.

If you are building something that will be installed as a package (Debian, RPM, …) you almost certainly want to use -no-upgrade as well to prevent the built in upgrade system from being activated.

  • go run build.go -version v0.10.26 -no-upgrade tar – build a tar.gz distribution of syncthing for the current OS/arch, tagged as v0.10.26, with upgrades disabled.

Building with Docker

The Docker based build image exactly replicates the official build process and is a quick way to get up and running with the full cross compiled setup. Start by getting the build image. It is fairly large (about 2 GiB).

$ docker pull syncthing/build:latest

Then check out and build Syncthing.

$ git clone https://github.com/syncthing/syncthing
$ cd syncthing
$ ./build.sh docker-all

A full build is done for all supported architectures, and tests are run. The process should end with a bunch of release files (.tar.gz and .zip) created.