snappy

Snappy is part of Ubuntu Core and enables a fully transactional Ubuntu system.

Development

Setting up a GOPATH

When working with the source of Go programs, you should define a path within your home directory (or other workspace) which will be your GOPATH. GOPATH is similar to Java's CLASSPATH or Python's ~/.local. GOPATH is documented http://golang.org/pkg/go/build/ and inside the go tool itself

go help gopath

Various conventions exist for naming the location of your GOPATH, but it should exist, and be writable by you. For example

export GOPATH=${HOME}/work
mkdir $GOPATH

will define and create $HOME/work as your local GOPATH. The go tool itself will create three subdirectories inside your GOPATH when required; src, pkg and bin, which hold the source of Go programs, compiled packages and compiled binaries, respectively.

Setting GOPATH correctly is critical when developing Go programs. Set and export it as part of your login script.

Add $GOPATH/bin to your PATH, so you can run the go programs you install:

PATH="$PATH:$GOPATH/bin"

Getting the snappy sources

The easiest way to get the source for snappy is to use the go get command.

go get -d -v github.com/snapcore/snapd/...

This command will checkout the source of snappy and inspect it for any unmet Go package dependencies, downloading those as well. go get will also build and install snappy and its dependencies. To checkout without installing, use the -d flag. More details on the go get flags are available using

go help get

At this point you will have the git local repository of the snappy source at $GOPATH/github.com/snapcore/snapd. The source for any dependent packages will also be available inside $GOPATH.

Dependencies handling

To generate dependencies.tsv you need godeps, so

go get launchpad.net/godeps

To obtain the correct dependencies for the project, run:

godeps -t -u dependencies.tsv

You can use the script get-deps.sh to run the two previous steps.

If the dependencies need updating

godeps -t ./... > dependencies.tsv

Building

To build, once the sources are available and GOPATH is set, you can just run

go build -o /tmp/snap github.com/snapcore/snapd/cmd/snap

to get the snap binary in /tmp (or without -o to get it in the current working directory). Alternatively:

go install github.com/snapcore/snapd/...

to have it available in $GOPATH/bin

Contributing

Contributions are always welcome! Please make sure that you sign the Canonical contributor licence agreement at http://www.ubuntu.com/legal/contributors

Snappy can be found on Github, so in order to fork the source and contribute, go to https://github.com/snapcore/snapd. Check out Github's help pages to find out how to set up your local branch, commit changes and create pull requests.

We value good tests, so when you fix a bug or add a new feature we highly encourage you to create a test in $source_testing.go. See also the section about Testing.

Testing

To run the various tests that we have to ensure a high quality source just run:

./run-checks

This will check if the source format is consistent, that it build, all tests work as expected and that "go vet" and "golint" have nothing to complain.

You can run individual test with:

go test -check.f $testname

If a test hangs, you can enable verbose mode:

go test -v -check.vv

(or -check.v for less verbose output).

There is more to read about the testing framework on the website

Testing snapd on a snappy system

To test the snapd REST API daemon on a snappy system you need to transfer it to the snappy system and then run:

sudo systemctl stop snapd.service snapd.socket
sudo /lib/systemd/systemd-activate -E SNAPD_DEBUG=1 -l /run/snapd.socket ./snapd

This will stop the installed snapd and activate the new one. Once it's printed out something like Listening on /run/snapd.socket as 3. you should then

sudo chmod 0666 /run/snapd.socket

so the socket has the right permissions (otherwise you need sudo to connect).