Release process

6 min

Before releasing a new version of Garage, our code pass through a succession of checks and transformations. We define them as our release process.

Trigger and classify a release

While we run some tests on every commits, we do not make a release for all of them.

A release can be triggered manually by "promoting" a successful build. Otherwise, every night, a release build is triggered on the main branch.

If the build is from a tag following the regex: v[0-9]+\.[0-9]+\.[0-9]+, it will be listed as stable. If it is a tag but with a different format, it will be listed as Extra. Otherwise, if it is a commit, it will be listed as development. This logic is defined in nix/build_index.nix.


For each commit, we first pass the code to a formatter (rustfmt) and a linter (clippy). Then we try to build it in debug mode and run both unit tests and our integration tests.

Additionnaly, when releasing, our integration tests are run on the release build for amd64 and i686.

Generated Artifacts

We generate the following binary artifacts for now:

  • architecture: amd64, i686, aarch64, armv6
  • os: linux
  • format: static binary, docker container

Additionnaly we also build two web pages and one JSON document:

We publish the static binaries on our own garage cluster (you can access them through the releases page) and the docker containers on Docker Hub.


We automated our release process with Nix and Drone to make it more reliable. Here we describe how we have done in case you want to debug or improve it.

Caching build steps

To speed up the CI, we use the caching feature provided by Nix.

You can benefit from it by using our provided nix.conf as recommended or by simply adding the following lines to your file:

substituters =
trusted-public-keys =

Sending to the cache is done through nix copy, for example:

nix copy --to 's3://nix?' result

Note that you need the signing key. In our case, it is stored as a secret in Drone.

The previous command will only send the built packet and not its dependencies. To send its dependency, a tool named nix-copy-closure has been created but it is not compatible with the S3 protocol.

Instead, you can use the following commands to list all the runtime dependencies:

nix copy \
  --to 's3://nix?' \
  $(nix-store -qR result/)

We could also write this expression with xargs but this tool is not available in our container.

But in certain cases, we want to cache compile time dependencies also. For example, the Nix project does not provide binaries for cross compiling to i686 and thus we need to compile gcc on our own. We do not want to compile gcc each time, so even if it is a compile time dependency, we want to cache it.

This time, the command is a bit more involved:

nix copy --to \
  's3://nix?' \
   $(nix-store -qR --include-outputs \

This is the command we use in our CI as we expect the final binary to change, so we mainly focus on caching our development dependencies.

Currently there is no automatic garbage collection of the cache: we should monitor its growth. Hopefully, we can erase it totally without breaking any build, the next build will only be slower.

In practise, we concluded that we do not want to cache all the compilation dependencies. Instead, we want to cache the toolchain we use to build Garage each time we change it. So we removed from Drone any automatic update of the cache and instead handle them manually with:

source ~/.awsrc
nix-shell --run 'refresh_toolchain'

Internally, it will run nix-build on nix/toolchain.nix and send the output plus its depedencies to the cache.

To erase the cache:

mc rm --recursive --force 'garage/nix/'

Publishing Garage

We defined our publishing logic in Nix, mostly as shell hooks. You can inspect them in shell.nix to see exactly how. Here, we will give a quick explanation on how to use them to manually publish a release.

Supposing you just have built garage as follow:

nix-build --arg release true

To publish a static binary in result/bin on garagehq, run:

export AWS_ACCESS_KEY_ID=xxx
export DRONE_TAG=handcrafted-1.0.0 # or DRONE_COMMIT
export TARGET=x86_64-unknown-linux-musl

nix-shell --run to_s3

To create and publish a docker container, run:

export DOCKER_AUTH='{ "auths": { "": { "auth": "xxxx" }}}'
export DOCKER_PLATFORM='linux/amd64' # check GOARCH and GOOS from
export CONTAINER_NAME='me/amd64_garage'
export CONTAINER_TAG='handcrafted-1.0.0'

nix-shell --run to_docker

To rebuild the release page, run:

export AWS_ACCESS_KEY_ID=xxx

nix-shell --run refresh_index

If you want to compile for different architectures, you will need to repeat all these commands for each architecture.

In practise, and except for debugging, you will never directly run these commands. Release is handled by drone


Our instance is available at
You need an account on to use it.

Drone CLI - Drone has a CLI tool to interact with. It can be downloaded from its Github release page.

To communicate with our instance, you must setup some environment variables. You can get them from your Account Settings.

To make drone easier to use, you could create a ~/.dronerc that you could source each time you want to use it.

export DRONE_TOKEN=xxx
drone info

The CLI tool is very self-discoverable, just append --help to each subcommands. Start with:

drone --help

.drone.yml - The builds steps are defined in .drone.yml.
You can not edit this file without resigning it.

To sign it, you must be a maintainer and then run:

drone sign --save Deuxfleurs/garage

Looking at the file, you will see that most of the commands are nix-shell and nix-build commands with various parameters.