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Blockchain Client Release Process

Details of the release process for updating the blockchain client on the Celo platform.


Releases of celo-blockchain are numbered according to semantic versioning, as described at

All builds are identified as unstable (a development build) or stable (a commit released as a particular version number). There should only ever exist one commit with a version x.y.z-stable for any (x, y, z).


Artifacts produced by this build process (e.g. Docker images) will be signed by cosign.


Documentation for client features, such as APIs and commands, are maintained in the docs directory within the celo-blockchain repository. Documentation on protocol features, such as the proof-of-stake protocol, is hosted on

Identifying releases:

Git branches

Each minor version of celo-blockchain has its own “release branch”, e.g. release/1.0.

Development is done on the master branch, which corresponds to the next major or minor version. Changes to be included in a patch release of an existing minor version are cherry-picked to that existing release branch.

Git tags

All releases should be tagged with the version number, e.g. vX.Y.Z. Each release should include a summary of the release contents, including links to pull requests and issues with detailed description of any notable changes.

Tags should be signed and can be verified with the following command.

git verify-tag vX.Y.Z

On Github, each release tag should link to the respective Docker image, along with signatures that can be used to verify those images.

Docker tags

Each released Docker image should should be tagged with it’s version number such that for release x.y.z, the image should have tags x, x.y, and x.y.z, with the first two tags potentially being moved from a previous image. Just as a Git tag x.y.z immutably points to a commit hash, the Docker tag, x.y.z should immutably point to an image hash.

Build process

Docker images

Docker images are built automatically with Google Cloud Build upon pushes to master and all release branches. Automated builds will be tagged in Google Container Registry with the corresponding commit hash.

A signature should be produced over the image automatically built at the corresponding commit hash and included with the Github release.

Release image signatures can be verified with the following command:

docker save $(docker image inspect -f '{{ .Id }}') | gpg --verify celo-blockchain-vX.Y.Z.docker.asc -


All builds of celo-blockchain are automatically tested for performance and backwards compatibility in CI. Any regressions in these tests should be considered a blocker for a release.

Minor and major releases are expected to go through additional rounds of manual testing as needed to verify behavior under stress conditions, such as a network with faulty nodes, and poor network connectivity.

Promotion process

Source control

Patch releases should be constructed by cherry-picking all included commits from master to the release/x.y branch. The first commit of this process should change the version number encoded in the source from x.y.z-stable to x.y.z+1-unstable and the final commit should change the version number to x.y.z+1-stable.

Major and minor releases should be constructed by pushing a commit to the master branch to change the encoded version number from x.y.z-unstable to x.y.z-stable. A release/x.y branch should be created from this commit. The next commit must change the version number from x.y.z-stable to x.y+1.0-unstable, or x+1.0.0-unstable if the next planned release is a major release.

Only one commit should ever have a “stable” tag at any given version number. When that commit is created, a tag should be added along with release notes. Once the tag is published it should not be reused for any further release or changes.

Emergency Patches

Bugs which affect the security, stability, or core functionality of the network may need to be released outside the standard release cycle. In this case, an emergency patch release should be created on top of all supported minor releases which contains the minimal change and corresponding test for the fix.

If the issue is not exploitable, release notes should describe the issue in detail and the image should be distributed publicly.

If the issue is exploitable and mitigations are not readily available, a patch should be prepared privately and signed binaries should be distributed from private commits. Establishing trust is key to pushing out the fix. An audit from a reputable third party may be contracted to verify the release to help earn that trust. Once a majority of validators updated, patch details can be made public.

Pushing an upgrade with this process will be disruptive to any nodes that do not upgrade quickly. It should only be used when the circumstances require it.

Vulnerability Disclosure

Vulnerabilities in celo-blockchain releases should be disclosed according to the security policye