automated semantic version bumping
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Semver Resource

A resource for managing a version number. Persists the version number in one of several backing stores.

Source Configuration

  • initial_version: Optional. The version number to use when bootstrapping, i.e. when there is not a version number present in the source.

  • driver: Optional. Default s3. The driver to use for tracking the version. Determines where the version is stored.

There are four supported drivers, with their own sets of properties for configuring them.

git Driver

The git driver works by modifying a file in a repository with every bump. The git driver has the advantage of being able to do atomic updates.

  • uri: Required. The repository URL.

  • branch: Required. The branch the file lives on.

  • file: Required. The name of the file in the repository.

  • private_key: Optional. The SSH private key to use when pulling from/pushing to to the repository.

  • username: Optional. Username for HTTP(S) auth when pulling/pushing. This is needed when only HTTP/HTTPS protocol for git is available (which does not support private key auth) and auth is required.

  • password: Optional. Password for HTTP(S) auth when pulling/pushing.

  • git_user: Optional. The git identity to use when pushing to the repository support RFC 5322 address of the form "Gogh Fir <>" or "".

  • depth: Optional. If a positive integer is given, shallow clone the repository using the --depth option.

  • commit_message: Optional. If specified overides the default commit message with the one provided. The user can use %version% and %file% to get them replaced automatically with the correct values.

s3 Driver

The s3 driver works by modifying a file in an S3 compatible bucket.

  • bucket: Required. The name of the bucket.

  • key: Required. The key to use for the object in the bucket tracking the version.

  • access_key_id: Required. The AWS access key to use when accessing the bucket.

  • secret_access_key: Required. The AWS secret key to use when accessing the bucket.

  • region_name: Optional. Default us-east-1. The region the bucket is in.

  • endpoint: Optional. Custom endpoint for using S3 compatible provider.

  • disable_ssl: Optional. Disable SSL for the endpoint, useful for S3 compatible providers without SSL.

  • skip_ssl_verification: Optional. Skip SSL verification for S3 endpoint. Useful for S3 compatible providers using self-signed SSL certificates.

  • server_side_encryption: Optional. The server-side encryption algorithm used when storing the version object (e.g. AES256, aws:kms).

  • use_v2_signing: Optional. Use v2 signing, default false.

swift Driver

The swift driver works by modifying a file in a container.

  • openstack Required. All openstack configuration must go under this key.

    • container: Required. The name of the container.

    • item_name: Required. The item name to use for the object in the container tracking the version.

    • region: Required. The region the container is in.

    • identity_endpoint, username, user_id, password, api_key, domain_id, domain_name, tenant_id, tenant_name, allow_reauth, token_id: See below The swift driver uses gophercloud to handle interacting with OpenStack. All OpenStack Identity versions are supported through this library. The Authentication properties will pass through to it. For detailed information about the individual parameters, see

gcs Driver

The gcs driver works by modifying a file in a Google Cloud Storage bucket.

  • bucket: Required. The name of the bucket.

  • key: Required. The key to use for the object in the bucket tracking the version.

  • json_key: Required. The contents of your GCP Account JSON Key. Example:

    json_key: |
        "private_key_id": "...",
        "private_key": "...",
        "client_email": "...",
        "client_id": "...",
        "type": "service_account"


With the following resource configuration:

- name: version
  type: semver
    driver: git
    branch: version
    file: version
    private_key: {{concourse-repo-private-key}}

Bumping with a get and then a put:

- get: version
  params: {bump: minor}
- task: a-thing-that-needs-a-version
- put: version
  params: {file: version/version}

Or, bumping with an atomic put:

- put: version
  params: {bump: minor}
- task: a-thing-that-needs-a-version


check: Report the current version number.

Detects new versions by reading the file from the specified source. If the file is empty, it returns the initial_version. If the file is not empty, it returns the version specified in the file if it is equal to or greater than current version, otherwise it returns no versions.

in: Provide the version as a file, optionally bumping it.

Provides the version number to the build as a version file in the destination.

Can be configured to bump the version locally, which can be useful for getting the final version ahead of time when building artifacts.


Note that bump and pre don't update the version resource - they just modify the version that gets provided to the build. An output must be explicitly specified to actually update the version.

out: Set the version or bump the current one.

Given a file, use its contents to update the version. Or, given a bump strategy, bump whatever the current version is. If there is no current version, the bump will be based on initial_version.

The file parameter should be used if you have a particular version that you want to force the current version to be. This can be used in combination with in, but it's probably better to use the bump and pre params as they'll perform an atomic in-place bump if possible with the driver.


One of the following must be specified:

  • file: Optional. Path to a file containing the version number to set.

  • bump and pre: Optional. See Version Bumping Semantics.

When bump and/or pre are used, the version bump will be applied atomically, if the driver supports it. That is, if we pull down version N, and bump to N+1, the driver can then compare-and-swap. If the compare-and-swap fails because there's some new version M, the driver will re-apply the bump to get M+1, and try again (in a loop).

Version Bumping Semantics

Both in and out support bumping the version semantically via two params: bump and pre:

  • bump: Optional. Bump the version number semantically. The value must be one of:

    • major: Bump the major version number, e.g. 1.0.0 -> 2.0.0.
    • minor: Bump the minor version number, e.g. 0.1.0 -> 0.2.0.
    • patch: Bump the patch version number, e.g. 0.0.1 -> 0.0.2.
    • final: Promote the version to a final version, e.g. 1.0.0-rc.1 -> 1.0.0.
  • pre: Optional. When bumping, bump to a prerelease (e.g. rc or alpha), or bump an existing prerelease.

    If present, and the version is already a prerelease matching this value, its number is bumped. If the version is already a prerelease of another type, (e.g. alpha vs. beta), the type is switched and the prerelease version is reset to 1. If the version is not already a pre-release, then pre is added, starting at 1.

    The value of pre can be anything you like; the value will be pre-pended (hah) to a numeric value. For example, pre: build will result in a semver of x.y.z-build.<number>, pre: alpha becomes x.y.z-alpha.<number>, and pre: my-preferred-naming-convention becomes x.y.z-my-preferred-naming-convention.<number>

Running the tests

The tests have been embedded with the Dockerfile; ensuring that the testing environment is consistent across any docker enabled platform. When the docker image builds, the test are run inside the docker container, on failure they will stop the build.

Run the tests with the following command:

docker build -t semver-resource .

Integration tests

The integration requires two AWS S3 buckets, one without versioning and another with. The docker build step requires setting --build-args so the integration will run.

You will need:

  • AWS key and secret
  • An S3 bucket
  • The region you are in (i.e. us-east-1, us-west-2)

Run the tests with the following command, replacing each build-arg value with your own values:

docker build . -t semver-resource --build-arg SEMVER_TESTING_ACCESS_KEY_ID="some-key" --build-arg SEMVER_TESTING_SECRET_ACCESS_KEY="some-secret" --build-arg SEMVER_TESTING_BUCKET="some-bucket" --build-arg SEMVER_TESTING_REGION="some-region"


Please make all pull requests to the master branch and ensure tests pass locally.