This document describes Firecracker release planning, API support, and the Firecracker release lifetime. Firecracker provides this Release Policy to help customers effectively plan their Firecracker based operations.
Firecracker uses semantic versioning 2.0.0 for all
releases. By definition, the API version implemented by a Firecracker binary
is equivalent to that binary’s version. Semantic versions are comprised of
three fields in the form: vMAJOR.MINOR.PATCH. Additional labels for
pre-release and build metadata are available as extensions to the
MAJOR.MINOR.PATCH format.
For example: v0.20.0, v0.22.0-beta5, and v99.123.77+foo.bar.baz.5.
Firecracker publishes major, minor and patch releases:
- Patch release - The
PATCHfield is incremented whenever critical bugs and/or security issues are found in a supported release. The fixes in a PATCH release do not change existing behavior or the user interface. Upgrade is recommended. - Minor release - When the
MINORfield is incremented, the new release adds new features, bug fixes, or both without changing the existing user interface or user facing functionality. Adding new APIs can be done in aMINORFirecracker release as long as it doesn’t change the functionality of the APIs available in the previous release. Minor releases are shipped when features are ready for production. Multiple features may be bundled in the same release. - Major release - When the
MAJORfield is incremented, the new release adds new features and/or bug fixes, changing the existing user interface or user facing functionality. This may make the new release it incompatible with previous ones. A major release will likely require changes from other components interacting with Firecracker, e.g. API request, commands, or guest components. The changes will be detailed in the release notes. Major releases are published whenever features or bug fixes that changes the existing user interface, or user facing functionality, are ready for production.
The Firecracker maintainers will only provide support for Firecracker releases under our repository's release page.
The Firecracker maintainers will provide patch releases for critical bugs and security issues when they are found, for:
- the last two Firecracker
vMAJOR.MINORreleases for up to 1 year from release date; - any Firecracker
vMAJOR.MINORrelease for at least 6 months from release date; - for each
vMAJOR, the latestMINORfor 1 year since release date;
Starting with release v1.0, for each major and minor release, we will also be specifying the supported kernel versions.
- Considering an example where the last Firecracker releases are:
- v2.10.0 released on 2022-05-01
- v2.11.0 released on 2022-07-10
- v2.12.0 released on 2022-09-11
In case of an event occurring in 2022-10-03, all three releases will be patched since less than 6 months elapsed from their MINOR release time.
- Considering an example where the last Firecracker releases are:
- v2.10.0 released on 2022-05-01
- v2.11.0 released on 2022-07-10
- v2.12.0 released on 2022-09-11
In case of of an event occurring in 2023-05-04, v2.11 and v2.12 will be patched since those were the last 2 Firecracker major releases and less than an year passed since their release time.
- Considering an example where the last Firecracker releases are:
- v2.14.0 released on 2022-05-01
- v3.0.0 released on 2022-07-10
- v3.1.0 released on 2022-09-11
In case of of an event occurring in 2023-01-13, v2.14 will be patched since is the last minor of v2 and has less than one year since release while v3.0 and v3.1 will be patched since were the last two Firecracker releases and less than 6 months have passed since release time.
| Release | Release Date | Latest Patch | Min. end of support | Official end of Support |
|---|---|---|---|---|
| v1.2 | 2022-11-30 | v1.2.0 | 2023-05-30 | Supported |
| v1.1 | 2022-05-06 | v1.1.4 | 2022-11-06 | Supported |
| v1.0 | 2022-01-31 | v1.0.2 | 2022-07-31 | 2022-11-30 (v1.2 released) |
| v0.25 | 2021-03-13 | v0.25.2 | 2021-09-13 | 2022-03-13 (end of 1y support) |
The Firecracker API follows the semantic versioning standard. For a new release, we will increment the:
- MAJOR version when we make breaking changes in our API;
- MINOR version when we add or change functionality in a backwards compatible manner;
- PATCH version when we make backwards compatible bug fixes.
Given a Firecracker version X.Y.Z user-generated client, it is guaranteed to work as expected with all Firecracker binary versions X.V.W, where V >= Y.
We will consider a deprecated API endpoint to be an endpoint which still has backing functionality and can be used, but will be removed completely along with said functionality in an upcoming API version. All deprecated endpoints are supported until at least the next MAJOR version release, where they may be removed.
When elements of the API are deprecated in a MINOR release, they will still work for the longest of the following:
- all subsequent Firecracker MINOR releases of the same MAJOR release;
- any Firecracker MINOR release for at least 6 months from release date;
- the next 2 Firecracker releases, regardless if they are MAJOR or MINOR.
A feature is "in" developer preview if it’s marked as such in the Firecracker roadmap and/or in the Firecracker release notes.
Features in developer preview should not be used in production as they are not supported. Firecracker team may not provide patch releases for critical bug fixes or security issues found in features marked as developer preview.
Features in developer preview may be subject to changes at any time. Changes in existing user interface or user facing functionality of a feature marked as developer preview can be released without changing the major version.
Firecracker feature planning is outlined in the Firecracker roadmap.