167 lines
7.8 KiB
Markdown
167 lines
7.8 KiB
Markdown
# OCI Image Format Specification
|
|
<div>
|
|
<a href="https://travis-ci.org/opencontainers/image-spec">
|
|
<img src="https://travis-ci.org/opencontainers/image-spec.svg?branch=master"></img>
|
|
</a>
|
|
</div>
|
|
|
|
The OCI Image Format project creates and maintains the software shipping container image format spec (OCI Image Format).
|
|
|
|
**[The specification can be found here](spec.md).**
|
|
|
|
This repository also provides [Go types](specs-go), [intra-blob validation tooling, and JSON Schema](schema).
|
|
The Go types and validation should be compatible with the current Go release; earlier Go releases are not supported.
|
|
|
|
Additional documentation about how this group operates:
|
|
|
|
- [Code of Conduct](https://github.com/opencontainers/tob/blob/d2f9d68c1332870e40693fe077d311e0742bc73d/code-of-conduct.md)
|
|
- [Roadmap](#roadmap)
|
|
- [Releases](RELEASES.md)
|
|
- [Project Documentation](project.md)
|
|
|
|
The _optional_ and _base_ layers of all OCI projects are tracked in the [OCI Scope Table](https://www.opencontainers.org/about/oci-scope-table).
|
|
|
|
## Running an OCI Image
|
|
|
|
The OCI Image Format partner project is the [OCI Runtime Spec project](https://github.com/opencontainers/runtime-spec).
|
|
The Runtime Specification outlines how to run a "[filesystem bundle](https://github.com/opencontainers/runtime-spec/blob/master/bundle.md)" that is unpacked on disk.
|
|
At a high-level an OCI implementation would download an OCI Image then unpack that image into an OCI Runtime filesystem bundle.
|
|
At this point the OCI Runtime Bundle would be run by an OCI Runtime.
|
|
|
|
This entire workflow supports the UX that users have come to expect from container engines like Docker and rkt: primarily, the ability to run an image with no additional arguments:
|
|
|
|
* docker run example.com/org/app:v1.0.0
|
|
* rkt run example.com/org/app,version=v1.0.0
|
|
|
|
To support this UX the OCI Image Format contains sufficient information to launch the application on the target platform (e.g. command, arguments, environment variables, etc).
|
|
|
|
## FAQ
|
|
|
|
**Q: Why doesn't this project mention distribution?**
|
|
|
|
A: Distribution, for example using HTTP as both Docker v2.2 and AppC do today, is currently out of scope on the [OCI Scope Table](https://www.opencontainers.org/about/oci-scope-table).
|
|
There has been [some discussion on the TOB mailing list](https://groups.google.com/a/opencontainers.org/d/msg/tob/A3JnmI-D-6Y/tLuptPDHAgAJ) to make distribution an optional layer, but this topic is a work in progress.
|
|
|
|
**Q: What happens to AppC or Docker Image Formats?**
|
|
|
|
A: Existing formats can continue to be a proving ground for technologies, as needed.
|
|
The OCI Image Format project strives to provide a dependable open specification that can be shared between different tools and be evolved for years or decades of compatibility; as the deb and rpm format have.
|
|
|
|
Find more [FAQ on the OCI site](https://www.opencontainers.org/faq).
|
|
|
|
## Roadmap
|
|
|
|
The [GitHub milestones](https://github.com/opencontainers/image-spec/milestones) lay out the path to the OCI v1.0.0 release in late 2016.
|
|
|
|
# Contributing
|
|
|
|
Development happens on GitHub for the spec.
|
|
Issues are used for bugs and actionable items and longer discussions can happen on the [mailing list](#mailing-list).
|
|
|
|
The specification and code is licensed under the Apache 2.0 license found in the `LICENSE` file of this repository.
|
|
|
|
## Discuss your design
|
|
|
|
The project welcomes submissions, but please let everyone know what you are working on.
|
|
|
|
Before undertaking a nontrivial change to this specification, send mail to the [mailing list](#mailing-list) to discuss what you plan to do.
|
|
This gives everyone a chance to validate the design, helps prevent duplication of effort, and ensures that the idea fits.
|
|
It also guarantees that the design is sound before code is written; a GitHub pull-request is not the place for high-level discussions.
|
|
|
|
Typos and grammatical errors can go straight to a pull-request.
|
|
When in doubt, start on the [mailing-list](#mailing-list).
|
|
|
|
## Weekly Call
|
|
|
|
The contributors and maintainers of all OCI projects have a weekly meeting Wednesdays at 2:00 PM (USA Pacific).
|
|
Everyone is welcome to participate via [UberConference web][UberConference] or audio-only: +1-415-968-0849 (no PIN needed).
|
|
An initial agenda will be posted to the [mailing list](#mailing-list) earlier in the week, and everyone is welcome to propose additional topics or suggest other agenda alterations there.
|
|
Minutes are posted to the [mailing list](#mailing-list) and minutes from past calls are archived [here][minutes].
|
|
|
|
## Mailing List
|
|
|
|
You can subscribe and join the mailing list on [Google Groups](https://groups.google.com/a/opencontainers.org/forum/#!forum/dev).
|
|
|
|
## IRC
|
|
|
|
OCI discussion happens on #opencontainers on Freenode ([logs][irc-logs]).
|
|
|
|
## Markdown style
|
|
|
|
To keep consistency throughout the Markdown files in the Open Container spec all files should be formatted one sentence per line.
|
|
This fixes two things: it makes diffing easier with git and it resolves fights about line wrapping length.
|
|
For example, this paragraph will span three lines in the Markdown source.
|
|
|
|
## Git commit
|
|
|
|
### Sign your work
|
|
|
|
The sign-off is a simple line at the end of the explanation for the patch, which certifies that you wrote it or otherwise have the right to pass it on as an open-source patch.
|
|
The rules are pretty simple: if you can certify the below (from [developercertificate.org](http://developercertificate.org/)):
|
|
|
|
```
|
|
Developer Certificate of Origin
|
|
Version 1.1
|
|
|
|
Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
|
|
660 York Street, Suite 102,
|
|
San Francisco, CA 94110 USA
|
|
|
|
Everyone is permitted to copy and distribute verbatim copies of this
|
|
license document, but changing it is not allowed.
|
|
|
|
|
|
Developer's Certificate of Origin 1.1
|
|
|
|
By making a contribution to this project, I certify that:
|
|
|
|
(a) The contribution was created in whole or in part by me and I
|
|
have the right to submit it under the open source license
|
|
indicated in the file; or
|
|
|
|
(b) The contribution is based upon previous work that, to the best
|
|
of my knowledge, is covered under an appropriate open source
|
|
license and I have the right under that license to submit that
|
|
work with modifications, whether created in whole or in part
|
|
by me, under the same open source license (unless I am
|
|
permitted to submit under a different license), as indicated
|
|
in the file; or
|
|
|
|
(c) The contribution was provided directly to me by some other
|
|
person who certified (a), (b) or (c) and I have not modified
|
|
it.
|
|
|
|
(d) I understand and agree that this project and the contribution
|
|
are public and that a record of the contribution (including all
|
|
personal information I submit with it, including my sign-off) is
|
|
maintained indefinitely and may be redistributed consistent with
|
|
this project or the open source license(s) involved.
|
|
```
|
|
|
|
then you just add a line to every git commit message:
|
|
|
|
Signed-off-by: Joe Smith <joe@gmail.com>
|
|
|
|
using your real name (sorry, no pseudonyms or anonymous contributions.)
|
|
|
|
You can add the sign off when creating the git commit via `git commit -s`.
|
|
|
|
### Commit Style
|
|
|
|
Simple house-keeping for clean git history.
|
|
Read more on [How to Write a Git Commit Message](http://chris.beams.io/posts/git-commit/) or the Discussion section of [`git-commit(1)`](http://git-scm.com/docs/git-commit).
|
|
|
|
1. Separate the subject from body with a blank line
|
|
2. Limit the subject line to 50 characters
|
|
3. Capitalize the subject line
|
|
4. Do not end the subject line with a period
|
|
5. Use the imperative mood in the subject line
|
|
6. Wrap the body at 72 characters
|
|
7. Use the body to explain what and why vs. how
|
|
* If there was important/useful/essential conversation or information, copy or include a reference
|
|
8. When possible, one keyword to scope the change in the subject (i.e. "README: ...", "runtime: ...")
|
|
|
|
|
|
[UberConference]: https://www.uberconference.com/opencontainers
|
|
[irc-logs]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/
|
|
[minutes]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/
|