1# OCI Image Format Specification 2<div> 3<a href="https://travis-ci.org/opencontainers/image-spec"> 4<img src="https://travis-ci.org/opencontainers/image-spec.svg?branch=master"></img> 5</a> 6</div> 7 8The OCI Image Format project creates and maintains the software shipping container image format spec (OCI Image Format). 9 10**[The specification can be found here](spec.md).** 11 12This repository also provides [Go types](specs-go), [intra-blob validation tooling, and JSON Schema](schema). 13The Go types and validation should be compatible with the current Go release; earlier Go releases are not supported. 14 15Additional documentation about how this group operates: 16 17- [Code of Conduct](https://github.com/opencontainers/tob/blob/d2f9d68c1332870e40693fe077d311e0742bc73d/code-of-conduct.md) 18- [Roadmap](#roadmap) 19- [Releases](RELEASES.md) 20- [Project Documentation](project.md) 21 22The _optional_ and _base_ layers of all OCI projects are tracked in the [OCI Scope Table](https://www.opencontainers.org/about/oci-scope-table). 23 24## Running an OCI Image 25 26The OCI Image Format partner project is the [OCI Runtime Spec project](https://github.com/opencontainers/runtime-spec). 27The Runtime Specification outlines how to run a "[filesystem bundle](https://github.com/opencontainers/runtime-spec/blob/master/bundle.md)" that is unpacked on disk. 28At a high-level an OCI implementation would download an OCI Image then unpack that image into an OCI Runtime filesystem bundle. 29At this point the OCI Runtime Bundle would be run by an OCI Runtime. 30 31This 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: 32 33* docker run example.com/org/app:v1.0.0 34* rkt run example.com/org/app,version=v1.0.0 35 36To 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). 37 38## FAQ 39 40**Q: Why doesn't this project mention distribution?** 41 42A: 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). 43There 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. 44 45**Q: What happens to AppC or Docker Image Formats?** 46 47A: Existing formats can continue to be a proving ground for technologies, as needed. 48The 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. 49 50Find more [FAQ on the OCI site](https://www.opencontainers.org/faq). 51 52## Roadmap 53 54The [GitHub milestones](https://github.com/opencontainers/image-spec/milestones) lay out the path to the future improvements. 55 56# Contributing 57 58Development happens on GitHub for the spec. 59Issues are used for bugs and actionable items and longer discussions can happen on the [mailing list](#mailing-list). 60 61The specification and code is licensed under the Apache 2.0 license found in the `LICENSE` file of this repository. 62 63## Discuss your design 64 65The project welcomes submissions, but please let everyone know what you are working on. 66 67Before undertaking a nontrivial change to this specification, send mail to the [mailing list](#mailing-list) to discuss what you plan to do. 68This gives everyone a chance to validate the design, helps prevent duplication of effort, and ensures that the idea fits. 69It also guarantees that the design is sound before code is written; a GitHub pull-request is not the place for high-level discussions. 70 71Typos and grammatical errors can go straight to a pull-request. 72When in doubt, start on the [mailing-list](#mailing-list). 73 74## Weekly Call 75 76The contributors and maintainers of all OCI projects have a weekly meeting Wednesdays at 2:00 PM (USA Pacific). 77Everyone is welcome to participate via [UberConference web][UberConference] or audio-only: +1-415-968-0849 (no PIN needed). 78An 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. 79Minutes are posted to the [mailing list](#mailing-list) and minutes from past calls are archived [here][minutes]. 80 81## Mailing List 82 83You can subscribe and join the mailing list on [Google Groups](https://groups.google.com/a/opencontainers.org/forum/#!forum/dev). 84 85## IRC 86 87OCI discussion happens on #opencontainers on Freenode ([logs][irc-logs]). 88 89## Markdown style 90 91To keep consistency throughout the Markdown files in the Open Container spec all files should be formatted one sentence per line. 92This fixes two things: it makes diffing easier with git and it resolves fights about line wrapping length. 93For example, this paragraph will span three lines in the Markdown source. 94 95## Git commit 96 97### Sign your work 98 99The 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. 100The rules are pretty simple: if you can certify the below (from [developercertificate.org](http://developercertificate.org/)): 101 102``` 103Developer Certificate of Origin 104Version 1.1 105 106Copyright (C) 2004, 2006 The Linux Foundation and its contributors. 107660 York Street, Suite 102, 108San Francisco, CA 94110 USA 109 110Everyone is permitted to copy and distribute verbatim copies of this 111license document, but changing it is not allowed. 112 113 114Developer's Certificate of Origin 1.1 115 116By making a contribution to this project, I certify that: 117 118(a) The contribution was created in whole or in part by me and I 119 have the right to submit it under the open source license 120 indicated in the file; or 121 122(b) The contribution is based upon previous work that, to the best 123 of my knowledge, is covered under an appropriate open source 124 license and I have the right under that license to submit that 125 work with modifications, whether created in whole or in part 126 by me, under the same open source license (unless I am 127 permitted to submit under a different license), as indicated 128 in the file; or 129 130(c) The contribution was provided directly to me by some other 131 person who certified (a), (b) or (c) and I have not modified 132 it. 133 134(d) I understand and agree that this project and the contribution 135 are public and that a record of the contribution (including all 136 personal information I submit with it, including my sign-off) is 137 maintained indefinitely and may be redistributed consistent with 138 this project or the open source license(s) involved. 139``` 140 141then you just add a line to every git commit message: 142 143 Signed-off-by: Joe Smith <joe@gmail.com> 144 145using your real name (sorry, no pseudonyms or anonymous contributions.) 146 147You can add the sign off when creating the git commit via `git commit -s`. 148 149### Commit Style 150 151Simple house-keeping for clean git history. 152Read 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). 153 1541. Separate the subject from body with a blank line 1552. Limit the subject line to 50 characters 1563. Capitalize the subject line 1574. Do not end the subject line with a period 1585. Use the imperative mood in the subject line 1596. Wrap the body at 72 characters 1607. Use the body to explain what and why vs. how 161 * If there was important/useful/essential conversation or information, copy or include a reference 1628. When possible, one keyword to scope the change in the subject (i.e. "README: ...", "runtime: ...") 163 164 165[UberConference]: https://www.uberconference.com/opencontainers 166[irc-logs]: http://ircbot.wl.linuxfoundation.org/eavesdrop/%23opencontainers/ 167[minutes]: http://ircbot.wl.linuxfoundation.org/meetings/opencontainers/ 168