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| 1 | +# OpenShift's fork of k8s.io/kubernetes |
| 2 | + |
| 3 | +This respository contains core Kubernetes components with OpenShift-specific patches. |
| 4 | + |
| 5 | +## Cherry-picking an upstream commit into openshift/kubernetes: Why, how, and when. |
| 6 | + |
| 7 | +`openshift/kubernetes` carries patches on top of each rebase in one of two ways: |
| 8 | + |
| 9 | +1. *periodic rebases* against an upstream Kubernetes tag. Eventually, |
| 10 | +any code you have in upstream Kubernetes will land in Openshift via |
| 11 | +this mechanism. |
| 12 | + |
| 13 | +2. Cherry-picked patches for important *bug fixes*. We really try to |
| 14 | +limit feature back-porting entirely. Unless there are exceptional circumstances, your backport should at least be merged in kubernetes master branch. With every carry patch (not included in upstream) you are introducing a maintenance burden for the team managing rebases. |
| 15 | + |
| 16 | +### For Openshift newcomers: Pick my Kubernetes fix into Openshift vs. wait for the next rebase? |
| 17 | + |
| 18 | +Assuming you read the bullets above... If your patch is really far behind, for |
| 19 | +example, if there have been 5 commits modifying the directory you care about, |
| 20 | +cherry picking will be increasingly difficult and you should consider waiting |
| 21 | +for the next rebase, which will likely include the commit you care about or at |
| 22 | +least decrease the amount of cherry picks you need to do to merge. |
| 23 | + |
| 24 | +To really know the answer, you need to know *how many commits behind you are in |
| 25 | +a particular directory*, often. |
| 26 | + |
| 27 | +To do this, just use git log, like so (using pkg/scheduler/ as an example). |
| 28 | + |
| 29 | +``` |
| 30 | +MYDIR=pkg/scheduler/algorithm git log --oneline -- |
| 31 | + ${MYDIR} | grep UPSTREAM | cut -d' ' -f 4-10 | head -1 |
| 32 | +``` |
| 33 | + |
| 34 | +The commit message printed above will tell you: |
| 35 | + |
| 36 | +- what the LAST commit in Kubernetes was (which effected |
| 37 | +"/pkg/scheduler/algorithm") |
| 38 | +- directory, which will give you an intuition about how "hot" the code you are |
| 39 | +cherry picking is. If it has changed a lot, recently, then that means you |
| 40 | +probably will want to wait for a rebase to land. |
| 41 | + |
| 42 | +### Cherry-picking an upstream change |
| 43 | + |
| 44 | +Since `openshift/kubernetes` closely resembles `k8s.io/kubernetes`, |
| 45 | +cherry-picking largely involves proposing upstream commits in a PR to our |
| 46 | +downstream fork. Other than the usual potential for merge conflicts, the |
| 47 | +commit messages for all commits proposed to `openshift/kubernetes` must |
| 48 | +reflect the following: |
| 49 | + |
| 50 | +- `UPSTREAM: <UPSTREAM PR ID>:` The prefix for upstream commits to ensure |
| 51 | + correct handling during a future rebase. The person performing the rebase |
| 52 | + will know to omit a commit with this prefix if the referenced PR is already |
| 53 | + present in the new base history. |
| 54 | +- `UPSTREAM: <drop>:` The prefix for downstream commits of code that is |
| 55 | + generated (i.e. via `make update`) or that should not be retained by the |
| 56 | + next rebase. |
| 57 | +- `UPSTREAM: <carry>:` The prefix for downstream commits that maintain |
| 58 | + downstream-specific behavior (i.e. to ensure an upstream change is |
| 59 | + compatible with OpenShift). Commits with this are usually retained across |
| 60 | + rebases. |
| 61 | + |
| 62 | +## Updating openshift/kubernetes to a new upstream release |
| 63 | + |
| 64 | +Instructions for rebasing `openshift/kubernetes` are maintained in a [separate |
| 65 | +document](REBASE.openshift.md). |
| 66 | + |
| 67 | +## RPM Packaging |
| 68 | + |
| 69 | +A specfile is included in this repo which can be used to produce RPMs |
| 70 | +including the openshift binary. While the specfile will be kept up to |
| 71 | +date with build requirements the version is not updated. Building the |
| 72 | +rpm with the `openshift-hack/build-rpms.sh` helper script will ensure |
| 73 | +that the version is set correctly. |
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