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development.md: rewrite for clarity, grammar, and spelling

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@ -1,115 +1,119 @@
# Development Guide
This document is the canonical source of truth for things like
supported toolchain versions for building Kubernetes.
This document is the canonical source of truth for things like supported
toolchain versions for building Kubernetes.
Please submit an [issue] on github if you
* find a requirement that this doc does not capture,
* find other docs with references to requirements that
are not simply links to this doc.
This document is intended to be relative to the branch in which it is found.
Please submit an [issue] on Github if you
* Notice a requirement that this doc does not capture.
* Find a different doc that specifies requirements (the doc should instead link
here).
Development branch requirements will change over time, but release branch
requirements are frozen.
## Pre submit flight checks
Make sure you decide whether your issue and/or pull request is improving kubernetes architecture or whether its simply fixing a bug.
Determine whether your issue or pull request is improving Kubernetes'
architecture or whether it's simply fixing a bug.
Make sure there are no typos, if you need a diagram, add it. Make sure you SEPARATE the description of the problem
(i.e. Y is a critical component that is too slow for an SLA that we care about) from the solution (i.e. make X faster).
If you need a diagram, add it. SEPARATE the description of the problem (e.g. Y
is a critical component that is too slow for an SLA that we care about) from the
solution (e.g. make X faster).
Some of these checks were less common in Kubernetes earlier days, but now having over 1000 contributors, each issue should be
filed with care, and should be sanity-checkable in under 5 minutes (even the busiest of reviewers can spare up to 5 minutes to
review a patch that is thoughtfully justified).
Some of these checks were less common in Kubernetes' earlier days. Now that we
have over 1000 contributors, each issue should be filed with care. No issue
should take more than 5 minutes to check for sanity (even the busiest of
reviewers can spare 5 minutes to review a patch that is thoughtfully justified).
### Is this just a simple bug fix?
These patches can be easy to review since test coverage is submitted with the patch. Bug fixes don't usually require alot
of extra testing: But please update the unit tests so that they catch the bug !
Simple bug patches are easy to review since test coverage is submitted with the
patch. Bug fixes don't usually require a lot of extra testing, but please
update the unit tests so they catch the bug!
### Is this an architecture improvement?
Some examples of "Architecture" improvements:
Some examples of "Architecture" improvements include:
- Adding a new feature or making a feature more configurable/modular.
- Converting structs to interfaces.
- Adding a new feature or making a feature more configurable or modular.
- Improving test coverage.
- Decoupling logic or creation of new utilities.
- Making code more resilient (sleeps, backoffs, reducing flakiness, etc).
- Making code more resilient (sleeps, backoffs, reducing flakiness, etc.).
These sorts of improvements are easily evaluated if they decrease lines of code without breaking functionality.
These sorts of improvements are easily evaluated, especially when they decrease
lines of code without breaking functionality. That said, please explain exactly
what you are 'cleaning up' in your Pull Request so as not to waste a reviewer's
time.
If you are improving the quality of code, then justify/state exactly what you 'cleaning up' in your Pull Request so as
not to waste reviewer time.
If you're making code more resilient, test it with a local cluster to demonstrate how exactly your patch changes
things.
Example: If you made a controller more robust to inconsistent data, make a mock object which returns incorrect data a
few times and verify the controllers behaviour accordingly.
If you're making code more resilient, include tests that demonstrate the new
resilient behavior. For example: if your patch causes a controller to better
handle inconsistent data, make a mock object which returns incorrect data a few
times and verify the controller's new behaviour.
### Is this a performance improvement ?
If you are submitting a performance bug, you MUST ALSO submit data that demonstrates your problem if you want the issue to
remain open. This can be done locally using kubemark, scheduler_perf, unit tests, go benchmark tests, or e2e tests on
a real cluster with metrics plots.
Performance bug reports MUST include data that demonstrates the bug. Without
data, the issue will be closed. You can measure performance using kubemark,
scheduler_perf, go benchmark tests, or e2e tests on a real cluster with metric
plots.
Examples of how NOT to suggest a performance bug (these can really lead to a long review process and waste cycles):
Examples of how NOT to suggest a performance bug (these lead to a long review
process and waste cycles):
- We *should* be doing X instead of Y because it *might* lead to better performance.
- We *should* be doing X instead of Y because it *might* lead to better
performance.
- Doing X instead of Y would reduce calls to Z.
The above statements have basically no value to a reviewer, because neither is a strong, testable, assertive statement.
This will land your PR in a no-man's-land zone (at best), or waste tons of time for a busy reviewer (at worst).
The above statements have no value to a reviewer because neither is backed by
data. Writing issues like this lands your PR in a no-man's-land and waste your
reviewers' time.
Of course any improvement is welcome, but performance improvements are the hardest to review. They often make code more
complex, and to-often are not easily evaluated at review time due to lack of sufficient data submitted by the author
of a performance improvement patch.
Some examples of "Performance" improvements:
Examples of possible performance improvements include (remember, you MUST
document the improvement with data):
- Improving a caching implementation.
- Reducing calls to functions which are O(n^2), or reducing dependence on API server requests.
- Changing the value of default parameters for proceeses, or making those values 'smarter'.
- Parallelizing a calculation that needs to run on a large set of node/pod objects.
- Reducing calls to functions which are O(n^2)
- Reducing dependence on API server requests.
- Changing the value of default parameters for processes, or making those values
'smarter'.
- Parallelizing a calculation that needs to run on a large set of node/pod
objects.
These issues should always be submitted with (in decreasing order or value):
- A golang Benchmark test.
- A visual depiction of reduced metric load on a cluster (measurable using metrics/ endpoints and grafana).
- A hand-instrumented timing test (i.e. adding some logs into the controller manager).
- A visual depiction of reduced metric load on a cluster (measurable using
metrics/ endpoints and grafana).
- A hand-instrumented timing test (i.e. adding some logs into the controller
manager).
Without submitting data and results for your suggested performance improvements, its very possible that bikeshedding
about meaningless possible performance optimizations could waste both reviewer time as well as your own.
Some examples of properly submitted performance issues, from different parts of the codebase. They all have one thing
in common: Lots of data in the issue definition. If you are new to kubernetes and thinking about filing a performance
optimization, re-read one or all of these before you get started.
Here are some examples of properly submitted performance issues. If you are new
to kubernetes and thinking about filing a performance optimization, re-read one
or all of these before you get started.
- https://github.com/kubernetes/kubernetes/issues/18266 (apiserver)
- https://github.com/kubernetes/kubernetes/issues/32833 (node)
- https://github.com/kubernetes/kubernetes/issues/31795 (scheduler)
Since performance improvements deal with empirical systems, one playing in this space should be intimately familiar with
the "scientific method" of creating a hypothesis, collecting data, and then revising your hypothesis. The above issues
tend to do this transparently, using figures and data rather then theoretical postulations, as a first pass before a
single line of code is reviewed.
Since performance improvements can be empirically measured, you should follow
the "scientific method" of creating a hypothesis, collecting data, and then
revising your hypothesis. The above issues do this transparently, using figures
and data rather then conjecture. Notice that the problem is analyzed and a
correct solution is created before a single line of code is reviewed.
## Building Kubernetes with Docker
Official releases are built using Docker containers. To build Kubernetes using Docker please follow
[these instructions](http://releases.k8s.io/HEAD/build/README.md).
Official releases are built using Docker containers. To build Kubernetes using
Docker please follow [these
instructions](http://releases.k8s.io/HEAD/build/README.md).
## Building Kubernetes on a local OS/shell environment
Kubernetes development helper scripts assume an up-to-date
GNU tools environment. Most recent Linux distros should work
out-of-the-box.
Kubernetes development helper scripts assume an up-to-date GNU tools
environment. Recent Linux distros should work out-of-the-box.
Mac OS X ships with outdated BSD-based tools.
We recommend installing [Os X GNU tools].
Mac OS X ships with outdated BSD-based tools. We recommend installing [OS X GNU
tools].
### etcd
@ -119,36 +123,30 @@ Please [install it locally][etcd-install] to run local integration tests.
### Go
Kubernetes is written in [Go](http://golang.org).
If you don't have a Go development environment,
please [set one up](http://golang.org/doc/code.html).
Kubernetes is written in [Go](http://golang.org). If you don't have a Go
development environment, please [set one up](http://golang.org/doc/code.html).
| Kubernetes | requires Go |
|----------------|--------------|
| 1.0 - 1.2 | 1.4.2 |
| 1.3, 1.4 | 1.6 |
| 1.5 and higher | 1.7 - 1.7.5 |
| | [1.8][go-1.8] not verified as of Feb 2017 |
| Kubernetes | requires Go |
|----------------|-------------------------------------------|
| 1.0 - 1.2 | 1.4.2 |
| 1.3, 1.4 | 1.6 |
| 1.5 and higher | 1.7 - 1.7.5 |
| | [1.8][go-1.8] not verified as of Feb 2017 |
After installation, you'll need `GOPATH` defined,
and `PATH` modified to access your Go binaries.
Ensure your GOPATH and PATH have been configured in accordance with the Go
environment instructions.
A common setup is
```sh
export GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin
```
#### Upgrading Go
#### Upgrading Go
Upgrading Go requires specific modification of some scripts and container
images.
- The image for cross compiling in [build/build-image/cross].
The `VERSION` file and `Dockerfile`.
- Update [dockerized-e2e-runner.sh] to run a kubekins-e2e with the desired Go version.
This requires pushing the [e2e][e2e-image] and [test][test-image] images that are `FROM` the desired Go version.
- Update [dockerized-e2e-runner.sh] to run a kubekins-e2e with the desired Go
version. This requires pushing the [e2e][e2e-image] and [test][test-image]
images that are `FROM` the desired Go version.
- The cross tag `KUBE_BUILD_IMAGE_CROSS_TAG` in [build/common.sh].
@ -161,13 +159,16 @@ manage dependencies.
go get -u github.com/tools/godep
```
Check your version; `v63` or higher is known to work for Kubernetes.
The Godep version that Kubernetes is using is listed in `Godep/Godep.json` (in
the kubernetes repo root). See what version you are running with this command:
```sh
godep version
```
Developers planning to manage dependencies in the `vendor/` tree may want to
explore alternative environment setups. See [using godep to manage dependencies](godep.md).
explore alternative environment setups. See [using godep to manage
dependencies](godep.md).
@ -223,18 +224,6 @@ git remote set-url --push upstream no_push
git remote -v
```
#### Define a pre-commit hook
Please link the Kubernetes pre-commit hook into your `.git` directory.
This hook checks your commits for formatting, building, doc generation, etc.
It requires both `godep` and `etcd` on your `PATH`.
```sh
cd $working_dir/kubernetes/.git/hooks
ln -s ../../hooks/pre-commit .
```
### 3 Branch
Get your local master up to date:
@ -260,12 +249,13 @@ cd $working_dir/kubernetes
make
```
To remove the limit on the number of errors the Go compiler reports (default limit is 10 errors):
To remove the limit on the number of errors the Go compiler reports (default
limit is 10 errors):
```sh
make GOGCFLAGS="-e"
```
To build with optimizations disabled for enabling use of source debug tools:
To build with optimizations disabled (enables use of source debug tools):
```sh
make GOGCFLAGS="-N -l"
@ -283,7 +273,7 @@ make cross
cd $working_dir/kubernetes
# Run every unit test
make test
make test
# Run package tests verbosely
make test WHAT=pkg/util/cache GOFLAGS=-v
@ -322,13 +312,13 @@ When ready to review (or just to establish an offsite backup or your work),
push your branch to your fork on `github.com`:
```sh
git push -f origin myfeature
git push -f ${your_remote_name} myfeature
```
### 7 Create a pull request
1. Visit your fork at https://github.com/$user/kubernetes (replace `$user` obviously).
2. Click the `Compare & pull request` button next to your `myfeature` branch.
1. Visit your fork at https://github.com/$user/kubernetes
2. Click the `Compare & Pull Request` button next to your `myfeature` branch.
3. Check out the pull request [process](pull-requests.md) for more details.
_If you have upstream write access_, please refrain from using the GitHub UI for
@ -345,12 +335,10 @@ and style.
Commit changes made in response to review comments to the same branch on your
fork.
Very small PRs are easy to review. Very large PRs are very difficult to
review.
Very small PRs are easy to review. Very large PRs are very difficult to review.
At the assigned reviewer's discretion, a PR may be switched to use
[Reviewable](https://reviewable.k8s.io) instead. Once a PR is switched to
Reviewable, please ONLY send or reply to comments through reviewable. Mixing
Reviewable, please ONLY send or reply to comments through Reviewable. Mixing
code review tools can be very confusing.
See [Faster Reviews](faster_reviews.md) for some thoughts on how to streamline
@ -364,7 +352,7 @@ branch should represent meaningful milestones or units of work. Use commits to
add clarity to the development and review process.
Before merging a PR, squash any _fix review feedback_, _typo_, and _rebased_
sorts of commits.
sorts of commits.
It is not imperative that every commit in a PR compile and pass tests
independently, but it is worth striving for.
@ -377,7 +365,7 @@ masse. This makes reviews easier.
[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/docs/devel/development.md?pixel)]()
<!-- END MUNGE: GENERATED_ANALYTICS -->
[Os X GNU tools]: https://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x
[OS X GNU tools]: https://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x
[build/build-image/cross]: https://github.com/kubernetes/kubernetes/blob/master/build/build-image/cross
[build/common.sh]: https://github.com/kubernetes/kubernetes/blob/master/build/common.sh
[dockerized-e2e-runner.sh]: https://github.com/kubernetes/test-infra/blob/master/jenkins/dockerized-e2e-runner.sh