Coding Conventions

A collection of guidelines, style suggestions, and tips for writing code in the different programming languages used throughout the project.

Table of Contents

Code conventions

  • Bash

  • Go

    • Go Code Review Comments

    • Effective Go

    • Know and avoid Go landmines

    • Comment your code.

    • Command-line flags should use dashes, not underscores

    • Naming

      • Please consider package name when selecting an interface name, and avoid redundancy.

        • e.g.: storage.Interface is better than storage.StorageInterface.
      • Do not use uppercase characters, underscores, or dashes in package names.

      • Please consider parent directory name when choosing a package name.

        • so pkg/controllers/autoscaler/foo.go should say package autoscaler not package autoscalercontroller.
        • Unless there’s a good reason, the package foo line should match the name of the directory in which the .go file exists.
        • Importers can use a different name if they need to disambiguate.
      • Locks should be called lock and should never be embedded (always lock sync.Mutex). When multiple locks are present, give each lock a distinct name following Go conventions - stateLock, mapLock etc.

    • API changes

    • API conventions

    • Kubectl conventions

    • Logging conventions

Testing conventions

  • All new packages and most new significant functionality must come with unit tests

  • Table-driven tests are preferred for testing multiple scenarios/inputs; for example, see TestNamespaceAuthorization

  • Significant features should come with integration (test/integration) and/or end-to-end (test/e2e) tests

    • Including new kubectl commands and major features of existing commands
  • Unit tests must pass on macOS and Windows platforms - if you use Linux specific features, your test case must either be skipped on windows or compiled out (skipped is better when running Linux specific commands, compiled out is required when your code does not compile on Windows).

  • Avoid relying on Docker hub (e.g. pull from Docker hub). Use instead.

  • Avoid waiting for a short amount of time (or without waiting) and expect an asynchronous thing to happen (e.g. wait for 1 seconds and expect a Pod to be running). Wait and retry instead.

  • See the testing guide for additional testing advice.

Directory and file conventions

  • Avoid package sprawl. Find an appropriate subdirectory for new packages. (See #4851 for discussion.)

    • Libraries with no more appropriate home belong in new package subdirectories of pkg/util
  • Avoid general utility packages. Packages called “util” are suspect. Instead, derive a name that describes your desired function. For example, the utility functions dealing with waiting for operations are in the “wait” package and include functionality like Poll. So the full name is wait.Poll

  • All filenames should be lowercase

  • Go source files and directories use underscores, not dashes

    • Package directories should generally avoid using separators as much as possible (when packages are multiple words, they usually should be in nested subdirectories).
  • Document directories and filenames should use dashes rather than underscores

  • Contrived examples that illustrate system features belong in /docs/user-guide or /docs/admin, depending on whether it is a feature primarily intended for users that deploy applications or cluster administrators, respectively. Actual application examples belong in /examples.

  • Third-party code

    • Go code for normal third-party dependencies is managed using go modules and is described in the kubernetes vendoring guide

    • Other third-party code belongs in /third_party

      • forked third party Go code goes in /third_party/forked
      • forked golang stdlib code goes in /third_party/forked/golang
    • Third-party code must include licenses

    • This includes modified third-party code and excerpts, as well