controller-gen CLI

KubeBuilder makes use of a tool called controller-gen for generating utility code and Kubernetes YAML. This code and config generation is controlled by the presence of special “marker comments” in Go code.

controller-gen is built out of different “generators” (which specify what to generate) and “output rules” (which specify how and where to write the results).

Both are configured through command line options specified in marker format.

For instance,

controller-gen paths=./... crd:trivialVersions=true rbac:roleName=controller-perms output:crd:artifacts:config=config/crd/bases

generates CRDs and RBAC, and specifically stores the generated CRD YAML in config/crd/bases. For the RBAC, it uses the default output rules (config/rbac). It considers every package in the current directory tree (as per the normal rules of the go ... wildcard).

Generators

Each different generator is configured through a CLI option. Multiple generators may be used in a single invocation of controller-gen.

webhook
generates (partial) {Mutating,Validating}WebhookConfiguration objects.
rbac
roleName
string
generates ClusterRole objects.
roleName
string
sets the name of the generated ClusterRole.
object
headerFile
string
year
string
generates code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations.
headerFile
string
specifies the header text (e.g. license) to prepend to generated files.
year
string
specifies the year to substitute for " YEAR" in the header file.
crd
trivialVersions
bool
generates CustomResourceDefinition objects.
trivialVersions
bool
indicates that we should produce a single-version CRD.

Single “trivial-version“ CRDs are compatible with older (pre 1.13) Kubernetes API servers. The storage version‘s schema will be used as the CRD‘s schema.

Output Rules

Output rules configure how a given generator outputs its results. There is always one global “fallback” output rule (specified as output:<rule>), plus per-generator overrides (specified as output:<generator>:<rule>).

For brevity, the per-generator output rules (output:<generator>:<rule>) are omitted below. They are equivalent to the global fallback options listed here.

output:artifacts
code
string
config
string
outputs artifacts to different locations, depending on whether they're package-associated or not.

Non-package associated artifacts are output to the Config directory, while package-associated ones are output to their package‘s source files‘ directory, unless an alternate path is specified in Code.

code
string
overrides the directory in which to write new code (defaults to where the existing code lives).
config
string
points to the directory to which to write configuration.
output:dir
string
outputs each artifact to the given directory, regardless of if it's package-associated or not.
string
output:none
skips outputting anything.
output:stdout
outputs everything to standard-out, with no separation.

Generally useful for single-artifact outputs.

Other Options

paths
string
represents paths and go-style path patterns to use as package roots.
string