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.
schemapatch
manifests
string
maxDescLen
int
patches existing CRDs with new schemata.

For legacy (v1beta1) single-version CRDs, it will simply replace the global schema. For legacy (v1beta1) multi-version CRDs, and any v1 CRDs, it will replace schemata of existing versions and clear the schema from any versions not specified in the Go code. It will not add new versions, or remove old ones. For legacy multi-version CRDs with identical schemata, it will take care of lifting the per-version schema up to the global schema. It will generate output for each “CRD Version“ (API version of the CRD type itself) , e.g. apiextensions/v1beta1 and apiextensions/v1) available.

manifests
string
contains the CustomResourceDefinition YAML files.
maxDescLen
int
specifies the maximum description length for fields in CRD's OpenAPI schema.

0 indicates drop the description for all fields completely. n indicates limit the description to at most n characters and truncate the description to closest sentence boundary if it exceeds n characters.

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
crdVersions
string
maxDescLen
int
preserveUnknownFields
bool
trivialVersions
bool
generates CustomResourceDefinition objects.
crdVersions
string
specifies the target API versions of the CRD type itself to generate. Defaults to v1beta1.

The first version listed will be assumed to be the “default“ version and will not get a version suffix in the output filename. You‘ll need to use “v1“ to get support for features like defaulting, along with an API server that supports it (Kubernetes 1.16+).

maxDescLen
int
specifies the maximum description length for fields in CRD's OpenAPI schema.

0 indicates drop the description for all fields completely. n indicates limit the description to at most n characters and truncate the description to closest sentence boundary if it exceeds n characters.

preserveUnknownFields
bool
indicates whether or not we should turn off pruning.

Left unspecified, it‘ll default to true when only a v1beta1 CRD is generated (to preserve compatibility with older versions of this tool), or false otherwise. It‘s required to be false for v1 CRDs.

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. Only works with the v1beta1 CRD version.

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