Markers

Operator Builder uses commented markers as the basis for defining a new API. The fields for a custom resource kind are created when it finds a +operator-builder marker in a source manifest.

A workload marker is commented out so the manifest is still valid and can be used if needed. The marker must begin with +operator-builder followed by some colon-separated fields:

These markers should always be provided as an in-line comment or as a head comment. The marker always begins with +operator-builder:field: or +operator-builder:collection:field: (more on this later).

That is followed by arguments separated by ,. Arguments can be given in any order.

Arguments

Arguments come after the actual marker and are separated from the marker name with a :. They are given in the format of argument=value and separated by the ,. Additionally, if the argument name is given by itself with no value, it is assumed to have an implict =true on the end and is treated as a flag.

Below you will find the supported markers and their supported arguments.

Field Markers

Defined as +operator-builder:field this marker can be used to define a CRD field for your workload.

Field	Type	Required
name	string	true
type	string{string, int, bool}	true
default	type	false
replace	string	false
arbitrary	bool	false
description	string	false

Name (required if Parent is unspecified)

The name you want to use for the field in the custom resource that Operator Builder will create. If you're not sure what that means, it will become clear shortly.

ex. +operator-builder:field:name=myName

Parent (required if Name is unspecified)

The parent field in which you wish to substitute. Currently, only metadata.name is supported. This will allow you to use the parent name as a value in the child resource.

ex. +operator-builder:field:parent=metadata.name

Type (required)

The other required field is the type field which specifies the data type for the value.

#supported-field-types The supported data types are:

bool
string
int
int32
int64
float32
float64

ex. +operator-builder:field:name=myName,type=string

Default (optional)

This will make configuration optional for your operator's end user. the supplied value will be used for the default value. If a field has no default, it will be a required field in the custom resource. For example:

+operator-builder:field:name=myName,type=string,default=test

Replace (optional)

There may be some instances where you only want a specific portion of a value to be configurable (such as config maps). In these scenarios you can use the replace argument to specify a search string (or regex) to target for configuration.

Consider the following example:

apiVersion: v1
kind: ConfigMap
metadata:
  labels:
    # +operator-builder:field:name=environment,default=dev,type=string,replace="dev"
    app: myapp-dev
  name: contour-configmap
  namespace: ingress-system
data:
  # +operator-builder:field:name=configOption,default=myoption,type=string,replace="configuration2"
  # +operator-builder:field:name=yamlType,default=myoption,type=string,replace="multi.*yaml"
  config.yaml: |
    ---
    someoption: configuration2
    anotheroption: configuration1
    justtesting: multistringyaml

In this scenario three custom resource fields will be generated. The value from the environment field will replace the dev portion of myapp-dev. For example, if prod is provided as a value for the environment field, the resulting config map will get the label app: myapp-prod. Values from the configOption and yamlType fields will replace corresponding strings in the content of config.yaml. The resulting configmap will look as follows:

apiVersion: v1
kind: ConfigMap
metadata:
  labels:
    app: myapp-prod
  name: contour-configmap
  namespace: ingress-system
data:
  config.yaml: |-
    ---
    someoption: myoption
    anotheroption: configuration1
    justtesting: myoption

Arbitrary (optional)

If you wish to create a field for a custom resource that does not directly map to a value in a child resource, mark a field as arbitrary.

Here is an example of how to mark a field as arbitrary:

---
# +operator-builder:field:name=nginx.installType,arbitrary,default="deployment",type=string,description=`
# +kubebuilder:validation:Enum=deployment;daemonset
# Method of install nginx ingress controller.  One of: deployment | daemonset.`
apiVersion: v1
kind: Namespace
metadata:
  # +operator-builder:field:name=namespace,default="nukleros-ingress-system",type=string,description=`
  # Namespace to use for ingress support services.`
  name: nukleros-ingress-system

On the first line you can see the nginx.installType custom resource field is marked as arbitrary with the arbitrary marker field. Where you place this marker is unimportant but it is recommended you put all arbitrary fields at the beginning of one chosen manifest for ease of maintenance.

This will result in a custom resource sample that looks as follows:

apiVersion: platform.addons.nukleros.io/v1alpha1
kind: IngressComponent
metadata:
  name: ingresscomponent-sample
spec:
  #collection:
    #name: "supportservices-sample"
    #namespace: ""
  nginx:
    installType: "deployment"            # <---- arbitary field
    image: "nginx/nginx-ingress"
    version: "2.3.0"
    replicas: 2
  namespace: "nukleros-ingress-system"

This arbitrary field will not map to any child resource value. However it can be leveraged by some custom mutation code or by a resource marker such as this:

---
# +operator-builder:resource:field=nginx.installType,value="deployment",include
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ingress
  namespace: nukleros-ingress-system # +operator-builder:field:name=namespace,default="nukleros-ingress-system",type=string
...

The marker on line one indicates the deployment resource only be created if nginx.installType has a value of deployment (as shown in the custom resource sample above). In this example, we are providing an option to install the Nginx Ingress Controller as a deployment or a daemonset.

Description (optional)

An optional description can be provided which will be used in the source code as a Doc String, backticks ` may be used to capture multiline strings (head comments only).

By injecting documentation to the CRD, the consumer of the custom resource gets the added benefit by being able to run kubectl explain against their resource and having documentation right at their fingertips without having to navigate to API documentation in order to see the usage of the API. For example:

+operator-builder:field:name=myName,type=string,default=test,description="Hello World"

Note: that you can use a single custom resource field name to configure multiple fields in the resource.

Consider the following Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: webapp-deploy
  labels:
    production: false  # +operator-builder:field:name=production,default=false,type=bool
spec:
  replicas: 2  # +operator-builder:field:name=webAppReplicas,default=2,type=int
  selector:
    matchLabels:
      app: webapp
  template:
    metadata:
      labels:
        app: webapp
    spec:
      containers:
      - name: webapp-container
        image: nginx:1.17  # +operator-builder:field:name=webAppImage,type=string
        ports:
        - containerPort: 8080

In this case, operator-builder will create and add three fields to the custom resource:

A production field that is a boolean. It will have a default of false and will inform the value of the label when the deployment is configured.
A webAppReplicas field that will default to 2 and allow the user to specify the number of replicas for the deployment in the custom resource manifest.
A webAppImage field that will set the value for the images used in the pods.

Now the end-user of the operator will be able to define a custom resource similar to the following to configure the deployment created:

apiVersion: product.apps.acme.com/v1alpha1
kind: WebApp
metadata:
  name: dev-webapp
spec:
  production: false
  webAppReplicas: 2
  webAppImage: acmerepo/webapp:3.5.3

Collection Markers

A second marker type +operator-builder:collection:field can be used with the same arguments as a Field Marker. These markers are used to define global fields for your Collection and can be used in any of its associated components.

If you include any marker on a collection resource it will be treated as a collection marker and will configure a field in the collection's custom resource.

Resource Markers

Defined as +operator-builder:resource this marker can be used to control a specific resource with arguments in the marker.

Note: a resource marker must reference a field defined by a field marker. If you include a resource marker with a unique field name that is not also defined by a field marker you will get an error. You may use an arbitrary field on a field marker if you don't wish to associate the field with a value in a child resource.

Field	Type	Required
field	string	true
collectionField	string{string, int, bool}	true
value	type	true
include	bool	true

Field / CollectionField (required)

The conditional field to associate with an action (currently only include). One of field or collectionField must be provided depending upon if you are checking a condition against a collection, or a component/standalone workload spec. The field input relates directly to a given workload marker such as +operator-builder:field:name=provider would produce a field of provider to be used in a resource marker with argument field=provider.

ex. +operator-builder:resource:collectionField=provider,value="aws",include ex. +operator-builder:resource:field=provider,value="aws",include=false

Value (required)

The conditional value to associate with an action (currently only include - see above). The value input relates directly to the value of field as it exists in the API spec requested by the user.

Examples:

+operator-builder:resource:collectionField=provider,value="aws",include
+operator-builder:resource:field=provider,value="aws",include=false

Include (required)

The action to perform on the resource. Include will include the resource for deployment during a control loop given a field or collectionField and a value. Using this means that the resource will only be included if this condition is met. If the condition is not met, the resource will not be deployed.

Here are some sample marker examples:

+operator-builder:resource:field=provider,value="aws",include
+operator-builder:resource:field=provider,value="aws",include=true
+operator-builder:resource:collectionField=provider,value="aws",include
+operator-builder:resource:collectionField=provider,value="aws",include=true

With include set to false, the opposite is true and the resource is excluded from being deployed during a control loop if a condition is met:

Examples:

+operator-builder:resource:field=provider,value="aws",include=false
+operator-builder:resource:collectionField=provider,value="aws",include=false

At this time, the include argument with field and value can be simply thought of as (pseudo-code):

if field == value {
  if include {
    includeResource()
  }
}

IMPORTANT: A resource marker is not required and should only be used when there is a desire to act upon a resource. If no resource marker is provided, a resource is always deployed during a control loop.

Include Resource On Condition

Below is a sample of how to include a resource only if a condition is met. If the condition is not met, the resource is not deployed during the control loop:

# +operator-builder:resource:field=provider,value="aws",include
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: aws-storage-class
  annotations:
    storageclass.kubernetes.io/is-default-class: true
  labels:
    provider: "aws" # +operator-builder:field:name=provider,type=string,default="aws"
allowVolumeExpansion: false
provisioner: "kubernetes.io/aws-ebs"
reclaimPolicy: "Delete"
volumeBindingMode: WaitForFirstConsumer
parameters:
  type: "gp2"
  iopsPerGB: 10
  fsType: "ext4"
  encrypted: false

Given the below CRD, the resource would be included:

apiVersion: apps.acme.com/v1alpha1
kind: Sample
metadata:
  name: sample
  namespace: default
spec:
  provider: "aws"

Given the below CRD, the resource would NOT be included:

apiVersion: apps.acme.com/v1alpha1
kind: Sample
metadata:
  name: sample
  namespace: default
spec:
  provider: "azure"

Exclude Resource On Condition

Below is a sample of how to exclude a resource only if a condition is met. If the condition is not met, the resource is not deployed during the control loop:

# +operator-builder:resource:field=provider,value="azure",include=false
---
kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: aws-storage-class
  annotations:
    storageclass.kubernetes.io/is-default-class: true
  labels:
    provider: "aws" # +operator-builder:field:name=provider,type=string,default="aws"
allowVolumeExpansion: false
provisioner: "kubernetes.io/aws-ebs"
reclaimPolicy: "Delete"
volumeBindingMode: WaitForFirstConsumer
parameters:
  type: "gp2"
  iopsPerGB: 10
  fsType: "ext4"
  encrypted: false

Given the below CRD, the resource would be included:

apiVersion: apps.acme.com/v1alpha1
kind: Sample
metadata:
  name: sample
  namespace: default
spec:
  provider: "aws"

Given the below CRD, the resource would NOT be included:

apiVersion: apps.acme.com/v1alpha1
kind: Sample
metadata:
  name: sample
  namespace: default
spec:
  provider: "azure"

Stacking Resource Markers

You can include multiple resource markers on a particular resource. For example:

---
# +operator-builder:resource:field=nginx.include,value=true,include
# +operator-builder:resource:field=nginx.installType,value="deployment",include
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ingress
...

The purpose of the first marker is to include all nginx ingress contoller resources when spec.nginx.include: true. The second gives users a choice to install nginx ingress controller as a deployment or daemonset. When spec.nginx.installType: deployment the deployment resource is included. Therefore the custom resource will need to look as follows for this deployment resource to be created:

apiVersion: platform.addons.nukleros.io/v1alpha1
kind: IngressComponent
metadata:
  name: ingresscomponent-sample
spec:
  nginx:
    installType: "deployment"  # if not "deployment" deployment resource excluded
    include: true  # if false, no nginx resources are created
    image: "nginx/nginx-ingress"
    version: "2.3.0"
    replicas: 2

The resulting source code looks as follows. If either if-statement is evaluated as true, the function will return without any object - hence the deployment will not be included.

// CreateDeploymentNamespaceNginxIngress creates the Deployment resource with name nginx-ingress.
func CreateDeploymentNamespaceNginxIngress(
	parent *platformv1alpha1.IngressComponent,
	collection *setupv1alpha1.SupportServices,
	reconciler workload.Reconciler,
	req *workload.Request,
) ([]client.Object, error) {

	if parent.Spec.Nginx.Include != true {
		return []client.Object{}, nil
	}

	if parent.Spec.Nginx.InstallType != "deployment" {
		return []client.Object{}, nil
	}

	var resourceObj = &unstructured.Unstructured{
		Object: map[string]interface{}{
			// +operator-builder:resource:field=nginx.include,value=true,include
			// +operator-builder:resource:field=nginx.installType,value="deployment",include
			"apiVersion": "apps/v1",
			"kind":       "Deployment",
      ...
			}

	return mutate.MutateDeploymentNamespaceNginxIngress(resourceObj, parent, collection, reconciler, req)
}

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markers.md

markers.md

Markers

Arguments

Field Markers

Name (required if Parent is unspecified)

Parent (required if Name is unspecified)

Type (required)

Default (optional)

Replace (optional)

Arbitrary (optional)

Description (optional)

Collection Markers

Resource Markers

Field / CollectionField (required)

Value (required)

Include (required)

Include Resource On Condition

Exclude Resource On Condition

Stacking Resource Markers

Files

markers.md

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markers.md

File metadata and controls

Markers

Arguments

Field Markers

Name (required if Parent is unspecified)

Parent (required if Name is unspecified)

Type (required)

Default (optional)

Replace (optional)

Arbitrary (optional)

Description (optional)

Collection Markers

Resource Markers

Field / CollectionField (required)

Value (required)

Include (required)

Include Resource On Condition

Exclude Resource On Condition

Stacking Resource Markers