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function-status-transformer

CI

Requirements

This function requires Crossplane v1.17 or newer.

Usage

Function Status Transformer allows you to create hooks that will trigger by matching the status conditions of managed resources. Each hook can be configured to set one or more status conditions on the composite resource and the claim.

Basic Usage

Here is a basic usage example. The function will look for the cloudsql-instance resource within the observed resource map. If that resource matches the specified condition criteria, the condition in setConditions will get set on both the composite resource and the claim.

apiVersion: apiextensions.crossplane.io/v1
kind: Composition
spec:
  compositeTypeRef:
    apiVersion: your.api.group/v1alpha1
    kind: XYourCompositeKind
  mode: Pipeline
  pipeline:
  # Insert your pipeline steps here.
  - step: status-handler
    functionRef:
      name: function-status-transformer
    input:
      apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
      kind: StatusTransformation
      statusConditionHooks:
      - matchers:
        - resources: 
          - key: "cloudsql-instance"
          conditions:
          - type: Synced
            status: "False"
            reason: ReconcileError
            message: "failed to create the database: some internal error."
        setConditions:
        - target: CompositeAndClaim
          condition:
            type: DatabaseReady
            status: "False"
            reason: FailedToCreate
            message: "failed to create the database"

Using Regular Expressions to Capture Message Data

You can use regular expressions to capture data from the status condition message on the managed resource. The captured groups can then be inserted into status condition and event messages on the composite resource and claim.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
- matchers:
  - resources:
    - key: "cloudsql-instance"
    conditions:
    - type: Synced
      status: "False"
      reason: ReconcileError
      message: "failed to create the database: (?P<Error>.+)"
  setConditions:
  - target: CompositeAndClaim
    condition:
      type: DatabaseReady
      status: "False"
      reason: FailedToCreate
      message: "Encountered an error creating the database: {{ .Error }}"
  createEvents:
  - target: CompositeAndClaim
    event:
      type: Warning
      reason: FailedToCreate
      message: "Encountered an error creating the database: {{ .Error }}"

Using Regular Expressions to Match Multiple Resources

You can use regular expressions in the resourceKey. This will allow you to match multiple resources of a similar type. For instance, say you spin up multiple instances of the same type and name them like cloudsql-1, cloudsql-2, etc. You could write a single hook to handle all of these by using a resource key of cloudsql-\\d+.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
- matchers:
  - resources:
    - key: "cloudsql-\\d+"
    conditions:
    - type: Synced
      status: "False"
      reason: ReconcileError

Condition Matching Wildcards

If you do not care about the particular value of a status condition that you are matching against, you can leave it empty and it will act as a wildcard. The only value that cannot be left empty is the type.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
- matchers:
  - resources:
    - key: "cloudsql-\\d+"
    conditions:
      # The "reason" and "message" fields will be treated as wildcards.
    - type: Synced
      status: "False"

Matchers are ANDed

When using multiple matchers, they must all match before setConditions will be triggered.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
# Both matchers must be true before the corresponding setConditions will
# be set
- matchers:
  - resources:
    - key: "cloudsql"
    conditions:
    - type: Synced
      status: "True"
  - resources:
    - "cloudsql"
    conditions:
    - type: Ready
      status: "True"
  setConditions: {...}

Overriding Conditions

Hooks will be executed in order. By default a setCondition will not set a condition that was previously set by function-status-transformer (Note: This does not apply to conditions set by previous functions in the pipeline). Condition uniqueness is determined by the type. To override a condition that was already set, you can use force.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
- setConditions:
    # This condition will be set as it is the first time the type is set.
  - target: CompositeAndClaim
    condition:
      type: DatabaseReady
      status: "True"
      reason: Example
- setConditions:
    # This condition will not be set as it has been set before and is not
    # forceful.
  - target: CompositeAndClaim
    condition:
      type: DatabaseReady
      status: "False"
      reason: FailedToCreate
      message: "Encountered an error creating the database: {{ .Error }}"
- setConditions:
    # This condition will be set as it is forceful.
  - target: CompositeAndClaim
    force: true
    condition:
      type: DatabaseReady
      status: "False"
      reason: FailedToCreate
      message: "Encountered an error creating the database: {{ .Error }}"

Matching Missing Conditions

You can match against missing conditions. To do this, use the default unknown condition values.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
- matchers:
  - resources:
    - key: "cloudsql"
    conditions:
      # These are the values seen when a condition does not exist.
    - type: Synced
      status: "Unknown"
      reason: ""
      message: ""

Setting Default Conditions

If you want to set one or more conditions when no other hook has matched, you can do this by placing a hook at the end and make sure the setCondition force values are omitted or set to false. For matching, you can either use all wildcard fields (see Condition Matching Wildcards) or you can specify a type that will never exist. The only requirement is that the resourceKey must match one or more resources.

apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
kind: StatusTransformation
statusConditionHooks:
- matchers:
  - resourceKey: "cloudsql"
    condition:
      # This is a type that does not exist on the resource.
      type: ThisTypeDoesNotExist
      # These are the values seen when a condition does not exist.
      status: "Unknown"
      reason: ""
      message: ""
- setConditions:
  - target: CompositeAndClaim
    force: false
    condition:
      type: DatabaseReady
      status: "Unknown"
      reason: Unknown

Creating Events

In addition to setting conditions, you can also create events for both the composite resource and the claim. You should note that events should be created sparingly, and will be limited by the behavior documented in 5802

To create events, use createEvents as seen below.

apiVersion: apiextensions.crossplane.io/v1
kind: Composition
spec:
  compositeTypeRef:
    apiVersion: your.api.group/v1alpha1
    kind: XYourCompositeKind
  mode: Pipeline
  pipeline:
  # Insert your pipeline steps here.
  - step: status-handler
    functionRef:
      name: function-status-transformer
    input:
      apiVersion: function-status-transformer.fn.crossplane.io/v1beta1
      kind: StatusTransformation
      statusConditionHooks:
      - matchers:
        - resources:
          - key: "cloudsql-instance"
          conditions:
          - type: Synced
            status: "False"
            reason: ReconcileError
            message: "failed to create the database: some internal error."
        createEvents:
        - target: CompositeAndClaim
          event:
            type: Warning
            reason: FailedToCreate
            message: "failed to create the database"

Customizing Matching Behavior

Any given matcher will first find all resources selected by matcher.resources. It will then compare the status conditions of the resources against the status conditions found in matcher.conditions. You can customize the comparison behavior by setting matcher.type. The different match types and their behaviors can be seen below.

  • AnyResourceMatchesAnyCondition - Considered a match if any resource matches any condition. An example use case would be if you want to transform any error condition from one of your managed resources into an error condition on your composite and claim.
  • AnyResourceMatchesAllConditions - Considered a match if any resources matches all conditions. An example use case would be if you want to check if any resource is synced but not ready. You could then communicate to the user that everything is valid and they just need to wait for resources to become ready.
  • AllResourcesMatchAnyCondition - Considered a match if all resources match any condition. An example use case would be if you want to check that some resources match one of the many possible good states.
  • AllResourcesMatchAllConditions (default) - Considered a match if all resources match all conditions. An example use case would be checking that all resources are both synced and ready. You could then let the user know that everything is ready to go.

Determining the Status of the Function Itself

The status of this function can be found by viewing the StatusTransformationSuccess status condition on the composite resource. The function will use this status condition to communicate its own state and will not emit fatal results. This means that the overall state of the claim and composite resource will not be affected by this functions failure. See the following sections on some common conditions you may encounter and what they mean.

Notes:

  • Any error encountered within a statusConditionHook will be logged, but only the last error will be present on the StatusTransformationSuccess condition.

Success

If no failures are encountered, the StatusTransformationSuccess condition will be set to True with a reason of Available.

- lastTransitionTime: "2024-08-02T15:57:20Z"
  reason: Available
  status: "True"
  type: StatusTransformationSuccess

Failure to Parse Input

If an invalid input is provided, the StatusTransformationSuccess condition will be set to False with a reason of InputFailure. Note that no matchCondition or setCondition will be evaluated.

- lastTransitionTime: "2024-08-02T15:11:35Z"
  message: 'cannot get Function input from *v1beta1.RunFunctionRequest: cannot get
    function input *v1beta1.StatusTransformation from *v1beta1.RunFunctionRequest:
    cannot unmarshal JSON from *structpb.Struct into *v1beta1.StatusTransformation:
    json: cannot unmarshal Go value of type v1beta1.StatusTransformation: unknown
    name "statusConditionHookss"'
  reason: InputFailure
  status: "False"
  type: StatusTransformationSuccess

Failure to Match a Regular Expression

If an invalid regular expression is provided in a matchCondition message or resourceKey, the StatusTransformationSuccess condition will be set to False with a reason of MatchFailure. Note that no further matchCondition will be evaluated for corresponding statusConditionHook and the overall result of matching for the hook will be a failure. All other statusConditionHooks will attempt to be evaluated as normal.

- lastTransitionTime: "2024-08-02T15:29:51Z"
  message: 'error when matching, statusConditionHookIndex: 0, matchConditionIndex:
    0: [failed to compile message regex, error parsing regexp: invalid or unsupported
    Perl syntax: `(?!`]'
  reason: MatchFailure
  status: "False"
  type: StatusTransformationSuccess

Failure to Set a Condition Message Template

If an invalid template is provided in a setCondition message, the StatusTransformationSuccess condition will be set to False with a reason of SetConditionFailure.

- lastTransitionTime: "2024-08-02T15:46:45Z"
  message: 'failed to set condition, statusConditionHookIndex: 0, setConditionIndex:
    0: [failed to parse template, template: :1: unexpected "}" in operand]'
  reason: SetConditionFailure
  status: "False"
  type: StatusTransformationSuccess