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Merge pull request #502 from scothis/aspect-oriented-reconciler
Advice reconciler
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,155 @@ | ||
| /* | ||
| Copyright 2024 the original author or authors. | ||
| Licensed under the Apache License, Version 2.0 (the "License"); | ||
| you may not use this file except in compliance with the License. | ||
| You may obtain a copy of the License at | ||
| http://www.apache.org/licenses/LICENSE-2.0 | ||
| Unless required by applicable law or agreed to in writing, software | ||
| distributed under the License is distributed on an "AS IS" BASIS, | ||
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| See the License for the specific language governing permissions and | ||
| limitations under the License. | ||
| */ | ||
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| package reconcilers | ||
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| import ( | ||
| "context" | ||
| "fmt" | ||
| "sync" | ||
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| "github.com/go-logr/logr" | ||
| ctrl "sigs.k8s.io/controller-runtime" | ||
| "sigs.k8s.io/controller-runtime/pkg/builder" | ||
| "sigs.k8s.io/controller-runtime/pkg/client" | ||
| ) | ||
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| var ( | ||
| _ SubReconciler[client.Object] = (*Advice[client.Object])(nil) | ||
| ) | ||
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| // Advice is a sub reconciler for advising the lifecycle of another sub reconciler in an aspect | ||
| // oriented programming style. | ||
| type Advice[Type client.Object] struct { | ||
| // Name used to identify this reconciler. Defaults to `Advice`. Ideally unique, but | ||
| // not required to be so. | ||
| // | ||
| // +optional | ||
| Name string | ||
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| // Setup performs initialization on the manager and builder this reconciler | ||
| // will run with. It's common to setup field indexes and watch resources. | ||
| // | ||
| // +optional | ||
| Setup func(ctx context.Context, mgr ctrl.Manager, bldr *builder.Builder) error | ||
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| // Reconciler being advised | ||
| Reconciler SubReconciler[Type] | ||
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| // Before is called preceding Around. A modified context may be returned. Errors are returned | ||
| // immediately. | ||
| // | ||
| // If Before is not defined, there is no effect. | ||
| // | ||
| // +optional | ||
| Before func(ctx context.Context, resource Type) (context.Context, Result, error) | ||
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| // Around is responsible for invoking the reconciler and returning the result. Implementations | ||
| // may choose to not invoke the reconciler, invoke a different reconciler or invoke the | ||
| // reconciler multiple times. | ||
| // | ||
| // If Around is not defined, the Reconciler is invoked once. | ||
| // | ||
| // +optional | ||
| Around func(ctx context.Context, resource Type, reconciler SubReconciler[Type]) (Result, error) | ||
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| // After is called following Around. The result and error from Around are provided and may be | ||
| // modified before returning. | ||
| // | ||
| // If After is not defined, the result and error are returned directly. | ||
| // | ||
| // +optional | ||
| After func(ctx context.Context, resource Type, result Result, err error) (Result, error) | ||
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| lazyInit sync.Once | ||
| } | ||
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| func (r *Advice[T]) init() { | ||
| r.lazyInit.Do(func() { | ||
| if r.Name == "" { | ||
| r.Name = "Advice" | ||
| } | ||
| if r.Before == nil { | ||
| r.Before = func(ctx context.Context, resource T) (context.Context, Result, error) { | ||
| return nil, Result{}, nil | ||
| } | ||
| } | ||
| if r.Around == nil { | ||
| r.Around = func(ctx context.Context, resource T, reconciler SubReconciler[T]) (Result, error) { | ||
| return reconciler.Reconcile(ctx, resource) | ||
| } | ||
| } | ||
| if r.After == nil { | ||
| r.After = func(ctx context.Context, resource T, result Result, err error) (Result, error) { | ||
| return result, err | ||
| } | ||
| } | ||
| }) | ||
| } | ||
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| func (r *Advice[T]) SetupWithManager(ctx context.Context, mgr ctrl.Manager, bldr *builder.Builder) error { | ||
| r.init() | ||
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| log := logr.FromContextOrDiscard(ctx). | ||
| WithName(r.Name) | ||
| ctx = logr.NewContext(ctx, log) | ||
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| if r.Setup == nil { | ||
| return nil | ||
| } | ||
| if err := r.validate(ctx); err != nil { | ||
| return err | ||
| } | ||
| if err := r.Setup(ctx, mgr, bldr); err != nil { | ||
| return err | ||
| } | ||
| return r.Reconciler.SetupWithManager(ctx, mgr, bldr) | ||
| } | ||
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| func (r *Advice[T]) validate(ctx context.Context) error { | ||
| if r.Reconciler == nil { | ||
| return fmt.Errorf("Advice %q must implement Reconciler", r.Name) | ||
| } | ||
| if r.Before == nil && r.Around == nil && r.After == nil { | ||
| return fmt.Errorf("Advice %q must implement at least one of Before, Around or After", r.Name) | ||
| } | ||
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| return nil | ||
| } | ||
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| func (r *Advice[T]) Reconcile(ctx context.Context, resource T) (Result, error) { | ||
| r.init() | ||
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| log := logr.FromContextOrDiscard(ctx). | ||
| WithName(r.Name) | ||
| ctx = logr.NewContext(ctx, log) | ||
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| // before phase | ||
| beforeCtx, result, err := r.Before(ctx, resource) | ||
| if err != nil { | ||
| return result, err | ||
| } | ||
| if beforeCtx != nil { | ||
| ctx = beforeCtx | ||
| } | ||
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| // around phase | ||
| aroundResult, err := r.Around(ctx, resource, r.Reconciler) | ||
| result = AggregateResults(result, aroundResult) | ||
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| // after phase | ||
| return r.After(ctx, resource, result, err) | ||
| } |
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