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Remove the big example, there's now something better in the docs. The linked guide won't exist until the below PR is merged. crossplane/docs#597 Signed-off-by: Nic Cope <[email protected]>
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| # function-sdk-go | ||
| [](https://github.com/crossplane/function-sdk-go/actions/workflows/ci.yml)  [](https://pkg.go.dev/github.com/crossplane/function-sdk-go) | ||
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| The Go SDK for Composition Functions. | ||
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| This SDK is currently a beta and does not yet have a stable API. It follows the | ||
| same [contributing guidelines] as Crossplane. | ||
| This SDK is currently a beta. We try to avoid breaking changes, but it will not | ||
| have a stable API until it reaches v1.0.0. It follows the same [contributing | ||
| guidelines] as Crossplane. | ||
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| ```go | ||
| func (f *Function) RunFunction(_ context.Context, req *fnv1beta1.RunFunctionRequest) (*fnv1beta1.RunFunctionResponse, error) { | ||
| // This creates a new response to the supplied request. Note that Functions | ||
| // are run in a pipeline! Other Functions may have run before this one. If | ||
| // they did, response.To will copy their desired state from req to rsp. Be | ||
| // sure to pass through any desired state your Function is not concerned | ||
| // with unmodified. | ||
| rsp := response.To(req, response.DefaultTTL) | ||
| To learn how to use this SDK: | ||
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| // Input is supplied by the author of a Composition when they choose to run | ||
| // your Function. Input is arbitrary, except that it must be a KRM-like | ||
| // object. Supporting input is also optional - if you don't need to you can | ||
| // delete this, and delete the input directory. | ||
| in := &v1beta1.Input{} | ||
| if err := request.GetInput(req, in); err != nil { | ||
| response.Fatal(rsp, errors.Wrapf(err, "cannot get Function input from %T", req)) | ||
| return rsp, nil | ||
| } | ||
| * [Follow the guide to writing a composition function in Go][function guide] | ||
| * [Read the package documentation][package docs] | ||
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| // Get the observed composite resource (XR) from the request. There should | ||
| // always be an observed XR in the request - this represents the current | ||
| // state of the XR. | ||
| oxr, err := request.GetObservedCompositeResource(req) | ||
| if err != nil { | ||
| response.Fatal(rsp, errors.Wrapf(err, "cannot get observed XR from %T", req)) | ||
| return rsp, nil | ||
| } | ||
| If you just want to jump in and get started, consider using the | ||
| [function-template-go] template repository. | ||
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| // Read the desired number of widgets from our observed XR. We don't have | ||
| // a struct for the XR, so we use an unstructured, fieldpath based getter. | ||
| widgets, err := oxr.Resource.GetInteger("spec.widgets") | ||
| if err != nil { | ||
| response.Fatal(rsp, errors.Wrap(err, "cannot get desired spec.widgets from observed XR")) | ||
| return rsp, nil | ||
| } | ||
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| // Get any existing desired composed resources from the request. | ||
| // Desired composed resources would exist if a previous Function in the | ||
| // pipeline added them. | ||
| desired, err := request.GetDesiredComposedResources(req) | ||
| if err != nil { | ||
| response.Fatal(rsp, errors.Wrapf(err, "cannot get desired composed resources from %T", req)) | ||
| return rsp, nil | ||
| } | ||
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| // Create a desired composed resource using unstructured data. | ||
| desired["new"] = &resource.DesiredComposed{Resource: composed.New()} | ||
| desired["new"].Resource.SetAPIVersion("example.org/v1") | ||
| desired["new"].Resource.SetKind("CoolResource") | ||
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| // Set the desired composed resource's widgets to the value extracted from | ||
| // the observed XR. | ||
| desired["new"].Resource.SetInteger("spec.widgets", widgets) | ||
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| // You could create a desired composed resource using structured data, too. | ||
| // db, _ := composed.From(&v1beta1.Instance{}) | ||
| // desired["database"] = &resource.DesiredComposed{Resource: db} | ||
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| // Set the labels of all desired resources, including our new one. | ||
| for _, r := range desired { | ||
| r.Resource.SetLabels(map[string]string{"coolness": "high"}) | ||
| } | ||
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| // Set our updated desired composed resource in the response we'll return. | ||
| if err := response.SetDesiredComposedResources(rsp, desired); err != nil { | ||
| response.Fatal(rsp, errors.Wrapf(err, "cannot set desired composed resources in %T", rsp)) | ||
| return rsp, nil | ||
| } | ||
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| return rsp, nil | ||
| } | ||
| ``` | ||
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| [contributing guidelines]: https://github.com/crossplane/crossplane/tree/master/contributing | ||
| [function guide]: https://docs.crossplane.io/knowledge-base/guides/write-a-composition-function-in-go | ||
| [package docs]: https://pkg.go.dev/github.com/crossplane/function-sdk-go | ||
| [function-template-go]: https://github.com/crossplane/function-template-go |