Implement POSTing request bodies to the endpoint.

This adds support to the APIClient generator to generate by posting a
body against an HTTP endpoint.

api/v1alpha1/gitopsset_types.go

@@ -75,7 +75,7 @@ type APIClientGenerator struct {
 	Interval metav1.Duration `json:"interval"`
 
 	// This is the API endpoint to use.
-	// +kubebuilder:validation:Pattern="^https://"
+	// +kubebuilder:validation:Pattern="^(http|https)://"
 	// +optional
 	Endpoint string `json:"endpoint,omitempty"`
 
@@ -99,6 +99,11 @@ type APIClientGenerator struct {
 	//
 	// +optional
 	HeadersRef *HeadersReference `json:"headersRef"`
+
+	// Body is set as the body in a POST request.
+	//
+	// If set, this will configure the Method to be POST automatically.
+	Body *apiextensionsv1.JSON `json:"body"`
 }
 
 // HeadersReference references either a Secret or ConfigMap to be used for

config/crd/bases/templates.weave.works_gitopssets.yaml

@@ -58,9 +58,13 @@ spec:
                       description: APIClientGenerator defines a generator that queries
                         an API endpoint and uses that to generate data.
                       properties:
+                        body:
+                          description: "Body is set as the body in a POST request.
+                            \n If set, this will configure the Method to be POST automatically."
+                          x-kubernetes-preserve-unknown-fields: true
                         endpoint:
                           description: This is the API endpoint to use.
-                          pattern: ^https://
+                          pattern: ^(http|https)://
                           type: string
                         headersRef:
                           description: "HeadersRef allows optional configuration of
@@ -100,6 +104,7 @@ spec:
                           - POST
                           type: string
                       required:
+                      - body
                       - interval
                       type: object
                     cluster:
@@ -222,9 +227,14 @@ spec:
                                   that queries an API endpoint and uses that to generate
                                   data.
                                 properties:
+                                  body:
+                                    description: "Body is set as the body in a POST
+                                      request. \n If set, this will configure the
+                                      Method to be POST automatically."
+                                    x-kubernetes-preserve-unknown-fields: true
                                   endpoint:
                                     description: This is the API endpoint to use.
-                                    pattern: ^https://
+                                    pattern: ^(http|https)://
                                     type: string
                                   headersRef:
                                     description: "HeadersRef allows optional configuration
@@ -267,6 +277,7 @@ spec:
                                     - POST
                                     type: string
                                 required:
+                                - body
                                 - interval
                                 type: object
                               cluster:

controllers/templates/generators/apiclient/api_client.go

@@ -1,6 +1,7 @@
 package apiclient
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"fmt"
@@ -97,11 +98,25 @@ func (g *APIClientGenerator) Interval(sg *templatesv1.GitOpsSetGenerator) time.D
 }
 
 func (g *APIClientGenerator) createRequest(ctx context.Context, ac *templatesv1.APIClientGenerator, namespace string) (*http.Request, error) {
-	req, err := http.NewRequestWithContext(ctx, ac.Method, ac.Endpoint, nil)
+	method := ac.Method
+	if ac.Body != nil {
+		method = http.MethodPost
+	}
+
+	var body io.Reader
+	if ac.Body != nil {
+		body = bytes.NewReader(ac.Body.Raw)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, ac.Endpoint, body)
 	if err != nil {
 		return nil, err
 	}
 
+	if body != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
 	if ac.HeadersRef != nil {
 		if ac.HeadersRef.Kind == "Secret" {
 			return req, addHeadersFromSecretToRequest(ctx, g.Client, req, client.ObjectKey{Name: ac.HeadersRef.Name, Namespace: namespace})

controllers/templates/generators/apiclient/api_client_test.go

@@ -11,15 +11,17 @@ import (
 
 	"github.com/go-logr/logr"
 	"github.com/google/go-cmp/cmp"
-	templatesv1 "github.com/weaveworks/gitopssets-controller/api/v1alpha1"
-	"github.com/weaveworks/gitopssets-controller/controllers/templates/generators"
-	"github.com/weaveworks/gitopssets-controller/test"
 	corev1 "k8s.io/api/core/v1"
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/client/fake"
+
+	templatesv1 "github.com/weaveworks/gitopssets-controller/api/v1alpha1"
+	"github.com/weaveworks/gitopssets-controller/controllers/templates/generators"
+	"github.com/weaveworks/gitopssets-controller/test"
 )
 
 var _ generators.Generator = (*APIClientGenerator)(nil)
@@ -85,6 +87,20 @@ func TestGenerate(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "simple API endpoint with POST body request",
+			apiClient: &templatesv1.APIClientGenerator{
+				Endpoint: ts.URL + "/api/post-body",
+				Method:   http.MethodPost,
+				Body:     &apiextensionsv1.JSON{Raw: []byte(`{"user":"demo","groups":["group1"]}`)},
+			},
+			want: []map[string]any{
+				{
+					"name":   "demo",
+					"groups": []any{"group1"},
+				},
+			},
+		},
 		{
 			name: "api endpoint returning map with JSONPath",
 			apiClient: &templatesv1.APIClientGenerator{
@@ -370,6 +386,33 @@ func newTestMux(t *testing.T) *http.ServeMux {
 		writeResponse(w)
 	})
 
+	mux.HandleFunc("/api/post-body", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			http.Error(w, "unsupported method", http.StatusMethodNotAllowed)
+			return
+		}
+		if r.Header.Get("Content-Type") != "application/json" {
+			http.Error(w, "unsupported content type", http.StatusUnsupportedMediaType)
+			return
+		}
+		var body map[string]any
+		decoder := json.NewDecoder(r.Body)
+		if err := decoder.Decode(&body); err != nil {
+			http.Error(w, "invalid json "+err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		enc := json.NewEncoder(w)
+		if err := enc.Encode([]map[string]any{
+			{
+				"name":   body["user"],
+				"groups": body["groups"],
+			},
+		}); err != nil {
+			t.Fatal(err)
+		}
+	})
+
 	mux.HandleFunc("/api/non-array", func(w http.ResponseWriter, r *http.Request) {
 		enc := json.NewEncoder(w)
 		if err := enc.Encode(map[string]any{

docs/README.md

@@ -131,12 +131,11 @@ In this case, six different `ConfigMaps` are generated, three for the "dev-team"
 ## Generators
 
 We currently provide these generators:
-
-- list
-- pullRequests
-- gitRepository
-- matrix
-- apiClient
+ - [list](#list-generator)
+ - [pullRequests](#pullrequests-generator)
+ - [gitRepository](#gitrepository-generator)
+ - [matrix](#matrix-generator)
+ - [apiClient](#apiclient-generator)
 
 ### List generator
 
@@ -537,7 +536,7 @@ Not all APIs return an array of JSON objects, sometimes it's nested within a res
 }
 ```
 You can use JSONPath to extract the fields from this data...
-```
+```yaml
 apiVersion: templates.weave.works/v1alpha1
 kind: GitOpsSet
 metadata:
@@ -557,6 +556,38 @@ spec:
 ```
 This will generate three maps for templates, with just the _env_ and _team_ keys.
 
+#### APIClient POST body
+
+Another piece of functionality in the APIClient generator is the ability to POST
+JSON to the API.
+```yaml
+apiVersion: templates.weave.works/v1alpha1
+kind: GitOpsSet
+metadata:
+  labels:
+    app.kubernetes.io/name: gitopsset
+    app.kubernetes.io/instance: gitopsset-sample
+    app.kubernetes.io/part-of: gitopssets-controller
+    app.kubernetes.io/managed-by: kustomize
+    app.kubernetes.io/created-by: gitopssets-controller
+  name: api-client-sample
+spec:
+  generators:
+    - apiClient:
+        interval: 5m
+        endpoint: https://api.example.com/demo
+        body:
+          name: "testing"
+          value: "testing2"
+```
+This will send a request body as JSON (Content-Type "application/json") to the
+server and interpret the result.
+
+The JSON body sent will look like this:
+```json
+{"name":"testing","value":"testing2"}
+```
+
 ## Templating functions
 
 Currently, the [Sprig](http://masterminds.github.io/sprig/) functions are available in the templating, with some functions removed[^sprig] for security reasons.