implement helper function for environment variables

Signed-off-by: twobiers <[email protected]>

README.md

@@ -176,6 +176,7 @@ example:
 | [`getResourceCondition`](example/functions/getResourceCondition) | Helper function to retreive conditions of resources          |
 | [`getComposedResouce`](example/functions/getComposedResource)    | Helper function to retrieve observed composed resources      |
 | [`getCompositeResource`](example/functions/getCompositeResource) | Helper function to retreive the observed composite resource |
+| [`getCompositionEnvVar`](example/functions/getCompositionEnvVar) | Helper function to retreive an environment variable from the request context |
 | [`setResourceNameAnnotation`](example/inline)                    | Returns the special resource-name annotation with given name |
 | [`include`](example/functions/include)                           | Outputs template as a string                                 |
 

example/functions/getCompositionEnvVar/README.md

@@ -0,0 +1,2 @@
+# getCompositionEnvVar
+The getCompositionEnvVar function is a helper function used to retrieve [environment variables](https://docs.crossplane.io/latest/concepts/environment-configs/) from the request context. Upon successful retrieval, the function returns a string containing the variable. If no variable with the key exists, an empty string is returned.

example/functions/getCompositionEnvVar/composition.yaml

@@ -0,0 +1,31 @@
+apiVersion: apiextensions.crossplane.io/v1
+kind: Composition
+metadata:
+  name: example-function-get-composition-env-var
+spec:
+  compositeTypeRef:
+    apiVersion: example.crossplane.io/v1beta1
+    kind: XR
+  mode: Pipeline
+  pipeline:
+    - step: render-templates
+      functionRef:
+        name: function-go-templating
+      input:
+        apiVersion: gotemplating.fn.crossplane.io/v1beta1
+        kind: GoTemplate
+        source: Inline
+        inline:
+          template: |
+            ---
+            apiVersion: dbforpostgresql.azure.upbound.io/v1beta1
+            kind: FlexibleServer
+            metadata:
+              annotations:
+                {{ setResourceNameAnnotation "flexserver" }}
+                gotemplating.fn.crossplane.io/ready: "False"
+            spec:
+              forProvider:
+            
+                # Retrieve AdminLogin from request context
+                adminLogin: {{ getCompositionEnvVar . "adminLogin" }}

example/functions/getCompositionEnvVar/environment.yaml

@@ -0,0 +1,6 @@
+apiVersion: apiextensions.crossplane.io/v1alpha1
+kind: EnvironmentConfig
+metadata:
+  name: example-environment
+data:
+  adminLogin: admin

example/functions/getCompositionEnvVar/functions.yaml

@@ -0,0 +1,6 @@
+apiVersion: pkg.crossplane.io/v1beta1
+kind: Function
+metadata:
+  name: function-go-templating
+spec:
+  package: xpkg.upbound.io/crossplane-contrib/function-go-templating:v0.5.0

example/functions/getCompositionEnvVar/xr.yaml

@@ -0,0 +1,10 @@
+apiVersion: example.crossplane.io/v1beta1
+kind: XR
+metadata:
+  name: example
+spec:
+  environment:
+    environmentConfigs:
+    - type: Reference
+      ref:
+        name: example-environment

function_maps.go

@@ -26,6 +26,7 @@ var funcMaps = []template.FuncMap{
 		"setResourceNameAnnotation": setResourceNameAnnotation,
 		"getComposedResource":       getComposedResource,
 		"getCompositeResource":      getCompositeResource,
+		"getCompositionEnvVar":      getCompositionEnvVar,
 	},
 }
 
@@ -130,3 +131,14 @@ func getCompositeResource(req map[string]any) map[string]any {
 
 	return cr
 }
+
+func getCompositionEnvVar(req map[string]any, name string) (string, error) {
+	path := fmt.Sprintf("context[\"apiextensions.crossplane.io/environment\"][\"%s\"]", name)
+
+	env, err := fieldpath.Pave(req).GetString(path); 
+	if err != nil {
+		return "", err
+	}
+
+	return env, nil
+}

function_maps_test.go

@@ -459,3 +459,85 @@ func Test_getCompositeResource(t *testing.T) {
 		})
 	}
 }
+
+func Test_getCompositionEnvVar(t *testing.T) {
+	type args struct {
+		req map[string]any
+		name string
+	}
+
+	type want struct {
+		rsp string
+		err error
+	}
+
+	cases := map[string]struct {
+		reason string
+		args   args
+		want   want
+	}{
+		"RetrieveCompositionEnvVar": {
+			reason: "Should successfully retrieve a composition env var",
+			args: args{
+				req: map[string]any{
+					"context": map[string]any{
+						"apiextensions.crossplane.io/environment": map[string]any{
+							"test": "abc",
+						},
+					},
+				},
+				name: "test",
+			},
+			want: want{
+				rsp: "abc",
+				err: nil,
+			},
+		},
+		"RetrieveCompositionEnvVarCaseInsensitive": {
+			reason: "Should successfully retrieve a composition env var case insensitive",
+			args: args{
+				req: map[string]any{
+					"context": map[string]any{
+						"apiextensions.crossplane.io/environment": map[string]any{
+							"TEST": "abc",
+						},
+					},
+				},
+				name: "TEST",
+			},
+			want: want{
+				rsp: "abc",
+				err: nil,
+			},
+		},
+		"NotExistingEnvVar": {
+			reason: "Should return empty string when env var does not exist",
+			args: args{
+				req: map[string]any{
+					"context": map[string]any{
+						"apiextensions.crossplane.io/environment": map[string]any{},
+					},
+				},
+				name: "test",
+			},
+			want: want{
+				rsp: "",
+				err: cmpopts.AnyError,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			rsp, err := getCompositionEnvVar(tc.args.req, tc.args.name)
+
+			if diff := cmp.Diff(tc.want.rsp, rsp, protocmp.Transform()); diff != "" {
+				t.Errorf("%s\ngetCompositionEnvVar(...): -want rsp, +got rsp:\n%s", tc.reason, diff)
+			}
+
+			if diff := cmp.Diff(tc.want.err, err, cmpopts.EquateErrors()); diff != "" {
+				t.Errorf("%s\ntgetCompositionEnvVar(...): -want err, +got err:\n%s", tc.reason, diff)
+			}
+		})
+	}
+}