Add project_from_id provider-defined function

.changelog/10021.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+provider: added provider-defined function `project_from_id` for retrieving the project id from a resource's self link or id
+```

google-beta/functions/element_from_id.go

@@ -0,0 +1,44 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+package functions
+
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/hashicorp/terraform-plugin-framework/function"
+)
+
+const noMatchesErrorSummary string = "No matches present in the input string"
+const ambiguousMatchesWarningSummary string = "Ambiguous input string could contain more than one match"
+
+// ValidateElementFromIdArguments is reusable validation logic used in provider-defined functions that use the getElementFromId function
+func ValidateElementFromIdArguments(input string, regex *regexp.Regexp, pattern string, resp *function.RunResponse) {
+	submatches := regex.FindAllStringSubmatchIndex(input, -1)
+
+	// Zero matches means unusable input; error returned
+	if len(submatches) == 0 {
+		resp.Diagnostics.AddArgumentError(
+			0,
+			noMatchesErrorSummary,
+			fmt.Sprintf("The input string \"%s\" doesn't contain the expected pattern \"%s\".", input, pattern),
+		)
+	}
+
+	// >1 matches means input usable but not ideal; issue warning
+	if len(submatches) > 1 {
+		resp.Diagnostics.AddArgumentWarning(
+			0,
+			ambiguousMatchesWarningSummary,
+			fmt.Sprintf("The input string \"%s\" contains more than one match for the pattern \"%s\". Terraform will use the first found match.", input, pattern),
+		)
+	}
+}
+
+// GetElementFromId is reusable logic that is used in multiple provider-defined functions for pulling elements out of self links and ids of resources and data sources
+func GetElementFromId(input string, regex *regexp.Regexp, template string) string {
+	submatches := regex.FindAllStringSubmatchIndex(input, -1)
+	submatch := submatches[0] // Take the only / left-most submatch
+	dst := []byte{}
+	return string(regex.ExpandString(dst, template, input, submatch))
+}

google-beta/functions/element_from_id_internal_test.go

@@ -0,0 +1,97 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+package functions_test
+
+import (
+	"regexp"
+	"testing"
+
+	"github.com/hashicorp/terraform-plugin-framework/function"
+	"github.com/hashicorp/terraform-plugin-framework/types/basetypes"
+	tpg_functions "github.com/hashicorp/terraform-provider-google-beta/google-beta/functions"
+)
+
+func TestFunctionInternals_ValidateElementFromIdArguments(t *testing.T) {
+
+	// Values here are matched to test case values below
+	regex := regexp.MustCompile("two/(?P<Element>[^/]+)/")
+	pattern := "two/{two}/"
+
+	cases := map[string]struct {
+		Input           string
+		ExpectedElement string
+		ExpectError     bool
+		ExpectWarning   bool
+	}{
+		"it sets an error in diags if no match is found": {
+			Input:       "one/element-1/three/element-3",
+			ExpectError: true,
+		},
+		"it sets a warning in diags if more than one match is found": {
+			Input:           "two/element-2/two/element-2/two/element-2",
+			ExpectedElement: "element-2",
+			ExpectWarning:   true,
+		},
+	}
+
+	for tn, tc := range cases {
+		t.Run(tn, func(t *testing.T) {
+
+			// Arrange
+			resp := function.RunResponse{
+				Result: function.NewResultData(basetypes.StringValue{}),
+			}
+
+			// Act
+			tpg_functions.ValidateElementFromIdArguments(tc.Input, regex, pattern, &resp)
+
+			// Assert
+			if resp.Diagnostics.HasError() && !tc.ExpectError {
+				t.Fatalf("Unexpected error(s) were set in response diags: %s", resp.Diagnostics.Errors())
+			}
+			if !resp.Diagnostics.HasError() && tc.ExpectError {
+				t.Fatal("Expected error(s) to be set in response diags, but there were none.")
+			}
+			if (resp.Diagnostics.WarningsCount() > 0) && !tc.ExpectWarning {
+				t.Fatalf("Unexpected warning(s) were set in response diags: %s", resp.Diagnostics.Warnings())
+			}
+			if (resp.Diagnostics.WarningsCount() == 0) && tc.ExpectWarning {
+				t.Fatal("Expected warning(s) to be set in response diags, but there were none.")
+			}
+		})
+	}
+}
+
+func TestFunctionInternals_GetElementFromId(t *testing.T) {
+
+	// Values here are matched to test case values below
+	regex := regexp.MustCompile("two/(?P<Element>[^/]+)/")
+	template := "$Element"
+
+	cases := map[string]struct {
+		Input           string
+		ExpectedElement string
+	}{
+		"it can pull out a value from a string using a regex with a submatch": {
+			Input:           "one/element-1/two/element-2/three/element-3",
+			ExpectedElement: "element-2",
+		},
+		"it will pull out the first value from a string with more than one submatch": {
+			Input:           "one/element-1/two/element-2/two/not-this-one/three/element-3",
+			ExpectedElement: "element-2",
+		},
+	}
+
+	for tn, tc := range cases {
+		t.Run(tn, func(t *testing.T) {
+
+			// Act
+			result := tpg_functions.GetElementFromId(tc.Input, regex, template)
+
+			// Assert
+			if result != tc.ExpectedElement {
+				t.Fatalf("Expected function logic to retrieve %s from input %s, got %s", tc.ExpectedElement, tc.Input, result)
+			}
+		})
+	}
+}

google-beta/functions/project_from_id.go

@@ -0,0 +1,61 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+package functions
+
+import (
+	"context"
+	"regexp"
+
+	"github.com/hashicorp/terraform-plugin-framework/function"
+)
+
+var _ function.Function = ProjectFromIdFunction{}
+
+func NewProjectFromIdFunction() function.Function {
+	return &ProjectFromIdFunction{}
+}
+
+type ProjectFromIdFunction struct{}
+
+func (f ProjectFromIdFunction) Metadata(ctx context.Context, req function.MetadataRequest, resp *function.MetadataResponse) {
+	resp.Name = "project_from_id"
+}
+
+func (f ProjectFromIdFunction) Definition(ctx context.Context, req function.DefinitionRequest, resp *function.DefinitionResponse) {
+	resp.Definition = function.Definition{
+		Summary:     "Returns the project within a provided resource's id, resource URI, self link, or full resource name.",
+		Description: "Takes a single string argument, which should be a resource's id, resource URI, self link, or full resource name. This function will either return the project name from the input string or raise an error due to no project being present in the string. The function uses the presence of \"projects/{{project}}/\" in the input string to identify the project name, e.g. when the function is passed the id \"projects/my-project/zones/us-central1-c/instances/my-instance\" as an argument it will return \"my-project\".",
+		Parameters: []function.Parameter{
+			function.StringParameter{
+				Name:        "id",
+				Description: "A string of a resource's id, resource URI, self link, or full resource name. For example, \"projects/my-project/zones/us-central1-c/instances/my-instance\", \"https://www.googleapis.com/compute/v1/projects/my-project/zones/us-central1-c/instances/my-instance\" and \"//gkehub.googleapis.com/projects/my-project/locations/us-central1/memberships/my-membership\" are valid values",
+			},
+		},
+		Return: function.StringReturn{},
+	}
+}
+
+func (f ProjectFromIdFunction) Run(ctx context.Context, req function.RunRequest, resp *function.RunResponse) {
+	// Load arguments from function call
+	var arg0 string
+	resp.Diagnostics.Append(req.Arguments.GetArgument(ctx, 0, &arg0)...)
+
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	// Prepare how we'll identify project id from input string
+	regex := regexp.MustCompile("projects/(?P<ProjectId>[^/]+)/") // Should match the pattern below
+	template := "$ProjectId"                                      // Should match the submatch identifier in the regex
+	pattern := "projects/{project}/"                              // Human-readable pseudo-regex pattern used in errors and warnings
+
+	// Validate input
+	ValidateElementFromIdArguments(arg0, regex, pattern, resp)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+
+	// Get and return element from input string
+	projectId := GetElementFromId(arg0, regex, template)
+	resp.Diagnostics.Append(resp.Result.Set(ctx, projectId)...)
+}

google-beta/functions/project_from_id_internal_test.go

@@ -0,0 +1,115 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+package functions
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/hashicorp/terraform-plugin-framework/attr"
+	"github.com/hashicorp/terraform-plugin-framework/diag"
+	"github.com/hashicorp/terraform-plugin-framework/function"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+	"github.com/hashicorp/terraform-plugin-framework/types/basetypes"
+)
+
+func TestFunctionRun_project_from_id(t *testing.T) {
+	t.Parallel()
+
+	projectId := "my-project"
+
+	// Happy path inputs
+	validId := fmt.Sprintf("projects/%s/zones/us-central1-c/instances/my-instance", projectId)
+	validSelfLink := fmt.Sprintf("https://www.googleapis.com/compute/v1/%s", validId)
+	validOpStyleResourceName := fmt.Sprintf("//gkehub.googleapis.com/projects/%s/locations/us-central1/memberships/my-membership", projectId)
+
+	// Unhappy path inputs
+	repetitiveInput := fmt.Sprintf("https://www.googleapis.com/compute/v1/projects/%s/projects/not-this-1/projects/not-this-2/instances/my-instance", projectId) // Multiple /projects/{{project}}/
+	invalidInput := "zones/us-central1-c/instances/my-instance"
+
+	testCases := map[string]struct {
+		request  function.RunRequest
+		expected function.RunResponse
+	}{
+		"it returns the expected output value when given a valid resource id input": {
+			request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.StringValue(validId)}),
+			},
+			expected: function.RunResponse{
+				Result: function.NewResultData(types.StringValue(projectId)),
+			},
+		},
+		"it returns the expected output value when given a valid resource self_link input": {
+			request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.StringValue(validSelfLink)}),
+			},
+			expected: function.RunResponse{
+				Result: function.NewResultData(types.StringValue(projectId)),
+			},
+		},
+		"it returns the expected output value when given a valid OP style resource name input": {
+			request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.StringValue(validOpStyleResourceName)}),
+			},
+			expected: function.RunResponse{
+				Result: function.NewResultData(types.StringValue(projectId)),
+			},
+		},
+		"it returns a warning and the first submatch when given repetitive input": {
+			request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.StringValue(repetitiveInput)}),
+			},
+			expected: function.RunResponse{
+				Result: function.NewResultData(types.StringValue(projectId)),
+				Diagnostics: diag.Diagnostics{
+					diag.NewArgumentWarningDiagnostic(
+						0,
+						ambiguousMatchesWarningSummary,
+						fmt.Sprintf("The input string \"%s\" contains more than one match for the pattern \"projects/{project}/\". Terraform will use the first found match.", repetitiveInput),
+					),
+				},
+			},
+		},
+		"it returns an error when given input with no submatches": {
+			request: function.RunRequest{
+				Arguments: function.NewArgumentsData([]attr.Value{types.StringValue(invalidInput)}),
+			},
+			expected: function.RunResponse{
+				Result: function.NewResultData(types.StringNull()),
+				Diagnostics: diag.Diagnostics{
+					diag.NewArgumentErrorDiagnostic(
+						0,
+						noMatchesErrorSummary,
+						fmt.Sprintf("The input string \"%s\" doesn't contain the expected pattern \"projects/{project}/\".", invalidInput),
+					),
+				},
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		tn, tc := name, testCase
+
+		t.Run(tn, func(t *testing.T) {
+			t.Parallel()
+
+			// Arrange
+			got := function.RunResponse{
+				Result: function.NewResultData(basetypes.StringValue{}),
+			}
+
+			// Act
+			NewProjectFromIdFunction().Run(context.Background(), tc.request, &got)
+
+			// Assert
+			if diff := cmp.Diff(got.Result, tc.expected.Result); diff != "" {
+				t.Errorf("unexpected diff between expected and received result: %s", diff)
+			}
+			if diff := cmp.Diff(got.Diagnostics, tc.expected.Diagnostics); diff != "" {
+				t.Errorf("unexpected diff between expected and received diagnostics: %s", diff)
+			}
+		})
+	}
+}