feat: Implemented str_truncate_label() as a function.

corefuncprovider/provider.go

@@ -139,9 +139,11 @@ func (p *coreFuncProvider) Functions(ctx context.Context) []func() function.Func
 		StrCamelFunction,
 		StrConstantFunction,
 		StrKebabFunction,
+		// StrIterativeReplaceFunction,
 		StrLeftpadFunction,
 		StrPascalFunction,
 		StrSnakeFunction,
+		StrTruncateLabelFunction,
 	}
 }
 

corefuncprovider/str_truncate_label_function.go

@@ -0,0 +1,134 @@
+// Copyright 2023-2024, Northwood Labs
+// Copyright 2023-2024, Ryan Parman <[email protected]>
+//
+// 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.
+
+package corefuncprovider // lint:no_dupe
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/hashicorp/terraform-plugin-framework/function"
+	"github.com/hashicorp/terraform-plugin-log/tflog"
+	"github.com/lithammer/dedent"
+	"github.com/northwood-labs/terraform-provider-corefunc/corefunc"
+)
+
+// Ensure the implementation satisfies the expected interfaces.
+var _ function.Function = &strTruncateLabelFunction{}
+
+type (
+	// strTruncateLabelFunction is the function implementation.
+	strTruncateLabelFunction struct{}
+)
+
+// StrTruncateLabelFunction is a method that exposes its paired Go function as a
+// Terraform Function.
+// https://developer.hashicorp.com/terraform/plugin/framework/functions/implementation
+func StrTruncateLabelFunction() function.Function { // lint:allow_return_interface
+	return &strTruncateLabelFunction{}
+}
+
+func (f *strTruncateLabelFunction) Metadata(
+	ctx context.Context,
+	req function.MetadataRequest,
+	resp *function.MetadataResponse,
+) {
+	tflog.Debug(ctx, "Starting StrTruncateLabel Function Metadata method.")
+
+	resp.Name = "str_truncate_label"
+
+	tflog.Debug(ctx, fmt.Sprintf("resp.Name = %s", resp.Name))
+
+	tflog.Debug(ctx, "Ending StrTruncateLabel Function Metadata method.")
+}
+
+// Definition defines the parameters and return type for the function.
+func (f *strTruncateLabelFunction) Definition(
+	ctx context.Context,
+	req function.DefinitionRequest,
+	resp *function.DefinitionResponse,
+) {
+	tflog.Debug(ctx, "Starting StrTruncateLabel Function Definition method.")
+
+	resp.Definition = function.Definition{
+		Summary: "Supports prepending a prefix to a label, while truncating them to meet the maximum " +
+			"length constraints.",
+		MarkdownDescription: strings.TrimSpace(dedent.Dedent(`
+        Supports prepending a prefix to a label, while truncating them
+        to meet the maximum length constraints. Useful when grouping labels with a
+        kind of prefix. Both the prefix and the label will be truncated if necessary.
+
+        Uses a “balancing” algorithm between the prefix and the label, so that each
+        section is truncated as a factor of how much space it takes up in the merged
+        string.
+
+        -> The motivation for this is in working with monitoring systems such
+        as New Relic and Datadog where there are hundreds of applications in a
+        monitoring “prod” account, and also hundreds of applications in a monitoring
+        “nonprod” account. This allows us to group lists of monitors together using a
+        shared prefix, but also truncate them appropriately to fit length
+        constraints for names.
+
+        Maps to the ` + linkPackage("TruncateLabel") + ` Go method, which can be used in
+        ` + Terratest + `.
+        `)),
+		Parameters: []function.Parameter{
+			function.Int64Parameter{
+				Name:                "max_length",
+				MarkdownDescription: "The maximum allowed length of the combined label. Minimum value is `1`.",
+			},
+			function.StringParameter{
+				Name:                "prefix",
+				MarkdownDescription: "The prefix to prepend to the label.",
+			},
+			function.StringParameter{
+				Name:                "label",
+				MarkdownDescription: "The label itself.",
+			},
+		},
+		Return: function.StringReturn{},
+	}
+
+	tflog.Debug(ctx, "Ending StrTruncateLabel Function Definition method.")
+}
+
+func (f *strTruncateLabelFunction) Run(ctx context.Context, req function.RunRequest, resp *function.RunResponse) {
+	tflog.Debug(ctx, "Starting StrTruncateLabel Function Run method.")
+
+	var (
+		maxLength int64
+		prefix    string
+		label     string
+	)
+
+	resp.Error = function.ConcatFuncErrors(req.Arguments.Get(ctx, &maxLength, &prefix, &label))
+	if resp.Error != nil {
+		return
+	}
+
+	if maxLength < 1 {
+		resp.Error = function.ConcatFuncErrors(
+			function.NewArgumentFuncError(0, "max_length must be at least 1"),
+		)
+
+		return
+	}
+
+	value := corefunc.TruncateLabel(maxLength, prefix, label)
+	resp.Error = function.ConcatFuncErrors(resp.Result.Set(ctx, value))
+
+	tflog.Debug(ctx, "Ending StrTruncateLabel Function Run method.")
+}

corefuncprovider/str_truncate_label_function_fixture.tftpl

@@ -0,0 +1,8 @@
+output "label" {
+    value = provider::corefunc::str_truncate_label(
+      {{ .MaxLength }},
+      "{{ .Prefix }}",
+      "{{ .Label }}",
+    )
+}
+#=> {{ .Expected }}

corefuncprovider/str_truncate_label_function_test.go

@@ -0,0 +1,88 @@
+// Copyright 2023-2024, Northwood Labs
+// Copyright 2023-2024, Ryan Parman <[email protected]>
+//
+// 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.
+
+package corefuncprovider // lint:no_dupe
+
+import (
+	"bytes"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+	"testing"
+	"text/template"
+
+	"github.com/northwood-labs/terraform-provider-corefunc/testfixtures"
+
+	"github.com/hashicorp/go-version"
+	"github.com/hashicorp/terraform-plugin-testing/helper/resource"
+	"github.com/hashicorp/terraform-plugin-testing/tfversion"
+)
+
+func TestAccStrTruncateLabelFunction(t *testing.T) {
+	t.Parallel()
+
+	funcName := traceFuncName()
+
+	for name, tc := range testfixtures.TruncateLabelTestTable { // lint:no_dupe
+		fmt.Printf(
+			"=== RUN   %s/%s\n",
+			strings.TrimSpace(funcName),
+			strings.TrimSpace(name),
+		)
+
+		buf := &bytes.Buffer{}
+		tmpl := template.Must(
+			template.ParseFiles("str_truncate_label_function_fixture.tftpl"),
+		)
+
+		// Minimum value for the provider is 1.
+		if tc.MaxLength == 0 {
+			tc.MaxLength += 1
+		}
+
+		err := tmpl.Execute(buf, tc)
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		if os.Getenv("PROVIDER_DEBUG") != "" {
+			fmt.Fprintln(os.Stderr, buf.String())
+		}
+
+		resource.UnitTest(t, resource.TestCase{
+			TerraformVersionChecks: []tfversion.TerraformVersionCheck{
+				tfversion.SkipBelow(
+					version.Must(version.NewVersion("1.7.999")),
+				),
+			},
+			ProtoV6ProviderFactories: testAccProtoV6ProviderFactories,
+			Steps: []resource.TestStep{
+				{
+					Config: providerConfig + buf.String(),
+					Check: resource.ComposeTestCheckFunc(
+						resource.TestCheckOutput("label", func() string {
+							if tc.Expected == "" {
+								return "…"
+							}
+
+							return tc.Expected
+						}()),
+					),
+				},
+			},
+		})
+	}
+}

examples/functions/corefunc_str_truncate_label/function.tf

@@ -0,0 +1,9 @@
+output "label" {
+  value = provider::corefunc::str_truncate_label(
+    64,
+    "NW-ZZZ-CLOUD-TEST-APP-CLOUD-PROD-CRIT",
+    "K8S Pods Not Running Deployment Check",
+  )
+}
+
+#=> NW-ZZZ-CLOUD-TEST-APP-CLOUD-PR…: K8S Pods Not Running Deploymen…

examples/functions/corefunc_str_truncate_label/versions.tf

@@ -0,0 +1,13 @@
+terraform {
+  required_version = "~> 1.8"
+
+  required_providers {
+    corefunc = {
+      source  = "northwood-labs/corefunc"
+      version = "~> 1.4"
+    }
+  }
+}
+
+# There are no configuration options
+provider "corefunc" {}