add distroless otel init (#10035)

add distroless otel init

images/opentelemetry/rootfs/init_module.go

@@ -0,0 +1,104 @@
+/*
+Copyright 2023 The Kubernetes Authors.
+
+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 main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+func main() {
+	// Enable error handling for all operations
+	err := run()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	// Create the target directory if it doesn't exist
+	targetDir := "/modules_mount/etc/nginx/modules/otel"
+	err := os.MkdirAll(targetDir, os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("failed to create target directory: %w", err)
+	}
+
+	// Copy files from source directory to target directory
+	sourceDir := "/etc/nginx/modules/"
+	err = filepath.Walk(sourceDir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Skip directories
+		if info.IsDir() {
+			return nil
+		}
+
+		// Calculate the destination path
+		relPath, err := filepath.Rel(sourceDir, path)
+		if err != nil {
+			return err
+		}
+		destPath := filepath.Join(targetDir, relPath)
+
+		// Create the destination directory if it doesn't exist
+		destDir := filepath.Dir(destPath)
+		err = os.MkdirAll(destDir, os.ModePerm)
+		if err != nil {
+			return err
+		}
+
+		// Copy the file
+		err = copyFile(path, destPath)
+		if err != nil {
+			return err
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return fmt.Errorf("failed to copy files: %w", err)
+	}
+
+	return nil
+}
+
+func copyFile(sourcePath, destPath string) error {
+	sourceFile, err := os.Open(sourcePath)
+	if err != nil {
+		return err
+	}
+	defer sourceFile.Close()
+
+	destFile, err := os.Create(destPath)
+	if err != nil {
+		return err
+	}
+	defer destFile.Close()
+
+	_, err = io.Copy(destFile, sourceFile)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}