Enhance local backend (#2017)

make local backend able to clone from private

---------
*Sponsored by Kithara Software GmbH*
Co-authored-by: Bruno BELANYI <bruno@belanyi.fr>

pipeline/backend/local/clone.go

@@ -0,0 +1,185 @@
+// Copyright 2023 Woodpecker 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 local
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+
+	"github.com/rs/zerolog/log"
+	"github.com/woodpecker-ci/woodpecker/pipeline/backend/types"
+	"github.com/woodpecker-ci/woodpecker/shared/constant"
+)
+
+// checkGitCloneCap check if we have the git binary on hand
+func checkGitCloneCap() error {
+	_, err := exec.LookPath("git")
+	return err
+}
+
+// loadClone on backend start determine if there is a global plugin-git binary
+func (e *local) loadClone() {
+	binary, err := exec.LookPath("plugin-git")
+	if err != nil || binary == "" {
+		// could not found global git plugin, just ignore it
+		return
+	}
+	e.pluginGitBinary = binary
+}
+
+// setupClone prepare the clone environment before exec
+func (e *local) setupClone(state *workflowState) error {
+	if e.pluginGitBinary != "" {
+		state.pluginGitBinary = e.pluginGitBinary
+		return nil
+	}
+
+	log.Info().Msg("no global 'plugin-git' installed, try to download for current workflow")
+	state.pluginGitBinary = filepath.Join(state.homeDir, "plugin-git")
+	if runtime.GOOS == "windows" {
+		state.pluginGitBinary += ".exe"
+	}
+	return downloadLatestGitPluginBinary(state.pluginGitBinary)
+}
+
+// execClone executes a clone-step locally
+func (e *local) execClone(ctx context.Context, step *types.Step, state *workflowState, env []string) error {
+	if err := e.setupClone(state); err != nil {
+		return fmt.Errorf("setup clone step failed: %w", err)
+	}
+
+	if err := checkGitCloneCap(); err != nil {
+		return fmt.Errorf("check for git clone capabilities failed: %w", err)
+	}
+
+	if step.Image != constant.DefaultCloneImage {
+		// TODO: write message into log
+		log.Warn().Msgf("clone step image '%s' does not match default git clone image. We ignore it assume git.", step.Image)
+	}
+
+	rmCmd, err := writeNetRC(step, state)
+	if err != nil {
+		return err
+	}
+
+	env = append(env, "CI_WORKSPACE="+state.workspaceDir)
+
+	// Prepare command
+	var cmd *exec.Cmd
+	if runtime.GOOS == "windows" {
+		pwsh, err := exec.LookPath("powershell.exe")
+		if err != nil {
+			return err
+		}
+		cmd = exec.CommandContext(ctx, pwsh, "-Command", fmt.Sprintf("%s ; $code=$? ; %s ; if (!$code) {[Environment]::Exit(1)}", state.pluginGitBinary, rmCmd))
+	} else {
+		cmd = exec.CommandContext(ctx, "/bin/sh", "-c", fmt.Sprintf("%s ; $code=$? ; %s ; exit $code", state.pluginGitBinary, rmCmd))
+	}
+	cmd.Env = env
+	cmd.Dir = state.workspaceDir
+
+	// Get output and redirect Stderr to Stdout
+	e.output, _ = cmd.StdoutPipe()
+	cmd.Stderr = cmd.Stdout
+
+	state.stepCMDs[step.Name] = cmd
+
+	return cmd.Start()
+}
+
+// writeNetRC write a netrc file into the home dir of a given workflow state
+func writeNetRC(step *types.Step, state *workflowState) (string, error) {
+	if step.Environment["CI_NETRC_MACHINE"] == "" {
+		return "", nil
+	}
+
+	file := filepath.Join(state.homeDir, ".netrc")
+	rmCmd := fmt.Sprintf("rm \"%s\"", file)
+	if runtime.GOOS == "windows" {
+		file = filepath.Join(state.homeDir, "_netrc")
+		rmCmd = fmt.Sprintf("del \"%s\"", file)
+	}
+
+	return rmCmd, os.WriteFile(file, []byte(fmt.Sprintf(
+		netrcFile,
+		step.Environment["CI_NETRC_MACHINE"],
+		step.Environment["CI_NETRC_USERNAME"],
+		step.Environment["CI_NETRC_PASSWORD"],
+	)), 0o600)
+}
+
+// downloadLatestGitPluginBinary download the latest plugin-git binary based on runtime OS and Arch
+// and saves it to dest
+func downloadLatestGitPluginBinary(dest string) error {
+	type asset struct {
+		Name               string
+		BrowserDownloadURL string `json:"browser_download_url"`
+	}
+
+	type release struct {
+		Assets []asset
+	}
+
+	// get latest release
+	req, _ := http.NewRequest(http.MethodGet, "https://api.github.com/repos/woodpecker-ci/plugin-git/releases/latest", nil)
+	req.Header.Set("Accept", "application/vnd.github+json")
+	req.Header.Set("X-GitHub-Api-Version", "2022-11-28")
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("could not get latest release: %w", err)
+	}
+	raw, _ := io.ReadAll(resp.Body)
+	_ = resp.Body.Close()
+	var rel release
+	if err := json.Unmarshal(raw, &rel); err != nil {
+		return fmt.Errorf("could not unmarshal github response: %w", err)
+	}
+
+	for _, at := range rel.Assets {
+		if strings.Contains(at.Name, runtime.GOOS) && strings.Contains(at.Name, runtime.GOARCH) {
+			resp2, err := http.Get(at.BrowserDownloadURL)
+			if err != nil {
+				return fmt.Errorf("could not download plugin-git: %w", err)
+			}
+			defer resp2.Body.Close()
+
+			file, err := os.Create(dest)
+			if err != nil {
+				return fmt.Errorf("could not create plugin-git: %w", err)
+			}
+			defer file.Close()
+
+			if _, err := io.Copy(file, resp2.Body); err != nil {
+				return fmt.Errorf("could not download plugin-git: %w", err)
+			}
+			if err := os.Chmod(dest, 0o755); err != nil {
+				return err
+			}
+
+			// download successful
+			return nil
+		}
+	}
+
+	return fmt.Errorf("could not download plugin-git, binary for this os/arch not found")
+}