src/main.go

package main

import (
	"bytes"
	"encoding/xml"
	"errors"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path"
	"strings"
	"text/template"
)

type Config struct {
	XMLName     xml.Name   `xml:"config"`
	BuildEnv    []BuildEnv `xml:"buildenv"`
	BuildEnvMap map[string]BuildEnv

	Repository []Repository `xml:"repository"`
}

type BuildEnv struct {
	Name string `xml:"name,attr"`
	Host string `xml:"host"`
	User string `xml:"user"`
}

type Repository struct {
	Path      string `xml:"path"`
	BuildEnvs string `xml:"buildenvs"`
	Build     []struct {
		IsPlatform  string   `xml:"isplatform,attr"`
		NotPlatform string   `xml:"not,attr"`
		Test        []string `xml:"test"`
		Var         []struct {
			Name  string `xml:"name,attr"`
			Value string `xml:",chardata"`
		}
		Configure string `xml:"configure"`
		Compile   string `xml:"compile"`
		Check     string `xml:"check"`
	} `xml:"build"`
}

func main() {
	data, err := os.ReadFile("testconfig.xml")
	if err != nil {
		log.Fatal(err)
	}

	config := &Config{}
	if err := xml.Unmarshal(data, &config); err != nil {
		log.Fatal(err)
	}
	config.BuildEnvMap = make(map[string]BuildEnv)
	for _, env := range config.BuildEnv {
		config.BuildEnvMap[env.Name] = env
	}

	templateStr, err := os.ReadFile("build.template")
	if err != nil {
		log.Fatal(err)
	}

	tpl, err := template.New("").Parse(string(templateStr))
	if err != nil {
		log.Fatal(err)
	}

	err = os.Mkdir("tmp", 0755)
	if err != nil && !os.IsExist(err) {
		log.Fatal(err)
	}

	tmp := "tmp"

	for _, repo := range config.Repository {
		if err = create_repo_archive(&repo, tpl, tmp); err != nil {
			log.Fatal(err)
		}

		if err = exec_buildenvs(config, &repo, tmp); err != nil {
			log.Fatal(err)
		}
	}
}

func create_repo_archive(repo *Repository, tpl *template.Template, tmp_dir string) error {
	// create a build directory, that contains the repository source
	// and build scripts
	buildPath := path.Join(tmp_dir, "build")

	if err := os.RemoveAll(buildPath); err != nil {
		log.Print("remove build dir failed: ", err)
		return err
	}
	if err := os.RemoveAll(path.Join(tmp_dir, "build.tar")); err != nil {
		log.Print("remove build.tar failed")
		return err
	}
	if err := os.RemoveAll(path.Join(tmp_dir, "build.tar.gz")); err != nil {
		log.Print("remove build.tar.gz failed")
		return err
	}

	err := os.Mkdir(buildPath, 0755)
	if err != nil {
		log.Print("mkdir build dir failed: ", err)
		return err
	}

	// update repository and copy it to the build directory
	cmd := exec.Command("hg", "pull")
	var outb, errb bytes.Buffer
	cmd.Dir = repo.Path
	cmd.Stdout = &outb
	cmd.Stderr = &errb
	err = cmd.Run()
	if err != nil {
		log.Print("hg: ", errb.String())
		return err
	}

	outb.Reset()
	errb.Reset()
	cmd = exec.Command("hg", "update")
	cmd.Dir = repo.Path
	cmd.Stdout = &outb
	cmd.Stderr = &errb
	err = cmd.Run()
	if err != nil {
		log.Print("hg: ", errb.String())
		return err
	}

	// copy repository to the tmp_dir build directory
	cmd = exec.Command("cp", "-r", repo.Path, path.Join(buildPath, "src"))
	err = cmd.Run()
	if err != nil {
		log.Print("cannot copy the repository to the build dir")
		return err
	}

	// create build script
	file, err := os.Create(path.Join(buildPath, "build.sh"))
	if err != nil {
		log.Print("cannot create build.sh")
		return err
	}
	defer file.Close()

	err = tpl.Execute(file, repo)
	if err != nil {
		log.Print("cannot execute build.sh template")
		return err
	}
	file.Chmod(0755)

	// create tarball
	cmd = exec.Command("tar", "cvf", "../build.tar", "src", "build.sh")
	cmd.Dir = buildPath
	if err := cmd.Run(); err != nil {
		log.Print("tar error")
		return err
	}

	cmd = exec.Command("gzip", path.Join(tmp_dir, "build.tar"))
	if err := cmd.Run(); err != nil {
		log.Print("gzip error")
		return err
	}

	return nil
}

func host_is_available(host string) bool {
	cmd := exec.Command("ping", "-c", "1", host)
	if err := cmd.Run(); err != nil {
		return false
	}
	return true
}

func exec_buildenvs(config *Config, repo *Repository, tmp_dir string) error {
	if len(repo.BuildEnvs) == 0 {
		log.Print("repo %s has no buildenvs", repo.Path)
		return nil
	}
	buildenvs := strings.Split(repo.BuildEnvs, ",")
	for _, buildenv := range buildenvs {
		env, ok := config.BuildEnvMap[buildenv]
		if !ok {
			return errors.New("unknown build env: " + buildenv)
		}
		if !host_is_available(env.Host) {
			log.Print("skip unavailable host ", env.Host)
			return nil
		}

		// steps:
		// upload build.tar.gz
		// extract build.tar.gz on the buildenv host and run build.sh

		// upload using scp
		cmd := exec.Command("scp", path.Join(tmp_dir, "build.tar.gz"), env.Host+":")
		if err := cmd.Run(); err != nil {
			log.Print("cannot copy build env to ", env.Host)
			continue
		}

		// run build.sh
		build_dir := "build"
		remote_command := fmt.Sprintf("sh -c 'rm -Rf %s; mkdir -p %s; gzip -dc build.tar.gz | tar xf - -C %s ; (cd %s; ./build.sh)'", build_dir, build_dir, build_dir, build_dir)
		log.Printf("host: %s: command: %s", env.Host, remote_command)

		var outb, errb bytes.Buffer
		cmd = exec.Command("ssh", "-t", env.Host, remote_command)
		cmd.Stdout = &outb
		cmd.Stderr = &errb
		err := cmd.Run()
		log.Printf("host: %s: stdout: %s", env.Host, outb.String())
		if err != nil {
			log.Print("cannot execute build.sh on buildenv host ", env.Host)
			log.Print("stderr: ", errb.String())
		}
	}

	return nil
}