twins-upstream/config.go

package main

import (
	"errors"
	"io/ioutil"
	"log"
	"os"
	"regexp"
	"strconv"
	"strings"

	"github.com/kballard/go-shellquote"
	"gopkg.in/yaml.v3"
)

type pathConfig struct {
	// Path to match
	Path string

	// Resource to serve
	Root    string
	Proxy   string
	Command string

	r   *regexp.Regexp
	cmd []string
}

type certConfig struct {
	Cert string
	Key  string
}

type serverConfig struct {
	Listen string

	Certificates []*certConfig

	Hosts map[string][]*pathConfig

	hostname string
	port     int
}

var config = &serverConfig{
	hostname: "localhost",
	port:     1965,
}

func readconfig(configPath string) error {
	if configPath == "" {
		return errors.New("file unspecified")
	}

	if _, err := os.Stat(configPath); os.IsNotExist(err) {
		return errors.New("file not found")
	}

	configData, err := ioutil.ReadFile(configPath)
	if err != nil {
		return err
	}

	err = yaml.Unmarshal(configData, &config)
	if err != nil {
		return err
	}

	split := strings.Split(config.Listen, ":")
	if len(split) != 2 {
		config.hostname = config.Listen
		config.Listen += ":1965"
	} else {
		config.hostname = split[0]
		config.port, err = strconv.Atoi(split[1])
		if err != nil {
			log.Fatalf("invalid port specified: %s", err)
		}
	}

	for _, paths := range config.Hosts {
		for _, serve := range paths {
			if serve.Path == "" {
				log.Fatal("path must be specified in serve entry")
			} else if (serve.Root != "" && (serve.Proxy != "" || serve.Command != "")) ||
				(serve.Proxy != "" && (serve.Root != "" || serve.Command != "")) ||
				(serve.Command != "" && (serve.Root != "" || serve.Proxy != "")) {
				log.Fatal("only one root, reverse proxy or command may specified in a serve entry")
			}

			if serve.Path[0] == '^' {
				serve.r = regexp.MustCompile(serve.Path)
			} else if serve.Path[len(serve.Path)-1] == '/' {
				serve.Path = serve.Path[:len(serve.Path)-1]
			}

			if serve.Command != "" {
				serve.cmd, err = shellquote.Split(serve.Command)
				if err != nil {
					log.Fatalf("failed to parse command %s: %s", serve.cmd, err)
				}
			}
		}
	}

	return nil
}