twins-upstream/config.go

package main

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

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

type serveConfig struct {
	// Path to match
	Path string

	// Resource to serve
	Root    string
	Proxy   string
	Command string

	r   *regexp.Regexp
	cmd []string
}

type serverConfig struct {
	Cert     string
	Key      string
	Hostname string
	Port     int
	Serve    []*serveConfig
}

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
	}

	for _, serve := range config.Serve {
		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
}