flamenco/internal/worker/config.go

package worker

/* ***** BEGIN GPL LICENSE BLOCK *****
 *
 * Original Code Copyright (C) 2022 Blender Foundation.
 *
 * This file is part of Flamenco.
 *
 * Flamenco is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * Flamenco is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * Flamenco.  If not, see <https://www.gnu.org/licenses/>.
 *
 * ***** END GPL LICENSE BLOCK ***** */

import (
	"errors"
	"fmt"
	"io"
	"net/url"
	"os"
	"time"

	"github.com/rs/zerolog/log"
	yaml "gopkg.in/yaml.v2"
)

var (
	errURLWithoutHostName = errors.New("manager URL should contain a host name")
)

const (
	credentialsFilename = "flamenco-worker-credentials.yaml"
	configFilename      = "flamenco-worker.yaml"
)

// WorkerConfig represents the configuration of a single worker.
// It does not include authentication credentials.
type WorkerConfig struct {
	Manager   string   `yaml:"manager_url"`
	TaskTypes []string `yaml:"task_types"`
}

type WorkerCredentials struct {
	WorkerID string `yaml:"worker_id"`
	Secret   string `yaml:"worker_secret"`
}

func loadConfig(configWrangler FileConfigWrangler) (WorkerConfig, error) {
	logger := log.With().Str("filename", configFilename).Logger()

	var cfg WorkerConfig

	err := configWrangler.LoadConfig(configFilename, &cfg)

	// If the configuration file doesn't exist, write the defaults & retry loading them.
	if os.IsNotExist(err) {
		logger.Info().Msg("writing default configuration file")
		cfg = configWrangler.DefaultConfig()
		err = configWrangler.WriteConfig(configFilename, "Configuration", cfg)
		if err != nil {
			return cfg, fmt.Errorf("error writing default config: %w", err)
		}
		err = configWrangler.LoadConfig(configFilename, &cfg)
	}
	if err != nil {
		return cfg, fmt.Errorf("error loading config from %s: %w", configFilename, err)
	}

	// Validate the manager URL.
	if cfg.Manager != "" {
		_, err := ParseURL(cfg.Manager)
		if err != nil {
			return cfg, fmt.Errorf("error parsing manager URL %s: %w", cfg.Manager, err)
		}
		logger.Debug().Str("url", cfg.Manager).Msg("parsed manager URL")
	}

	return cfg, nil
}

func loadCredentials(configWrangler FileConfigWrangler) (WorkerCredentials, error) {
	var creds WorkerCredentials
	err := configWrangler.LoadConfig(credentialsFilename, &creds)
	if err != nil {
		return WorkerCredentials{}, err
	}

	log.Info().
		Str("filename", credentialsFilename).
		Msg("loaded credentials")
	return creds, nil
}

// FileConfigWrangler is the default config wrangler that actually reads & writes files.
type FileConfigWrangler struct{}

// NewConfigWrangler returns ConfigWrangler that reads files.
func NewConfigWrangler() FileConfigWrangler {
	return FileConfigWrangler{}
}

// DefaultConfig returns a fairly sane default configuration.
func (fcw FileConfigWrangler) DefaultConfig() WorkerConfig {
	return WorkerConfig{
		Manager:   "",
		TaskTypes: []string{"blender", "file-management", "exr-merge", "misc"},
	}
}

// WriteConfig stores a struct as YAML file.
func (fcw FileConfigWrangler) WriteConfig(filename string, filetype string, config interface{}) error {
	data, err := yaml.Marshal(config)
	if err != nil {
		return err
	}

	tempFilename := filename + "~"
	f, err := os.OpenFile(tempFilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
	if err != nil {
		return err
	}
	fmt.Fprintf(f, "# %s file for Flamenco Worker.\n", filetype)
	fmt.Fprintln(f, "# For an explanation of the fields, refer to flamenco-worker-example.yaml")
	fmt.Fprintln(f, "#")
	fmt.Fprintln(f, "# NOTE: this file can be overwritten by Flamenco Worker.")
	fmt.Fprintln(f, "#")
	now := time.Now()
	fmt.Fprintf(f, "# This file was written on %s\n\n", now.Format("2006-01-02 15:04:05 -07:00"))

	n, err := f.Write(data)
	if err != nil {
		f.Close() // ignore errors here
		return err
	}
	if n < len(data) {
		f.Close() // ignore errors here
		return io.ErrShortWrite
	}
	if err = f.Close(); err != nil {
		return err
	}

	log.Debug().Str("filename", tempFilename).Msg("config file written")
	log.Debug().
		Str("from", tempFilename).
		Str("to", filename).
		Msg("renaming config file")
	if err := os.Rename(tempFilename, filename); err != nil {
		return err
	}
	log.Info().Str("filename", filename).Msg("Saved configuration file")

	return nil
}

// LoadConfig loads a YAML configuration file into 'config'
func (fcw FileConfigWrangler) LoadConfig(filename string, config interface{}) error {
	log.Debug().Str("filename", filename).Msg("loading config file")
	f, err := os.OpenFile(filename, os.O_RDONLY, 0)
	if err != nil {
		return err
	}
	defer f.Close()

	dec := yaml.NewDecoder(f)
	if err = dec.Decode(config); err != nil {
		return err
	}

	return nil
}

// ParseURL allows URLs without scheme (assumes HTTP).
func ParseURL(rawURL string) (*url.URL, error) {
	var err error
	var parsedURL *url.URL

	parsedURL, err = url.Parse(rawURL)
	if err != nil {
		return nil, err
	}

	// url.Parse() is a bit weird when there is no scheme.
	if parsedURL.Host == "" && parsedURL.Path != "" {
		// This case happens when you just enter a hostname, like manager='thehost'
		parsedURL.Host = parsedURL.Path
		parsedURL.Path = "/"
	}
	if parsedURL.Host == "" && parsedURL.Scheme != "" && parsedURL.Opaque != "" {
		// This case happens when you just enter a hostname:port, like manager='thehost:8083'
		parsedURL.Host = parsedURL.Scheme + ":" + parsedURL.Opaque
		parsedURL.Opaque = ""
		parsedURL.Scheme = "http"
	}
	if parsedURL.Scheme == "" {
		parsedURL.Scheme = "http"
	}
	if parsedURL.Host == "" {
		return nil, errURLWithoutHostName
	}

	return parsedURL, nil
}