Dynamic Configuration Refactoring

old/provider/file/file.go

@@ -0,0 +1,253 @@
+package file
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+	"text/template"
+
+	"github.com/containous/traefik/old/log"
+	"github.com/containous/traefik/old/provider"
+	"github.com/containous/traefik/old/types"
+	"github.com/containous/traefik/safe"
+	"github.com/containous/traefik/tls"
+	"github.com/pkg/errors"
+	"gopkg.in/fsnotify.v1"
+)
+
+var _ provider.Provider = (*Provider)(nil)
+
+// Provider holds configurations of the provider.
+type Provider struct {
+	provider.BaseProvider `mapstructure:",squash" export:"true"`
+	Directory             string `description:"Load configuration from one or more .toml files in a directory" export:"true"`
+	TraefikFile           string
+}
+
+// Init the provider
+func (p *Provider) Init(constraints types.Constraints) error {
+	return p.BaseProvider.Init(constraints)
+}
+
+// Provide allows the file provider to provide configurations to traefik
+// using the given configuration channel.
+func (p *Provider) Provide(configurationChan chan<- types.ConfigMessage, pool *safe.Pool) error {
+	configuration, err := p.BuildConfiguration()
+	if err != nil {
+		return err
+	}
+
+	if p.Watch {
+		var watchItem string
+
+		if len(p.Directory) > 0 {
+			watchItem = p.Directory
+		} else if len(p.Filename) > 0 {
+			watchItem = filepath.Dir(p.Filename)
+		} else {
+			watchItem = filepath.Dir(p.TraefikFile)
+		}
+
+		if err := p.addWatcher(pool, watchItem, configurationChan, p.watcherCallback); err != nil {
+			return err
+		}
+	}
+
+	sendConfigToChannel(configurationChan, configuration)
+	return nil
+}
+
+// BuildConfiguration loads configuration either from file or a directory specified by 'Filename'/'Directory'
+// and returns a 'Configuration' object
+func (p *Provider) BuildConfiguration() (*types.Configuration, error) {
+	if len(p.Directory) > 0 {
+		return p.loadFileConfigFromDirectory(p.Directory, nil)
+	}
+
+	if len(p.Filename) > 0 {
+		return p.loadFileConfig(p.Filename, true)
+	}
+
+	if len(p.TraefikFile) > 0 {
+		return p.loadFileConfig(p.TraefikFile, false)
+	}
+
+	return nil, errors.New("error using file configuration backend, no filename defined")
+}
+
+func (p *Provider) addWatcher(pool *safe.Pool, directory string, configurationChan chan<- types.ConfigMessage, callback func(chan<- types.ConfigMessage, fsnotify.Event)) error {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		return fmt.Errorf("error creating file watcher: %s", err)
+	}
+
+	err = watcher.Add(directory)
+	if err != nil {
+		return fmt.Errorf("error adding file watcher: %s", err)
+	}
+
+	// Process events
+	pool.Go(func(stop chan bool) {
+		defer watcher.Close()
+		for {
+			select {
+			case <-stop:
+				return
+			case evt := <-watcher.Events:
+				if p.Directory == "" {
+					var filename string
+					if len(p.Filename) > 0 {
+						filename = p.Filename
+					} else {
+						filename = p.TraefikFile
+					}
+
+					_, evtFileName := filepath.Split(evt.Name)
+					_, confFileName := filepath.Split(filename)
+					if evtFileName == confFileName {
+						callback(configurationChan, evt)
+					}
+				} else {
+					callback(configurationChan, evt)
+				}
+			case err := <-watcher.Errors:
+				log.Errorf("Watcher event error: %s", err)
+			}
+		}
+	})
+	return nil
+}
+
+func (p *Provider) watcherCallback(configurationChan chan<- types.ConfigMessage, event fsnotify.Event) {
+	watchItem := p.TraefikFile
+	if len(p.Directory) > 0 {
+		watchItem = p.Directory
+	} else if len(p.Filename) > 0 {
+		watchItem = p.Filename
+	}
+
+	if _, err := os.Stat(watchItem); err != nil {
+		log.Debugf("Unable to watch %s : %v", watchItem, err)
+		return
+	}
+
+	configuration, err := p.BuildConfiguration()
+
+	if err != nil {
+		log.Errorf("Error occurred during watcher callback: %s", err)
+		return
+	}
+
+	sendConfigToChannel(configurationChan, configuration)
+}
+
+func sendConfigToChannel(configurationChan chan<- types.ConfigMessage, configuration *types.Configuration) {
+	configurationChan <- types.ConfigMessage{
+		ProviderName:  "file",
+		Configuration: configuration,
+	}
+}
+
+func readFile(filename string) (string, error) {
+	if len(filename) > 0 {
+		buf, err := ioutil.ReadFile(filename)
+		if err != nil {
+			return "", err
+		}
+		return string(buf), nil
+	}
+	return "", fmt.Errorf("invalid filename: %s", filename)
+}
+
+func (p *Provider) loadFileConfig(filename string, parseTemplate bool) (*types.Configuration, error) {
+	fileContent, err := readFile(filename)
+	if err != nil {
+		return nil, fmt.Errorf("error reading configuration file: %s - %s", filename, err)
+	}
+
+	var configuration *types.Configuration
+	if parseTemplate {
+		configuration, err = p.CreateConfiguration(fileContent, template.FuncMap{}, false)
+	} else {
+		configuration, err = p.DecodeConfiguration(fileContent)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+	if configuration == nil || configuration.Backends == nil && configuration.Frontends == nil && configuration.TLS == nil {
+		configuration = &types.Configuration{
+			Frontends: make(map[string]*types.Frontend),
+			Backends:  make(map[string]*types.Backend),
+		}
+	}
+	return configuration, err
+}
+
+func (p *Provider) loadFileConfigFromDirectory(directory string, configuration *types.Configuration) (*types.Configuration, error) {
+	fileList, err := ioutil.ReadDir(directory)
+
+	if err != nil {
+		return configuration, fmt.Errorf("unable to read directory %s: %v", directory, err)
+	}
+
+	if configuration == nil {
+		configuration = &types.Configuration{
+			Frontends: make(map[string]*types.Frontend),
+			Backends:  make(map[string]*types.Backend),
+		}
+	}
+
+	configTLSMaps := make(map[*tls.Configuration]struct{})
+	for _, item := range fileList {
+
+		if item.IsDir() {
+			configuration, err = p.loadFileConfigFromDirectory(filepath.Join(directory, item.Name()), configuration)
+			if err != nil {
+				return configuration, fmt.Errorf("unable to load content configuration from subdirectory %s: %v", item, err)
+			}
+			continue
+		} else if !strings.HasSuffix(item.Name(), ".toml") && !strings.HasSuffix(item.Name(), ".tmpl") {
+			continue
+		}
+
+		var c *types.Configuration
+		c, err = p.loadFileConfig(path.Join(directory, item.Name()), true)
+
+		if err != nil {
+			return configuration, err
+		}
+
+		for backendName, backend := range c.Backends {
+			if _, exists := configuration.Backends[backendName]; exists {
+				log.Warnf("Backend %s already configured, skipping", backendName)
+			} else {
+				configuration.Backends[backendName] = backend
+			}
+		}
+
+		for frontendName, frontend := range c.Frontends {
+			if _, exists := configuration.Frontends[frontendName]; exists {
+				log.Warnf("Frontend %s already configured, skipping", frontendName)
+			} else {
+				configuration.Frontends[frontendName] = frontend
+			}
+		}
+
+		for _, conf := range c.TLS {
+			if _, exists := configTLSMaps[conf]; exists {
+				log.Warnf("TLS Configuration %v already configured, skipping", conf)
+			} else {
+				configTLSMaps[conf] = struct{}{}
+			}
+		}
+
+	}
+	for conf := range configTLSMaps {
+		configuration.TLS = append(configuration.TLS, conf)
+	}
+	return configuration, nil
+}