Refactor into dual Rancher API/Metadata providers

Introduces Rancher's metadata service as an optional provider source for
Traefik, enabled by setting `rancher.MetadataService`.

The provider uses a long polling technique to watch the metadata service and
obtain near instantaneous updates. Alternatively it can be configured to poll
the metadata service every `rancher.RefreshSeconds` by setting
`rancher.MetadataPoll`.

The refactor splits API and metadata service code into separate source
files respectively, and specific configuration is deferred to
sub-structs.

Incorporates bugfix #1414

provider/rancher/api.go

@@ -0,0 +1,234 @@
+package rancher
+
+import (
+	"context"
+	"os"
+	"time"
+
+	"github.com/cenk/backoff"
+	"github.com/containous/traefik/job"
+	"github.com/containous/traefik/log"
+	"github.com/containous/traefik/safe"
+	"github.com/containous/traefik/types"
+
+	rancher "github.com/rancher/go-rancher/client"
+)
+
+var (
+	withoutPagination *rancher.ListOpts
+)
+
+// APIConfiguration contains configuration properties specific to the Rancher
+// API provider.
+type APIConfiguration struct {
+	Endpoint  string `description:"Rancher server API HTTP(S) endpoint"`
+	AccessKey string `description:"Rancher server API access key"`
+	SecretKey string `description:"Rancher server API secret key"`
+}
+
+func init() {
+	withoutPagination = &rancher.ListOpts{
+		Filters: map[string]interface{}{"limit": 0},
+	}
+}
+
+func (p *Provider) createClient() (*rancher.RancherClient, error) {
+	rancherURL := getenv("CATTLE_URL", p.API.Endpoint)
+	accessKey := getenv("CATTLE_ACCESS_KEY", p.API.AccessKey)
+	secretKey := getenv("CATTLE_SECRET_KEY", p.API.SecretKey)
+
+	return rancher.NewRancherClient(&rancher.ClientOpts{
+		Url:       rancherURL,
+		AccessKey: accessKey,
+		SecretKey: secretKey,
+	})
+}
+
+func getenv(key, fallback string) string {
+	value := os.Getenv(key)
+	if len(value) == 0 {
+		return fallback
+	}
+	return value
+}
+
+func (p *Provider) apiProvide(configurationChan chan<- types.ConfigMessage, pool *safe.Pool, constraints types.Constraints) error {
+	p.Constraints = append(p.Constraints, constraints...)
+
+	if p.API == nil {
+		p.API = &APIConfiguration{}
+	}
+
+	safe.Go(func() {
+		operation := func() error {
+			rancherClient, err := p.createClient()
+
+			if err != nil {
+				log.Errorf("Failed to create a client for rancher, error: %s", err)
+				return err
+			}
+
+			ctx := context.Background()
+			var environments = listRancherEnvironments(rancherClient)
+			var services = listRancherServices(rancherClient)
+			var container = listRancherContainer(rancherClient)
+
+			var rancherData = parseAPISourcedRancherData(environments, services, container)
+
+			configuration := p.loadRancherConfig(rancherData)
+			configurationChan <- types.ConfigMessage{
+				ProviderName:  "rancher",
+				Configuration: configuration,
+			}
+
+			if p.Watch {
+				_, cancel := context.WithCancel(ctx)
+				ticker := time.NewTicker(time.Second * time.Duration(p.RefreshSeconds))
+				pool.Go(func(stop chan bool) {
+					for {
+						select {
+						case <-ticker.C:
+
+							log.Debugf("Refreshing new Data from Provider API")
+							var environments = listRancherEnvironments(rancherClient)
+							var services = listRancherServices(rancherClient)
+							var container = listRancherContainer(rancherClient)
+
+							rancherData := parseAPISourcedRancherData(environments, services, container)
+
+							configuration := p.loadRancherConfig(rancherData)
+							if configuration != nil {
+								configurationChan <- types.ConfigMessage{
+									ProviderName:  "rancher",
+									Configuration: configuration,
+								}
+							}
+						case <-stop:
+							ticker.Stop()
+							cancel()
+							return
+						}
+					}
+				})
+			}
+
+			return nil
+		}
+		notify := func(err error, time time.Duration) {
+			log.Errorf("Provider connection error %+v, retrying in %s", err, time)
+		}
+		err := backoff.RetryNotify(operation, job.NewBackOff(backoff.NewExponentialBackOff()), notify)
+		if err != nil {
+			log.Errorf("Cannot connect to Provider Endpoint %+v", err)
+		}
+	})
+
+	return nil
+}
+
+func listRancherEnvironments(client *rancher.RancherClient) []*rancher.Project {
+
+	// Rancher Environment in frontend UI is actually project in API
+	// https://forums.rancher.com/t/api-key-for-all-environments/279/9
+
+	var environmentList = []*rancher.Project{}
+
+	environments, err := client.Project.List(nil)
+
+	if err != nil {
+		log.Errorf("Cannot get Rancher Environments %+v", err)
+	}
+
+	for k := range environments.Data {
+		environmentList = append(environmentList, &environments.Data[k])
+	}
+
+	return environmentList
+}
+
+func listRancherServices(client *rancher.RancherClient) []*rancher.Service {
+
+	var servicesList = []*rancher.Service{}
+
+	services, err := client.Service.List(withoutPagination)
+
+	if err != nil {
+		log.Errorf("Cannot get Provider Services %+v", err)
+	}
+
+	for k := range services.Data {
+		servicesList = append(servicesList, &services.Data[k])
+	}
+
+	return servicesList
+}
+
+func listRancherContainer(client *rancher.RancherClient) []*rancher.Container {
+
+	containerList := []*rancher.Container{}
+
+	container, err := client.Container.List(withoutPagination)
+
+	if err != nil {
+		log.Errorf("Cannot get Provider Services %+v", err)
+	}
+
+	valid := true
+
+	for valid {
+		for k := range container.Data {
+			containerList = append(containerList, &container.Data[k])
+		}
+
+		container, err = container.Next()
+
+		if err != nil {
+			break
+		}
+
+		if container == nil || len(container.Data) == 0 {
+			valid = false
+		}
+	}
+
+	return containerList
+}
+
+func parseAPISourcedRancherData(environments []*rancher.Project, services []*rancher.Service, containers []*rancher.Container) []rancherData {
+	var rancherDataList []rancherData
+
+	for _, environment := range environments {
+
+		for _, service := range services {
+			if service.EnvironmentId != environment.Id {
+				continue
+			}
+
+			rancherData := rancherData{
+				Name:       environment.Name + "/" + service.Name,
+				Health:     service.HealthState,
+				State:      service.State,
+				Labels:     make(map[string]string),
+				Containers: []string{},
+			}
+
+			if service.LaunchConfig == nil || service.LaunchConfig.Labels == nil {
+				log.Warnf("Rancher Service Labels are missing. Environment: %s, service: %s", environment.Name, service.Name)
+			} else {
+				for key, value := range service.LaunchConfig.Labels {
+					rancherData.Labels[key] = value.(string)
+				}
+			}
+
+			for _, container := range containers {
+				if container.Labels["io.rancher.stack_service.name"] == rancherData.Name &&
+					containerFilter(container.Name, container.HealthState, container.State) {
+					rancherData.Containers = append(rancherData.Containers, container.PrimaryIpAddress)
+				}
+			}
+			rancherDataList = append(rancherDataList, rancherData)
+		}
+	}
+
+	return rancherDataList
+}