From 8aa11ecee2f5b073e3f8b53240ec1555ca1663c4 Mon Sep 17 00:00:00 2001
From: Murat Kabilov <murat@kabilov.com>
Date: Wed, 30 Aug 2017 16:01:18 +0200
Subject: [PATCH] Add patroni api client

---
 pkg/cluster/cluster.go      |  3 ++
 pkg/util/patroni/patroni.go | 80 +++++++++++++++++++++++++++++++++++++
 2 files changed, 83 insertions(+)
 create mode 100644 pkg/util/patroni/patroni.go

diff --git a/pkg/cluster/cluster.go b/pkg/cluster/cluster.go
index f48b94fb1..b5882448f 100644
--- a/pkg/cluster/cluster.go
+++ b/pkg/cluster/cluster.go
@@ -23,6 +23,7 @@ import (
 	"github.com/zalando-incubator/postgres-operator/pkg/util/config"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/constants"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/k8sutil"
+	"github.com/zalando-incubator/postgres-operator/pkg/util/patroni"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/teams"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/users"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/volumes"
@@ -55,6 +56,7 @@ type Cluster struct {
 	spec.Postgresql
 	Config
 	logger           *logrus.Entry
+	patroni          patroni.Interface
 	pgUsers          map[string]spec.PgUser
 	systemUsers      map[string]spec.PgUser
 	podSubscribers   map[spec.NamespacedName]chan spec.PodEvent
@@ -105,6 +107,7 @@ func New(cfg Config, kubeClient k8sutil.KubernetesClient, pgSpec spec.Postgresql
 		teamsAPIClient:   teams.NewTeamsAPI(cfg.OpConfig.TeamsAPIUrl, logger),
 	}
 	cluster.logger = logger.WithField("pkg", "cluster").WithField("cluster-name", cluster.clusterName())
+	cluster.patroni = patroni.New(cluster.logger)
 
 	return cluster
 }
diff --git a/pkg/util/patroni/patroni.go b/pkg/util/patroni/patroni.go
new file mode 100644
index 000000000..6c254b41a
--- /dev/null
+++ b/pkg/util/patroni/patroni.go
@@ -0,0 +1,80 @@
+package patroni
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"github.com/Sirupsen/logrus"
+	"k8s.io/client-go/pkg/api/v1"
+)
+
+const (
+	failoverPath = "/failover"
+	apiPort      = 8008
+	timeout      = 30 * time.Second
+)
+
+// Interface describe patroni methods
+type Interface interface {
+	Failover(master *v1.Pod, candidate string) error
+}
+
+// Patroni API client
+type Patroni struct {
+	httpClient *http.Client
+	logger     *logrus.Entry
+}
+
+// New create patroni
+func New(logger *logrus.Entry) *Patroni {
+	cl := http.Client{
+		Timeout: timeout,
+	}
+
+	return &Patroni{
+		logger:     logger,
+		httpClient: &cl,
+	}
+}
+
+func (p *Patroni) apiURL(masterPod *v1.Pod) string {
+	return fmt.Sprintf("http://%s:%d", masterPod.Status.PodIP, apiPort)
+}
+
+// Failover does manual failover via patroni api
+func (p *Patroni) Failover(master *v1.Pod, candidate string) error {
+	buf := &bytes.Buffer{}
+
+	err := json.NewEncoder(buf).Encode(map[string]string{"leader": master.Name, "member": candidate})
+	if err != nil {
+		return fmt.Errorf("could not encode json: %v", err)
+	}
+
+	request, err := http.NewRequest(http.MethodPost, p.apiURL(master)+failoverPath, buf)
+	if err != nil {
+		return fmt.Errorf("could not create request: %v", err)
+	}
+
+	p.logger.Debugf("making http request: %s", request.URL.String())
+
+	resp, err := p.httpClient.Do(request)
+	if err != nil {
+		return fmt.Errorf("could not make request: %v", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		bodyBytes, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return fmt.Errorf("could not read response: %v", err)
+		}
+
+		return fmt.Errorf("patroni returned '%s'", string(bodyBytes))
+	}
+
+	return nil
+}