From 4e9c0f27d56f0b87931d21dac2d7f5ba1ef83741 Mon Sep 17 00:00:00 2001
From: Dries De Peuter <dries@stenic.io>
Date: Wed, 4 Jan 2023 01:35:59 +0100
Subject: [PATCH] feat(agent): enable leader election

---
 charts/ledger/templates/agent_role.yaml       | 22 ++++++++++++
 .../ledger/templates/agent_rolebinding.yaml   | 19 +++++++++-
 cmd/ledger/agent.go                           | 17 +++++----
 internal/agent/agent.go                       | 36 ++++++++++++-------
 4 files changed, 71 insertions(+), 23 deletions(-)

diff --git a/charts/ledger/templates/agent_role.yaml b/charts/ledger/templates/agent_role.yaml
index 6c44b77..f8f0d25 100644
--- a/charts/ledger/templates/agent_role.yaml
+++ b/charts/ledger/templates/agent_role.yaml
@@ -1,4 +1,5 @@
 {{- if .Values.ledgerAgent.enabled -}}
+---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: {{ .Values.ledgerAgent.namespaced | ternary "Role" "ClusterRole" }}
 metadata:
@@ -23,4 +24,25 @@ rules:
   verbs:
   - create
   - patch
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: {{ include "ledger.fullname" . }}-agent-le
+  labels:
+    {{- include "ledger.labels" . | nindent 4 }}
+    component: agent
+rules:
+- apiGroups:
+  - coordination.k8s.io
+  resources:
+  - leases
+  verbs:
+  - get
+  - list
+  - watch
+  - create
+  - update
+  - patch
+  - delete
 {{- end }}
\ No newline at end of file
diff --git a/charts/ledger/templates/agent_rolebinding.yaml b/charts/ledger/templates/agent_rolebinding.yaml
index 1a1d942..258f74c 100644
--- a/charts/ledger/templates/agent_rolebinding.yaml
+++ b/charts/ledger/templates/agent_rolebinding.yaml
@@ -1,4 +1,5 @@
 {{- if .Values.ledgerAgent.enabled -}}
+---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: {{ .Values.ledgerAgent.namespaced | ternary "RoleBinding" "ClusterRoleBinding" }}
 metadata:
@@ -14,4 +15,20 @@ subjects:
 - kind: ServiceAccount
   name: {{ include "ledger.serviceAccountName" . }}-agent
   namespace: {{ .Release.Namespace }}
-{{- end }}
\ No newline at end of file
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+  name: {{ include "ledger.fullname" . }}-agent-le
+  labels:
+    {{- include "ledger.labels" . | nindent 4 }}
+    component: agent
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: Role
+  name: {{ include "ledger.fullname" . }}-agent-le
+subjects:
+- kind: ServiceAccount
+  name: {{ include "ledger.serviceAccountName" . }}-agent
+  namespace: {{ .Release.Namespace }}
+{{- end }}
diff --git a/cmd/ledger/agent.go b/cmd/ledger/agent.go
index d6b375c..6b4a4fb 100644
--- a/cmd/ledger/agent.go
+++ b/cmd/ledger/agent.go
@@ -6,24 +6,23 @@ import (
 	"github.com/stenic/ledger/internal/pkg/utils/env"
 )
 
+var opts agent.Options
+
 func NewAgentCmd() *cobra.Command {
-	var (
-		endpoint  string
-		namespace string
-		location  string
-	)
 
 	cmd := &cobra.Command{
 		Use:   "agent",
 		Short: "Ledger cluster agent",
 		Run: func(c *cobra.Command, args []string) {
-			agent.Run(endpoint, namespace, location)
+			agent.Run(opts)
 		},
 	}
 
-	cmd.Flags().StringVar(&endpoint, "endpoint", env.GetString("LEDGER_ENDPOINT", "http://127.0.0.1:8080"), "Ledger endpoint url")
-	cmd.Flags().StringVar(&namespace, "namespace", env.GetString("LEDGER_NAMESPACE", ""), "Ledger namespace, empty for all")
-	cmd.Flags().StringVar(&location, "location", env.GetString("LEDGER_LOCATION", ""), "Location")
+	cmd.Flags().StringVar(&opts.Endpoint, "endpoint", env.GetString("LEDGER_ENDPOINT", "http://127.0.0.1:8080"), "Ledger endpoint url")
+	cmd.Flags().StringVar(&opts.Namespaces, "namespace", env.GetString("LEDGER_NAMESPACE", ""), "Ledger namespace, empty for all")
+	cmd.Flags().StringVar(&opts.Location, "location", env.GetString("LEDGER_LOCATION", ""), "Location")
+	cmd.Flags().BoolVar(&opts.LeaderElection, "leader-election", env.GetBool("LEDGER_LEADER_ELECTION", false), "Leader election")
+	cmd.Flags().StringVar(&opts.LeaderElectionNamespace, "leader-election-namespace", env.GetString("LEDGER_LEADER_ELECTION_NAMESPACE", "ledger"), "Leader election namespace")
 
 	return cmd
 }
diff --git a/internal/agent/agent.go b/internal/agent/agent.go
index 3495a6f..9675489 100644
--- a/internal/agent/agent.go
+++ b/internal/agent/agent.go
@@ -25,19 +25,29 @@ func init() {
 	utilruntime.Must(clientgoscheme.AddToScheme(scheme))
 }
 
-func Run(endpoint, namespace, envLocation string) {
-	location = envLocation
+type Options struct {
+	Endpoint   string
+	Namespaces string
+	Location   string
+
+	LeaderElection          bool
+	LeaderElectionNamespace string
+}
+
+func Run(opts Options) {
+	location = opts.Location
 	ctrl.SetLogger(logrusr.New(logrus.StandardLogger()))
-	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
-		Scheme:                 scheme,
-		MetricsBindAddress:     ":8082",
-		Port:                   9443,
-		HealthProbeBindAddress: ":8081",
-		Namespace:              namespace,
-		// LeaderElection:          true,
-		// LeaderElectionID:        "ledger.stenic.io",
-		// LeaderElectionNamespace: "ledger",
-	})
+	mgrOpts := ctrl.Options{
+		Scheme:                  scheme,
+		MetricsBindAddress:      ":8082",
+		Port:                    9443,
+		HealthProbeBindAddress:  ":8081",
+		Namespace:               opts.Namespaces,
+		LeaderElection:          opts.LeaderElection,
+		LeaderElectionID:        "ledger.stenic.io",
+		LeaderElectionNamespace: opts.LeaderElectionNamespace,
+	}
+	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), mgrOpts)
 	if err != nil {
 		logrus.Fatal(err)
 	}
@@ -47,7 +57,7 @@ func Run(endpoint, namespace, envLocation string) {
 		logrus.Fatal("Please provide a TOKEN environment variable")
 	}
 	lc = client.LedgerClient{
-		Endpoint: endpoint + "/query",
+		Endpoint: opts.Endpoint + "/query",
 		Token:    tkn,
 	}