feat: add Pooler resource and controller for PgBouncer

Add a new `Pooler` API and the relative controller, enabling the user to
create a PgBouncer deployment to be used as a connection pooler
for a local PostgreSQL `Cluster`.

The PgBouncer controller supports:

- logging in JSON format
- Prometheus exporter for stats, pools, and lists.
- TLS connections with clients and the server
- integration with the Cluster TLS authentication for the `auth_user` connections
- password authentication for clients
- High Availability
- PodTemplates
- control of `PAUSE` and `RESUME` through declarative configuration

Details in `docs/src/connection_pooling.md`

Co-authored-by: Philippe Scorsolini <philippe.scorsolini@enterprisedb.com>
Co-authored-by: Gabriele Bartolini <gabriele.bartolini@enterprisedb.com>
Co-authored-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>
Co-authored-by: Francesco Canovai <francesco.canovai@enterprisedb.com>

Author: 5 people

.wordlist-en-custom.txt

@@ -6,9 +6,12 @@ AdditionalPodAffinity
 AdditionalPodAntiAffinity
 AffinityConfiguration
 Anand
+AuthQuery
+AuthQuerySecret
 Autoscaler
 AzureCredentials
 Azurite
+BDR
 BackupConfiguration
 BackupList
 BackupPhase
@@ -17,7 +20,6 @@ BackupStatus
 BarmanObjectStoreConfiguration
 Bartolini
 Battiato
-BDR
 BootstrapConfiguration
 BootstrapInitDB
 BootstrapPgBaseBackup
@@ -87,6 +89,7 @@ Gi
 Golang
 GolangCI
 Grafana
+HH
 IfNotPresent
 InfoSec
 JSON
@@ -132,13 +135,26 @@ PVCs
 Patroni
 PersistentVolumeClaim
 PersistentVolumeClaimSpec
+PgBouncer's
+PgBouncerPoolMode
+PgBouncerSpec
+PgbouncerIntegrationStatus
 Philippe
 PodAffinity
 PodAntiAffinity
 PodAntiAffinityType
 PodDisruptionBudget
+PodMeta
 PodMonitor
+PodSpec
 PodStatus
+PodTemplateSpec
+Pooler
+PoolerIntegrations
+PoolerList
+PoolerSpec
+PoolerStatus
+PoolerType
 Postgres
 PostgresConfiguration
 PrimaryUpdateStrategy
@@ -200,6 +216,7 @@ WALs
 Wadle
 WalBackupConfiguration
 YXBw
+YYYY
 accessKeyId
 accessModes
 adc
@@ -274,10 +291,12 @@ commandOutput
 conf
 config
 config's
+configMap
 configmap
 configmapkeyselector
 configmaps
 configs
+conn
 connectionParameters
 containerPort
 coreos
@@ -309,6 +328,7 @@ ddl
 de
 declaratively
 defaultMode
+defaultPoolSize
 destinationPath
 dev
 devel
@@ -332,6 +352,7 @@ externalClusters
 facto
 failover
 fastpath
+fd
 ffd
 filesystem
 fio
@@ -409,6 +430,7 @@ malcolm
 mallocs
 matchExpressions
 matchLabels
+maxClientConnections
 maxSyncReplicas
 mcache
 md
@@ -450,6 +472,8 @@ openshift
 operatorframework
 operatorgroups
 operatorhub
+parseable
+passwd
 pc
 pdf
 persistentvolumeclaim
@@ -459,6 +483,7 @@ pgaudit
 pgbarman
 pgbasebackup
 pgbench
+pgbouncer
 pgdata
 pgpass
 pgstatstatements
@@ -472,6 +497,9 @@ podAntiAffinity
 podAntiAffinityType
 podMetricsEndpoints
 podmonitor
+poolMode
+pooler
+poolers
 pos
 postInitSQL
 postgres
@@ -492,6 +520,7 @@ pvc
 pvcCount
 pvcTemplate
 quantile
+queryable
 quickstart
 rbac
 readService
@@ -548,6 +577,7 @@ sslrootcert
 sso
 startDelay
 startedAt
+stderr
 stdout
 stopDelay
 stoppedAt

DEVELOPERS.md

@@ -63,6 +63,12 @@ export GPG_AGENT_INFO=~/.gnupg/S.gpg-agent::1
 export GPG_TTY=$(tty)
 ```
 
+You also need to set:
+
+```
+export GOPATH="${HOME}/go"
+```
+
 ### Setting your docker engine
 
 Please allow a reasonable amount of memory for Docker.

PROJECT

@@ -19,4 +19,7 @@ resources:
 - group: postgresql
   kind: ScheduledBackup
   version: v1
+- group: postgresql
+  kind: Pooler
+  version: v1
 version: "2"

api/v1/cluster_types.go

@@ -77,6 +77,9 @@ const (
 
 	// PodAntiAffinityTypePreferred is the label for preferred anti-affinity type
 	PodAntiAffinityTypePreferred = "preferred"
+
+	// DefaultPgBouncerPoolerSecretSuffix is the suffix for the default pgbouncer Pooler secret
+	DefaultPgBouncerPoolerSecretSuffix = "-pooler"
 )
 
 // ClusterSpec defines the desired state of Cluster
@@ -300,6 +303,19 @@ type ClusterStatus struct {
 
 	// The timestamp when the last request for a new primary has occurred
 	TargetPrimaryTimestamp string `json:"targetPrimaryTimestamp,omitempty"`
+
+	// The integration needed by poolers referencing the cluster
+	PoolerIntegrations *PoolerIntegrations `json:"poolerIntegrations,omitempty"`
+}
+
+// PoolerIntegrations encapsulates the needed integration for the poolers referencing the cluster
+type PoolerIntegrations struct {
+	PgBouncerIntegration PgbouncerIntegrationStatus `json:"pgBouncerIntegration,omitempty"`
+}
+
+// PgbouncerIntegrationStatus encapsulates the needed integration for the pgbouncer poolers referencing the cluster
+type PgbouncerIntegrationStatus struct {
+	Secrets []string `json:"secrets,omitempty"`
 }
 
 // ReplicaClusterConfiguration encapsulates the configuration of a replica

api/v1/groupversion_info.go

@@ -25,12 +25,22 @@ var (
 		Resource: "clusters",
 	}
 
+	// PoolerGVK is the triple to reach Pooler resources in k8s
+	PoolerGVK = schema.GroupVersionResource{
+		Group:    GroupVersion.Group,
+		Version:  GroupVersion.Version,
+		Resource: "poolers",
+	}
+
 	// ClusterKind is the kind name of Clusters
 	ClusterKind = "Cluster"
 
 	// BackupKind is the kind name of Backups
 	BackupKind = "Backup"
 
+	// PoolerKind is the kind name of Poolers
+	PoolerKind = "Pooler"
+
 	// SchemeBuilder is used to add go types to the GroupVersionKind scheme
 	SchemeBuilder = &scheme.Builder{GroupVersion: GroupVersion}