feat: Add PostgreSQL Retriever

cmd/relayproxy/config/retriever.go

@@ -30,6 +30,9 @@ type RetrieverConf struct {
 	URI          string              `mapstructure:"uri" koanf:"uri"`
 	Database     string              `mapstructure:"database" koanf:"database"`
 	Collection   string              `mapstructure:"collection" koanf:"collection"`
+	Type         string              `mapstructure:"type" koanf:"type"`
+	Table        string              `mapstructure:"table" koanf:"table"`
+	Column       string              `mapstructure:"column" koanf:"column"`
 	RedisOptions *redis.Options      `mapstructure:"redisOptions" koanf:"redisOptions"`
 	RedisPrefix  string              `mapstructure:"redisPrefix" koanf:"redisPrefix"`
 	AccountName  string              `mapstructure:"accountName" koanf:"accountname"`
@@ -67,6 +70,9 @@ func (c *RetrieverConf) IsValid() error {
 	if c.Kind == MongoDBRetriever {
 		return c.validateMongoDBRetriever()
 	}
+	if c.Kind == PostgreSQLRetriever {
+		return c.validatePostgreSQLRetriever()
+	}
 	if c.Kind == RedisRetriever {
 		return c.validateRedisRetriever()
 	}
@@ -112,6 +118,23 @@ func (c *RetrieverConf) validateMongoDBRetriever() error {
 	return nil
 }
 
+func (c *RetrieverConf) validatePostgreSQLRetriever() error {
+	if c.Column == "" {
+		return fmt.Errorf("invalid retriever: no \"column\" property found for kind \"%s\"", c.Kind)
+	}
+	if c.Table == "" {
+		return fmt.Errorf("invalid retriever: no \"table\" property found for kind \"%s\"", c.Kind)
+	}
+	if c.URI == "" {
+		return fmt.Errorf("invalid retriever: no \"uri\" property found for kind \"%s\"", c.Kind)
+	}
+	if c.Type == "" || !(c.Type == "json") {
+		return fmt.Errorf("invalid retriever: no \"type\" property or not a valid type in kind \"%s\"", c.Kind)
+	}
+
+	return nil
+}
+
 func (c *RetrieverConf) validateRedisRetriever() error {
 	if c.RedisOptions == nil {
 		return fmt.Errorf("invalid retriever: no \"redisOptions\" property found for kind \"%s\"", c.Kind)
@@ -144,6 +167,7 @@ const (
 	GoogleStorageRetriever RetrieverKind = "googleStorage"
 	KubernetesRetriever    RetrieverKind = "configmap"
 	MongoDBRetriever       RetrieverKind = "mongodb"
+	PostgreSQLRetriever    RetrieverKind = "postgresql"
 	RedisRetriever         RetrieverKind = "redis"
 	BitbucketRetriever     RetrieverKind = "bitbucket"
 	AzBlobStorageRetriever RetrieverKind = "azureBlobStorage"
@@ -154,7 +178,7 @@ func (r RetrieverKind) IsValid() error {
 	switch r {
 	case HTTPRetriever, GitHubRetriever, GitlabRetriever, S3Retriever, RedisRetriever,
 		FileRetriever, GoogleStorageRetriever, KubernetesRetriever, MongoDBRetriever,
-		BitbucketRetriever, AzBlobStorageRetriever:
+		PostgreSQLRetriever, BitbucketRetriever, AzBlobStorageRetriever:
 		return nil
 	}
 	return fmt.Errorf("invalid retriever: kind \"%s\" is not supported", r)

cmd/relayproxy/config/retriever_test.go

@@ -262,6 +262,73 @@ func TestRetrieverConf_IsValid(t *testing.T) {
 			wantErr:  true,
 			errValue: "invalid retriever: no \"redisOptions\" property found for kind \"redis\"",
 		},
+		{
+			name: "kind postgreSQL without Table",
+			fields: config.RetrieverConf{
+				Kind:   "postgresql",
+				URI:    "xxx",
+				Column: "xxx",
+				Type:   "json",
+			},
+			wantErr:  true,
+			errValue: "invalid retriever: no \"table\" property found for kind \"postgresql\"",
+		},
+		{
+			name: "kind postgreSQL without Column",
+			fields: config.RetrieverConf{
+				Kind:  "postgresql",
+				URI:   "xxx",
+				Table: "xxx",
+				Type:  "json",
+			},
+			wantErr:  true,
+			errValue: "invalid retriever: no \"column\" property found for kind \"postgresql\"",
+		},
+		{
+			name: "kind postgreSQL without URI",
+			fields: config.RetrieverConf{
+				Kind:   "postgresql",
+				Column: "xxx",
+				Table:  "xxx",
+				Type:   "json",
+			},
+			wantErr:  true,
+			errValue: "invalid retriever: no \"uri\" property found for kind \"postgresql\"",
+		},
+		{
+			name: "kind postgreSQL without Type",
+			fields: config.RetrieverConf{
+				Kind:   "postgresql",
+				Column: "xxx",
+				Table:  "xxx",
+				URI:    "xxx",
+			},
+			wantErr:  true,
+			errValue: "invalid retriever: no \"type\" property or not a valid type in kind \"postgresql\"",
+		},
+		{
+			name: "kind postgreSQL wrong Type",
+			fields: config.RetrieverConf{
+				Kind:   "postgresql",
+				Column: "xxx",
+				Table:  "xxx",
+				URI:    "xxx",
+				Type:   "wrong",
+			},
+			wantErr:  true,
+			errValue: "invalid retriever: no \"type\" property or not a valid type in kind \"postgresql\"",
+		},
+
+		{
+			name: "kind postgreSQL valid",
+			fields: config.RetrieverConf{
+				Kind:   "postgresql",
+				URI:    "xxx",
+				Table:  "xxx",
+				Type:   "json",
+				Column: "xxx",
+			},
+		},
 		{
 			name: "kind mongoDB without Collection",
 			fields: config.RetrieverConf{

cmd/relayproxy/service/gofeatureflag.go

@@ -35,6 +35,7 @@
 	"github.com/thomaspoignant/go-feature-flag/retriever/httpretriever"
 	"github.com/thomaspoignant/go-feature-flag/retriever/k8sretriever"
 	"github.com/thomaspoignant/go-feature-flag/retriever/mongodbretriever"
+	"github.com/thomaspoignant/go-feature-flag/retriever/postgresqlretriever"
 	"github.com/thomaspoignant/go-feature-flag/retriever/redisretriever"
 	"github.com/thomaspoignant/go-feature-flag/retriever/s3retrieverv2"
 	"go.uber.org/zap"
@@ -185,6 +186,8 @@
 			ClientConfig: *client}, nil
 	case config.MongoDBRetriever:
 		return &mongodbretriever.Retriever{Database: c.Database, URI: c.URI, Collection: c.Collection}, nil
+	case config.PostgreSQLRetriever:
+		return &postgresqlretriever.Retriever{Type: c.Type, URI: c.URI, Table: c.Table, Column: c.Column}, nil
 	case config.RedisRetriever:
 		return &redisretriever.Retriever{Options: c.RedisOptions, Prefix: c.RedisPrefix}, nil
 	case config.AzBlobStorageRetriever:

examples/retriever_postgresql/README.md

@@ -0,0 +1,30 @@
+# PostgreSQL example
+
+This example contains everything you need to use **`PostgreSQL`** as the source for your flags.
+
+As you can see the `main.go` file contains a basic HTTP server that expose an API that use your flags.
+
+## How to setup the example
+_All commands should be run in the root level of the repository._
+
+1. Load all dependencies
+
+```shell
+make vendor
+```
+
+2. Run the PostgreSQL container provided in the `docker-compose.yml` file.
+
+```shell
+docker compose -f ./example/retriever_postgresql/docker-compose.yml up
+```
+
+The container will run an initialization script that populates the database with example flags
+
+3. Run the example app to visualize the flags being evaluated
+
+```shell
+go run ./examples/retriever_postgresql/main.go
+```
+
+4. Play with the values in the configured MongoDB documents to see different outputs

examples/retriever_postgresql/docker-compose.yml

@@ -0,0 +1,17 @@
+# Use root/example as user/password credentials
+version: '3.1'
+
+services:
+
+  postgres:
+    container_name: goff_postgres
+    hostname: postgres
+    image: postgres:16-alpine
+    environment:
+      - POSTGRES_USER=root
+      - POSTGRES_PASSWORD=example
+      - POSTGRES_DB=flags_db
+    ports:
+      - "5432:5432"
+    volumes:
+      - ./init-db.sh:/docker-entrypoint-initdb.d/init-db.sh:ro

examples/retriever_postgresql/init-db.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+
+set -e
+
+psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" --dbname "$POSTGRES_DB" <<-EOSQL
+  CREATE TABLE IF NOT EXISTS flags (
+    id SERIAL PRIMARY KEY,
+    flag JSONB
+  );
+
+  INSERT INTO flags (flag) VALUES
+  (
+    '{
+      "flag": "new-admin-access",
+      "variations": {
+          "default_var": false,
+          "false_var": false,
+          "true_var": true
+      },
+      "defaultRule": {
+          "percentage": {
+              "false_var": 70,
+              "true_var": 30
+          }
+      }
+    }'::jsonb
+  );
+
+  INSERT INTO flags (flag) VALUES
+  (
+    '{
+      "flag": "flag-only-for-admin",
+      "variations": {
+          "default_var": false,
+          "false_var": false,
+          "true_var": true
+      },
+      "targeting": [
+          {
+              "query": "admin eq true",
+              "percentage": {
+                  "false_var": 0,
+                  "true_var": 100
+              }
+          }
+      ],
+      "defaultRule": {
+          "variation": "default_var"
+      }
+    }'::jsonb
+  );
+EOSQL
+

examples/retriever_postgresql/main.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"log/slog"
+	"time"
+
+	"github.com/thomaspoignant/go-feature-flag/ffcontext"
+
+	"github.com/thomaspoignant/go-feature-flag/exporter/fileexporter"
+	"github.com/thomaspoignant/go-feature-flag/retriever/postgresqlretriever"
+
+	ffclient "github.com/thomaspoignant/go-feature-flag"
+)
+
+func main() {
+	// Init ffclient with a file retriever.
+	err := ffclient.Init(ffclient.Config{
+		PollingInterval: 10 * time.Second,
+		LeveledLogger:   slog.Default(),
+		Context:         context.Background(),
+		Retriever: &postgresqlretriever.Retriever{
+			Table:  "flags",
+			Type:  "json",
+			Column: "flag",
+			URI:    "postgres://root:example@localhost:5432/flags_db?sslmode=disable",
+		},
+		DataExporter: ffclient.DataExporter{
+			FlushInterval:    1 * time.Second,
+			MaxEventInMemory: 100,
+			Exporter: &fileexporter.Exporter{
+				OutputDir: "./",
+			},
+		},
+	})
+	// Check init errors.
+	if err != nil {
+		log.Fatal(err)
+	}
+	// defer closing ffclient
+	defer ffclient.Close()
+
+	// create users
+	user1 := ffcontext.
+		NewEvaluationContextBuilder("aea2fdc1-b9a0-417a-b707-0c9083de68e3").
+		AddCustom("anonymous", true).
+		AddCustom("environment", "dev").
+		Build()
+	user2 := ffcontext.NewEvaluationContext("332460b9-a8aa-4f7a-bc5d-9cc33632df9a")
+	user3 := ffcontext.NewEvaluationContextBuilder("785a14bf-d2c5-4caa-9c70-2bbc4e3732a5").
+		AddCustom("email", "[email protected]").
+		AddCustom("firstname", "John").
+		AddCustom("lastname", "Doe").
+		AddCustom("admin", true).
+		Build()
+
+	// --- test flag with no rule
+	// user1
+	user1HasAccessToNewAdmin, err := ffclient.BoolVariation("new-admin-access", user1, false)
+	if err != nil {
+		// we log the error, but we still have a meaningful value in user1HasAccessToNewAdmin (the default value).
+		log.Printf("something went wrong when getting the flag: %v", err)
+	}
+	if user1HasAccessToNewAdmin {
+		fmt.Println("user1 has access to the new admin")
+	}
+
+	// user2
+	user2HasAccessToNewAdmin, err := ffclient.BoolVariation("new-admin-access", user2, false)
+	if err != nil {
+		// we log the error, but we still have a meaningful value in hasAccessToNewAdmin (the default value).
+		log.Printf("something went wrong when getting the flag: %v", err)
+	}
+	if !user2HasAccessToNewAdmin {
+		fmt.Println("user2 has not access to the new admin")
+	}
+
+	// --- test flag with rule only for admins
+	// user 1 is not admin so should not access to the flag
+	user1HasAccess, _ := ffclient.BoolVariation("flag-only-for-admin", user1, false)
+	if !user1HasAccess {
+		fmt.Println("user1 is not admin so no access to the flag")
+	}
+
+	// user 3 is admin and the flag apply to this key.
+	if user3HasAccess, _ := ffclient.BoolVariation("flag-only-for-admin", user3, false); user3HasAccess {
+		fmt.Println("user 3 is admin and the flag apply to this key.")
+	}
+}

go.mod

@@ -27,6 +27,7 @@ require (
 	github.com/google/uuid v1.6.0
 	github.com/gorilla/websocket v1.5.3
 	github.com/invopop/jsonschema v0.12.0
+	github.com/jackc/pgx/v5 v5.5.4
 	github.com/jessevdk/go-flags v1.6.1
 	github.com/jsternberg/zap-logfmt v1.3.0
 	github.com/knadh/koanf/parsers/json v0.1.0
@@ -39,6 +40,7 @@ require (
 	github.com/knadh/koanf/v2 v2.1.2
 	github.com/labstack/echo-contrib v0.17.1
 	github.com/labstack/echo/v4 v4.13.0
+	github.com/lib/pq v1.10.9
 	github.com/luci/go-render v0.0.0-20160219211803-9a04cc21af0f
 	github.com/nikunjy/rules v1.5.0
 	github.com/pablor21/echo-etag/v4 v4.0.3
@@ -54,6 +56,7 @@ require (
 	github.com/testcontainers/testcontainers-go v0.34.0
 	github.com/testcontainers/testcontainers-go/modules/azurite v0.34.0
 	github.com/testcontainers/testcontainers-go/modules/mongodb v0.34.0
+	github.com/testcontainers/testcontainers-go/modules/postgres v0.34.0
 	github.com/testcontainers/testcontainers-go/modules/redis v0.34.0
 	github.com/thejerf/slogassert v0.3.4
 	github.com/xitongsys/parquet-go v1.6.2
@@ -164,6 +167,9 @@ require (
 	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/hashicorp/go-uuid v1.0.3 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
+	github.com/jackc/puddle/v2 v2.2.1 // indirect
 	github.com/jcmturner/aescts/v2 v2.0.0 // indirect
 	github.com/jcmturner/dnsutils/v2 v2.0.0 // indirect
 	github.com/jcmturner/gofork v1.7.6 // indirect