postgresql: Configurable max open connections to the database

builtin/logical/postgresql/backend.go

@@ -6,9 +6,9 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/lib/pq"
 	"github.com/hashicorp/vault/logical"
 	"github.com/hashicorp/vault/logical/framework"
+	"github.com/lib/pq"
 )
 
 func Factory(conf *logical.BackendConfig) (logical.Backend, error) {
@@ -70,11 +70,13 @@ func (b *backend) DB(s logical.Storage) (*sql.DB, error) {
 			fmt.Errorf("configure the DB connection with config/connection first")
 	}
 
-	var conn string
-	if err := entry.DecodeJSON(&conn); err != nil {
+	var connConfig connectionConfig
+	if err := entry.DecodeJSON(&connConfig); err != nil {
 		return nil, err
 	}
 
+	conn := connConfig.ConnectionString
+
 	// Ensure timezone is set to UTC for all the conenctions
 	if strings.HasPrefix(conn, "postgres://") || strings.HasPrefix(conn, "postgresql://") {
 		var err error
@@ -92,7 +94,7 @@ func (b *backend) DB(s logical.Storage) (*sql.DB, error) {
 
 	// Set some connection pool settings. We don't need much of this,
 	// since the request rate shouldn't be high.
-	b.db.SetMaxOpenConns(2)
+	b.db.SetMaxOpenConns(connConfig.MaxOpenConnections)
 
 	return b.db, nil
 }

builtin/logical/postgresql/path_config_connection.go

@@ -17,6 +17,10 @@ func pathConfigConnection(b *backend) *framework.Path {
 				Type:        framework.TypeString,
 				Description: "DB connection string",
 			},
+			"max_open_connections": &framework.FieldSchema{
+				Type:        framework.TypeInt,
+				Description: "Maximum number of open connections to the database",
+			},
 		},
 
 		Callbacks: map[logical.Operation]framework.OperationFunc{
@@ -32,6 +36,11 @@ func (b *backend) pathConnectionWrite(
 	req *logical.Request, data *framework.FieldData) (*logical.Response, error) {
 	connString := data.Get("value").(string)
 
+	maxOpenConns := data.Get("max_open_connections").(int)
+	if maxOpenConns == 0 {
+		maxOpenConns = 2
+	}
+
 	// Verify the string
 	db, err := sql.Open("postgres", connString)
 	if err != nil {
@@ -45,7 +54,10 @@ func (b *backend) pathConnectionWrite(
 	}
 
 	// Store it
-	entry, err := logical.StorageEntryJSON("config/connection", connString)
+	entry, err := logical.StorageEntryJSON("config/connection", connectionConfig{
+		ConnectionString:   connString,
+		MaxOpenConnections: maxOpenConns,
+	})
 	if err != nil {
 		return nil, err
 	}
@@ -59,6 +71,11 @@ func (b *backend) pathConnectionWrite(
 	return nil, nil
 }
 
+type connectionConfig struct {
+	ConnectionString   string `json:"value"`
+	MaxOpenConnections int    `json:"max_open_connections"`
+}
+
 const pathConfigConnectionHelpSyn = `
 Configure the connection string to talk to PostgreSQL.
 `