mysql: made max_open_connections configurable

builtin/logical/mysql/backend.go

@@ -68,11 +68,13 @@ 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
+
 	b.db, err = sql.Open("mysql", conn)
 	if err != nil {
 		return nil, err
@@ -80,7 +82,7 @@ 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/mysql/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 database",
+			},
 		},
 
 		Callbacks: map[logical.Operation]framework.OperationFunc{
@@ -32,8 +36,14 @@ 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("mysql", connString)
+
 	if err != nil {
 		return logical.ErrorResponse(fmt.Sprintf(
 			"Error validating connection info: %s", err)), nil
@@ -45,7 +55,10 @@ 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
 	}
@@ -58,6 +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 MySQL.
 `

website/source/docs/secrets/mysql/index.html.md

@@ -129,6 +129,16 @@ allowed to read.
       </li>
     </ul>
   </dd>
+  <dd>
+    <ul>
+      <li>
+        <span class="param">max_open_connections</span>
+        <span class="param-flags">optional</span>
+        Maximum number of open connections to the database.
+	Defaults to 2.
+      </li>
+    </ul>
+  </dd>
 
   <dt>Returns</dt>
   <dd>