SDK Reference

The GatewayD plugin SDK provides a number of interfaces, structs and methods to help you build your plugin. This section provides a reference to all of them. The SDK is built for Go, but the protocol buffers definitions can be used to build plugins in other languages.

This documentation is not complete. Please refer to the SDK source code for more information. Also, it might be removed in the future in favor of GoDoc.

The SDK is still in development and subject to change.

Packages

The root of the SDK is the github.com/gatewayd-io/gatewayd-plugin-sdk. It contains the following sub-packages:

`config`

GetEnv returns the value of an environment variable. If the environment variable is not set, it returns the default value as fallback.
```
  func GetEnv(key, fallback string) string
```

`databases/postgres`

IsPostgresStartupMessage checks if a message is a Postgres startup message. It returns true if the message is a startup message, false otherwise.
```
  func IsPostgresStartupMessage(message []byte) bool
```
DecodeBytes decodes a base64 encoded string to bytes. It uses the base64.StdEncoding decoder. It returns the decoded bytes and an empty byte array if there is an error.
```
  func DecodeBytes(encoded string) ([]byte, error)
```
HandleClientMessage handles a client message. This function should be called from onTrafficFromClient hook. It returns a v1.Struct with extra fields that are decoded from the message. It logs the error and returns nil if there is an error.
```
  func HandleClientMessage(req *v1.Struct, logger hclog.Logger) (*v1.Struct, error)
```
HandleServerMessage handles a server message. This function should be called from onTrafficFromServer hook. It returns a v1.Struct with extra fields that are decoded from the message. It logs the error and returns nil if there is an error.
```
  func HandleServerMessage(resp *v1.Struct, logger hclog.Logger) (*v1.Struct, error)
```
GetQueryFromRequest decodes the request and returns the query. It returns an error if the request cannot be decoded. It returns an empty string if the query is not found.
```
  func GetQueryFromRequest(req *v1.Struct) (string, error)
```
GetTablesFromQuery returns the tables used in a query. It returns an error if the query cannot be parsed.
```
  func GetTablesFromQuery(query string) ([]string, error)
```

`logging`

GetLogLevel returns the hclog level based on the (log level) string passed in.
```
  func GetLogLevel(level string) hclog.Level
```

`metrics`

NewMetricsConfig returns a new MetricsConfig struct. It returns an error if the environment variables are not set. It returns nil if the metrics are disabled.
```
  func NewMetricsConfig(config map[string]interface{}) *MetricsConfig
```
ExposeMetrics exposes the Prometheus metrics via HTTP over Unix domain socket. It logs an error if the metrics cannot be exposed.
```
  func ExposeMetrics(config *MetricsConfig, logger hclog.Logger) error
```

`plugin`

DefaultGRPCServer returns a gRPC server with a 2GB max message size.

  func DefaultGRPCServer(opts []grpc.ServerOption) *grpc.Server

GetAttr returns the value of an attribute from the v1.Struct. It returns the default value if the attribute is not found.
```
  func GetAttr(req *v1.Struct, key string, defaultValue interface{}) interface{}
```

`plugin/v1`

GetPluginMap returns the plugin map for the plugin.

  func GetPluginMap(pluginName string) map[string]goplugin.Plugin

GetPluginSetMap returns the plugin set map for the plugin.

  func GetPluginSetMap(plugins map[string]goplugin.Plugin) goplugin.PluginSet

plugin.proto is the protocol buffers definition for the plugin and its generated Go code stubs are in plugin.pb.go and plugin_grpc.pb.go.
struct.proto is the protocol buffers definition for the v1.Struct and its generated Go code stubs are in struct.pb.go and structpb.go. This is a modified version of the Struct from the Google Protobuf library with an additional bytes field.