github.com/goadesign/goa
goa
import "github.com/goadesign/goa"
Overview
Package goa provides the runtime support for goa microservices.
Code Generation
goa service development begins with writing the design of a service. The design is described using
the goa language implemented by the github.com/goadesign/goa/design/apidsl package. The goagen
tool
consumes the metadata produced from executing the design language to generate service specific code
that glues the underlying HTTP server with action specific code and data structures.
The goa package contains supporting functionality for the generated code including basic request and response state management through the RequestData and ResponseData structs, error handling via error classes, middleware support via the Middleware data structure as well as decoding and encoding algorithms.
Request Context
The RequestData and ResponseData structs provides access to the request and response state. goa request handlers also accept a context.Context interface as first parameter so that deadlines and cancelation signals may easily be implemented.
The request state exposes the underlying http.Request object as well as the deserialized payload (request body) and parameters (both path and querystring parameters). Generated action specific contexts wrap the context.Context, ResponseData and RequestData data structures. They expose properly typed fields that correspond to the request parameters and body data structure descriptions appearing in the design.
The response state exposes the response status and body length as well as the underlying ResponseWriter. Action contexts provide action specific helper methods that write the responses as described in the design optionally taking an instance of the media type for responses that contain a body.
Here is an example showing an “update” action corresponding to following design (extract):
Resource("bottle", func() {
DefaultMedia(Bottle)
Action("update", func() {
Params(func() {
Param("bottleID", Integer)
})
Payload(UpdateBottlePayload)
Response(OK)
Response(NotFound)
})
})
The action signature generated by goagen is:
type BottleController interface {
goa.Controller
Update(*UpdateBottleContext) error
}
where UpdateBottleContext is:
type UpdateBottleContext struct {
context.Context // Timeout and deadline support
*goa.ResponseData // Response state access
*goa.RequestData // Request state access
Service *goa.Service // Service handling request
BottleID int // Properly typed parameter fields
Payload *UpdateBottlePayload // Properly typed payload
}
and implements:
func (ctx *UpdateBottleContext) OK(resp *Bottle) error
func (ctx *UpdateBottleContext) NotFound() error
The definitions of the Bottle and UpdateBottlePayload data structures are ommitted for brievity.
Controllers
There is one controller interface generated per resource defined via the design language. The interface exposes the controller actions. User code must provide data structures that implement these interfaces when mounting a controller onto a service. The controller data structure should include an anonymous field of type *goa.Controller which takes care of implementing the middleware handling.
Middleware
A goa middleware is a function that takes and returns a Handler. A Handler is a the low level function which handles incoming HTTP requests. goagen generates the handlers code so each handler creates the action specific context and calls the controller action with it.
Middleware can be added to a goa service or a specific controller using the corresponding Use methods. goa comes with a few stock middleware that handle common needs such as logging, panic recovery or using the RequestID header to trace requests across multiple services.
Error Handling
The controller action methods generated by goagen such as the Update method of the BottleController interface shown above all return an error value. goa defines an Error struct that action implementations can use to describe the content of the corresponding HTTP response. Errors can be created using error classes which are functions created via NewErrorClass.
The ErrorHandler middleware maps errors to HTTP responses. Errors that are instances of the Error struct are mapped using the struct fields while other types of errors return responses with status code 500 and the error message in the body.
Validation
The goa design language documented in the dsl package makes it possible to attach validations to data structure definitions. One specific type of validation consists of defining the format that a data structure string field must follow. Example of formats include email, data time, hostnames etc. The ValidateFormat function provides the implementation for the format validation invoked from the code generated by goagen.
Encoding
The goa design language makes it possible to specify the encodings supported by the API both as input (Consumes) and output (Produces). goagen uses that information to registed the corresponding packages with the service encoders and decoders via their Register methods. The service exposes the DecodeRequest and EncodeResponse that implement a simple content type negotiation algorithm for picking the right encoder for the “Content-Type” (decoder) or “Accept” (encoder) request header.
Package goa standardizes on structured error responses: a request that fails because of an invalid input or an unexpected condition produces a response that contains a structured error.
The error data structures returned to clients contains five fields: an ID, a code, a status, a detail and metadata. The ID is unique for the occurrence of the error, it helps correlate the content of the response with the content of the service logs. The code defines the class of error (e.g. “invalid_parameter_type”) and the status the corresponding HTTP status (e.g. 400). The detail contains a message specific to the error occurrence. The metadata contains key/value pairs that provide contextual information (name of parameters, value of invalid parameter etc.).
Instances of Error can be created via Error Class functions. See http://goa.design/implement/error_handling.html All instance of errors created via a error class implement the ServiceError interface. This interface is leveraged by the error handler middleware to produce the error responses.
The code generated by goagen calls the helper functions exposed in this file when it encounters invalid data (wrong type, validation errors etc.) such as InvalidParamTypeError, InvalidAttributeTypeError etc. These methods return errors that get merged with any previously encountered error via the Error Merge method. The helper functions are error classes stored in global variable. This means your code can override their values to produce arbitrary error responses.
goa includes an error handler middleware that takes care of mapping back any error returned by previously called middleware or action handler into HTTP responses. If the error was created via an error class then the corresponding content including the HTTP status is used otherwise an internal error is returned. Errors that bubble up all the way to the top (i.e. not handled by the error middleware) also generate an internal error response.
Index
- Constants
- Variables
- func AddSample(key []string, val float32)
- func ContextAction(ctx context.Context) string
- func ContextController(ctx context.Context) string
- func ContextError(ctx context.Context) error
- func ContextRequiredScopes(ctx context.Context) []string
- func EmitKey(key []string, val float32)
- func IncrCounter(key []string, val float32)
- func InvalidAttributeTypeError(ctx string, val interface{}, expected string) error
- func InvalidEnumValueError(ctx string, val interface{}, allowed []interface{}) error
- func InvalidFormatError(ctx, target string, format Format, formatError error) error
- func InvalidLengthError(ctx string, target interface{}, ln, value int, min bool) error
- func InvalidParamTypeError(name string, val interface{}, expected string) error
- func InvalidPatternError(ctx, target string, pattern string) error
- func InvalidRangeError(ctx string, target interface{}, value interface{}, min bool) error
- func LogError(ctx context.Context, msg string, keyvals …interface{})
- func LogInfo(ctx context.Context, msg string, keyvals …interface{})
- func Logger(ctx context.Context) *log.Logger
- func MeasureSince(key []string, start time.Time)
- func MergeErrors(err, other error) error
- func MethodNotAllowedError(method string, allowed []string) error
- func MissingAttributeError(ctx, name string) error
- func MissingHeaderError(name string) error
- func MissingParamError(name string) error
- func MissingPayloadError() error
- func NewContext(ctx context.Context, rw http.ResponseWriter, req *http.Request, params url.Values) context.Context
- func NewMetrics(conf *metrics.Config, sink metrics.MetricSink) (err error)
- func NewNoOpSink() metrics.MetricSink
- func NoAuthMiddleware(schemeName string) error
- func SetGauge(key []string, val float32)
- func SetMetrics(m Collector)
- func ValidateFormat(f Format, val string) error
- func ValidatePattern(p string, val string) bool
- func WithAction(ctx context.Context, action string) context.Context
- func WithError(ctx context.Context, err error) context.Context
- func WithLogContext(ctx context.Context, keyvals …interface{}) context.Context
- func WithLogger(ctx context.Context, logger LogAdapter) context.Context
- func WithRequiredScopes(ctx context.Context, scopes []string) context.Context
- type APIKeySecurity
- type BasicAuthSecurity
- type Collector
- type Controller
- type DecodeFunc
- type Decoder
- type DecoderFunc
- type Encoder
- type EncoderFunc
- type ErrorClass
- type ErrorResponse
- type FileServer
- type Format
- type HTTPDecoder
- type HTTPEncoder
- type Handler
- type JWTSecurity
- type Location
- type LogAdapter
- type MethodNotAllowedHandler
- type Middleware
- type MuxHandler
- type Muxer
- type NoOpSink
- func (*NoOpSink) AddSample(key []string, val float32)
- func (*NoOpSink) AddSampleWithLabels(key []string, val float32, labels []metrics.Label)
- func (*NoOpSink) EmitKey(key []string, val float32)
- func (*NoOpSink) IncrCounter(key []string, val float32)
- func (*NoOpSink) IncrCounterWithLabels(key []string, val float32, labels []metrics.Label)
- func (*NoOpSink) SetGauge(key []string, val float32)
- func (*NoOpSink) SetGaugeWithLabels(key []string, val float32, labels []metrics.Label)
- type OAuth2Security
- type RequestData
- type ResettableDecoder
- type ResettableEncoder
- type ResponseData
- type ServeMux
- type Service
- func New(name string) *Service
- func (service *Service) CancelAll()
- func (service *Service) DecodeRequest(req *http.Request, v interface{}) error
- func (service *Service) EncodeResponse(ctx context.Context, v interface{}) error
- func (service *Service) ListenAndServe(addr string) error
- func (service *Service) ListenAndServeTLS(addr, certFile, keyFile string) error
- func (service *Service) LogError(msg string, keyvals …interface{})
- func (service *Service) LogInfo(msg string, keyvals …interface{})
- func (service *Service) NewController(name string) *Controller
- func (service *Service) Send(ctx context.Context, code int, body interface{}) error
- func (service *Service) Serve(l net.Listener) error
- func (service *Service) ServeFiles(path, filename string) error
- func (service *Service) Use(m Middleware)
- func (service *Service) WithLogger(logger LogAdapter)
- type ServiceError
- type ServiceMergeableError
- type Unmarshaler
Package files
context.go doc.go encoding.go error.go logging.go metrics.go middleware.go mux.go security.go service.go validation.go
Constants
const (
// FormatDate defines RFC3339 date values.
FormatDate Format = "date"
// FormatDateTime defines RFC3339 date time values.
FormatDateTime Format = "date-time"
// FormatUUID defines RFC4122 uuid values.
FormatUUID Format = "uuid"
// FormatEmail defines RFC5322 email addresses.
FormatEmail = "email"
// FormatHostname defines RFC1035 Internet host names.
FormatHostname = "hostname"
// FormatIPv4 defines RFC2373 IPv4 address values.
FormatIPv4 = "ipv4"
// FormatIPv6 defines RFC2373 IPv6 address values.
FormatIPv6 = "ipv6"
// FormatIP defines RFC2373 IPv4 or IPv6 address values.
FormatIP = "ip"
// FormatURI defines RFC3986 URI values.
FormatURI = "uri"
// FormatMAC defines IEEE 802 MAC-48, EUI-48 or EUI-64 MAC address values.
FormatMAC = "mac"
// FormatCIDR defines RFC4632 and RFC4291 CIDR notation IP address values.
FormatCIDR = "cidr"
// FormatRegexp Regexp defines regular expression syntax accepted by RE2.
FormatRegexp = "regexp"
// FormatRFC1123 defines RFC1123 date time values.
FormatRFC1123 = "rfc1123"
)
const ErrMissingLogValue = "MISSING"
ErrMissingLogValue is the value used to log keys with missing values
Variables
var (
// ErrorMediaIdentifier is the media type identifier used for error responses.
ErrorMediaIdentifier = "application/vnd.goa.error"
// ErrBadRequest is a generic bad request error.
ErrBadRequest = NewErrorClass("bad_request", 400)
// ErrUnauthorized is a generic unauthorized error.
ErrUnauthorized = NewErrorClass("unauthorized", 401)
// ErrInvalidRequest is the class of errors produced by the generated code when a request
// parameter or payload fails to validate.
ErrInvalidRequest = NewErrorClass("invalid_request", 400)
// ErrInvalidEncoding is the error produced when a request body fails to be decoded.
ErrInvalidEncoding = NewErrorClass("invalid_encoding", 400)
// ErrRequestBodyTooLarge is the error produced when the size of a request body exceeds
// MaxRequestBodyLength bytes.
ErrRequestBodyTooLarge = NewErrorClass("request_too_large", 413)
// ErrNoAuthMiddleware is the error produced when no auth middleware is mounted for a
// security scheme defined in the design.
ErrNoAuthMiddleware = NewErrorClass("no_auth_middleware", 500)
// ErrInvalidFile is the error produced by ServeFiles when requested to serve non-existant
// or non-readable files.
ErrInvalidFile = NewErrorClass("invalid_file", 404)
// ErrNotFound is the error returned to requests that don't match a registered handler.
ErrNotFound = NewErrorClass("not_found", 404)
// ErrMethodNotAllowed is the error returned to requests that match the path of a registered
// handler but not the HTTP method.
ErrMethodNotAllowed = NewErrorClass("method_not_allowed", 405)
// ErrInternal is the class of error used for uncaught errors.
ErrInternal = NewErrorClass("internal", 500)
)
func AddSample
func AddSample(key []string, val float32)
AddSample adds a sample to an aggregated metric reporting count, min, max, mean, and std deviation Usage:
AddSample([]string{"my","namespace","key"}, 15.0)
func ContextAction
func ContextAction(ctx context.Context) string
ContextAction extracts the action name from the given context.
func ContextController
func ContextController(ctx context.Context) string
ContextController extracts the controller name from the given context.
func ContextError
func ContextError(ctx context.Context) error
ContextError extracts the error from the given context.
func ContextRequiredScopes
func ContextRequiredScopes(ctx context.Context) []string
ContextRequiredScopes extracts the security scopes from the given context. This should be used in auth handlers to validate that the required scopes are present in the JWT or OAuth2 token.
func EmitKey
func EmitKey(key []string, val float32)
EmitKey emits a key/value pair Usage:
EmitKey([]string{"my","namespace","key"}, 15.0)
func IncrCounter
func IncrCounter(key []string, val float32)
IncrCounter increments the counter named by key
Usage:
IncrCounter([]key{"my","namespace","counter"}, 1.0)
func InvalidAttributeTypeError
func InvalidAttributeTypeError(ctx string, val interface{}, expected string) error
InvalidAttributeTypeError is the error produced when the type of payload field does not match the type defined in the design.
func InvalidEnumValueError
func InvalidEnumValueError(ctx string, val interface{}, allowed []interface{}) error
InvalidEnumValueError is the error produced when the value of a parameter or payload field does not match one the values defined in the design Enum validation.
func InvalidFormatError
func InvalidFormatError(ctx, target string, format Format, formatError error) error
InvalidFormatError is the error produced when the value of a parameter or payload field does not match the format validation defined in the design.
func InvalidLengthError
func InvalidLengthError(ctx string, target interface{}, ln, value int, min bool) error
InvalidLengthError is the error produced when the value of a parameter or payload field does not match the length validation defined in the design.
func InvalidParamTypeError
func InvalidParamTypeError(name string, val interface{}, expected string) error
InvalidParamTypeError is the error produced when the type of a parameter does not match the type defined in the design.
func InvalidPatternError
func InvalidPatternError(ctx, target string, pattern string) error
InvalidPatternError is the error produced when the value of a parameter or payload field does not match the pattern validation defined in the design.
func InvalidRangeError
func InvalidRangeError(ctx string, target interface{}, value interface{}, min bool) error
InvalidRangeError is the error produced when the value of a parameter or payload field does not match the range validation defined in the design. value may be a int or a float64.
func LogError
func LogError(ctx context.Context, msg string, keyvals ...interface{})
LogError extracts the logger from the given context and calls Error on it. This is intended for code that needs portable logging such as the internal code of goa and middleware. User code should use the log adapters instead.
func LogInfo
func LogInfo(ctx context.Context, msg string, keyvals ...interface{})
LogInfo extracts the logger from the given context and calls Info on it. This is intended for code that needs portable logging such as the internal code of goa and middleware. User code should use the log adapters instead.
func Logger
func Logger(ctx context.Context) *log.Logger
Logger returns the logger stored in the context if any, nil otherwise.
func MeasureSince
func MeasureSince(key []string, start time.Time)
MeasureSince creates a timing metric that records
the duration of elapsed time since start
Usage:
MeasureSince([]string{"my","namespace","action"}, time.Now())
Frequently used in a defer:
defer MeasureSince([]string{"my","namespace","action"}, time.Now())
func MergeErrors
func MergeErrors(err, other error) error
MergeErrors updates an error by merging another into it. It first converts other into a ServiceError if not already one - producing an internal error in that case. The merge algorithm is:
If any of e or other implements ServiceMergableError, it is handled by it’s Merge method.
If any of e or other is an internal error then the result is an internal error
If the status or code of e and other don’t match then the result is a 400 “bad_request”
The Detail field is updated by concatenating the Detail fields of e and other separated by a semi-colon. The MetaValues field of is updated by merging the map of other MetaValues into e’s where values in e with identical keys to values in other get overwritten.
Merge returns the updated error. This is useful in case the error was initially nil in which case other is returned.
func MethodNotAllowedError
func MethodNotAllowedError(method string, allowed []string) error
MethodNotAllowedError is the error produced to requests that match the path of a registered handler but not the HTTP method.
func MissingAttributeError
func MissingAttributeError(ctx, name string) error
MissingAttributeError is the error produced when a request payload is missing a required field.
func MissingHeaderError
func MissingHeaderError(name string) error
MissingHeaderError is the error produced when a request is missing a required header.
func MissingParamError
func MissingParamError(name string) error
MissingParamError is the error produced for requests that are missing path or querystring parameters.
func MissingPayloadError
func MissingPayloadError() error
MissingPayloadError is the error produced when a request is missing a required payload.
func NewContext
func NewContext(ctx context.Context, rw http.ResponseWriter, req *http.Request, params url.Values) context.Context
NewContext builds a new goa request context. If ctx is nil then context.Background() is used.
func NewMetrics
func NewMetrics(conf *metrics.Config, sink metrics.MetricSink) (err error)
NewMetrics initializes goa’s metrics instance with the supplied configuration and metrics sink This method is deprecated and SetMetrics should be used instead.
func NewNoOpSink
func NewNoOpSink() metrics.MetricSink
NewNoOpSink returns a NOOP sink.
func NoAuthMiddleware
func NoAuthMiddleware(schemeName string) error
NoAuthMiddleware is the error produced when goa is unable to lookup a auth middleware for a security scheme defined in the design.
func SetGauge
func SetGauge(key []string, val float32)
SetGauge sets the named gauge to the specified value Usage:
SetGauge([]string{"my","namespace"}, 2.0)
func SetMetrics
func SetMetrics(m Collector)
SetMetrics initializes goa’s metrics instance with the supplied metrics adapter interface.
func ValidateFormat
func ValidateFormat(f Format, val string) error
ValidateFormat validates a string against a standard format. It returns nil if the string conforms to the format, an error otherwise. The format specification follows the json schema draft 4 validation extension. see http://json-schema.org/latest/json-schema-validation.html#anchor105 Supported formats are:
- "date": RFC3339 date value
- "date-time": RFC3339 date time value
- "email": RFC5322 email address
- "hostname": RFC1035 Internet host name
- "ipv4", "ipv6", "ip": RFC2673 and RFC2373 IP address values
- "uri": RFC3986 URI value
- "mac": IEEE 802 MAC-48, EUI-48 or EUI-64 MAC address value
- "cidr": RFC4632 and RFC4291 CIDR notation IP address value
- "regexp": Regular expression syntax accepted by RE2
- "rfc1123": RFC1123 date time value
func ValidatePattern
func ValidatePattern(p string, val string) bool
ValidatePattern returns an error if val does not match the regular expression p. It makes an effort to minimize the number of times the regular expression needs to be compiled.
func WithAction
func WithAction(ctx context.Context, action string) context.Context
WithAction creates a context with the given action name.
func WithError
func WithError(ctx context.Context, err error) context.Context
WithError creates a context with the given error.
func WithLogContext
func WithLogContext(ctx context.Context, keyvals ...interface{}) context.Context
WithLogContext instantiates a new logger by appending the given key/value pairs to the context logger and setting the resulting logger in the context.
func WithLogger
func WithLogger(ctx context.Context, logger LogAdapter) context.Context
WithLogger sets the request context logger and returns the resulting new context.
func WithRequiredScopes
func WithRequiredScopes(ctx context.Context, scopes []string) context.Context
WithRequiredScopes builds a context containing the given required scopes.
type APIKeySecurity
type APIKeySecurity struct {
// Description of the security scheme
Description string
// In represents where to check for some data, `query` or `header`
In Location
// Name is the name of the `header` or `query` parameter to check for data.
Name string
}
APIKeySecurity represents the apiKey
security scheme. It handles a key that can be in the
headers or in the query parameters, and does authentication based on that. The Name field
represents the key of either the query string parameter or the header, depending on the In field.
type BasicAuthSecurity
type BasicAuthSecurity struct {
// Description of the security scheme
Description string
}
BasicAuthSecurity represents the Basic
security scheme, which consists of a simple login/pass,
accessible through Request.BasicAuth().
type Collector
type Collector interface {
AddSample(key []string, val float32)
EmitKey(key []string, val float32)
IncrCounter(key []string, val float32)
MeasureSince(key []string, start time.Time)
SetGauge(key []string, val float32)
}
Collector is the interface used for collecting metrics.
func GetMetrics
func GetMetrics() Collector
GetMetrics returns goa’s metrics collector adapter interface.
func NewNoOpCollector
func NewNoOpCollector() Collector
NewNoOpCollector returns a Collector that does no collection.
type Controller
type Controller struct {
// Controller resource name
Name string
// Service that exposes the controller
Service *Service
// Controller root context
Context context.Context
// MaxRequestBodyLength is the maximum length read from request bodies.
// Set to 0 to remove the limit altogether. Defaults to 1GB.
MaxRequestBodyLength int64
// FileSystem is used in FileHandler to open files. By default it returns
// http.Dir but you can override it with another one that implements http.FileSystem.
// For example using github.com/elazarl/go-bindata-assetfs is like below.
//
// ctrl.FileSystem = func(dir string) http.FileSystem {
// return &assetfs.AssetFS{
// Asset: Asset,
// AssetDir: AssetDir,
// AssetInfo: AssetInfo,
// Prefix: dir,
// }
// }
FileSystem func(string) http.FileSystem
// contains filtered or unexported fields
}
Controller defines the common fields and behavior of generated controllers.
func (*Controller) FileHandler
func (ctrl *Controller) FileHandler(path, filename string) Handler
FileHandler returns a handler that serves files under the given filename for the given route path. The logic for what to do when the filename points to a file vs. a directory is the same as the standard http package ServeFile function. The path may end with a wildcard that matches the rest of the URL (e.g. *filepath). If it does the matching path is appended to filename to form the full file path, so:
c.FileHandler("/index.html", "/www/data/index.html")
Returns the content of the file “/www/data/index.html” when requests are sent to “/index.html” and:
c.FileHandler("/assets/*filepath", "/www/data/assets")
returns the content of the file “/www/data/assets/x/y/z” when requests are sent to “/assets/x/y/z”.
func (*Controller) MuxHandler
func (ctrl *Controller) MuxHandler(name string, hdlr Handler, unm Unmarshaler) MuxHandler
MuxHandler wraps a request handler into a MuxHandler. The MuxHandler initializes the request context by loading the request state, invokes the handler and in case of error invokes the controller (if there is one) or Service error handler. This function is intended for the controller generated code. User code should not need to call it directly.
func (*Controller) ServeFiles
func (ctrl *Controller) ServeFiles(path, filename string) error
ServeFiles replies to the request with the contents of the named file or directory. See FileHandler for details.
func (*Controller) Use
func (ctrl *Controller) Use(m Middleware)
Use adds a middleware to the controller. Service-wide middleware should be added via the Service Use method instead.
type DecodeFunc
type DecodeFunc func(context.Context, io.ReadCloser, interface{}) error
DecodeFunc is the function that initialize the unmarshaled payload from the request body.
type Decoder
type Decoder interface {
Decode(v interface{}) error
}
A Decoder unmarshals an io.Reader into an interface.
func NewGobDecoder
func NewGobDecoder(r io.Reader) Decoder
NewGobDecoder is an adapter for the encoding package gob decoder.
func NewJSONDecoder
func NewJSONDecoder(r io.Reader) Decoder
NewJSONDecoder is an adapter for the encoding package JSON decoder.
func NewXMLDecoder
func NewXMLDecoder(r io.Reader) Decoder
NewXMLDecoder is an adapter for the encoding package XML decoder.
type DecoderFunc
type DecoderFunc func(r io.Reader) Decoder
DecoderFunc instantiates a decoder that decodes data read from the given io reader.
type Encoder
type Encoder interface {
Encode(v interface{}) error
}
An Encoder marshals from an interface into an io.Writer.
func NewGobEncoder
func NewGobEncoder(w io.Writer) Encoder
NewGobEncoder is an adapter for the encoding package gob encoder.
func NewJSONEncoder
func NewJSONEncoder(w io.Writer) Encoder
NewJSONEncoder is an adapter for the encoding package JSON encoder.
func NewXMLEncoder
func NewXMLEncoder(w io.Writer) Encoder
NewXMLEncoder is an adapter for the encoding package XML encoder.
type EncoderFunc
type EncoderFunc func(w io.Writer) Encoder
EncoderFunc instantiates an encoder that encodes data into the given writer.
type ErrorClass
type ErrorClass func(message interface{}, keyvals ...interface{}) error
ErrorClass is an error generating function. It accepts a message and optional key value pairs and produces errors that implement ServiceError. If the message is a string or a fmt.Stringer then the string value is used. If the message is an error then the string returned by Error() is used. Otherwise the string produced using fmt.Sprintf(“%v”) is used. The optional key value pairs are intended to provide additional contextual information and are returned to the client.
func NewErrorClass
func NewErrorClass(code string, status int) ErrorClass
NewErrorClass creates a new error class. It is the responsibility of the client to guarantee uniqueness of code.
type ErrorResponse
type ErrorResponse struct {
// ID is the unique error instance identifier.
ID string `json:"id" yaml:"id" xml:"id" form:"id"`
// Code identifies the class of errors.
Code string `json:"code" yaml:"code" xml:"code" form:"code"`
// Status is the HTTP status code used by responses that cary the error.
Status int `json:"status" yaml:"status" xml:"status" form:"status"`
// Detail describes the specific error occurrence.
Detail string `json:"detail" yaml:"detail" xml:"detail" form:"detail"`
// Meta contains additional key/value pairs useful to clients.
Meta map[string]interface{} `json:"meta,omitempty" yaml:"meta,omitempty" xml:"meta,omitempty" form:"meta,omitempty"`
}
ErrorResponse contains the details of a error response. It implements ServiceError. This struct is mainly intended for clients to decode error responses.
func (*ErrorResponse) Error
func (e *ErrorResponse) Error() string
Error returns the error occurrence details.
func (*ErrorResponse) ResponseStatus
func (e *ErrorResponse) ResponseStatus() int
ResponseStatus is the status used to build responses.
func (*ErrorResponse) Token
func (e *ErrorResponse) Token() string
Token is the unique error occurrence identifier.
type FileServer
type FileServer interface {
// FileHandler returns a handler that serves files under the given request path.
FileHandler(path, filename string) Handler
}
FileServer is the interface implemented by controllers that can serve static files.
type Format
type Format string
Format defines a validation format.
type HTTPDecoder
type HTTPDecoder struct {
// contains filtered or unexported fields
}
HTTPDecoder is a Decoder that decodes HTTP request or response bodies given a set of known Content-Type to decoder mapping.
func NewHTTPDecoder
func NewHTTPDecoder() *HTTPDecoder
NewHTTPDecoder creates a decoder that maps HTTP content types to low level decoders.
func (*HTTPDecoder) Decode
func (decoder *HTTPDecoder) Decode(v interface{}, body io.Reader, contentType string) error
Decode uses registered Decoders to unmarshal a body based on the contentType.
func (*HTTPDecoder) Register
func (decoder *HTTPDecoder) Register(f DecoderFunc, contentTypes ...string)
Register sets a specific decoder to be used for the specified content types. If a decoder is already registered, it is overwritten.
type HTTPEncoder
type HTTPEncoder struct {
// contains filtered or unexported fields
}
HTTPEncoder is a Encoder that encodes HTTP request or response bodies given a set of known Content-Type to encoder mapping.
func NewHTTPEncoder
func NewHTTPEncoder() *HTTPEncoder
NewHTTPEncoder creates an encoder that maps HTTP content types to low level encoders.
func (*HTTPEncoder) Encode
func (encoder *HTTPEncoder) Encode(v interface{}, resp io.Writer, accept string) error
Encode uses the registered encoders and given content type to marshal and write the given value using the given writer.
func (*HTTPEncoder) Register
func (encoder *HTTPEncoder) Register(f EncoderFunc, contentTypes ...string)
Register sets a specific encoder to be used for the specified content types. If an encoder is already registered, it is overwritten.
type Handler
type Handler func(context.Context, http.ResponseWriter, *http.Request) error
Handler defines the request handler signatures.
type JWTSecurity
type JWTSecurity struct {
// Description of the security scheme
Description string
// In represents where to check for the JWT, `query` or `header`
In Location
// Name is the name of the `header` or `query` parameter to check for data.
Name string
// TokenURL defines the URL where you'd get the JWT tokens.
TokenURL string
// Scopes defines a list of scopes for the security scheme, along with their description.
Scopes map[string]string
}
JWTSecurity represents an api key based scheme, with support for scopes and a token URL.
type Location
type Location string
Location is the enum defining where the value of key based security schemes should be read: either a HTTP request header or a URL querystring value
const LocHeader Location = "header"
LocHeader indicates the secret value should be loaded from the request headers.
const LocQuery Location = "query"
LocQuery indicates the secret value should be loaded from the request URL querystring.
type LogAdapter
type LogAdapter interface {
// Info logs an informational message.
Info(msg string, keyvals ...interface{})
// Error logs an error.
Error(msg string, keyvals ...interface{})
// New appends to the logger context and returns the updated logger logger.
New(keyvals ...interface{}) LogAdapter
}
LogAdapter is the logger interface used by goa to log informational and error messages. Adapters to different logging backends are provided in the logging sub-packages. goa takes care of initializing the logging context with the service, controller and action names.
func ContextLogger
func ContextLogger(ctx context.Context) LogAdapter
ContextLogger extracts the logger from the given context.
func NewLogger
func NewLogger(logger *log.Logger) LogAdapter
NewLogger returns a goa log adpater backed by a log logger.
type MethodNotAllowedHandler
type MethodNotAllowedHandler func(http.ResponseWriter, *http.Request, url.Values, map[string]httptreemux.HandlerFunc)
MethodNotAllowedHandler provides the implementation for an MethodNotAllowed handler. The values argument includes both the querystring and path parameter values. The methods argument includes both the allowed method identifier and the registered handler.
type Middleware
type Middleware func(Handler) Handler
Middleware represents the canonical goa middleware signature.
func NewMiddleware
func NewMiddleware(m interface{}) (mw Middleware, err error)
NewMiddleware creates a middleware from the given argument. The allowed types for the argument are:
a goa middleware: goa.Middleware or func(goa.Handler) goa.Handler
a goa handler: goa.Handler or func(context.Context, http.ResponseWriter, *http.Request) error
an http middleware: func(http.Handler) http.Handler
or an http handler: http.Handler or func(http.ResponseWriter, *http.Request)
An error is returned if the given argument is not one of the types above.
type MuxHandler
type MuxHandler func(http.ResponseWriter, *http.Request, url.Values)
MuxHandler provides the low level implementation for an API endpoint. The values argument includes both the querystring and path parameter values.
type Muxer
type Muxer interface {
MuxHandler(string, Handler, Unmarshaler) MuxHandler
}
Muxer implements an adapter that given a request handler can produce a mux handler.
type NoOpSink
type NoOpSink struct{}
NoOpSink default NOOP metrics recorder
func (*NoOpSink) AddSample
func (*NoOpSink) AddSample(key []string, val float32)
func (*NoOpSink) AddSampleWithLabels
func (*NoOpSink) AddSampleWithLabels(key []string, val float32, labels []metrics.Label)
func (*NoOpSink) EmitKey
func (*NoOpSink) EmitKey(key []string, val float32)
func (*NoOpSink) IncrCounter
func (*NoOpSink) IncrCounter(key []string, val float32)
func (*NoOpSink) IncrCounterWithLabels
func (*NoOpSink) IncrCounterWithLabels(key []string, val float32, labels []metrics.Label)
func (*NoOpSink) SetGauge
func (*NoOpSink) SetGauge(key []string, val float32)
func (*NoOpSink) SetGaugeWithLabels
func (*NoOpSink) SetGaugeWithLabels(key []string, val float32, labels []metrics.Label)
type OAuth2Security
type OAuth2Security struct {
// Description of the security scheme
Description string
// Flow defines the OAuth2 flow type. See http://swagger.io/specification/#securitySchemeObject
Flow string
// TokenURL defines the OAuth2 tokenUrl. See http://swagger.io/specification/#securitySchemeObject
TokenURL string
// AuthorizationURL defines the OAuth2 authorizationUrl. See http://swagger.io/specification/#securitySchemeObject
AuthorizationURL string
// Scopes defines a list of scopes for the security scheme, along with their description.
Scopes map[string]string
}
OAuth2Security represents the oauth2
security scheme. It is instantiated by the generated code
accordingly to the use of the different *Security()
DSL functions and Security()
in the
design.
type RequestData
type RequestData struct {
*http.Request
// Payload returns the decoded request body.
Payload interface{}
// Params contains the raw values for the parameters defined in the design including
// path parameters, query string parameters and header parameters.
Params url.Values
}
RequestData provides access to the underlying HTTP request.
func ContextRequest
func ContextRequest(ctx context.Context) *RequestData
ContextRequest extracts the request data from the given context.
type ResettableDecoder
type ResettableDecoder interface {
Decoder
Reset(r io.Reader)
}
ResettableDecoder is used to determine whether or not a Decoder can be reset and thus safely reused in a sync.Pool.
type ResettableEncoder
type ResettableEncoder interface {
Encoder
Reset(w io.Writer)
}
The ResettableEncoder is used to determine whether or not a Encoder can be reset and thus safely reused in a sync.Pool.
type ResponseData
type ResponseData struct {
http.ResponseWriter
// The service used to encode the response.
Service *Service
// ErrorCode is the code of the error returned by the action if any.
ErrorCode string
// Status is the response HTTP status code.
Status int
// Length is the response body length.
Length int
}
ResponseData provides access to the underlying HTTP response.
func ContextResponse
func ContextResponse(ctx context.Context) *ResponseData
ContextResponse extracts the response data from the given context.
func (*ResponseData) SwitchWriter
func (r *ResponseData) SwitchWriter(rw http.ResponseWriter) http.ResponseWriter
SwitchWriter overrides the underlying response writer. It returns the response writer that was previously set.
func (*ResponseData) Write
func (r *ResponseData) Write(b []byte) (int, error)
Write records the amount of data written and calls the underlying writer.
func (*ResponseData) WriteHeader
func (r *ResponseData) WriteHeader(status int)
WriteHeader records the response status code and calls the underlying writer.
func (*ResponseData) Written
func (r *ResponseData) Written() bool
Written returns true if the response was written, false otherwise.
type ServeMux
type ServeMux interface {
http.Handler
// Handle sets the MuxHandler for a given HTTP method and path.
Handle(method, path string, handle MuxHandler)
// HandleNotFound sets the MuxHandler invoked for requests that don't match any
// handler registered with Handle. The values argument given to the handler is
// always nil.
HandleNotFound(handle MuxHandler)
// HandleMethodNotAllowed sets the MethodNotAllowedHandler invoked for requests
// that match the path of a handler but not its HTTP method. The values argument
// given to the Handler is always nil.
HandleMethodNotAllowed(handle MethodNotAllowedHandler)
// Lookup returns the MuxHandler associated with the given HTTP method and path.
Lookup(method, path string) MuxHandler
}
ServeMux is the interface implemented by the service request muxes. It implements http.Handler and makes it possible to register request handlers for specific HTTP methods and request path via the Handle method.
func NewMux
func NewMux() ServeMux
NewMux returns a Mux.
type Service
type Service struct {
// Name of service used for logging, tracing etc.
Name string
// Mux is the service request mux
Mux ServeMux
// Server is the service HTTP server.
Server *http.Server
// Context is the root context from which all request contexts are derived.
// Set values in the root context prior to starting the server to make these values
// available to all request handlers.
Context context.Context
// Request body decoder
Decoder *HTTPDecoder
// Response body encoder
Encoder *HTTPEncoder
// contains filtered or unexported fields
}
Service is the data structure supporting goa services. It provides methods for configuring a service and running it. At the basic level a service consists of a set of controllers, each implementing a given resource actions. goagen generates global functions - one per resource - that make it possible to mount the corresponding controller onto a service. A service contains the middleware, not found handler, encoders and muxes shared by all its controllers.
func New
func New(name string) *Service
New instantiates a service with the given name.
func (*Service) CancelAll
func (service *Service) CancelAll()
CancelAll sends a cancel signals to all request handlers via the context. See https://golang.org/pkg/context/ for details on how to handle the signal.
func (*Service) DecodeRequest
func (service *Service) DecodeRequest(req *http.Request, v interface{}) error
DecodeRequest uses the HTTP decoder to unmarshal the request body into the provided value based on the request Content-Type header.
func (*Service) EncodeResponse
func (service *Service) EncodeResponse(ctx context.Context, v interface{}) error
EncodeResponse uses the HTTP encoder to marshal and write the response body based on the request Accept header.
func (*Service) ListenAndServe
func (service *Service) ListenAndServe(addr string) error
ListenAndServe starts a HTTP server and sets up a listener on the given host/port.
func (*Service) ListenAndServeTLS
func (service *Service) ListenAndServeTLS(addr, certFile, keyFile string) error
ListenAndServeTLS starts a HTTPS server and sets up a listener on the given host/port.
func (*Service) LogError
func (service *Service) LogError(msg string, keyvals ...interface{})
LogError logs the error and values at odd indeces using the keys at even indeces of the keyvals slice.
func (*Service) LogInfo
func (service *Service) LogInfo(msg string, keyvals ...interface{})
LogInfo logs the message and values at odd indeces using the keys at even indeces of the keyvals slice.
func (*Service) NewController
func (service *Service) NewController(name string) *Controller
NewController returns a controller for the given resource. This method is mainly intended for use by the generated code. User code shouldn’t have to call it directly.
func (*Service) Send
func (service *Service) Send(ctx context.Context, code int, body interface{}) error
Send serializes the given body matching the request Accept header against the service encoders. It uses the default service encoder if no match is found.
func (*Service) Serve
func (service *Service) Serve(l net.Listener) error
Serve accepts incoming HTTP connections on the listener l, invoking the service mux handler for each.
func (*Service) ServeFiles
func (service *Service) ServeFiles(path, filename string) error
ServeFiles create a “FileServer” controller and calls ServerFiles on it.
func (*Service) Use
func (service *Service) Use(m Middleware)
Use adds a middleware to the service wide middleware chain. goa comes with a set of commonly used middleware, see the middleware package. Controller specific middleware should be mounted using the Controller struct Use method instead.
func (*Service) WithLogger
func (service *Service) WithLogger(logger LogAdapter)
WithLogger sets the logger used internally by the service and by Log.
type ServiceError
type ServiceError interface {
// ServiceError extends the error interface
error
// ResponseStatus dictates the status used to build the response sent to the client.
ResponseStatus() int
// Token is a unique value associated with the occurrence of the error.
Token() string
}
ServiceError is the interface implemented by all errors created using a ErrorClass function.
type ServiceMergeableError
type ServiceMergeableError interface {
// ServiceMergeableError extends from the ServiceError interface.
ServiceError
// Merge updates an error by combining another error into it.
Merge(other error) error
}
ServiceMergeableError is the interface implemented by ServiceErrors that can merge another error into a combined error.
type Unmarshaler
type Unmarshaler func(context.Context, *Service, *http.Request) error
Unmarshaler defines the request payload unmarshaler signatures.
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