github.com/goadesign/goa


goa

import "github.com/goadesign/goa"

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.

Constants

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-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" xml:"id" form:"id"`
    // Code identifies the class of errors.
    Code string `json:"code" xml:"code" form:"code"`
    // Status is the HTTP status code used by responses that cary the error.
    Status int `json:"status" xml:"status" form:"status"`
    // Detail describes the specific error occurrence.
    Detail string `json:"detail" xml:"detail" form:"detail"`
    // Meta contains additional key/value pairs useful to clients.
    Meta map[string]interface{} `json:"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.

const (
    // 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"
)

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.