Google Cloud Platform
Go

The appengine package

import "google.golang.org/appengine"

Introduction

Package appengine provides basic functionality for Google App Engine.

For more information on how to write Go apps for Google App Engine, see: https://cloud.google.com/appengine/docs/go/

Index

func AccessToken(c context.Context, scopes ...string) (token string, expiry time.Time, err error)
func AppID(c context.Context) string
func Datacenter(c context.Context) string
func DefaultVersionHostname(c context.Context) string
func InstanceID() string
func IsDevAppServer() bool
func IsOverQuota(err error) bool
func IsTimeoutError(err error) bool
func ModuleHostname(c context.Context, module, version, instance string) (string, error)
func ModuleName(c context.Context) string
func Namespace(c context.Context, namespace string) (context.Context, error)
func NewContext(req *http.Request) context.Context
func PublicCertificates(c context.Context) ([]Certificate, error)
func RequestID(c context.Context) string
func ServerSoftware() string
func ServiceAccount(c context.Context) (string, error)
func SignBytes(c context.Context, bytes []byte) (keyName string, signature []byte, err error)
func VersionID(c context.Context) string
func WithContext(parent context.Context, req *http.Request) context.Context
type BlobKey
type Certificate
type GeoPoint
    func (g GeoPoint) Valid() bool
type MultiError
    func (m MultiError) Error() string

func AccessToken

func AccessToken(c context.Context, scopes ...string) (token string, expiry time.Time, err error)

AccessToken generates an OAuth2 access token for the specified scopes on behalf of service account of this application. This token will expire after the returned time.

func AppID

func AppID(c context.Context) string

AppID returns the application ID for the current application. The string will be a plain application ID (e.g. "appid"), with a domain prefix for custom domain deployments (e.g. "example.com:appid").

func Datacenter

func Datacenter(c context.Context) string

Datacenter returns an identifier for the datacenter that the instance is running in.

func DefaultVersionHostname

func DefaultVersionHostname(c context.Context) string

DefaultVersionHostname returns the standard hostname of the default version of the current application (e.g. "my-app.appspot.com"). This is suitable for use in constructing URLs.

func InstanceID

func InstanceID() string

InstanceID returns a mostly-unique identifier for this instance.

func IsDevAppServer

func IsDevAppServer() bool

IsDevAppServer reports whether the App Engine app is running in the development App Server.

func IsOverQuota

func IsOverQuota(err error) bool

IsOverQuota reports whether err represents an API call failure due to insufficient available quota.

func IsTimeoutError

func IsTimeoutError(err error) bool

IsTimeoutError reports whether err is a timeout error.

func ModuleHostname

func ModuleHostname(c context.Context, module, version, instance string) (string, error)

ModuleHostname returns a hostname of a module instance. If module is the empty string, it refers to the module of the current instance. If version is empty, it refers to the version of the current instance if valid, or the default version of the module of the current instance. If instance is empty, ModuleHostname returns the load-balancing hostname.

func ModuleName

func ModuleName(c context.Context) string

ModuleName returns the module name of the current instance.

func Namespace

func Namespace(c context.Context, namespace string) (context.Context, error)

Namespace returns a replacement context that operates within the given namespace.

func NewContext

func NewContext(req *http.Request) context.Context

NewContext returns a context for an in-flight HTTP request. This function is cheap.

func PublicCertificates

func PublicCertificates(c context.Context) ([]Certificate, error)

PublicCertificates retrieves the public certificates for the app. They can be used to verify a signature returned by SignBytes.

func RequestID

func RequestID(c context.Context) string

RequestID returns a string that uniquely identifies the request.

func ServerSoftware

func ServerSoftware() string

ServerSoftware returns the App Engine release version. In production, it looks like "Google App Engine/X.Y.Z". In the development appserver, it looks like "Development/X.Y".

func ServiceAccount

func ServiceAccount(c context.Context) (string, error)

ServiceAccount returns a string representing the service account name, in the form of an email address (typically app_id@appspot.gserviceaccount.com).

func SignBytes

func SignBytes(c context.Context, bytes []byte) (keyName string, signature []byte, err error)

SignBytes signs bytes using a private key unique to your application.

func VersionID

func VersionID(c context.Context) string

VersionID returns the version ID for the current application. It will be of the form "X.Y", where X is specified in app.yaml, and Y is a number generated when each version of the app is uploaded. It does not include a module name.

func WithContext

func WithContext(parent context.Context, req *http.Request) context.Context

WithContext returns a copy of the parent context and associates it with an in-flight HTTP request. This function is cheap.

type BlobKey

type BlobKey string

BlobKey is a key for a blobstore blob.

Conceptually, this type belongs in the blobstore package, but it lives in the appengine package to avoid a circular dependency: blobstore depends on datastore, and datastore needs to refer to the BlobKey type.

type Certificate

type Certificate struct {
    KeyName string
    Data    []byte // PEM-encoded X.509 certificate
}

Certificate represents a public certificate for the app.

type GeoPoint

type GeoPoint struct {
    Lat, Lng float64
}

GeoPoint represents a location as latitude/longitude in degrees.

func (GeoPoint) Valid

func (g GeoPoint) Valid() bool

Valid returns whether a GeoPoint is within [-90, 90] latitude and [-180, 180] longitude.

type MultiError

type MultiError []error

MultiError is returned by batch operations when there are errors with particular elements. Errors will be in a one-to-one correspondence with the input elements; successful elements will have a nil entry.

func (MultiError) Error

func (m MultiError) Error() string