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/
Functions
func APICall
APICall performs an API call.
This is not intended for general use; it is exported for use in conjunction with WithAPICallFunc.
func AccessToken
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
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 BackgroundContext
BackgroundContext returns a context not associated with a request. This should only be used when not servicing a request. This only works in App Engine "flexible environment".
func Datacenter
Datacenter returns an identifier for the datacenter that the instance is running in.
func DefaultVersionHostname
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() stringInstanceID returns a mostly-unique identifier for this instance.
func IsAppEngine
func IsAppEngine() boolIsAppEngine reports whether the App Engine app is running on App Engine, in either the standard or flexible environment.
func IsDevAppServer
func IsDevAppServer() boolIsDevAppServer reports whether the App Engine app is running in the development App Server.
func IsFlex
func IsFlex() boolIsFlex reports whether the App Engine app is running in the flexible environment.
func IsOverQuota
IsOverQuota reports whether err represents an API call failure due to insufficient available quota.
func IsSecondGen
func IsSecondGen() boolIsSecondGen reports whether the App Engine app is running on the second generation runtimes (>= Go 1.11).
func IsStandard
func IsStandard() boolIsStandard reports whether the App Engine app is running in the standard environment. This includes both the first generation runtimes (<= Go 1.9) and the second generation runtimes (>= Go 1.11).
func IsTimeoutError
IsTimeoutError reports whether err is a timeout error.
func Main
func Main()Main is the principal entry point for an app running in App Engine.
On App Engine Flexible it installs a trivial health checker if one isn't already registered, and starts listening on port 8080 (overridden by the $PORT environment variable).
See https://cloud.google.com/appengine/docs/flexible/custom-runtimes#health_check_requests for details on how to do your own health checking.
On App Engine Standard it ensures the server has started and is prepared to receive requests.
Main never returns.
Main is designed so that the app's main package looks like this:
package main
import (
"google.golang.org/appengine"
_ "myapp/package0"
_ "myapp/package1"
)
func main() {
appengine.Main()
}
The "myapp/packageX" packages are expected to register HTTP handlers in their init functions.
func ModuleHostname
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
ModuleName returns the module name of the current instance.
func Namespace
Namespace returns a replacement context that operates within the given namespace.
func NewContext
NewContext returns a context for an in-flight HTTP request. This function is cheap.
func RequestID
RequestID returns a string that uniquely identifies the request.
func ServerSoftware
func ServerSoftware() stringServerSoftware 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
ServiceAccount returns a string representing the service account name, in the form of an email address (typically app_id@appspot.gserviceaccount.com).
func SignBytes
SignBytes signs bytes using a private key unique to your application.
func VersionID
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 WithAPICallFunc
func WithAPICallFunc(ctx context.Context, f APICallFunc) context.ContextWithAPICallFunc returns a copy of the parent context that will cause API calls to invoke f instead of their normal operation.
This is intended for advanced users only.
func WithContext
WithContext returns a copy of the parent context and associates it with an in-flight HTTP request. This function is cheap.
APICallFunc
APICallFunc defines a function type for handling an API call. See WithCallOverride.
BlobKey
type BlobKey stringBlobKey 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.
Certificate
Certificate represents a public certificate for the app.
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.
GeoPoint
type GeoPoint struct {
Lat, Lng float64
}GeoPoint represents a location as latitude/longitude in degrees.
func (GeoPoint) Valid
Valid returns whether a GeoPoint is within [-90, 90] latitude and [-180, 180] longitude.
MultiError
type MultiError []errorMultiError 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