func handler2(w http.ResponseWriter, r *http.Request) {
ctx := appengine.NewContext(r)
// [START communication_between_modules_2]
hostname, err := appengine.ModuleHostname(ctx, "my-backend", "", "")
if err != nil {
// ...
}
url := "http://" + hostname + "/"
// ...
// [END communication_between_modules_2]
_ = url
}
func pushHandler(w http.ResponseWriter, r *http.Request) {
ctx := appengine.NewContext(r)
key := r.FormValue("key")
// Create a task pointed at a backend.
t := taskqueue.NewPOSTTask("/path/to/my/worker/", url.Values{
"key": {key},
})
host, err := appengine.ModuleHostname(ctx, "backend1", "", "")
if err != nil {
// Handle err
}
t.Header = http.Header{
"Host": {host},
}
// Add the task to the default queue.
if _, err := taskqueue.Add(ctx, t, ""); err != nil {
// Handle err
}
}
// Todo: When c==nil we are in a non-appengine environment.
// We still want to return at least ii.PureHostname
func GetByContext(c context.Context) *Instance {
tstart := time.Now()
if !ii.LastUpdated.IsZero() {
age := tstart.Sub(ii.LastUpdated)
if age < 200*time.Millisecond {
aelog.Infof(c, "instance info update too recently: %v, skipping.\n", age)
return ii
}
if age < 1*time.Hour {
if len(ii.Hostname) > 2 {
return ii
}
}
aelog.Infof(c, "instance info update too old: %v, recomputing.\n", age)
}
ii.ModuleName = appengine.ModuleName(c)
ii.InstanceID = appengine.InstanceID()
ii.VersionFull = appengine.VersionID(c)
majorMinor := strings.Split(ii.VersionFull, ".")
if len(majorMinor) != 2 {
panic("we need a version string of format X.Y")
}
ii.VersionMajor = majorMinor[0]
ii.VersionMinor = majorMinor[1]
var err = errors.New("dummy creation error message")
ii.NumInstances, err = module.NumInstances(c, ii.ModuleName, ii.VersionFull)
if err != nil {
// this never works with version full
// we do not log this - but try version major
err = nil
if !util_appengine.IsLocalEnviron() {
ii.NumInstances, err = module.NumInstances(c, ii.ModuleName, ii.VersionMajor)
if err != nil {
eStr := err.Error()
eCmp1, eCmp2, eCmp3 := "API error", "INVALID_VERSION)", "Could not find the given version"
if strings.Contains(eStr, eCmp1) && strings.Contains(eStr, eCmp2) && strings.Contains(eStr, eCmp3) {
aelog.Infof(c, "get num instances works only live and without autoscale; %v", err)
} else {
aelog.Errorf(c, "get num instances error; %v", err)
}
}
}
}
// in auto scaling, google reports "zero" - which can not be true
// we assume at least 1
if ii.NumInstances == 0 {
ii.NumInstances = 1
}
// http://[0-2].1.default.libertarian-islands.appspot.com/instance-info
ii.Hostname, err = appengine.ModuleHostname(c, ii.ModuleName, ii.VersionMajor, "")
if err != nil {
aelog.Errorf(c, "ModuleHostname1: %v", err)
}
ii.PureHostname = appengine.DefaultVersionHostname(c)
if !appengine.IsDevAppServer() {
ii.HostnameInst0, err = appengine.ModuleHostname(c, ii.ModuleName, ii.VersionMajor, "0")
if err != nil && (err.Error() == autoScalingErr1 || err.Error() == autoScalingErr2) {
aelog.Infof(c, "inst 0: "+autoScalingErrMsg)
err = nil
}
if err != nil {
aelog.Errorf(c, "ModuleHostname2: %v", err)
}
ii.HostnameInst1, err = appengine.ModuleHostname(c, ii.ModuleName, ii.VersionMajor, "1")
if err != nil && (err.Error() == autoScalingErr1 || err.Error() == autoScalingErr2) {
aelog.Infof(c, "inst 1: "+autoScalingErrMsg)
err = nil
}
if err != nil {
aelog.Errorf(c, "ModuleHostname3: %v", err)
}
ii.HostnameMod02, err = appengine.ModuleHostname(c, "mod02", "", "")
if err != nil {
aelog.Infof(c, "ModuleHostname4: %v", err)
}
}
ii.LastUpdated = time.Now()
aelog.Infof(c, "collectInfo() completed, %v - %v - %v - %v - %v, took %v",
stringspb.Ellipsoider(ii.InstanceID, 4), ii.VersionMajor, ii.ModuleName,
ii.Hostname, ii.PureHostname, time.Now().Sub(tstart))
return ii
}
func (g giImpl) ModuleHostname(module, version, instance string) (string, error) {
return appengine.ModuleHostname(g.aeCtx, module, version, instance)
}