google app engine - Go sendgrid failing -

im trying send mail sendgrid , golang. im using "github.com/sendgrid/sendgrid-go"

whenever run part sending email in code, error:

sendgrid.go: error:net/http: client transport of type init.failingtransport doesn't support cancelrequest; timeout not supported; response:<nil> 

i cant figure out is..

this code:

sg := sendgrid.newsendgridclientwithapikey("string")     email := sendgrid.newmail()     email.addto(req.email)     email.setsubject("confirm registration @ domain")     email.setfrom("noreply@domain.com")     email.setfromname("domain")     email.settext(url)     if r := sg.send(email); r == nil {         log.infof(ctx, "email sent")     } else {         log.errorf(ctx, "email not sent %v", r)         w.writeheader(http.statusinternalservererror)         return     } 

normal sendgrid api usage in go

the minimal program use sendgrid api in go following:

package main  import (     "fmt"     "github.com/sendgrid/sendgrid-go" )  func main() {     key := "sendgrid_api_key"     sg := sendgrid.newsendgridclientwithapikey(key)      message := sendgrid.newmail()     message.addto("ezra@usefultiftrue.com")     message.setfrom("test@example.org")     message.setsubject("subject here")     message.sethtml("body of email")      if r := sg.send(message); r == nil {         fmt.println("sent!")     } else {         fmt.println(r)     } } 

you can see sendgrid go documentation on github.

quirks on app engine

the issue you're attempting fetch url using default net/http client, not allowed app engine. you must use urlfetch make http requests on app engine.

you can solve specifying *http.client use urlfetch, since sendgrid uses client uses disallowed http.defaulttransport default. init.failingtransport dummy transport method throws error.

this simple change. import "appengine/urlfetch" , add

client := urlfetch.client(ctx) 

a complete example of sendgrid go api on app engine

package ezralalonde  import (     "appengine"     "appengine/urlfetch"     "fmt"     "github.com/sendgrid/sendgrid-go"     "net/http" )  func send(w http.responsewriter, r *http.request) {     key := "sendgrid_api_key"     sg := sendgrid.newsendgridclientwithapikey(key)      // must change net/http client not use default transport     ctx := appengine.newcontext(r)     client := urlfetch.client(ctx)     sg.client = client // <-- using urlfetch, "overriding" default      message := sendgrid.newmail()     message.addto("ezra@usefultiftrue.com")     message.setfrom("test@example.org")     message.setsubject("subject here")     message.sethtml("body of email")      if e := sg.send(message); e == nil {         fmt.fprintln(w, "sent!")     } else {         fmt.fprintln(w, e)     } }  func init() {     http.handlefunc("/", send) } 

now each visit / cause email sent sendgrid test@example.org.

to: test@example.org from: ezra@usefuliftrue.com subject: subject here  body of email 

please note

do not include api keys in source code, or commit them source control. above method not advisable.