Google Apps Script: testing doPost() with cURL - http

Question

I have created a very basic Google Apps Script. Here is my doPost() and doGet():
function doPost(e) {
return respond(JSON.stringify({result: "Hello world!"}));
}
function doGet(e) {
return respond(JSON.stringify({result: "Hello world!"}));
}
function respond(response) {
return ContentService
.createTextOutput(response)
.setMimeType(ContentService.MimeType.JSON)
}
I have deployed the app with a new version. It is set to run as me but everyone can run it including anonymous.
I am testing the endpoint by running cURL from the command line, and for GET it works as expected:
Request -
curl -L https://script.google.com/macros/s/AKfycbxYxgMfMkR6hGI5UO2Gn8tg369oqsy_W41-olb0Do1y8gOjaNvm/exec
Response -
{"result":"Hello world!"}
But for POST:
Request -
curl -H "Content-Length: 0" -D "p=p" -X POST -L https://script.google.com/macros/s/AKfycbxYxgMfMkR6hGI5UO2Gn8tg369oqsy_W41-olb0Do1y8gOjaNvm/exec
Response -
Sorry, unable to open the file at this time.
Please check the address and try again.
As you can see from the command, I had to manipulate things a bit to get this far: including dummy data, adding a content-length header, and adding the -L flag to consume the redirect.
However, I am stuck. Why can't it "find the file"? Why does it think there is a file?

Answer 1

I suspect you'll need to send data.
This works (I got {"result":"POST request received!"}):
curl -H 'Content-Type: application/json' -d {} -L https://script.google.com/macros/s/AKfycbxYxgMfMkR6hGI5UO2Gn8tg369oqsy_W41-olb0Do1y8gOjaNvm/exec
As does this:
curl -d "" -L https://script.google.com/macros/s/AKfycbxYxgMfMkR6hGI5UO2Gn8tg369oqsy_W41-olb0Do1y8gOjaNvm/exec