App engine downloading PHP code instead of displaying - php

Question

I'm using PHP55 to run a web-page on standard environment through Google App Engine. When I click the submit button on a form, it downloads the respective PHP code that should instead be executing. Here's my app.yaml:
runtime: php55
api_version: 1
threadsafe: true
handlers:
- url: /
static_files: www/index.html
upload: www/index.html
- url: /signUp.html
static_files: www/signUp.html
upload: www/signUp.html
- url: /submitEmail.php
static_files: www/submitEmail.php
upload: www/submitEmail.php
- url: /(.*)
static_files: www/\1
upload: www/(.*)
EDIT 1
So I initially tried the following for the handlers:
handlers:
-url: /(.+\.php)$
script: www/\1
-url: /
script: www/index.html
-url: /(.*)
script: www/\1
However this was in short - a disaster. Images and CSS didn't load after refreshing. All I want is for submitEmail.php to execute when the user clicks submit on the form in index.html.
To clarify this is my high-level structure:
www/
-index.html
-submitEmail.php
app.yaml
EDIT 2
Present state of app.yaml but when I submit the form I receive a 404 error.
handlers:
-url: /(.+\.php)$
script: www/\1
-url: /submitEmail.php
script: www/submitEmail.php
-url: /
script: www/index.html
-url: /(.*)
script: www/\1

Answer 1

Well the PHP code is delivered because you declared it as static_files. Static files are delivered as-is to the client when requested.
Change your handler like this:
- url: /submitEmail.php
script: www/submitEmail.php
upload: www/submitEmail.php
See also app.yaml reference.