I'm trying to set up an AWS API Gateway for something which was previously handled by an nginx reverse proxy. My endpoints are EC2 instances inside a VPC. I've already set it up so the gateway can access these instances.
The previous nginx setup looked like this:
http {
server {
listen 80;
location /host1/ {
proxy_pass http://host1:8000/;
}
location /host2/ {
proxy_pass http://host2:8070/;
}
...
}
}
The Problem arises when I try to rewrite the request path. I've set up a test route in the Gateway: ANY /test/{proxy+}, which I passed to the corresponding EC2 instance. I've verified, that requests pass through, but they contain the complete paths of the requests:
# machine 1:
curl -v 'https://<endpoint>.amazonaws.com/test/hello_world/test/a'
< HTTP/2 404
< date: Sat, 18 Dec 2021 09:21:42 GMT
< content-type: text/html;charset=utf-8
< content-length: 469
< server: SimpleHTTP/0.6 Python/3.7.10
< apigw-requestid: Kic2FiLIFiAEN_g=
<
--- response ---
# server:
192.168.9.6 - - [18/Dec/2021 09:15:05] "GET /test/hello_world/test/a HTTP/1.1" 404 -
(the 404 is expected, the important part is the request hitting the server)
I then tried to rewrite the request path to remove the leading /test using a parameter mapping: I specified "all incoming requests", Parameter to modify: path, Modification type: overwrite, Value: $request.path.proxy (the catch-all field defined in the route).
Now I get a 400 error, and the requests don't hit my server anymore:
# machine 1:
curl -v 'https://<endpoint>.amazonaws.com/test/hello_world/test/a'
< HTTP/2 400
< date: Sat, 18 Dec 2021 09:19:53 GMT
< content-type: text/html
< content-length: 122
< server: awselb/2.0
< apigw-requestid: KiclDhxXFiAEMhg=
<
<html>
<head><title>400 Bad Request</title></head>
<body>
<center><h1>400 Bad Request</h1></center>
</body>
</html>
# server:
-nothing-
When I map the $request.path.proxy to querystring.path, instead of path the requests hit the server:
# machine 1:
curl -v 'https://<endpoint>.amazonaws.com/test/hello_world/test/a'
< HTTP/2 404
< date: Sat, 18 Dec 2021 09:21:42 GMT
< content-type: text/html;charset=utf-8
< content-length: 469
< server: SimpleHTTP/0.6 Python/3.7.10
< apigw-requestid: Kic2FiLIFiAEN_g=
<
--- response ---
# server:
192.168.9.6 - - [18/Dec/2021 09:21:42] "GET /test/hello_world/test/a?path=hello_world%2Ftest%2Fa HTTP/1.1" 404 -
notice the value of the path query parameter is exactly the correct value which I would have wanted to replace the original requests path.
Is this a bug with AWS, or am I just missing some documentation, stating that you cannot rewrite path that way? Notably, when the {proxy+} path parameter is empty, requests get routed through correctly...
