How to proxy a re-written url in Nginx? - nginx

Question

I have the following config:
js_include /etc/nginx/scripts/encode_request.js;
js_set $encoded_request re_encode_url;
log_format logEncoded $encoded_request;
server {
listen 443 ssl;
listen [::]:443;
server_name myfirst-domain.com;
ssl on;
ssl_certificate /etc/ssl/certs/cert.cer;
ssl_certificate_key /etc/ssl/private/cert.key;
location / {
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
if ($request_uri ~ ^/lool/https%3A/alf.mydomain.com/(.*)$){
access_log /var/log/nginx/access.log logEncoded; #Output the encoded url to the logs. (For debugging purposes)
rewrite ^/lool/https%3A/alf.mydomain.com/(.*)$ $encoded_request;
}
proxy_pass https://localhost:9980;
}
}
The purpose of which is to filter a URL request that that contains a decoded URL that's required by the backend service. The problem is whilst the request URL has been successfully encoded, it is not being proxied to the backend service and instead I get the original decoded URL which in turn causes an error, though I do get the correctly encoded URL output in the access.log.
Not by far an NGINX or web server saavy person so I'd appreciate some pointers as to what I'm doing wrong / missing.
Another thing that might be of note is that the request upgrades to websocket communication between the client and the sever and I am proxying that.
I'm using NGINX 1.13.6 on Debian Jessie.

Answer 1

I solved the issue using nginScript in the end.
I tossed the conditional and just did everything in nginScript, so the virtual host file (or server block) is simplified thus:
server {
listen 443 ssl;
listen [::]:443;
server_name myfirst-domain.com;
ssl on;
ssl_certificate /path/to/ssl/certificate;
ssl_certificate_key /path/to/ssl/certificate/key;
location / {
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "Upgrade";
#Optional
access_log /var/log/nginx/ll_access.log;
error_log /var/log/nginx/ll_error.log;
proxy_pass https://127.0.0.1:9980$encoded_request;
}
}