Serving React frontend and Flask backend with Nginx reverse proxy

I’ve been trying to set up a React frontend and a Flask backend using Nginx as a reverse proxy to differentiate the two. I have the flask backend running a Gunicorn server on localhost:5000, but I can’t seem to get the Nginx location block to register it. My config file looks like this:

server {
  listen 80;
  root /var/www/[react-app-domain-name]/html;
  index index.html index.htm;

  access_log /var/log/nginx/reverse-access.log;
  error_log /var/log/nginx/reverse-error.log;

  location / {
    try_files $uri $uri/ = 404;

  location /api {
    include proxy_params;
    proxy_pass http://localhost:5000;

My understanding is that this should route all traffic through my react app at root, except for requests that have “/api”, which should then be routed through my backend Flask api. However, when I try to access a /api route, all I get back is a 404 response. This also happens if I true to access it through curl on the command line.

Here’s the 404 error log that I have:

2020/09/09 21:03:05 [crit] 36926#36926: *114 connect() to unix:/home/[name]/backend/backend.sock failed (2: No such file or directory) while connecting to upstream, client:, server: , request: "GET /api/ HTTP/1.0", upstream: "http://unix:/home/[name]/backend/backend.sock:/api/", host: "[hostname]"

Any help would be very much appreciated. I’m tearing my hair out here. Thanks.

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Jumping right in, does this file exist on the file system?


If that file doesn’t exist, then you need to figure out what should be running to create it.

If it does exist, then the nginx user might not have permission to access the parent directory.

Hope this helps… if you have more details or run into new errors please let us know - good luck!