Nginx Reverse Proxy Following Redirects

Question

I would like Nginx to return actual files instead of response with Location: redirect header. I use Nginx as a reverse proxy cache: cdn.mydomain.com receives a request and contacts api.mydomain.com/files/ to fetch image files from there, but api.mydomain.com/files/ returns a blank response with Location: redirect header to AWS S3, instead of a file itself.

Thus, Nginx caches the blank redirect response. How can I make Nginx to fetch and cache the actual file from S3.

user www-data;
worker_processes 4;
pid /var/run/nginx.pid;

http {
    server_names_hash_bucket_size 64;
    proxy_redirect off;

    proxy_cache_path /var/cache/nginx levels=2:2:2 keys_zone=my-cache:8m max_size=4G inactive=600m;
    proxy_temp_path /var/cache/tmp;

    server {
        listen 80;
        server_name cdn.mydomain.com;
        server_tokens off;
        location / {
            proxy_pass http://api.mydomain.com/files/;

            proxy_cache my-cache;
            proxy_cache_valid 200 302 30d;
            expires 30d;
            add_header Pragma public;
            add_header Cache-Control "public";
        }
}

Answer 1

I had just the same need and I couldn't find any working solution, so I combined what I have learned from Nginx mailing lists and Nginx documentation:

proxy_cache_path /tmp/docker/nginx/cache levels=1:2 keys_zone=DOCKERHUB:10m inactive=24h max_size=8g;

server {
    ...

    location /v2/ {
        proxy_pass https://registry-1.docker.io;
        proxy_cache            DOCKERHUB;
        #proxy_cache_valid      200  1d;
        #proxy_cache_use_stale  error timeout invalid_header updating
        #                       http_500 http_502 http_503 http_504;
        #proxy_cache_lock on;
        proxy_intercept_errors on;
        error_page 301 302 307 = @handle_redirect;
    }

    location @handle_redirect {
        set $saved_redirect_location '$upstream_http_location';
        proxy_pass $saved_redirect_location;
        proxy_cache            DOCKERHUB;
        #proxy_cache_valid      200  1d;
        #proxy_cache_use_stale  error timeout invalid_header updating
        #                       http_500 http_502 http_503 http_504;
        #proxy_cache_key $scheme$proxy_host$uri;
        #proxy_cache_lock on;
    }
}

P.S. I have commented out the proxy_cache options relevant to my use-case, but you may still find them useful.