HTTP Proxy Version 1.1

[XxLilBoPeepsxX]

@pat-s

# This block is useful for debugging TLS v1.3. Please feel free to remove this
# and use the `$ssl_early_data` variable exposed by nginx directly should you
# wish to do so.
map $ssl_early_data $tls1_3_early_data {
    "~." $ssl_early_data;
    default "";
}

proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=mattermost_cache:10m max_size=3g inactive=120m use_temp_path=off;

server {
    listen 443 ssl http2;

    [...] # other settings

    proxy_http_version 1.1;

    location ~ /mattermost/api/v[0-9]+/(users/)?websocket$ {
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        client_max_body_size 50M;
        proxy_set_header Host $http_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_set_header X-Frame-Options SAMEORIGIN;
        proxy_buffers 256 16k;
        proxy_buffer_size 16k;
        client_body_timeout 60;
        send_timeout 300;
        lingering_timeout 5;
        proxy_http_version 1.1;
        proxy_connect_timeout 90;
        proxy_send_timeout 300;
        proxy_read_timeout 90s;
        proxy_pass http://172.17.0.1:8065;
    }

    location /mattermost {

        client_max_body_size 50M;
        proxy_set_header Connection "";
        proxy_set_header Host $http_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_set_header X-Frame-Options SAMEORIGIN;
        proxy_buffers 256 16k;
        proxy_buffer_size 16k;
        proxy_read_timeout 600s;
        proxy_cache mattermost_cache;
        proxy_cache_revalidate on;
        proxy_cache_min_uses 2;
        proxy_cache_use_stale timeout;
        proxy_cache_lock on;
        proxy_http_version 1.1;

        proxy_pass http://172.17.0.1:8065/mattermost;
    }
}

I took the time to research the Official Nginx Proxy Configuration Documentation and compared the contents of the sample file that they provided on that webpage to the configuration that you provided (you can view this comparison here) and it seems like there is a lot that is missing, I’m wondering if this could be contributing to the issues your having.