# mattermost
# config can be tested on https://www.ssllabs.com/ssltest/ and a good nginx config generator https://ssl-config.mozilla.org/

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

# upstream - is being used in locations' proxy_pass below
upstream backend {
    # ip where Mattermost is running
    server mattermost:8065;
    keepalive 64;
}

# vhosts definitions
server {
    server_name _;
    listen 80;
    listen [::]:80;

    # redirect all HTTP requests to HTTPS with a 301 Moved Permanently response.
    return 301 https://$host$request_uri;
}

server {
    server_name _;
    listen 443 ssl http2;
    listen [::]:443 ssl http2;

    ## ssl
    ssl_dhparam /dhparams4096.pem;
    ssl_session_timeout 1d;
    ssl_session_cache shared:MozSSL:10m;  # about 40000 sessions
    ssl_session_tickets off;

    # intermediate configuration
    ssl_protocols TLSv1.2 TLSv1.3;
    ssl_ciphers ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384;
    ssl_prefer_server_ciphers off;

    # certs sent to the client in SERVER HELLO are concatenated in ssl_certificate
    ssl_certificate /fullchain.pem;
    ssl_certificate_key /privkey.pem;

    # OCSP stapling
    ssl_stapling on;
    ssl_stapling_verify on;

    # verify chain of trust of OCSP response using Root CA and Intermediate certs
    #ssl_trusted_certificate /etc/ssl/certs/ca-certificates.crt;

    ## security headers
    # https://securityheaders.com/
    # https://scotthelme.co.uk/tag/security-headers/
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-XSS-Protection "1; mode=block" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains; preload";

    # logging
    access_log /var/log/nginx/mm.access.log;
    error_log /var/log/nginx/mm.error.log warn;

    # max allowed size of uploaded files
    client_max_body_size 256M;

    # gzip for performance
    gzip on;
    gzip_vary on;
    gzip_proxied any;
    gzip_comp_level 6;
    gzip_types text/plain text/css text/xml application/json application/javascript application/rss+xml application/atom+xml image/svg+xml;

    ## locations
    # ACME-challenge
    location ^~ /.well-known {
        default_type "text/plain";
        root /usr/share/nginx/html;
        allow all;
    }

    # disable Google bots from indexing this site
    location = /robots.txt {
        add_header Content-Type text/plain;
        return 200 "User-agent: *\nDisallow: /\n";
    }

    # API websocket location
    location ~ /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_connect_timeout 90;
        proxy_send_timeout 300;
        proxy_read_timeout 90s;
        proxy_pass http://backend;
    }

    # reverse proxy location
    location / {
        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://backend;
    }
}