gnu-social/docker/nginx/nginx.conf

server {
    # Listen only on port 81 for localhost, and nothing else.
    server_name 127.0.0.1;
    listen 127.0.0.1:81 default_server;

    charset utf-8;

    # Certbot's folder used for the ACME challenge response.
    location ^~ /.well-known/acme-challenge {
        default_type text/plain;
        root /var/www/certbot;
        try_files $uri =404;
    }
}

server {

    listen [::]:80;
    listen 80;

    server_name %hostname%;

    location '/.well-known/acme-challenge' {
        proxy_pass http://localhost:81;
    }

    # redirect all traffic to HTTPS
    rewrite ^ https://$host$request_uri? permanent;
}

server {

    listen [::]:443 ssl http2;
    listen 443 ssl http2;

    ssl_certificate /etc/letsencrypt/live/%hostname%/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/%hostname%/privkey.pem;

    # Let's Encrypt best practices
    include /etc/letsencrypt/options-ssl-nginx.conf;
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem;

    root /var/www/social/public;

    # Server name
    server_name %hostname%;

    # Index
    index index.php;

    # X-Accel/X-Sendfile. Still needs to be enabled in the config
    location /file {
        internal;
        root /var/www/social;
    }

    location /.well-known/acme-challenge/ {
        allow all;
        root /var/www/certbot;
        try_files $uri =404;
        break;
    }

    # PHP
    location ~ ^/(index|install)\.php(/.*)?$ {
        include fastcgi_params;

        fastcgi_split_path_info ^(.+?\.php)(/.*)$;
        set $path_info $fastcgi_path_info;
        try_files $fastcgi_script_name =404;

        fastcgi_pass php:9000;
        fastcgi_index index.php;

        fastcgi_param PATH_INFO $path_info;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
    }

    # Don't allow any PHP file other than index.php to be executed
    # This will ensure that nor config.php nor plugin files with eventual hardcoded security information are downloadable
    # And this is better than allowing php files to be executed in case of forgotten `if (!defined('GNUSOCIAL')) { exit(1); }`
    location ~ \.php$ {
        deny all;
    }

    # Location
    location / {
        try_files $uri $uri/ @index_handler;
    }

    # Fancy URLs
    error_page 404 @index_handler;
    location @index_handler {
        rewrite ^(.*)$ /index.php?p=$1 last;
    }

    # Restrict access that is unnecessary anyway
    location ~ /\.(ht|git) {
        deny all;
    }

#
# Hardening (optional)
#
    add_header Strict-Transport-Security "max-age=15768000; preload;";
    add_header X-Content-Type-Options nosniff;
    add_header Referrer-Policy strict-origin-when-cross-origin;
    add_header Content-Security-Policy "default-src 'self' 'unsafe-inline'; frame-ancestors 'self'; form-action 'self'; style-src 'self' 'unsafe-inline'; img-src * blob: data:;";
    add_header X-Permitted-Cross-Domain-Policies none;
    add_header X-Robots-Tag all; # Not really hardening, just here for strictness purposes

    client_max_body_size 15M;
    client_body_buffer_size 128k;
    gzip_vary on;

    location ~* \.(?:css|js|woff|svg|gif|png|webp|ttf|ico|jpe?g)$ {
        gzip on;
        gzip_comp_level 4;
        add_header Cache-Control "public";
        expires 30d;
        access_log off;
        log_not_found off;
    }
}