# A template: the nginx image renders it into conf.d at container start,
# filling in PORT and nothing else. bin/entrypoint.sh sets PORT and that
# limit.
server {
    listen ${PORT};
    server_name _;

    # Keep the nginx version out of the Server header and error pages.
    server_tokens off;

    # The security headers, on every response. An add_header in a
    # location drops every add_header from here, so a location with one
    # of its own includes this file again.
    include /etc/nginx/security-headers.conf;

    root /usr/share/nginx/html;
    index index.html;

    # The client address comes from X-Forwarded-For only on a request
    # from the reverse proxies in TRUSTED_PROXIES: bin/entrypoint.sh
    # writes one set_real_ip_from line for each into this file, and
    # leaves it empty when TRUSTED_PROXIES is unset, so that by default
    # the client address is the one each request comes from.
    include /etc/nginx/trusted-proxies.conf;
    real_ip_header X-Forwarded-For;
    real_ip_recursive on;

    # Access log to stdout (Docker best practice)
    access_log /dev/stdout combined;
    error_log  /dev/stderr warn;

    location / {
        try_files $uri $uri/ /index.html;
    }

    # Cache static assets aggressively
    location /assets/ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        include /etc/nginx/security-headers.conf;
    }

    # netwatch-server, the Go backend, runs in the same container and
    # listens on loopback only: bin/entrypoint.sh starts it on
    # 127.0.0.1:8081. These headers go with every request passed to it.
    # X-Forwarded-For carries only the client address, as resolved by
    # the real IP settings above, and not the chain the request came
    # with: the backend takes the first entry, which a client can write.
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $remote_addr;
    proxy_set_header X-Forwarded-Proto $scheme;

    # netwatch-server sets the same security headers on its own
    # responses. Its copies are dropped so that each header goes out
    # once, as security-headers.conf sets it.
    proxy_hide_header Strict-Transport-Security;
    proxy_hide_header Content-Security-Policy;
    proxy_hide_header X-Frame-Options;
    proxy_hide_header X-Content-Type-Options;
    proxy_hide_header Referrer-Policy;
    proxy_hide_header Permissions-Policy;

    location /api/ {
        proxy_pass http://127.0.0.1:8081;
    }

    location = /.well-known/healthcheck {
        proxy_pass http://127.0.0.1:8081;
    }
}