picpeak/frontend/nginx.conf

    # URLs and Referer can contain gallery, image and customer bearer tokens.
    map $uri $request_surface {
        ~*^/api/(?<picpeak_surface>[a-z-]+)(?:/|$) /api/$picpeak_surface;
        default /;
    }
    log_format picpeak_safe '$remote_addr "$http_x_forwarded_for" [$time_local] "$request_method $request_surface" '
                            '$status $body_bytes_sent $request_time';

# Honour the outer reverse proxy's X-Forwarded-Proto when present (e.g. NPM,
# Traefik, Caddy in front of PicPeak). Falls back to nginx's own $scheme when
# the header is absent (direct access / no outer proxy). Without this the
# inner nginx was always forwarding "http" to the backend because the outer
# proxy → inner nginx hop is plain HTTP, breaking Secure cookies and HTTPS
# URL generation in the backend. See issue #547.
map $http_x_forwarded_proto $real_proto {
    default $http_x_forwarded_proto;
    ""      $scheme;
}

server {
    access_log /var/log/nginx/access.log picpeak_safe;
    # Native request errors include bearer URLs even at crit/alert severity.
    # Safe access logs retain status/timing; process diagnostics stay at main level.
    error_log /dev/null;
    listen 80;
    server_name localhost;
    server_tokens off;
    root /usr/share/nginx/html;
    index index.html;

    # Docker DNS resolver for dynamic service discovery (required for Swarm/Compose)
    resolver 127.0.0.11 valid=10s ipv6=off;
    resolver_timeout 5s;

    # Allow larger file uploads (up to 1GB for video support)
    client_max_body_size 1G;
    client_body_timeout 300s;

    # Defensive header buffer bump (#591). Default `4 8k` is too tight when
    # an outer Cloudflare / corp-proxy sits in front and injects long
    # Set-Cookie / X-Forwarded-* headers, or when a power-user accumulates
    # many per-gallery `gallery_token_<slug>` cookies over the 24h maxAge
    # in tokenUtils.js. Either way users hit "400 Request Header Or Cookie
    # Too Large" and clearing cookies is the only fix. 4×32k is cheap RAM
    # and matches what most reverse proxies already do upstream.
    large_client_header_buffers 4 32k;

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    gzip_types text/plain text/css text/xml text/javascript application/javascript application/xml+rss application/json;

    # Security headers
    add_header X-Frame-Options "SAMEORIGIN" always;
    add_header X-Content-Type-Options "nosniff" always;
    add_header Referrer-Policy "strict-origin-when-cross-origin" always;
    add_header Permissions-Policy "camera=(), microphone=(), geolocation=(), payment=()" always;
    add_header Content-Security-Policy "default-src 'self'; script-src 'self' https://www.google.com https://www.gstatic.com; style-src 'self' 'unsafe-inline' https:; img-src 'self' data: https: blob:; connect-src 'self' https://www.google.com https://www.gstatic.com; font-src 'self' https: data:; object-src 'none'; media-src 'self'; frame-src 'self' https://www.google.com" always;

    # Strip the same headers when emitted by the upstream backend so nginx
    # is the single source. Without this, helmet (in the Express app) and
    # nginx both emit the headers and clients see duplicates — testssl
    # flagged "Multiple X-Frame-Options / X-Content-Type-Options / CSP /
    # Permissions-Policy / Referrer-Policy headers" on the live origin.
    # proxy_hide_header at server level applies to every proxy_pass below.
    proxy_hide_header X-Frame-Options;
    proxy_hide_header X-Content-Type-Options;
    proxy_hide_header Referrer-Policy;
    proxy_hide_header Content-Security-Policy;
    proxy_hide_header Permissions-Policy;
    proxy_hide_header Strict-Transport-Security;

    # Health check endpoint
    location /health {
        access_log off;
        return 200 "healthy\n";
        add_header Content-Type text/plain;
    }

    # Cache static assets
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
        expires 1y;
        add_header Cache-Control "public, immutable";
        # Re-apply security headers (add_header in location block overrides server-level)
        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header Content-Security-Policy "default-src 'self'; script-src 'self' https://www.google.com https://www.gstatic.com; style-src 'self' 'unsafe-inline' https:; img-src 'self' data: https: blob:; connect-src 'self' https://www.google.com https://www.gstatic.com; font-src 'self' https: data:; object-src 'none'; media-src 'self'; frame-src 'self' https://www.google.com" always;
    }

    # Cache index.html with revalidation
    location = /index.html {
        add_header Cache-Control "no-cache, no-store, must-revalidate";
        add_header Pragma "no-cache";
        add_header Expires "0";
        # Re-apply security headers
        add_header X-Frame-Options "SAMEORIGIN" always;
        add_header X-Content-Type-Options "nosniff" always;
        add_header Referrer-Policy "strict-origin-when-cross-origin" always;
        add_header Content-Security-Policy "default-src 'self'; script-src 'self' https://www.google.com https://www.gstatic.com; style-src 'self' 'unsafe-inline' https:; img-src 'self' data: https: blob:; connect-src 'self' https://www.google.com https://www.gstatic.com; font-src 'self' https: data:; object-src 'none'; media-src 'self'; frame-src 'self' https://www.google.com" always;
    }

    # Analytics tracker proxy (backend). The tracker script is served from our
    # own origin so `script-src 'self'` / `connect-src 'self'` above already
    # cover it and no admin-configured tracker domain has to be added to the
    # CSP by hand. It NEEDS its own block: the script URL ends in `.js`, and
    # the `~* \.(js|css|…)$` regex location above outranks the plain `/api`
    # prefix in nginx's matching order, so `/api/analytics/tracker/script.js`
    # would otherwise be looked up as a static file and 404. `^~` stops regex
    # evaluation for this prefix. Keep in sync with the mount path in
    # backend/server.js.
    location ^~ /api/analytics/tracker/ {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
        proxy_read_timeout 30s;
        client_max_body_size 64k;
    }

    # API proxy
    location /api {
        # Use variable to force DNS resolution per request (required for Docker Swarm)
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $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 $real_proto;
        proxy_cache_bypass $http_upgrade;
        proxy_read_timeout 86400;

        # Allow larger uploads for API endpoints (up to 1GB for video support)
        client_max_body_size 1G;
        client_body_timeout 300s;
    }

    # Photo serving proxy
    location /photos {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;

        # Cache photos
        proxy_cache_valid 200 302 1d;
        proxy_cache_valid 404 1m;
    }

    # Thumbnail serving proxy
    location /thumbnails {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;

        # Cache thumbnails
        proxy_cache_valid 200 302 7d;
        proxy_cache_valid 404 1m;
    }

    # Uploads serving proxy (logos, favicons, watermarks)
    # ^~ modifier stops regex matching, ensuring uploads are proxied not served locally
    location ^~ /uploads {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;

        # Cache uploads
        proxy_cache_valid 200 302 7d;
        proxy_cache_valid 404 1m;
    }

    # Self-hosted webfonts proxy (bundled families + admin user additions).
    # ^~ modifier stops regex matching, ensuring fonts are proxied to the
    # backend (which scans backend/assets/fonts and STORAGE_PATH/fonts) and
    # NOT served locally — the .woff2 files do not exist in the frontend image.
    location ^~ /fonts {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;

        # Fonts rarely change; cache aggressively (matches backend Cache-Control).
        proxy_cache_valid 200 302 7d;
        proxy_cache_valid 404 1m;
    }

    # Dynamic robots.txt served by backend
    location = /robots.txt {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000/robots.txt;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
    }

    # Dynamic favicon / apple-touch-icon served by backend (resolves the
    # admin-configured branding favicon, falls back to the bundled asset).
    # Exact-match (=) wins over the static-asset regex below, so these reach
    # the backend instead of the build dir. Browsers (especially Safari)
    # request these at the site root regardless of any JS-injected
    # <link rel="icon">.
    location = /favicon.ico {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000/favicon.ico;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
    }
    location = /apple-touch-icon.png {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000/apple-touch-icon.png;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
    }
    location = /apple-touch-icon-precomposed.png {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000/apple-touch-icon-precomposed.png;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
    }

    # Delegate root requests to backend for public landing page handling
    location = / {
        # Use variable to force DNS resolution per request (required for Docker Swarm)
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000/;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
        proxy_set_header Host $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 $real_proto;
        proxy_read_timeout 60s;
    }

    # Social-crawler detection for gallery share URLs. Crawlers (WhatsApp,
    # Facebook, Slack, Twitter, etc.) don't run JS, so the SPA's client-side
    # meta tags never reach them. Route those UAs to backend's /og handler
    # via internal rewrite; humans fall through to the SPA via try_files.
    # {0,2} extra path segments so the deeper gallery share shapes match too:
    #   /gallery/<slug>                      (public / share-token link)
    #   /gallery/<slug>/client-access        (client-access; token is in ?query)
    #   /gallery/<slug>/show/<token>          (slideshow; token is a PATH segment)
    # The slideshow shape has TWO extra segments (show + token) — the old
    # single-segment `(?:/[^/]+)?` never matched it, so slideshow links fell
    # through to the SPA and got only the generic site-wide OG (#699 follow-up).
    # NB: the regex is QUOTED because the {0,2} quantifier's braces would
    # otherwise be parsed as nginx config block delimiters.
    location ~ "^/gallery/(?<gallery_slug>[A-Za-z0-9_-]+)(?:/[^/]+){0,2}/?$" {
        # Keep this list in sync with SOCIAL_CRAWLER_PATTERNS in
        # backend/src/services/galleryOgService.js. WhatsAppBot / wa-bot
        # and LinkPreview / Slack-ImgProxy added in #521 to catch
        # business-API preview fetchers that aren't the main WhatsApp app.
        # Viber + the broader set below added in #699 follow-up. Only
        # CRAWLER-EXCLUSIVE tokens — the backend OG response is meta-only (no
        # redirect), so UAs shared with real human in-app browsers (WeChat's
        # MicroMessenger, LINE's "Line/", Zalo, "InAppBrowser") are NOT added.
        if ($http_user_agent ~* "(facebookexternalhit|facebookcatalog|facebot|Twitterbot|WhatsApp|WhatsAppBot|wa-bot|Slackbot|Slack-ImgProxy|TelegramBot|SkypeUriPreview|Discordbot|LinkedInBot|Pinterest|vkShare|redditbot|Embedly|iframely|Snapchat|Applebot|Mastodon|Bluesky|Cardyb|OpenGraph|LinkPreview|Viber|Signal|Misskey|Pleroma|Synapse|Nextcloud|Rocket\.Chat|kakaotalk-scrap|Google-PageRenderer|OdklBot|ZoomBot)") {
            rewrite ^ /og/gallery/$gallery_slug last;
        }
        try_files $uri $uri/ /index.html;
    }

    # OG preview endpoint (proxied to backend). Public endpoint by design —
    # only exposes event_name + branding logo, no protected photo content.
    location ^~ /og/gallery/ {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
    }

    # Branded URL shortener (#699). The backend `/s/<short_slug>` route both
    # 302-redirects humans to the target gallery AND server-renders OG for
    # social crawlers. Without this proxy, `/s/...` fell through to the SPA
    # (which has no /s/ route) — so branded short links were dead for humans
    # and crawlers alike. `^~` beats the regex SPA fallback below. The backend
    # does its own UA detection, so no crawler `if` is needed here.
    location ^~ /s/ {
        set $backend_upstream backend;
        proxy_pass http://$backend_upstream:3000;
        proxy_http_version 1.1;
        proxy_set_header Host $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 $real_proto;
    }

    # SPA fallback
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Deny access to hidden files
    location ~ /\. {
        deny all;
    }
}