NGINX vs Caddy as de facto IoT standard

Hi balena community,

I have been having a debate in my head over the pros and cons of NGINX over Caddy ( And where better to flush out those thoughts than in the open!

If you’re not familiar with Caddy, it is a production ready web server that can be used as an alternative to NGINX and has multi-arch Docker images maintained by Caddy. Here it is in action on a balena project by @alanb128: GitHub - alanb128/landr-buddy: Easily upload a website and test with a public URL..

And here are some key comparisons between NGINX and Caddy:

Caddy Nginx
Compressed Docker Image Size 14.8 9.51
Language Golang C
Automatic HTTPS yes no

Market share (Comparing the best web servers: Caddy, Apache, and Nginx - LogRocket Blog)

Performance (centminmod-caddy-v2/ at master · centminmod/centminmod-caddy-v2 · GitHub)

HTTP/2 HTTPS Benchmarks
server h2load HTTP/2 requests/s ttfb min ttfb avg ttfb max cipher protocol successful req failed req
caddy v2 t1 c150 n1000 m50 959.57 213.30ms 696.74ms 1.03s ECDHE-ECDSA-AES256-GCM-SHA384 h2 TLSv1.2 100% 0%
caddy v2 t1 c500 n2000 m100 990.03 711.60ms 1.36s 1.98s ECDHE-ECDSA-AES256-GCM-SHA384 h2 TLSv1.2 100% 0%
caddy v2 t1 c1000 n10000 m100 1049.00 965.65ms 3.34s 6.53s ECDHE-ECDSA-AES256-GCM-SHA384 h2 TLSv1.2 68.89% 31.11%
nginx 1.17.10 t1 c150 n1000 m50 2224.74 158.04ms 300.22ms 440.22ms ECDHE-ECDSA-AES128-GCM-SHA256 h2 TLSv1.2 100% 0%
nginx 1.17.10 t1 c500 n2000 m100 1600.52 583.80ms 861.70ms 1.23s ECDHE-ECDSA-AES128-GCM-SHA256 h2 TLSv1.2 100% 0%
nginx 1.17.10 t1 c1000 n10000 m100 1912.05 949.61ms 2.98s 5.16s ECDHE-ECDSA-AES128-GCM-SHA256 h2 TLSv1.2 100% 0%

Looks like a no-brainer right? Performance is better on NGINX, market share is greater for NGINX, the Docker image size is smaller, it is in C rather than Go which has performance benefits.

But then comes the question of how much this really matters for IoT? Marketshare is somewhat valuable a statistic, but Caddy is already well known and respected for stability and quality. The 5mb difference in compressed image size I will choose not to lose any sleep over. The big one is performance, but when running on IoT devices it seems to be far more likely we will experience other bottle necks before the NGINX vs Caddy comparison comes in to play. Network speeds, SD card write speeds, processing power, the number of cores on the devices and so forth. And with low traffic, will we notice any at all? NGINX is designed for scaling large web web services and I suspect these performance differences will be relatively insignificant for IoT devices.

Then comes the big plus side for Caddy: the ease of configuration. Here is the default NGINX config file from their Docker image:

user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/;

events {
    worker_connections  1024;

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;

Trust me when I say this is just the beginning of a slippery slope. When you start adding in reverse proxies, encounter the differences between URLs with a / and those without, begin using ~ and ^, compression, root vs alias and the many other NGINX caveats, things quickly get complicated. Here is one of my NGINX config files to serve 3 routes (/, /storage, /website) and a reverse proxy on /dev-server:

user nginx;
worker_processes auto;
error_log stderr warn;
pid /run/;

# Set worker_connections to appropriate level for low resource hardware
events {
    worker_connections 256;

http {
    include mime.types;
    default_type application/octet-stream;

    # Switch off access logs and route error logs to docker console
    access_log off;
    error_log /proc/1/fd/2 notice;

    keepalive_timeout 75;

    # Write temporary files to /tmp so they can be created as a non-privileged user, and to avoid SD writes
    client_body_temp_path /tmp/client_temp;
    proxy_temp_path /tmp/proxy_temp_path;
    fastcgi_temp_path /tmp/fastcgi_temp;
    uwsgi_temp_path /tmp/uwsgi_temp;
    scgi_temp_path /tmp/scgi_temp;

    # Specify Docker resolver

    # Prevent port being added to end of URL on redirects
    port_in_redirect off;

    # Default server definition
    server {
        listen [::]:8081 default_server;
        listen 8081 default_server;
        server_name _;

        # Allow CORS
        add_header Access-Control-Allow-Origin *;

        sendfile on;

        root /app/public/interface;
        index index.html;

        # Set to allow large file uploads in File Manager
        client_max_body_size 0;

        location / {
            # First attempt to serve request as file, then
            # as directory, then fall back to index.html
            try_files $uri $uri/ /index.html?q=$uri&$args /index.html;

       # Redirect for the root storage volume
        location ^~ /storage {
            root /app/public;

        # Redirect for the 'website' feature
        location ^~ /website {
            root /app/public/storage;

        # Development Server
        location ~ /dev-server {
            set $interface;
            proxy_pass $interface;
            proxy_redirect off;
            proxy_http_version 1.1;
            proxy_set_header X-Real-Ip $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header Host $host;
            proxy_set_header REMOTE_ADDR $remote_addr;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "Upgrade";
            proxy_read_timeout 86400;
            # Disable caching for dev env
            add_header 'Cache-Control' 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0';
            expires off;
            etag off;
            proxy_no_cache 1;

        # Redirect server error pages to the static page /404.html
        error_page 404 500 502 503 504 /404;
        error_page 401 /401;

        # Cache these file types for 5 days to save bandwidth on each load
        location ~* \.(jpg|jpeg|gif|png|css|js|ico|xml)$ {
            expires 5d;

        # Deny access to . files, for security
        location ~ /\. {
            log_not_found off;
            deny all;

    # Light compression for page load speed on larger files
    gzip on;
    gzip_comp_level 1;
    gzip_min_length 1000;
    gzip_proxied any;
    gzip_types text/plain application/xml text/css text/js text/xml application/x-javascript text/javascript application/json application/xml+rss;
    gzip_vary on;
    gzip_disable "msie6";

Now let’s take a look at Caddy config file entry points, starting with a basic server:

:80 {
         # Set this path to your site's directory.
         root * /usr/share/caddy

         # Enable the static file server.

Or a load balanced reverse proxy: # Your site's domain name

# Load balance between three backends with custom health checks
reverse_proxy {
	lb_policy       random_choose 2
	health_path     /ok
	health_interval 10s

Or a HTTPS site with reverse proxying and compression

# Compress responses according to Accept-Encoding headers
encode gzip zstd

# Make HTML file extension optional
try_files {path}.html {path}

# Send API requests to backend
reverse_proxy /api/* localhost:9005

# Serve everything else from the file system

Looking back at the many days/weeks lost over the years on NGINX config files, a part of me wishes I had just used Caddy. I am still experimenting with Caddy, and there are likely some Caddy quirks to experience yet, but if the goal is to utilise development time wisely and reduce user friction, I think there is a good case for Caddy.

It would be great to hear thoughts or arguments for one over the other.

1 Like

Without having knowledge about Caddy, which seems promising by the way, never heard of it, but what about taking HAProxy into comparison?

I’ve been a fan of NGINX since as long as I can remember setting up websites, but since I’ve been using HAProxy on Kubernetes (see the open-balena repo), I’m a huge fan. Simple structure, really reliable and high throughput. They also support many architectures.

Also, why would you need Let’s Encrypt / SSL for IoT devices on the device-side? Maybe I’m missing something, but all of our Balena devices in the field don’t have a signed SSL certificate, because how would you manage that?

I’m really looking forward hearing other thoughts, but that’s just my 2 cents!

1 Like

HAProxy is another great candidate. I guess I tend to think of HAProxy for load balancing and maybe not for a serving a singe site though, but haven’t got a good rationale for why.

An IoT device could be used just like any other server where you could have the certificates on the device, say for serving webpages. NGINX sits up front with the certificates and something like Cloudflare manages the domains that point to it. LinuxServer have a nice image they maintain with Let’s Encrypt built in to auto generate certificates (GitHub - linuxserver/docker-swag: Nginx webserver and reverse proxy with php support and a built-in Certbot (Let's Encrypt) client. It also contains fail2ban for intrusion prevention.) and could run nicely on a device. I guess as always, it comes down to use case.

Traefik probably deserves a mention too?

+1 that Traefik deserves a mention, especially for simple configuration of reverse proxies.

I found a nice way to configure NGINX was with NGINX Proxy Manager. I have an archived block here that could probably be revived and put on hub if it’s not already there.

1 Like

For someone just starting up and merely wanting to serve pages (or files), caddy would be the right choice IMO. Caddy is the simplest of the 4 (caddy, nginx, haproxy, traefik). Caddy takes care of serving content + fetching Lets Encrypt (or ZeroSSL) certs without even needing a config file. That is an amazingly low barrier for entry.
Of course, there is nothing caddy can do that the others can’t. Just that caddy is low effort and suitable for beginners. If effort and learning curve is not a concern, then my vote goes to Traefik.
Just my 2 cents :v:

I think that is where I am at right now too. Been giving it some more thought, and agree with @klutchell on Traefik deserving a mention, but it feels like a slightly different category of service. I think NGINX often appears because it is lightweight and subsequently ideal for when we want basic serving of content and reserve proxying. If there is lots of scaling going on, then Traefik for sure, or if you really want as simple as possible to configure for those with no technical knowledge, and no interest in reading docs, then NGINX Proxy Manager (although at 200mb+ it is hard to argue it is in the same category for comparison to NGINX). But Traefik and NGINX proxy manager having user interfaces seems too much, and wouldn’t use it in production unless I really really needed that level of complexity in a reverse proxy.

So I think I am back to Caddy as my #1 favourite for now at least. It seems to be the most in line with NGINX in terms of features, purpose etc., doesn’t add user interfaces that I often won’t need, or complex processes that are overkill for basic apps (like Traefik would be for many) but allows much much easier configuration and performance.