all-in-one/reverse-proxy.md

Reverse Proxy Documentation

A reverse proxy is basically a web server that enables computers on the internet to access a service in a private subnet.

Please note: Publishing the AIO interface with a valid certificate to the public internet is not the goal of this documentation! Instead, the main goal is to publish Nextcloud with a valid certificate to the public internet which is not running inside the mastercontainer but in a different container! If you need a valid certificate for the AIO interface, see point 5.

In order to run Nextcloud behind a web server or reverse proxy (like Apache, Nginx and else), you need to specify the port that AIO's Apache container shall use, add a specific config to your web server or reverse proxy and modify the startup command a bit. All examples below will use port 11000 as example Apache port which will be exposed on the host. Modify the port to your needings.

Attention: The process to run Nextcloud behind a reverse proxy consists of at least steps 1, 2 and 4:

1. Configure the reverse proxy! See point 1
2. Use the in this document provided startup command! See point 2
3. Optional: If the reverse proxy is installed on the same host and in the host network, you should limit the apache container to only listen on localhost. See point 3
4. Open the AIO interface. See point 4
5. Optional: Get a valid certificate for the AIO interface! See point 5
6. Optional: How to debug things? See point 6

1. Add this to your reverse proxy config

Please note: Since the Apache container gets created by the mastercontainer, there is NO way to provide custom docker labels or custom environmental variables for the Apache container. So please do not attempt to do this because you will fail! Only the documented way will work!

Apache

click here to expand

Disclaimer: It might be possible that the config below is not working 100% correctly, yet. Improvements to it are very welcome!

Add this as a new Apache site config:

(The config below assumes that you are using certbot to get your certificates. You need to create them first in order to make it work.)

<VirtualHost *:80>
    ServerName <your-nc-domain>

    RewriteEngine On
    RewriteCond %{HTTPS} off
    RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}
    RewriteCond %{SERVER_NAME} =<your-nc-domain>
    RewriteRule ^ https://%{SERVER_NAME}%{REQUEST_URI} [END,NE,R=permanent]
</VirtualHost>

<VirtualHost *:443>
    ServerName <your-nc-domain>

    # Reverse proxy based on https://httpd.apache.org/docs/current/mod/mod_proxy_wstunnel.html
    RewriteEngine On
    ProxyPreserveHost On
    AllowEncodedSlashes NoDecode
    
    ProxyPass / http://localhost:11000/ nocanon
    ProxyPassReverse / http://localhost:11000/
    
    RewriteCond %{HTTP:Upgrade} websocket [NC]
    RewriteCond %{HTTP:Connection} upgrade [NC]
    RewriteCond %{THE_REQUEST} "^[a-zA-Z]+ /(.*) HTTP/\d+(\.\d+)?$"
    RewriteRule .? "ws://localhost:11000/%1" [P,L]

    # Enable h2, h2c and http1.1
    Protocols h2 h2c http/1.1
    
    # Solves slow upload speeds caused by http2
    H2WindowSize 5242880

    # SSL
    SSLEngine on
    Include /etc/letsencrypt/options-ssl-apache.conf
    SSLCertificateFile /etc/letsencrypt/live/<your-nc-domain>/fullchain.pem
    SSLCertificateKeyFile /etc/letsencrypt/live/<your-nc-domain>/privkey.pem

    # Disable HTTP TRACE method.
    TraceEnable off
    <Files ".ht*">
        Require all denied
    </Files>

    # Support big file uploads
    LimitRequestBody 0
</VirtualHost>

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

To make the config work you can run the following command: sudo a2enmod rewrite proxy proxy_http proxy_wstunnel ssl headers http2

Caddy (Recommended)

click here to expand

Add this to your Caddyfile:

https://<your-nc-domain>:443 {
    reverse_proxy localhost:11000
}

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Advice: You may have a look at this for a more complete example.

Caddy with ACME DNS-challenge

click here to expand

You can get AIO running using the ACME DNS-challenge. Here is how to do it.

1. Follow this documentation in order to get a Caddy build that is compatible with your domain provider's DNS challenge.
2. Add this to your Caddyfile:

   https://<your-nc-domain>:443 {
       reverse_proxy localhost:11000
       tls {
           dns <provider> <key>
       }
   }
   

   Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. You also need to adjust <provider> and <key> to match your case. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)
3. Now continue with point 2 but additionally, add --env SKIP_DOMAIN_VALIDATION=true to the docker run command of the mastercontainer (but before the last line nextcloud/all-in-one:latest) which will disable the dommain validation (because it is known that the domain validation will not when using the DNS-challenge since no port is publicly opened.

Advice: In order to make it work in your home network, you may add the internal ipv4-address of your reverse proxy as A DNS-record to your domain and disable the dns-rebind-protection in your router. Another way it to set up a local dns-server like a pi-hole and set up a custom dns-record for that domain that points to the internal ip-adddress of your reverse proxy (see https://github.com/nextcloud/all-in-one#how-can-i-access-nextcloud-locally). If both is not possible, you may add the domain to the hosts file which is needed then for any devices that shall use the server.

Cloudflare Tunnel

click here to expand

Although it does not seems like it is the case but from AIO perspective a Cloudflare Tunnel works like a reverse proxy. Please see the caveats before proceeding. Here is then how to make it work:

1. Install the Cloudflare Tunnel on the same machine where AIO will be running on and point the Tunnel with the domain that you want to use for AIO to http://localhost:11000. If the Tunnel is running on a different machine, you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)
2. Now continue with point 2 but additionally, add --env SKIP_DOMAIN_VALIDATION=true to the docker run command which will disable the dommain validation (because it is known that the domain validation will not work behind a Cloudflare Tunnel). So you need to ensure yourself that you've configured everything correctly.

Advice: Make sure to disable Cloudflares Rocket Loader feature as otherwise Nextcloud's login prompt will not be shown.

HaProxy

click here to expand

Disclaimer: It might be possible that the config below is not working 100% correctly, yet. Improvements to it are very welcome!

Here is an example HaProxy config:

global
    chroot                      /var/haproxy
    log                         /var/run/log audit debug
    lua-prepend-path            /tmp/haproxy/lua/?.lua

defaults
    log     global
    option redispatch -1
    retries 3
    default-server init-addr last,libc

# Frontend: LetsEncrypt_443 ()
frontend LetsEncrypt_443
    bind 0.0.0.0:443 name 0.0.0.0:443 ssl prefer-client-ciphers ssl-min-ver TLSv1.2 ciphers ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES128-SHA256 ciphersuites TLS_AES_128_GCM_SHA256:TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256 crt-list /tmp/haproxy/ssl/605f6609f106d1.17683543.certlist 
    mode http
    option http-keep-alive
    default_backend acme_challenge_backend
    option forwardfor
    # tuning options
    timeout client 30s

    # logging options
    # ACL: find_acme_challenge
    acl acl_605f6d4b6453d2.03059920 path_beg -i /.well-known/acme-challenge/
    # ACL: Nextcloud
    acl acl_60604e669c3ca4.13013327 hdr(host) -i <your-nc-domain>

    # ACTION: redirect_acme_challenges
    use_backend acme_challenge_backend if acl_605f6d4b6453d2.03059920
    # ACTION: Nextcloud
    use_backend Nextcloud if acl_60604e669c3ca4.13013327


# Frontend: LetsEncrypt_80 ()
frontend LetsEncrypt_80
    bind 0.0.0.0:80 name 0.0.0.0:80 
    mode tcp
    default_backend acme_challenge_backend
    # tuning options
    timeout client 30s

    # logging options
    # ACL: find_acme_challenge
    acl acl_605f6d4b6453d2.03059920 path_beg -i /.well-known/acme-challenge/

    # ACTION: redirect_acme_challenges
    use_backend acme_challenge_backend if acl_605f6d4b6453d2.03059920

# Frontend (DISABLED): 1_HTTP_frontend ()

# Frontend (DISABLED): 1_HTTPS_frontend ()

# Frontend (DISABLED): 0_SNI_frontend ()

# Backend: acme_challenge_backend (Added by Let's Encrypt plugin)
backend acme_challenge_backend
    # health checking is DISABLED
    mode http
    balance source
    # stickiness
    stick-table type ip size 50k expire 30m  
    stick on src
    # tuning options
    timeout connect 30s
    timeout server 30s
    http-reuse safe
    server acme_challenge_host 127.0.0.1:43580 

# Backend: Nextcloud ()
backend Nextcloud
    mode http
    balance source
    server Nextcloud localhost:11000 

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Nginx

click here to expand

Disclaimer: It might be possible that the config below is not working 100% correctly, yet. Improvements to it are very welcome!

Add this to you nginx config:

map $http_upgrade $connection_upgrade {
    default upgrade;
    '' close;
}

server {
    listen 80;
    listen [::]:80;            # comment to disable IPv6

    if ($scheme = "http") {
        return 301 https://$host$request_uri;
    }

    listen 443 ssl http2;
    listen [::]:443 ssl http2; # comment to disable IPv6

    server_name <your-nc-domain>;

    location / {
        proxy_pass http://127.0.0.1:11000$request_uri;

        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Port $server_port;
        proxy_set_header X-Forwarded-Scheme $scheme;
        proxy_set_header X-Forwarded-Proto $scheme;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Accept-Encoding "";
        proxy_set_header Host $host;
    
        client_body_buffer_size 512k;
        proxy_read_timeout 86400s;
        client_max_body_size 0;

        # Websocket
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
    }

    ssl_certificate /etc/letsencrypt/live/<your-nc-domain>/fullchain.pem;   # managed by certbot on host machine
    ssl_certificate_key /etc/letsencrypt/live/<your-nc-domain>/privkey.pem; # managed by certbot on host machine

    ssl_session_timeout 1d;
    ssl_session_cache shared:MozSSL:10m; # about 40000 sessions
    ssl_session_tickets off;

    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;
}

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of 127.0.0.1 use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Advice: You may have a look at this for a more complete example.

Nginx-Proxy

click here to expand

Unfortunately it is not possible to configure nginx-proxy in a way that works because it completely relies on environmental variables of the docker containers itself. Providing these variables does not work as stated above.

If you really want to use AIO, we recommend you to switch to caddy. It is simply amazing!
Of course understandable if that is not possible for you.

Apart from that, there is this: manual-install

Nginx-Proxy-Manager

click here to expand

First, please make sure that the environmental variables PUID and PGID in the docker-compose.yml file for NPM are either unset or set to 0.

Second, see these screenshots for a working config:

client_body_buffer_size 512k;
proxy_read_timeout 86400s;
client_max_body_size 0;

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Also change <you>@<your-mail-provider-domain> to a mail address of yours. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Advice: You may have a look at this for a more complete example.

Synology Reverse Proxy

click here to expand

Disclaimer: It might be possible that the config below is not working 100% correctly, yet. Improvements to it are very welcome!

See these screenshots for a working config:

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Traefik 2

click here to expand

Disclaimer: It might be possible that the config below is not working 100% correctly, yet. Improvements to it are very welcome!

Traefik's building blocks (router, service, middlewares) need to be defined using dynamic configuration similar to this official Traefik configuration example. Using docker labels won't work because of the nature of the project.

The examples below define the dynamic configuration in YAML files. If you rather prefer TOML, use a YAML to TOML converter.

1. In Traefik's static configuration define a file provider for dynamic providers:

   # STATIC CONFIGURATION
   
   entryPoints:
       https:
           address: ":443" # Create an entrypoint called "https" that uses port 443
   
   certificatesResolvers:
       # Define "letsencrypt" certificate resolver
       letsencrypt:
           acme:
               storage: /letsencrypt/acme.json # Defines the path where certificates should be stored
               email: <your-email-address> # Where LE sends notification about certificates expiring
               tlschallenge: true
   
   providers:
       file:
           directory: "/path/to/dynamic/conf" # Adjust the path according your needs.
           watch: true
   

2. Declare the router, service and middlewares for Nextcloud in /path/to/dynamic/conf/nextcloud.yml:

   http:
       routers:
           nextcloud:
               rule: "Host(<your-nextcloud-domain>)"
               entrypoints:
                   - "https"
               service: nextcloud
               middlewares:
                   - nextcloud-chain
               tls:
                   certresolver: "letsencrypt"
   
       services:
           nextcloud:
               loadBalancer:
                   servers:
                       - url: "http://localhost:11000" # Use the host's IP address if Traefik runs outside the host network
   
       middlewares:
           nextcloud-secure-headers:
               headers:
                   hostsProxyHeaders:
                       - "X-Forwarded-Host"
                   referrerPolicy: "same-origin"
   
           https-redirect:
               redirectscheme:
                   scheme: https 
   
           nextcloud-chain:
               chain:
                   middlewares:
                       # - ... (e.g. rate limiting middleware)
                       - https-redirect
                       - nextcloud-secure-headers
   

---

Of course you need to modify <your-nextcloud-domain> in the nextcloud.yml to the domain on which you want to run Nextcloud. Also make sure to adjust the port 11000 to match the chosen APACHE_PORT.

Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host option (or network_mode: host for docker-compose) when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Hint: Possibly the following link is useful to understand how AIO configures things: https://github.com/nextcloud/all-in-one/blob/main/manual-install/latest.yml

Others

click here to expand

Config examples for other reverse proxies are currently not documented. Pull requests are welcome!

2. Use this startup command

After adjusting your reverse proxy config, use the following command to start AIO:

(For an docker-compose example, see the example further below.)

# For Linux:
sudo docker run \
--sig-proxy=false \
--name nextcloud-aio-mastercontainer \
--restart always \
--publish 8080:8080 \
--env APACHE_PORT=11000 \
--env APACHE_IP_BINDING=0.0.0.0 \
--volume nextcloud_aio_mastercontainer:/mnt/docker-aio-config \
--volume /var/run/docker.sock:/var/run/docker.sock:ro \
nextcloud/all-in-one:latest

Note: You may be interested in adjusting Nextcloud’s datadir to store the files in a different location than the default docker volume. See this documentation on how to do it.

You should also think about limiting the apache container to listen only on localhost in case the reverse proxy is running on the same host and in the host network, by providing an additional environmental variable to this docker run command. See point 3.

On macOS see https://github.com/nextcloud/all-in-one#how-to-run-aio-on-macos.

Command for Windows

On Windows, install Docker Desktop (and don't forget to enable ipv6 if you should need that) and run the following command in the command prompt:

docker run ^
--sig-proxy=false ^
--name nextcloud-aio-mastercontainer ^
--restart always ^
--publish 8080:8080 ^
--env APACHE_PORT=11000 ^
--env APACHE_IP_BINDING=0.0.0.0 ^
--volume nextcloud_aio_mastercontainer:/mnt/docker-aio-config ^
--volume //var/run/docker.sock:/var/run/docker.sock:ro ^
nextcloud/all-in-one:latest

Also, you may be interested in adjusting Nextcloud's Datadir to store the files on the host system. See this documentation on how to do it.

On Synology DSM see https://github.com/nextcloud/all-in-one#how-to-run-aio-on-synology-dsm

Inspiration for a docker-compose file

Simply translate the docker run command into a docker-compose file. You can have a look at this file for some inspiration but you will need to modify it either way. You can find further examples here: https://github.com/nextcloud/all-in-one/discussions/588

3. Limit the access to the apache container

Use this envorinmental variable during the initial startup of the mastercontainer to make the apache container only listen on localhost: --env APACHE_IP_BINDING=127.0.0.1. Attention: This is only recommended to be set if you use localhost in your reverse proxy config to connect to your AIO instance. If you use an ip-address instead of localhost, you should set it to 0.0.0.0.

4. Open the AIO interface.

After starting AIO, you should be able to access the AIO Interface via https://ip.address.of.the.host:8080. Enter your domain that you've entered in the reverse proxy config and you should be done. Please do not forget to open/forward port 3478/TCP and 3478/UDP in your firewall/router for the Talk container!

5. Optional: get a valid certificate for the AIO interface

If you want to also access your AIO interface publicly with a valid certificate, you can add e.g. the following config to your Caddyfile:

https://<your-nc-domain>:8443 {
    reverse_proxy https://localhost:8080 {
        transport http {
            tls_insecure_skip_verify
        }
    }
}

Of course you need to modify <your-nc-domain> to the domain on which you want to run Nextcloud. Please note: The above configuration will only work if your reverse proxy is running directly on the host that is running the docker daemon. If the reverse proxy is running in a docker container, you can use the --network host when starting the reverse proxy container in order to connect the reverse proxy container to the host network. If that is not an option or not possible for you (like e.g. on Windows or if the reverse proxy is running on a different host), you can alternatively instead of localhost use the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)

Afterwards should the AIO interface be accessible via https://ip.address.of.the.host:8443. You can alternatively change the domain to a different subdomain by using https://<your-alternative-domain>:443 instead of https://<your-nc-domain>:8443 in the Caddyfile and use that to access the AIO interface.

6. How to debug things?

If something does not work, follow the steps below:

1. Make sure to exactly follow the whole reverse proxy documentation step-for-step from top to bottom!
2. Make sure that you used the docker run command that is described in this reverse proxy documentation.
3. Make sure to set the APACHE_IP_BINDING variable correctly. If in doubt, set it to --env APACHE_IP_BINDING=0.0.0.0
4. Make sure that all ports match the chosen APACHE_PORT.
5. Make sure that the reverse proxy is running on the host OS or if running in a container, connected to the host network. If that is not possible (e.g. on Windows or if the reverse proxy is running on a different host), substitute localhost or 127.0.0.1 in the default configurations by the private ip-address of the host that is running the docker daemon. If you are not sure how to retrieve that, you can run: ip a | grep "scope global" | head -1 | awk '{print $2}' | sed 's|/.*||'. If the command returns a public ip-address, use ip a | grep "scope global" | grep docker0 | awk '{print $2}' | sed 's|/.*||' instead (the commands only work on Linux)
6. Make sure that the mastercontainer is able to spawn other containers. You can do so by checking that the mastercontainer indeed has access to the Docker socket which might not be positioned in one of the suggested directories like /var/run/docker.sock but in a different directory, based on your OS and the way how you installed Docker. The mastercontainer logs should help figuring this out. You can have a look at them by running sudo docker logs nextcloud-aio-mastercontainer after the container is started the first time.
7. Check if after the mastercontainer was started, the reverse proxy if running inside a container, can reach the provided apache port. You can test this by running nc -z localhost 11000; echo $? from inside the reverse proxy container. If the output is 0, everything works. Alternatively you can of course use instead of localhost the ip-address of the host here for the test.
8. Make sure that you are not behind CGNAT. If that is the case, you will not be able to open ports properly. In that case you might use a Cloudflare Tunnel.
9. If you use Cloudflare, you might need to skip the domain validation anyways since it is known that Cloudflare might block the validation attempts. In that case, see the last option below.
10. Check if you have a public IPv4- and public IPv6-address. If you only have a public IPv6-address (e.g. due to DS-Lite), make sure to enable IPv6 in Docker and your whole networking infrastructure (e.g. also by adding an AAAA DNS-entry to your domain).
11. Try to configure everything from scratch if it still does not work by following https://github.com/nextcloud/all-in-one#how-to-properly-reset-the-instance.
12. As last resort, you may disable the domain validation by adding --env SKIP_DOMAIN_VALIDATION=true to the docker run command. But only use this if you are completely sure that you've correctly configured everything!