Proxy examples

In this document, <SERVER> refers to the IP or domain where you access vaultwarden. If both the reverse proxy and vaultwarden are running on the same system, simply use localhost.

By default, vaultwarden listens on port 80 for web (REST API) traffic and on port 3012 for WebSocket traffic (if WebSocket notifications are enabled). The reverse proxy should be configured to terminate SSL/TLS connections (preferably on port 443, the standard port for HTTPS). The reverse proxy then passes incoming client requests to vaultwarden on port 80 or 3012 as appropriate, and upon receiving a response from vaultwarden, passes that response back to the client.

Note that when you put vaultwarden behind a reverse proxy, the connections between the reverse proxy and vaultwarden are typically assumed to be going through a secure private network, and thus do not need to be encrypted. The examples below assume you are running in this configuration, in which case you should not enable the HTTPS functionality built into vaultwarden (i.e., you should not set the ROCKET_TLS environment variable). If you do, connections will fail since the reverse proxy is using HTTP to connect to vaultwarden, but you're configuring vaultwarden to expect HTTPS.

It's common to use Docker Compose to link containerized services together (e.g., vaultwarden and a reverse proxy). See Using Docker Compose for an example of this.

Secure TLS protocol and cipher configurations for webservers can be generated using Mozilla's SSL Configuration Generator. All supported browsers and the Mobile apps are known to work with the "Modern" configuration.

Caddy 2.x

Caddy 2 will automatically enable HTTPS in most circumstances, check the docs.

In the Caddyfile syntax, {$VAR} denotes the value of the environment variable VAR. If you prefer, you can also directly specify a value instead of substituting an env var value.

{$DOMAIN} {
  log {
    level INFO
    output file {$LOG_FILE} {
      roll_size 10MB
      roll_keep 10
    }
  }

  # Uncomment this if you want to get a cert via ACME (Let's Encrypt or ZeroSSL).
  # tls {$EMAIL}

  # Or uncomment this if you're providing your own cert. You would also use this option
  # if you're running behind Cloudflare.
  # tls {$SSL_CERT_PATH} {$SSL_KEY_PATH}

  # This setting may have compatibility issues with some browsers
  # (e.g., attachment downloading on Firefox). Try disabling this
  # if you encounter issues.
  encode gzip

  # Uncomment to improve security (WARNING: only use if you understand the implications!)
  # header {
  #      # Enable HTTP Strict Transport Security (HSTS)
  #      Strict-Transport-Security "max-age=31536000;"
  #      # Enable cross-site filter (XSS) and tell browser to block detected attacks
  #      X-XSS-Protection "1; mode=block"
  #      # Disallow the site to be rendered within a frame (clickjacking protection)
  #      X-Frame-Options "DENY"
  #      # Prevent search engines from indexing (optional)
  #      X-Robots-Tag "none"
  #      # Server name removing
  #      -Server
  # }

  # Uncomment to allow access to the admin interface only from local networks
  # @insecureadmin {
  #   not remote_ip 192.168.0.0/16 172.16.0.0/12 10.0.0.0/8
  #   path /admin*
  # }
  # redir @insecureadmin /

  # Notifications redirected to the websockets server
  reverse_proxy /notifications/hub <SERVER>:3012

  # Proxy everything else to Rocket
  reverse_proxy <SERVER>:80 {
       # Send the true remote IP to Rocket, so that vaultwarden can put this in the
       # log, so that fail2ban can ban the correct IP.
       header_up X-Real-IP {remote_host}
  }
}

lighttpd (by forkbomb9)

server.modules += ( "mod_proxy" )

$HTTP["host"] == "vault.example.net" {
    $HTTP["url"] == "/notifications/hub" {
       # WebSocket proxy
       proxy.server  = ( "" => ("vaultwarden" => ( "host" => "<SERVER>", "port" => 3012 )))
       proxy.forwarded = ( "for" => 1 )
       proxy.header = (
           "https-remap" => "enable",
           "upgrade" => "enable",
           "connect" => "enable"
       )
    } else {
       proxy.server  = ( "" => ("vaultwarden" => ( "host" => "<SERVER>", "port" => 4567 )))
       proxy.forwarded = ( "for" => 1 )
       proxy.header = ( "https-remap" => "enable" )
    }
}

You'll have to set IP_HEADER to X-Forwarded-For instead of X-Real-IP in the Vaultwarden environment.

Nginx (by blackdex)

# The `upstream` directives ensure that you have a http/1.1 connection
# This enables the keepalive option and better performance
#
# Define the server IP and ports here.
upstream vaultwarden-default {
  zone vaultwarden-default 64k;
  server 127.0.0.1:8080;
  keepalive 2;
}
upstream vaultwarden-ws {
  zone vaultwarden-ws 64k;
  server 127.0.0.1:3012;
  keepalive 2;
}

# Redirect HTTP to HTTPS
server {
    listen 80;
    listen [::]:80;
    server_name vaultwarden.example.tld;
    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name vaultwarden.example.tld;

    # Specify SSL Config when needed
    #ssl_certificate /path/to/certificate/letsencrypt/live/vaultwarden.example.tld/fullchain.pem;
    #ssl_certificate_key /path/to/certificate/letsencrypt/live/vaultwarden.example.tld/privkey.pem;
    #ssl_trusted_certificate /path/to/certificate/letsencrypt/live/vaultwarden.example.tld/fullchain.pem;

    client_max_body_size 128M;

    location / {
      proxy_http_version 1.1;
      proxy_set_header "Connection" "";

      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 $scheme;

      proxy_pass http://vaultwarden-default;
    }

    location /notifications/hub/negotiate {
      proxy_http_version 1.1;
      proxy_set_header "Connection" "";

      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 $scheme;

      proxy_pass http://vaultwarden-default;
    }

    location /notifications/hub {
      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 Forwarded $remote_addr;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header X-Forwarded-Proto $scheme;

      proxy_pass http://vaultwarden-ws;
    }

    # Optionally add extra authentication besides the ADMIN_TOKEN
    # Remove the comments below `#` and create the htpasswd_file to have it active
    #
    #location /admin {
    #  # See: https://docs.nginx.com/nginx/admin-guide/security-controls/configuring-http-basic-authentication/
    #  auth_basic "Private";
    #  auth_basic_user_file /path/to/htpasswd_file;
    #
    #  proxy_http_version 1.1;
    #  proxy_set_header "Connection" "";
    #
    #  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 $scheme;
    #
    #  proxy_pass http://vaultwarden-default;
    #}
}

If you run into 504 Gateway Timeout problems, tell nginx to wait longer for vaultwarden by adding longer timeouts to the server { section, for example:

  proxy_connect_timeout       777;
  proxy_send_timeout          777;
  proxy_read_timeout          777;
  send_timeout                777;

Nginx with sub-path (by BlackDex)

In this example vaultwarden will be available via https://bitwarden.example.tld/vault/
If you want to use any other sub-path, like bitwarden or secret-vault you should change /vault/ in the example below to match.

For this to work you need to configure your DOMAIN variable to match so it should look like:

; Add the sub-path! Else this will not work!
DOMAIN=https://bitwarden.example.tld/vault/

# The `upstream` directives ensure that you have a http/1.1 connection
# This enables the keepalive option and better performance
#
# Define the server IP and ports here.
upstream vaultwarden-default {
  zone vaultwarden-default 64k;
  server 127.0.0.1:8080;
  keepalive 2;
}
upstream vaultwarden-ws {
  zone vaultwarden-ws 64k;
  server 127.0.0.1:3012;
  keepalive 2;
}

# Redirect HTTP to HTTPS
server {
    if ($host = bitwarden.example.tld) {
        return 301 https://$host$request_uri;
    }


    listen 80;
    listen [::]:80;
    server_name bitwarden.example.tld;
    return 404;


}


server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name vaultwarden.example.tld;

    # Specify SSL Config when needed
    #ssl_certificate /path/to/certificate/letsencrypt/live/vaultwarden.example.tld/fullchain.pem;
    #ssl_certificate_key /path/to/certificate/letsencrypt/live/vaultwarden.example.tld/privkey.pem;
    #ssl_trusted_certificate /path/to/certificate/letsencrypt/live/vaultwarden.example.tld/fullchain.pem;

    client_max_body_size 128M;

    ## Using a Sub Path Config
    # Path to the root of your installation
    # Be sure to add the trailing /, else you could have issues
    location /vault/ {
      proxy_http_version 1.1;
      proxy_set_header "Connection" "";

      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 $scheme;

      proxy_pass http://vaultwarden-default;
    }

    location /vault/notifications/hub/negotiate {
      proxy_http_version 1.1;
      proxy_set_header "Connection" "";

      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 $scheme;

      proxy_pass http://vaultwarden-default;
    }

    location /vault/notifications/hub {
      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 Forwarded $remote_addr;
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header X-Forwarded-Proto $scheme;

      proxy_pass http://vaultwarden-ws;
    }

    # Optionally add extra authentication besides the ADMIN_TOKEN
    # Remove the comments below `#` and create the htpasswd_file to have it active
    #
    #location /vault/admin {
    #  # See: https://docs.nginx.com/nginx/admin-guide/security-controls/configuring-http-basic-authentication/
    #  auth_basic "Private";
    #  auth_basic_user_file /path/to/htpasswd_file;
    #
    #  proxy_http_version 1.1;
    #  proxy_set_header "Connection" "";
    #
    #  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 $scheme;
    #
    #  proxy_pass http://vaultwarden-default;
    #}
}

Nginx (by ypid)

Ansible inventory example that uses DebOps to configure nginx as a reverse proxy for vaultwarden. I choose to go with the PSK in the URL for additional security to not expose the API to everyone on the Internet because the client apps do not support client certificates yet (I tested it). Note: Using subpath/PSK requires to patch the source code and recompile, ref: https://github.com/dani-garcia/vaultwarden/issues/241#issuecomment-436376497. /admin is untested. For general discussion about subpath hosting for security refer to: https://github.com/debops/debops/issues/1233

bitwarden__fqdn: 'vault.example.org'

nginx__upstreams:

  - name: 'bitwarden'
    type: 'default'
    enabled: True
    server: 'localhost:8000'

nginx__servers:

  - name: '{{ bitwarden__fqdn }}'
    filename: 'debops.bitwarden'
    by_role: 'debops.bitwarden'
    favicon: False
    root: '/usr/share/vaultwarden/web-vault'

    location_list:

      - pattern: '/'
        options: |-
          deny all;

      - pattern: '= /ekkP9wtJ_psk_changeme_Hr9CCTud'
        options: |-
          return 307 $scheme://$host$request_uri/;

      ## All the security HTTP headers would then need to be set by nginx as well.
      # - pattern: '/ekkP9wtJ_psk_changeme_Hr9CCTud/'
      #   options: |-
      #     alias /usr/share/vaultwarden/web-vault/;

      - pattern: '/ekkP9wtJ_psk_changeme_Hr9CCTud/'
        options: |-
          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 $scheme;
          proxy_set_header X-Forwarded-Port  443;

          proxy_pass http://bitwarden;

      ## Do not use the icons features as long as it reveals all domains from
      ## our credentials to the server.
      - pattern: '/ekkP9wtJ_psk_changeme_Hr9CCTud/icons/'
        options: |-
          access_log off;
          log_not_found off;
          deny all;

Nginx (NixOS)(by tklitschi)

Example NixOS nginx config. For more Information about NixOS Deployment see Deployment Wiki page.

{ config, ... }:
{
  security.acme.acceptTerms = true;
  security.acme.email = "me@example.com";
  security.acme.certs = {

    "vw.example.com" = {
      group = "vaultwarden";
      keyType = "rsa2048";
      allowKeysForGroup = true;
    };
  };

  services.nginx = {
    enable = true;

    recommendedGzipSettings = true;
    recommendedOptimisation = true;
    recommendedProxySettings = true;
    recommendedTlsSettings = true;

    virtualHosts = {
      "vw.example.com" = {
        forceSSL = true;
        enableACME = true;
        locations."/" = {
          proxyPass = "http://localhost:8812"; #changed the default rocket port due to some conflict
          proxyWebsockets = true;
        };
        locations."/notifications/hub" = {
          proxyPass = "http://localhost:3012";
          proxyWebsockets = true;
        };
        locations."/notifications/hub/negotiate" = {
          proxyPass = "http://localhost:8812";
          proxyWebsockets = true;
        };
      };
    };
  };
}

Apache (by fbartels)

Remember to enable mod_proxy_wstunnel and mod_proxy_http, for example with: a2enmod proxy_wstunnel and a2enmod proxy_http.

<VirtualHost *:443>
    SSLEngine on
    ServerName bitwarden.$hostname.$domainname

    SSLCertificateFile ${SSLCERTIFICATE}
    SSLCertificateKeyFile ${SSLKEY}
    SSLCACertificateFile ${SSLCA}
    ${SSLCHAIN}

    ErrorLog \${APACHE_LOG_DIR}/bitwarden-error.log
    CustomLog \${APACHE_LOG_DIR}/bitwarden-access.log combined

    RewriteEngine On
    RewriteCond %{HTTP:Upgrade} =websocket [NC]
    RewriteRule /notifications/hub(.*) ws://<SERVER>:3012/$1 [P,L]
    ProxyPass / http://<SERVER>:80/

    ProxyPreserveHost On
    ProxyRequests Off
    RequestHeader set X-Real-IP %{REMOTE_ADDR}s
</VirtualHost>

Apache in a sub-location (by ss89)

Modify your docker start-up to include the sub-location.

; Add the sub-location! Else this will not work!
DOMAIN=https://$hostname.$domainname/$sublocation/

Ensure you have the websocket proxy module loaded somewhere in your apache config. It can look something like:

LoadModule proxy_wstunnel_module modules/mod_proxy_wstunnel.so`

On some OS's you can use a2enmod, for example with: a2enmod proxy_wstunnel and a2enmod proxy_http.

<VirtualHost *:443>
    SSLEngine on
    ServerName $hostname.$domainname

    SSLCertificateFile ${SSLCERTIFICATE}
    SSLCertificateKeyFile ${SSLKEY}
    SSLCACertificateFile ${SSLCA}
    ${SSLCHAIN}

    ErrorLog \${APACHE_LOG_DIR}/error.log
    CustomLog \${APACHE_LOG_DIR}/access.log combined

    <Location /$sublocation/> #adjust here if necessary
        RewriteEngine On
        RewriteCond %{HTTP:Upgrade} =websocket [NC]
        RewriteRule /notifications/hub(.*) ws://<SERVER>:3012/$1 [P,L]
        ProxyPass http://<SERVER>:80/$sublocation/

        ProxyPreserveHost On
        RequestHeader set X-Real-IP %{REMOTE_ADDR}s
    </Location>
</VirtualHost>

Traefik v1 (docker-compose example)

labels:
    - traefik.enable=true
    - traefik.docker.network=traefik
    - traefik.web.frontend.rule=Host:bitwarden.domain.tld
    - traefik.web.port=80
    - traefik.hub.frontend.rule=Host:bitwarden.domain.tld;Path:/notifications/hub
    - traefik.hub.port=3012
    - traefik.hub.protocol=ws

Traefik v2 (docker-compose example by hwwilliams)

Traefik v1 labels migrated to Traefik v2

labels:
  - traefik.enable=true
  - traefik.docker.network=traefik
  - traefik.http.routers.bitwarden-ui.rule=Host(`bitwarden.domain.tld`)
  - traefik.http.routers.bitwarden-ui.service=bitwarden-ui
  - traefik.http.services.bitwarden-ui.loadbalancer.server.port=80
  - traefik.http.routers.bitwarden-websocket.rule=Host(`bitwarden.domain.tld`) && Path(`/notifications/hub`)
  - traefik.http.routers.bitwarden-websocket.service=bitwarden-websocket
  - traefik.http.services.bitwarden-websocket.loadbalancer.server.port=3012

Migrated labels plus HTTP to HTTPS redirect

These labels assume that the entrypoints defined in Traefik for port 80 and 443 are 'web' and 'websecure' respectively.

These labels also assume you already have a default certificates resolver defined in Traefik.

labels:
  - traefik.enable=true
  - traefik.docker.network=traefik
  - traefik.http.middlewares.redirect-https.redirectScheme.scheme=https
  - traefik.http.middlewares.redirect-https.redirectScheme.permanent=true
  - traefik.http.routers.bitwarden-ui-https.rule=Host(`bitwarden.domain.tld`)
  - traefik.http.routers.bitwarden-ui-https.entrypoints=websecure
  - traefik.http.routers.bitwarden-ui-https.tls=true
  - traefik.http.routers.bitwarden-ui-https.service=bitwarden-ui
  - traefik.http.routers.bitwarden-ui-http.rule=Host(`bitwarden.domain.tld`)
  - traefik.http.routers.bitwarden-ui-http.entrypoints=web
  - traefik.http.routers.bitwarden-ui-http.middlewares=redirect-https
  - traefik.http.routers.bitwarden-ui-http.service=bitwarden-ui
  - traefik.http.services.bitwarden-ui.loadbalancer.server.port=80
  - traefik.http.routers.bitwarden-websocket-https.rule=Host(`bitwarden.domain.tld`) && Path(`/notifications/hub`)
  - traefik.http.routers.bitwarden-websocket-https.entrypoints=websecure
  - traefik.http.routers.bitwarden-websocket-https.tls=true
  - traefik.http.routers.bitwarden-websocket-https.service=bitwarden-websocket
  - traefik.http.routers.bitwarden-websocket-http.rule=Host(`bitwarden.domain.tld`) && Path(`/notifications/hub`)
  - traefik.http.routers.bitwarden-websocket-http.entrypoints=web
  - traefik.http.routers.bitwarden-websocket-http.middlewares=redirect-https
  - traefik.http.routers.bitwarden-websocket-http.service=bitwarden-websocket
  - traefik.http.services.bitwarden-websocket.loadbalancer.server.port=3012

HAproxy (by BlackDex)

Add these lines to your haproxy configuration.

frontend vaultwarden
    bind 0.0.0.0:80
    option forwardfor header X-Real-IP
    http-request set-header X-Real-IP %[src]
    default_backend vaultwarden_http
    use_backend vaultwarden_ws if { path_beg /notifications/hub } !{ path_beg /notifications/hub/negotiate }

backend vaultwarden_http
    # Enable compression if you want
    # compression algo gzip
    # compression type text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript
    server vwhttp 0.0.0.0:8080

backend vaultwarden_ws
    server vwws 0.0.0.0:3012

HAproxy (by @williamdes)

Add these lines to your HAproxy configuration.

backend static-success-default
  mode http
  errorfile 503 /usr/local/etc/haproxy/static/index.static.default.html
  errorfile 200 /usr/local/etc/haproxy/static/index.static.default.html

frontend http-in
    bind *:80
    bind *:443 ssl crt /acme.sh/domain.tld/domain.tld.pem
    option forwardfor header X-Real-IP
    http-request set-header X-Real-IP %[src]
    default_backend static-success-default

    # Define hosts
    acl host_bitwarden_domain_tld hdr(Host) -i bitwarden.domain.tld

    ## figure out which one to use
    use_backend vaultwarden_http if host_bitwarden_domain_tld !{ path_beg /notifications/hub } or { path_beg /notifications/hub/negotiate }
    use_backend vaultwarden_ws if host_bitwarden_domain_tld { path_beg /notifications/hub } !{ path_beg /notifications/hub/negotiate }

backend vaultwarden_http
    # Enable compression if you want
    # compression algo gzip
    # compression type text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript
    # You can use the container hostname if you are using haproxy with docker-compose
    server vw_http 0.0.0.0:8080

backend vaultwarden_ws
    # You can use the container hostname if you are using haproxy with docker-compose
    server vw_ws 0.0.0.0:3012

HAproxy inside PfSense (by @RichardMawdsley)

Being a GUI setup, details\instructions below for you to add where required.

• Assumes you already have basic HTTP>HTTPS Redirection setup Basic Setup

Backend Creation

Backend 1:

Mode	Name	                   Forwardto	     Address	     Port	 Encrypt(SSL)	SSL checks	Weight	Actions
active 	Vaultwarden                Address+Port:     IPADDRESSHERE   80          no             no

Backend 2:

Mode	Name	                   Forwardto	     Address	     Port	 Encrypt(SSL)	SSL checks	Weight	Actions
active 	Vaultwarden-Notifications  Address+Port:     IPADDRESSHERE   3012        no             no

Frontend Creation - 1 - Domain

ACCESS CONTROL LIST

ACL00
Host matches:
no
no
FQDN.com     -  NOTE:  This needs to be your root domain.  
 	
ACL00
Path starts with:
no
yes
/big-ass-randomised-test-that-really-no-one-is-ever-going-to-type-DONT-USE-THIS-LINE-THOUGH-make-your-own-up

ACL01
Host matches:
no
no
VAULTWARDEN.MYDOMAIN.COM

ACL01
Host matches:
no
no
EXAMPLE-OTHER-SUB-DOMAIN-1.MYDOMAIN.COM

ACL01
Host matches:
no
no
EXAMPLE-OTHER-SUB-DOMAIN-2.MYDOMAIN.COM

ACTIONS - 1 - Domain

http-request allow
See below
ACL01

http-request deny
See below
ACL00

Frontend Creation - 2 - VaultWarden

ACCESS CONTROL LIST

ACL1
Path starts with:
no
yes
/notifications/hub  
 	
ACL2
Path starts with:
no
no
/notifications/hub/negotiate  
 	
ACL3
Path starts with:
no
no
/notifications/hub  
 	
ACL4
Path starts with:
no
yes
/notifications/hub/negotiate

ACL5
Path starts with:
no
no
/admin

ACTIONS - 2 - VaultWarden

Use Backend
See below
ACL1  
backend: VaultWarden
 	
Use Backend
See below
ACL2  
backend: VaultWarden
 	
Use Backend
See below
ACL3  
backend: VaultWarden-Notifications
 	
Use Backend
See below
ACL4
backend: VaultWarden-Notifications

http-request deny
See below
ACL5

Updates

Updated above 30/07 - I realised after the first config that because ACL1-4 have 'Not' in, they were matching anything to their actions.  So BlahBlahMcGee.FQDN.com was passing through.  This was not intended, so ACL5 has been added above which resolves this, it also removes the need for the default backend.
Updated again 30/07 - ^ Yeah that didnt work.  This all stems because HaProxy doesnt allow for 'AND' in ACL's. Sigh.  Now with the above, you cofigure a front end for you root domain.  This has a deny for itself, and anything not specified.  So if you have multiple other subdomains you're passing through, you need to add them here all under ACL01.  Now everything works as it should!

Important Notes

1) You must keep the Domain FrontEnd up to date with any other sub domains on an allow list
2) On the Domain FrontEnd, ACL01 must be top of the Actions table - or atleast above ACL00
3) Duplicate Use of ACL names is intentional. No I havent typoed them.  ACL00, ACL01 etc

OPTIONAL

ACL5 above denies access to the /admin portal.  I'm not particually fond of the admin portal not having any form of 2FA and only a password.  Thus when I'm not using it, I just deny access.  If I need it, unblock, do the required job and reblock.

Complete! - Go test!

This in turn will add the equivilent of below to your config (note this is an extract for example).

acl			ACL00	var(txn.txnhost) -m str -i VAULTWARDEN.MYDOMAIN.COM
acl			ACL00	var(txn.txnpath) -m beg -i /big-ass-randomised-test-that-really-no-one-is-ever-going-to-type-DONT-USE-THIS-LINE-THOUGH-make-your-own-up
acl			ACL01	var(txn.txnhost) -m str -i EXAMPLE-OTHER-SUB-DOMAIN-1.MYDOMAIN.COM
acl			ACL01	var(txn.txnhost) -m str -i EXAMPLE-OTHER-SUB-DOMAIN-2.MYDOMAIN.COM
acl			ACL1	var(txn.txnpath) -m beg -i /notifications/hub
acl			ACL2	var(txn.txnpath) -m beg -i /notifications/hub/negotiate
acl			ACL3	var(txn.txnpath) -m beg -i /notifications/hub
acl			ACL4	var(txn.txnpath) -m beg -i /notifications/hub/negotiate
acl			ACL5	var(txn.txnpath) -m beg -i /admin

http-request allow  if  ACL01 
http-request deny   if  !ACL00 
http-request deny   if  !ACL5 
http-request deny   if  ACL5 
use_backend VaultWarden_ipvANY  if  !ACL1 
use_backend VaultWarden_ipvANY  if  ACL2 
use_backend VaultWarden-Notifications_ipvANY  if  ACL3 
use_backend VaultWarden-Notifications_ipvANY  if  !ACL4 

To test, if you navigate in a browser to /notifications/hub then you should get a page saying "WebSocket Protocol Error: Unable to parse WebSocket key.".. that means its working! - all other sub pages should get a Rocket error.

Istio k8s (by @dpoke)

apiVersion: networking.istio.io/v1beta1
kind: Gateway
metadata:
  name: vaultwarden-gateway
  namespace: vaultwarden
spec:
  selector:
    istio: ingressgateway-internal # use Istio default gateway implementation
  servers:
  - hosts:
    - vw.k8s.prod
    port:
      number: 80
      name: http
      protocol: HTTP
    tls:
      httpsRedirect: true
  - hosts:
    - vw.k8s.prod
    port:
      name: https-443
      number: 443
      protocol: HTTPS
    tls:
      mode: SIMPLE
      credentialName: vw-k8s-prod-tls
---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: vaultwarden-vs
  namespace: vaultwarden
spec:
  hosts:
  - vw.k8s.prod
  gateways:
  - vaultwarden-gateway
  http:
  - match:
    - uri:
        exact: /notifications/hub
    route:
    - destination:
        port:
          number: 3012
        host: vaultwarden-ws
  - match:
    - uri:
        prefix: /
    route:
    - destination:
        port:
          number: 80
        host: vaultwarden