docs(docker): Rewrite Docker DNS workaround with custom resolv.conf

Instead of /etc/resolv.conf on host. This works around the
systemd-resolved footgunning issue and provide an inline way to
configure resolvers, separate from that of the host system.

docs/deploying/docker.mdx

@@ -112,19 +112,25 @@ See the [reference configuration](../reference/config) page for all config optio
 
 These examples include reverse proxy configurations for Matrix federation, which will route your Matrix domain (and optionally .well-known paths) to Continuwuity.
 
-:::note DNS Performance
-Docker's default DNS resolver can cause performance issues with Matrix
-federation. If you experience slow federation or DNS timeouts, you may need to
-use your host's DNS resolver instead. Add this volume mount to the
-`continuwuity` service:
+:::note Docker DNS Performance
+Docker's default DNS resolver are known to cause issues for Matrix federation, such as very slow federation or DNS timeout. As a workaround, we will mount a custom `/etc/resolv.conf` config file into the Continuwuity service, in order to bypass Docker and use a more performant resolver.
 
-```yaml
-volumes:
-  - /etc/resolv.conf:/etc/resolv.conf:ro
+```yaml title='docker-compose.yml'
+services:
+  homeserver:
+    # ...
+    configs:
+      - source: continuwuity-resolv.conf
+        target: /etc/resolv.conf
+
+configs:
+  continuwuity-resolv.conf:
+    content: |
+      nameserver 1.0.0.1
+      nameserver 1.1.1.1
 ```
 
-See [Troubleshooting - DNS Issues](../troubleshooting.mdx#potential-dns-issues-when-using-docker)
-for more details and alternative solutions.
+See [**Troubleshooting - DNS Issues**](../troubleshooting.mdx#potential-dns-issues-when-using-docker) for more details and alternative solutions.
 :::
 
 #### Caddy (using Caddyfile)
@@ -197,9 +203,9 @@ You will then need to point your reverse proxy towards Continuwuity at `127.0.0.
 
 ### Starting Your Server
 
-1. Choose your compose file and rename it to `docker-compose.yml`
+1. Choose your compose file from the above, and rename it to `docker-compose.yml`. Edit values as you see fit.
 2. If using the override file, rename it to `docker-compose.override.yml` and
-   edit your values
+   edit your values.
 3. Start the server:
 
     ```bash

docs/public/deploying/docker-compose.for-traefik.yml

@@ -39,6 +39,9 @@ services:
       nofile:
         soft: 1048567
         hard: 1048567
+    configs: # using custom resolver instead of Docker's
+      - source: continuwuity-resolv.conf
+        target: /etc/resolv.conf
 
 volumes:
   db:
@@ -48,3 +51,9 @@ networks:
   # name, don't forget to change it here and in the docker-compose.override.yml
   proxy:
     external: true
+
+configs:
+  continuwuity-resolv.conf:
+    content: |
+      nameserver 1.0.0.1
+      nameserver 1.1.1.1

docs/public/deploying/docker-compose.with-caddy-labels.yml

@@ -24,7 +24,6 @@ services:
         command: /sbin/conduwuit
         volumes:
             - db:/var/lib/continuwuity
-            - /etc/resolv.conf:/etc/resolv.conf:ro # Use the host's DNS resolver rather than Docker's.
             #- ./continuwuity.toml:/etc/continuwuity.toml
         environment:
             CONTINUWUITY_SERVER_NAME: example.com # EDIT THIS
@@ -41,9 +40,18 @@ services:
         labels:
             caddy: matrix.example.com
             caddy.reverse_proxy: "{{upstreams 8008}}"
-
+        configs: # using custom resolver instead of Docker's
+            - source: continuwuity-resolv.conf
+              target: /etc/resolv.conf
 volumes:
     db:
 
 networks:
     caddy:
+
+configs:
+    continuwuity-resolv.conf:
+        content: |
+            nameserver 1.0.0.1
+            nameserver 1.1.1.1
+

docs/public/deploying/docker-compose.with-caddy.yml

@@ -1,16 +1,3 @@
-networks:
-    caddy:
-
-volumes:
-    db:
-
-configs:
-    dynamic.yml:
-        content: |
-            https://example.com, https://example.com:8448 {
-                reverse_proxy http://homeserver:8008
-            }
-
 services:
     caddy:
         image: docker.io/caddy:latest
@@ -33,7 +20,6 @@ services:
         command: /sbin/conduwuit
         volumes:
             - db:/var/lib/continuwuity
-            - /etc/resolv.conf:/etc/resolv.conf:ro # Use the host's DNS resolver rather than Docker's.
             #- ./continuwuity.toml:/etc/continuwuity.toml
         environment:
             CONTINUWUITY_SERVER_NAME: example.com
@@ -42,4 +28,25 @@ services:
             CONTINUWUITY_PORT: 8008
             #CONTINUWUITY_CONFIG: '/etc/continuwuity.toml' # Uncomment if you mapped config toml above
         networks:
-            - caddy
+            - caddy
+        configs: # using custom resolvers instead of Docker's
+            - source: continuwuity-resolv.conf
+              target: /etc/resolv.conf
+
+networks:
+    caddy:
+
+volumes:
+    db:
+
+configs:
+    dynamic.yml:
+        content: |
+            https://example.com, https://example.com:8448 {
+                reverse_proxy http://homeserver:8008
+            }
+
+    continuwuity-resolv.conf:
+        content: |
+            nameserver 1.0.0.1
+            nameserver 1.1.1.1

docs/public/deploying/docker-compose.with-traefik.yml

@@ -7,7 +7,6 @@ services:
     command: /sbin/conduwuit
     volumes:
       - db:/var/lib/continuwuity
-      - /etc/resolv.conf:/etc/resolv.conf:ro # Use the host's DNS resolver rather than Docker's.
       #- ./continuwuity.toml:/etc/continuwuity.toml
     networks:
       - proxy
@@ -37,6 +36,9 @@ services:
       nofile:
         soft: 1048567
         hard: 1048567
+    configs: # using custom resolver instead of Docker's
+      - source: continuwuity-resolv.conf
+        target: /etc/resolv.conf
 
   traefik:
     image: "traefik:latest"
@@ -48,7 +50,6 @@ services:
     volumes:
       - "/var/run/docker.sock:/var/run/docker.sock:z"
       - "acme:/etc/traefik/acme"
-      #- "./traefik_config:/etc/traefik:z"
     labels:
       - "traefik.enable=true"
 
@@ -90,3 +91,9 @@ volumes:
 
 networks:
     proxy:
+
+configs:
+  continuwuity-resolv.conf:
+    content: |
+      nameserver 1.0.0.1
+      nameserver 1.1.1.1

docs/public/deploying/docker-compose.yml

@@ -16,6 +16,16 @@ services:
             CONTINUWUITY_ADDRESS: 0.0.0.0
             CONTINUWUITY_PORT: 8008 
             #CONTINUWUITY_CONFIG: '/etc/continuwuity.toml' # Uncomment if you mapped config toml above
+        configs: # using custom resolver instead of Docker's
+            - source: continuwuity-resolv.conf
+              target: /etc/resolv.conf
+
 
 volumes:
     db:
+
+configs:
+    continuwuity-resolv.conf:
+        content: |
+            nameserver 1.0.0.1
+            nameserver 1.1.1.1