Updated README for DockerHub usage

README.md

@@ -2,10 +2,33 @@
 
 This package allows you to set up a server for dynamic DNS using docker with a
 few simple commands. You don't have to worry about nameserver setup, REST API
-and all that stuff. Setup is as easy as that:
+and all that stuff.
 
 ## Installation
 
+You can either take the image from DockerHub or build it on your own.
+
+### Using DockerHub
+
+Just customize this to your needs and run:
+
+```
+docker run -it -d \
+    -p 8080:8080 \
+    -p 53:53 \
+    -p 53:53/udp \
+    -e SHARED_SECRET=changeme \
+    -e ZONE=example.org \
+    -e RECORD_TTL=3600 \
+    --name=dyndns \
+    davd/docker-ddns:latest
+```
+
+If you want to persist DNS configuration across container recreation, add `-v /somefolder:/var/cache/bind`. If you are experiencing any issues updating DNS configuration using the API
+(`NOTAUTH` and `SERVFAIL`), make sure to add writing permissions for root (UID=0) to your persistent storage (e.g. `chmod -R a+w /somefolder`).
+
+### Build from source / GitHub
+
 ```
 git clone https://github.com/dprandzioch/docker-ddns
 cd docker-ddns
@@ -15,6 +38,8 @@ make deploy
 
 Make sure to change all environment variables in `envfile` to match your needs. Some more information can be found here: https://www.davd.eu/build-your-own-dynamic-dns-in-5-minutes/
 
+## Exposed ports
+
 Afterwards you have a running docker container that exposes three ports:
 
 * 53/TCP    -> DNS
@@ -67,3 +92,7 @@ http://ns.domain.tld:8080/update?...
 
 If you provide `foo` as a domain when using the REST API, the resulting domain
 will then be `foo.dyndns.domain.tld`.
+
+## Common pitfalls
+
+* If you're on a systemd-based distribution, the process `systemd-resolved` might occupy the DNS port 53. Therefore starting the container might fail. To fix this disable the DNSStubListener by adding `DNSStubListener=no` to `/etc/systemd/resolved.conf` and restart the service using `sudo systemctl restart systemd-resolved.service` but be aware of the implications... Read more here: https://www.freedesktop.org/software/systemd/man/systemd-resolved.service.html and https://github.com/dprandzioch/docker-ddns/issues/5