add documentation

README.md

@@ -1,2 +1,85 @@
 # hassio-addons
 Repository of custom addons for hass.io
+
+## Inadyn
+
+### About
+
+Inadyn is a small and simple Dynamic DNS, DDNS, client with HTTPS support. Commonly available in many GNU/Linux distributions, used in off the shelf routers and Internet gateways to automate the task of keeping your Internet name in sync with your public IP address.
+
+### This Hass.io Addon
+
+The objective is to provide a client to do dynamic dns updates on behalf of your hass.io server. The configuration of this addon allows you to setup your provider to dynamically update whenever a change of your public IP address occurs.
+
+### Configuration
+
+The available configuration options are as follows (this is filled in with some example data):
+
+```
+{
+  "providers": [
+    {
+      "provider": "providerslug",
+      "username": "yourusername",
+      "password": "yourpassword_or_token",
+      "hostname": "dynamic-subdomain.example.com",
+      "ssl": true,
+      "user_agent": "Mozilla/5.0",
+      "checkip_ssl": false,
+      "checkip_server": "api.example.com",
+      "checkip_command": "/sbin/ifconfig eth0 | grep 'inet6 addr'",
+      "checkip_path": "/",
+      "custom_provider": false,
+      "ddns_server": "ddns.example.com",
+      "ddns_path": ""
+    }
+  ]
+}
+```
+
+You should not fill in all of these, only use what is necessary. A typical example would look like:
+
+```
+{
+    {
+      "provider": "duckdns",
+      "username": "your-token",
+      "hostname": "sub.duckdns.org"
+    }
+  ]
+}
+```
+
+or:
+
+```
+{
+  "providers": [
+    {
+      "provider": "someprovider",
+      "username": "username",
+      "password": "password",
+      "hostname": "your.domain.com"
+    }
+  ]
+}
+```
+
+for a custom provider that is not supported by inadyn you can do:
+```
+{
+  "providers": [
+    {
+      "provider": "arbitraryname",
+      "username": "username",
+      "password": "password",
+      "hostname": "your.domain.com",
+      "ddns_server": "api.cp.easydns.com",
+      "ddns_path": "/dyn/generic.php?hostname=%h&myip=%i",
+      "custom_provider": true
+    }
+  ]
+}
+```
+
+the tokens in ddns_path are outlined in the `inadyn.conf(5)` man page.