Fix #296 (Cyberghost implementation) (#297)

* Reads the client key from /gluetun/client.key
* Read the client certificate from /gluetun/client.crt
* Additional checks for client key and client certificate validity
* Fix client key file parsing if environment variable isn't present

README.md

@@ -159,20 +159,15 @@ docker run --rm --network=container:gluetun alpine:3.12 wget -qO- https://ipinfo
     | --- | --- | --- | --- |
     | 🏁 `USER` | | | Your username |
     | 🏁 `PASSWORD` | | | Your password |
-    | 🏁 `CLIENT_KEY` | | | Your device client key content, **see below** |
+    | 🏁 | | | **See additional setup steps below** |
     | `REGION` | | One of the Cyberghost regions, [Wiki page](https://github.com/qdm12/gluetun/wiki/Cyberghost-Servers) | VPN server country |
     | `CYBERGHOST_GROUP` | `Premium UDP Europe` | One of the server groups (see above Wiki page) | Server group |
 
-    To specify your client key, you can either:
+    **Additional setup steps**: Bind mount your `client.key` file to `/gluetun/client.key` and your `client.crt` file to `/gluetun/client.crt`. For example, you can use with your `docker run` command:
 
-    - Bind mount it at `/files/client.key`, for example with `-v /yourpath/client.key:/files/client.key:ro`
-    - Convert it to a single line value using:
-
-        ```sh
-        docker run -it --rm -v /yourpath/client.key:/files/client.key:ro qmcgaw/private-internet-access clientkey
-        ```
-
-        And use the line produced as the value for the environment variable `CLIENT_KEY`.
+    ```sh
+    -v /yourpath/client.key:/gluetun/client.key:ro -v /yourpath/client.crt:/gluetun/client.crt:ro
+    ```
 
 - Vyprvpn