Merge pull request #208 from cnrmck/master

README.md

@@ -27,7 +27,7 @@ Every few minutes watchtower will pull the latest *centurylink/wetty-cli* image
 
 ## Usage
 
-Watchtower is itself packaged as a Docker container so installation is as simple as pulling the `v2tec/watchtower` image.
+Watchtower is itself packaged as a Docker container so installation is as simple as pulling the `v2tec/watchtower` image. If you are using ARM based architecture, pull the appropriate `v2tec/watchtower:armhf-<tag>` image from the [v2tec Docker Hub](https://hub.docker.com/r/v2tec/watchtower/tags/). 
 
 Since the watchtower code needs to interact with the Docker API in order to monitor the running containers, you need to mount */var/run/docker.sock* into the container with the -v flag when you run it.
 
@@ -43,6 +43,18 @@ docker run -d \
 If pulling images from private Docker registries, supply registry authentication credentials with the environment variables `REPO_USER` and `REPO_PASS`
 or by mounting the host's docker config file into the container (at the root of the container filesystem `/`).
 
+Passing environment variables:
+```bash
+docker run -d \
+  --name watchtower \
+  -e REPO_USER=username \
+  -e REPO_PASS=password \
+  -v /var/run/docker.sock:/var/run/docker.sock \
+  v2tec/watchtower container_to_watch --debug
+```
+Also check out [this Stack Overflow answer](https://stackoverflow.com/a/30494145/7872793) for more options on how to pass environment variables.
+
+Mounting the host's docker config file:
 ```bash
 docker run -d \
   --name watchtower \
@@ -51,7 +63,7 @@ docker run -d \
   v2tec/watchtower container_to_watch --debug
 ```
 
-If you mount the config file as described below, be sure to also prepend the url for the registry when starting up your watched image (you can omit the https://). Here is a complete docker-compose.yml file that starts up a docker container from a private repo at dockerhub and monitors it with watchtower. Note the command argument changing the interval to 30s rather than the default 5 minutes.
+If you mount the config file as described above, be sure to also prepend the url for the registry when starting up your watched image (you can omit the https://). Here is a complete docker-compose.yml file that starts up a docker container from a private repo at dockerhub and monitors it with watchtower. Note the command argument changing the interval to 30s rather than the default 5 minutes.
 
 ```json
 version: "3"