From c17725f26983a45d019d42ab05d591afd086a371 Mon Sep 17 00:00:00 2001
From: Brad Rydzewski <brad.rydzewski@gmail.com>
Date: Tue, 27 Oct 2015 17:26:08 -0700
Subject: [PATCH] Update DOCS.md

---
 DOCS.md | 55 +++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 47 insertions(+), 8 deletions(-)

diff --git a/DOCS.md b/DOCS.md
index 0a8e71d..989409e 100644
--- a/DOCS.md
+++ b/DOCS.md
@@ -1,14 +1,14 @@
 Use the Docker plugin to build and push Docker images to a registry.
 The following parameters are used to configure this plugin:
 
-* **registry** - authenticates to this registry
-* **username** - authenticates with this username
-* **password** - authenticates with this password
-* **email** - authenticates with this email
-* **repo** - repository name for the image
-* **tag** - repository tag for the image
-* **insecure** - enable insecure communication to this registry
-* **storage_driver** - use `aufs`, `devicemapper`, `btrfs` or `overlay` driver
+* `registry` - authenticates to this registry
+* `username` - authenticates with this username
+* `password` - authenticates with this password
+* `email` - authenticates with this email
+* `repo` - repository name for the image
+* `tag` - repository tag for the image
+* `insecure` - enable insecure communication to this registry
+* `storage_driver` - use `aufs`, `devicemapper`, `btrfs` or `overlay` driver
 
 The following is a sample Docker configuration in your .drone.yml file:
 
@@ -35,3 +35,42 @@ publish:
     repo: foo/bar
     tag: $$BRANCH
 ```
+
+## Troubleshooting
+
+For detailed output you can set the `DOCKER_LAUNCH_DEBUG` environment variable in your plugin configuration. This starts Docker with verbose logging enabled.
+
+```
+publish:
+  docker:
+    environment:
+      - DOCKER_LAUNCH_DEBUG=true
+```
+
+## Known Issues
+
+There are known issues when attempting to run this plugin on CentOS, RedHat, and Linux installations that do not have a supported storage driver installed. You can check by running `docker info | grep 'Storage Driver:'` on your host machine. If the storage driver is not `aufs` or `overlay` you will need to re-configure your host machine.
+
+This error occurs when trying to use the default `aufs` storage Driver but aufs is not installed:
+
+```
+level=fatal msg="Error starting daemon: error initializing graphdriver: driver not supported
+```
+
+This error occurs when trying to use the `overlay` storage Driver but overlay is not installed:
+
+```
+level=error msg="'overlay' not found as a supported filesystem on this host.
+Please ensure kernel is new enough and has overlay support loaded." 
+level=fatal msg="Error starting daemon: error initializing graphdriver: driver not supported"
+```
+
+This error occurs when using CentOS or RedHat which default to the `devicemapper` storage driver:
+
+```
+level=error msg="There are no more loopback devices available." 
+level=fatal msg="Error starting daemon: error initializing graphdriver: loopback mounting failed" 
+Cannot connect to the Docker daemon. Is 'docker -d' running on this host?
+```
+
+The above issue can be resolved by setting `storage_driver: vfs` in the `.drone.yml` file. This may work, but will have very poor performance as discussed [here](https://github.com/rancher/docker-from-scratch/issues/20).