Merge ~hloeung/charm-k8s-content-cache:master into charm-k8s-content-cache:master

[Haw Loeung]

Use default image contentcachecharmers/content-cache:edge and update README to suit

https://registry.hub.docker.com/r/contentcachecharmers/content-cache/tags?name=edge

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Laurent Sesquès (sajoupa)]

+1

review: Approve

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 45046f9f649f93695b9996a7a103aa7f469c55ca

diff --git a/README.md b/README.md
index aaaae75..b1002ff 100644
--- a/README.md
+++ b/README.md
@@ -6,20 +6,13 @@ Deploy content caching layer into K8s.
 
 ## Usage
 
-Build the docker image:
-
-    `cd docker`
-    `docker build . -t myimage:v<revision>`
-    `docker tag myimage:v<revision> localhost:32000/myimage:v<revision>`
-    `docker push localhost:32000/myimage:v<revision>`
-
 Build the charm:
 
     `charmcraft build`
 
 Deploy:
 
-    `juju deploy ./content-cache.charm --config image_path=localhost:32000/myimage:v<revision> --config site=mysite.local --config backend=http://mybackend.local:80`
+    `juju deploy ./content-cache.charm --config site=mysite.local --config backend=http://mybackend.local:80`
 
 ### Test Deployment
 
@@ -27,7 +20,25 @@ Deploy:
 
 ### Scale Out Usage
 
-Just run `juju add-unit <application name>`.
+Just run `juju scale-application <application name> 3`.
+
+## Using a Custom Image
+
+Build the docker image:
+
+    `git clone https://git.launchpad.net/charm-k8s-content-cache`
+    `cd charm-k8s-content-cache/docker`
+    `docker build . -t myimage:v<revision>`
+    `docker tag myimage:v<revision> localhost:32000/myimage:v<revision>`
+    `docker push localhost:32000/myimage:v<revision>`
+
+Then, to use your new image, either replace the `deploy` step above with
+
+    `juju deploy ./content-cache.charm --config image_path=localhost:32000/myimage:v<revision> --config site=mysite.local --config backend=http://mybackend.local:80`
+
+Or, if you have already deployed content-cache:
+
+    `juju config content-cache image_path=localhost:32000/myimage:v<revision>`
 
 ## Developing
 
diff --git a/config.yaml b/config.yaml
index 141b70d..d7dcb7c 100644
--- a/config.yaml
+++ b/config.yaml
@@ -5,6 +5,7 @@ options:
       The location of the image to use, e.g. "localhost:32000/myimage:latest"
 
       This setting is required.
+    default: contentcachecharmers/content-cache:edge
   image_username:
     type: string
     description: >-