Merge pull request #1307 from madorn/patch-1

Add some examples for Subscription config feature

doc/design/subscription-config.md

@@ -2,33 +2,85 @@
 
 ## Configuring Operators deployed by OLM
 
-It is possible to configure how OLM deploys an operator via the `config` field in the [subscription](../../pkg/api/apis/operators/subscription_types.go) object.
+It is possible to configure how OLM deploys an Operator via the `config` field in the [Subscription](https://github.com/operator-framework/operator-lifecycle-manager/blob/master/doc/install/install.md#subscribe-to-a-package-and-channel) object.
 
-Currently, the OLM supports the following configurations:
+Currently, OLM supports the following configurations:
 
 ### Env
 
-The `Env` field defines a list of environment variables that must exist in all containers in the `pod` created by OLM.
+The `env` field defines a list of [Environment Variables](https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/#define-an-environment-variable-for-a-container) that must exist in all containers in the Pod created by OLM.
 
 > Note: Values defined here will overwrite existing environment variables of the same name.
 
+#### Example
+
+Increase log verbosity on an Operator's container that utilizes the `ARGS` variable:
+
+```
+kind: Subscription
+metadata:
+  name: prometheus
+spec:
+  package: prometheus
+  channel: alpha
+  config:
+    env:
+    - name: ARGS
+      value: "-v=10"
+```
+
 ### EnvFrom
 
-The `EnvFrom` field defines a list of sources to populate environment variables in the container. 
-The keys defined within a source must be a C_IDENTIFIER. 
-All invalid keys will be reported as an event when the container is starting.
-When a key exists in multiple sources, the value associated with the last source will take precedence.
+The `envFrom` field defines a [list of sources to populate Environment Variables](https://kubernetes.io/docs/tasks/configure-pod-container/configure-pod-configmap/#configure-all-key-value-pairs-in-a-configmap-as-container-environment-variables) in the container. The keys defined within a source must be a C_IDENTIFIER. All invalid keys will be reported as an event when the container is starting. When a key exists in multiple sources, the value associated with the last source will take precedence.
 
 > Note: Values defined by an Env with a duplicate key will take precedence.
 
+#### Example
+
+Inject a license key residing in a Secret to unlock Operator features:
+
+```
+kind: Subscription
+metadata:
+  name: my-operator
+spec:
+  package: app-operator
+  channel: stable
+  config:
+    envFrom:
+    - secretRef:
+        name: license-secret
+```
+
 ### Volumes
 
-The `Volumes` field defines a list of [volumes](https://kubernetes.io/docs/concepts/storage/volumes/) that must exist on the `pod` created by OLM.
+The `volumes` field defines a list of [Volumes](https://kubernetes.io/docs/concepts/storage/volumes/) that must exist on the Pod created by OLM.
 
 > Note: Volumes defined here will overwrite existing Volumes of the same name.
 
 ### VolumeMounts
 
-The `VolumeMounts` field defines a list of [volumeMounts](https://kubernetes.io/docs/concepts/storage/volumes/) that must exist in all containers in the `pod` created by OLM. If a `volumeMount` references a `volume` that does not exist, OLM will fail to deploy the operator.
+The `volumeMounts` field defines a list of [VolumeMounts](https://kubernetes.io/docs/concepts/storage/volumes/) that must exist in all containers in the Pod created by OLM. If a `volumeMount` references a `volume` that does not exist, OLM will fail to deploy the operator.
 
 > Note: VolumeMounts defined here will overwrite existing VolumeMounts of the same name.
+
+#### Example
+
+Mount a ConfigMap as a Volume that contains configuration information that can change default Operator behavior. Modifications to the content of the ConfigMap should appear within the container's VolumeMount.
+
+```
+kind: Subscription
+metadata:
+  name: my-operator
+spec:
+  package: etcd
+  channel: alpha
+  config:
+    volumes:
+    - name: config-volume
+      configMap:
+        name: etcd-operator-config
+    volumeMounts:
+    - mountPath: /config
+      name: config-volume
+```