Added env var page (argoproj-labs#864)

Signed-off-by: Yi Cai <[email protected]>

docs/usage/custom_roles.md

@@ -37,20 +37,4 @@ spec:
             value: custom-controller-role
           - name: SERVER_CLUSTER_ROLE
             value: custom-server-role
-```
-
-
-When an Argo CD instance is deleted, namespaces managed by that instance (via the `argocd.argoproj.io/managed-by` label ) will retain the label by default. Users can change this behavior by setting the environment variable `REMOVE_MANAGED_BY_LABEL_ON_ARGOCD_DELETION` to `true` in the Subscription.
-
-```yaml
-apiVersion: operators.coreos.com/v1alpha1
-kind: Subscription
-metadata:
-  name: argocd-operator
-  namespace: argocd
-spec:
-  config:
-    env:
-    - name: REMOVE_MANAGED_BY_LABEL_ON_ARGOCD_DELETION
-      value: "true"
 ```

docs/usage/environment_variables.md

@@ -0,0 +1,39 @@
+# Environment Variables
+
+The following environment variables are available in `argocd-operator`:
+
+| Environment Variable | Default Value | Description |
+| --- | --- | --- |
+| `CONTROLLER_CLUSTER_ROLE` | none | Administrators can configure a common cluster role for all the managed namespaces in role bindings for the Argo CD application controller with this environment variable. Note: If this environment variable contains custom roles, the Operator doesn't create the default admin role. Instead, it uses the existing custom role for all managed namespaces. |
+| `SERVER_CLUSTER_ROLE` | none | Administrators can configure a common cluster role for all the managed namespaces in role bindings for the Argo CD server with this environment variable. Note: If this environment variable contains custom roles, the Operator doesn’t create the default admin role. Instead, it uses the existing custom role for all managed namespaces. |
+| `REMOVE_MANAGED_BY_LABEL_ON_ARGOCD_DELETION` | false | When an Argo CD instance is deleted, namespaces managed by that instance (via the `argocd.argoproj.io/managed-by` label ) will retain the label by default. Users can change this behavior by setting the environment variable `REMOVE_MANAGED_BY_LABEL_ON_ARGOCD_DELETION` to `true` in the Subscription. |
+
+Custom Environment Variables are supported in `applicationSet`, `controller`, `notifications`, `repo` and `server` components. For example:
+
+```
+...
+kind: ArgoCD
+metadata:
+  name: argocd
+  labels:
+    example: controller
+spec:
+  controller:
+    resources: {}
+    env:
+      - name: FOO
+        value: bar
+...
+```
+
+The following default value of images could be overridden by setting the environment variables:
+| Environment Variable | Default Value |
+| --- | --- |
+| `ARGOCD_IMAGE` | [quay.io/argoproj/argocd](quay.io/argoproj/argocd) |
+| `ARGOCD_REPOSERVER_IMAGE` | [quay.io/argoproj/argocd](quay.io/argoproj/argocd) |
+| `ARGOCD_DEX_IMAGE` | [ghcr.io/dexidp/dex](ghcr.io/dexidp/dex) |
+| `ARGOCD_KEYCLOAK_IMAGE` | [quay.io/keycloak/keycloak](quay.io/keycloak/keycloak) |
+| `ARGOCD_REDIS_IMAGE` | redis |
+| `ARGOCD_REDIS_HA_IMAGE` | redis |
+| `ARGOCD_REDIS_HA_PROXY_IMAGE` | haproxy |
+| `ARGOCD_GRAFANA_IMAGE` | grafana/grafana |