Document triggering a flux update

docs/design.md

@@ -167,3 +167,28 @@ similar as possible to a production installation, in particular using `flux` and
 `helm-operator` for the installation process, while still being completely
 separate from the production applications versions as prescribed by the master
 repository at `open.greenhost.net/openappstack/openappstack`.
+
+#### Triggering an update
+
+Both `flux` and `helm-operator` check at regular intervals (currently 1 hour
+and 20 minutes, respectively) whether there is an upgrade to perform. If you
+don't want to wait for that after making a change, you can trigger an update:
+* to let `flux` re-read the `HelmRelease` files from the git repo (be it the
+  OpenAppStack master one, a `local-flux` one, or yet another one), log in to
+  the host machine and do
+
+      $ fluxctl --k8s-fwd-ns=oas sync
+
+  If there are any changes to `HelmRelease` manifests, these should be
+  subsequently picked up by `helm-operator` more or less instantly (though the
+  actual installation or upgrade could take quite a while, depending on what
+  needs to be done).
+* If, for some reason, the `HelmRelease` manifests are still in sync between git
+  repository and cluster, but you'd still like to let `helm-operator` check
+  whether these `HelmRelease`s match what's actually installed, you can force
+  that by deleting the `helm-operator` pod:
+
+      $ kubectl delete pod -n oas -l app=helm-operator
+
+  A new `helm-operator` pod should be created automatically, and in our
+  experience will do a reconciliation run soon.