Added Setting the default max container root partition size for overlay with cri-o

Author: ahardin-rh

modules/set-the-default-max-container-root-partition-size-for-overlay-with-crio.adoc

@@ -0,0 +1,122 @@
+// Module included in the following assemblies:
+//
+// post_installation_configuration/machine-configuration-tasks.adoc
+
+[id="set-the-default-max-container-root-partition-size-for-overlay-with-crio_{context}"]
+= Setting the default maximum container root partition size for Overlay with CRI-O
+
+The root partition of each container shows all of the available disk space of the underlying host. Follow this guidance to set a maximum partition size for the root disk of all containers.
+
+To configure the maximum Overlay size, as well as other CRI-O options like the log level and PID limit, you can create the following `ContainerRuntimeConfig` custom resource definition (CRD):
+
+[source,yaml]
+----
+apiVersion: machineconfiguration.openshift.io/v1
+kind: ContainerRuntimeConfig
+metadata:
+ name: overlay-size
+spec:
+ machineConfigPoolSelector:
+   matchLabels:
+     custom-crio: overlay-size
+ containerRuntimeConfig:
+   pidsLimit: 2048
+   logLevel: debug
+   overlaySize: 8G
+----
+
+.Procedure
+
+. Create the configuration object:
++
+[source,terminal]
+----
+$ oc apply -f overlaysize.yml
+----
+
+. To apply the new CRI-O configuration to your worker nodes, edit the worker machine config pool:
++
+[source,terminal]
+----
+$ oc edit machineconfigpool worker
+----
+
+. Add the `custom-crio` label based on the `matchLabels` name you set in the `ContainerRuntimeConfig` CRD:
++
+[source,yaml]
+----
+apiVersion: machineconfiguration.openshift.io/v1
+kind: MachineConfigPool
+metadata:
+  creationTimestamp: "2020-07-09T15:46:34Z"
+  generation: 3
+  labels:
+    custom-crio: overlay-size
+    machineconfiguration.openshift.io/mco-built-in: ""
+----
+
+. Save the changes, then view the machine configs:
++
+[source,terminal]
+----
+$ oc get machineconfigs
+----
++
+New `99-worker-generated-containerruntime` and `rendered-worker-xyz` objects are created:
++
+.Example output
+[source,terminal]
+----
+99-worker-generated-containerruntime  4173030d89fbf4a7a0976d1665491a4d9a6e54f1   2.2.0             7m42s
+rendered-worker-xyz                   4173030d89fbf4a7a0976d1665491a4d9a6e54f1   2.2.0             7m36s
+----
+
+. After those objects are created, monitor the machine config pool for the changes to be applied:
++
+[source,terminal]
+----
+$ oc get mcp worker
+----
++
+The worker nodes show `UPDATING` as `True`, as well as the number of machines, the number updated, and other details:
++
+.Example output
+[source,terminal]
+----
+NAME   CONFIG              UPDATED   UPDATING   DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
+worker rendered-worker-xyz False True False     3             2                   2                    0                      20h
+----
++
+When complete, the worker nodes transition back to `UPDATING` as `False`, and the `UPDATEDMACHINECOUNT` number matches the `MACHINECOUNT`:
++
+.Example output
+[source,terminal]
+----
+NAME   CONFIG              UPDATED   UPDATING   DEGRADED  MACHINECOUNT  READYMACHINECOUNT  UPDATEDMACHINECOUNT   DEGRADEDMACHINECOUNT   AGE
+worker   rendered-worker-xyz   True      False      False      3         3            3             0           20h
+----
++
+Looking at a worker machine, you see that the new 8 GB max size configuration is applied to all of the workers:
++
+.Example output
+[source,terminal]
+----
+head -n 7 /etc/containers/storage.conf
+[storage]
+  driver = "overlay"
+  runroot = "/var/run/containers/storage"
+  graphroot = "/var/lib/containers/storage"
+  [storage.options]
+    additionalimagestores = []
+    size = "8G"
+----
++
+Looking inside a container, you see that the root partition is now 8 GB:
++
+.Example output
+[source,terminal]
+----
+~ $ df -h
+Filesystem                Size      Used Available Use% Mounted on
+overlay                   8.0G      8.0K      8.0G   0% /
+----

post_installation_configuration/machine-configuration-tasks.adoc

@@ -42,3 +42,4 @@ Besides managing `MachineConfig` objects, the MCO manages two custom resources (
 
 include::modules/create-a-kubeletconfig-crd-to-edit-kubelet-parameters.adoc[leveloffset=+2]
 include::modules/create-a-containerruntimeconfig-crd.adoc[leveloffset=+2]
+include::modules/set-the-default-max-container-root-partition-size-for-overlay-with-crio.adoc[leveloffset=+2]