Add disaster recovery documentation.

Documentation/disaster-recovery.md

@@ -0,0 +1,112 @@
+# Disaster Recovery
+
+Self-hosted Kubernetes clusters are vulnerable to the following catastrophic
+failure scenarios:
+
+- Loss of all api-servers
+- Loss of all schedulers
+- Loss of all controller-managers
+- Loss of all self-hosted etcd nodes
+
+To minimize the likelihood of any of the these scenarios, production
+self-hosted clusters should always run in a [high-availability
+configuration](https://kubernetes.io/docs/admin/high-availability/).
+
+Nevertheless, in the event of a control plane loss the bootkube project
+provides limited disaster avoidance and recovery support through the
+`pod-checkpointer` program and the `bootkube recover` subcommand.
+
+## Pod Checkpointer
+
+The Pod Checkpointer is a program that ensures that existing local pod state
+can be recovered in the absence of an api-server.
+
+This is accomplished by managing "checkpoints" of local pod state as static pod
+manifests:
+
+- When the checkpointer sees that a "parent pod" (a pod which should be
+  checkpointed), is successfully running, the checkpointer will save a local
+  copy of the manifest.
+- If the parent pod is detected as no longer running, the checkpointer will
+  "activate" the checkpoint manifest. It will allow the checkpoint to continue
+  running until the parent-pod is restarted on the local node, or it is able to
+  contact an api-server to determine that the parent pod is no longer scheduled
+  to this node.
+
+A Pod Checkpointer DaemonSet is deployed by default when using `bootkube
+render` to create cluster manifests. Using the Pod Checkpointer is highly
+recommended for all self-hosted clusters to ensure node reboot resiliency.
+
+For more information, see the [Pod Checkpointer
+README](https://github.com/kubernetes-incubator/bootkube/blob/master/cmd/checkpoint/README.md).
+
+## Bootkube Recover
+
+In the event of partial or total self-hosted control plane loss, `bootkube
+recover` may be able to assist in re-bootstrapping the self-hosted control
+plane.
+
+The `bootkube recover` subcommand does not recover a cluster directly. Instead,
+it extracts the control plane configuration from an available source and
+renders manifests in a format that `bootkube start` can use invoked to reboot
+the cluster.
+
+To see available options, run:
+
+```
+bootkube recover --help
+```
+
+To recover a cluster, first invoke `bootkube recover` with flags corresponding
+to the current state of the cluster (supported states listed below). Then,
+invoke `bootkube start` to reboot the cluster. For example:
+
+```
+scp bootkube user@master-node:
+ssh user@master-node
+./bootkube recover --asset-dir=recovered [scenario-specific options]
+sudo ./bootkube start --asset-dir=recovered
+```
+
+For complete recovery examples see the
+[hack/multi-node/bootkube-test-recovery](https://github.com/kubernetes-incubator/bootkube/blob/master/hack/multi-node/bootkube-test-recovery)
+and
+[hack/multi-node/bootkube-test-recovery-self-hosted-etcd](https://github.com/kubernetes-incubator/bootkube/blob/master/hack/multi-node/bootkube-test-recovery-self-hosted-etcd)
+scripts. The `bootkube-test-recovery` script is demoed below.
+
+[![asciicast](https://asciinema.org/a/dsp43ziuuzwcztni94y8l25s5.png)](https://asciinema.org/a/dsp43ziuuzwcztni94y8l25s5)
+
+### If an api-server is still running
+
+If an api-server is still running but other control plane components are down,
+preventing cluster functionality (i.e. the scheduler pods are all down), the
+control plane can be extracted directly from the api-server:
+
+```
+bootkube recover --asset-dir=recovered --kubeconfig=/etc/kubernetes/kubeconfig
+```
+### If an external etcd cluster is still running
+
+If using an external (non-self-hosted) etcd cluster, the control plane can be
+extracted directly from etcd:
+
+```
+bootkube recover --asset-dir=recovered --etcd-servers=http://127.0.0.1:2379 --kubeconfig=/etc/kubernetes/kubeconfig
+```
+
+### If an etcd backup is available (non-self-hosted etcd)
+
+First, recover the external etcd cluster from the backup. Then use the method
+described in the previous section to recover the control plane manifests.
+
+### If an etcd backup is available (self-hosted etcd)
+
+If using self-hosted etcd, recovery is supported via reading from an etcd
+backup file:
+
+```
+bootkube recover --asset-dir=recovered --etcd-backup-file=backup --kubeconfig=/etc/kubernetes/kubeconfig
+```
+
+In addition to rebooting the control plane, this will also destroy and recreate
+the self-hosted etcd cluster using the backup.

README.md

@@ -60,31 +60,7 @@ bootkube start --asset-dir=my-cluster
 
 In the case of a partial or total control plane outage (i.e. due to lost master nodes) an experimental `recover` command can extract and write manifests from a backup location. These manifests can then be used by the `start` command to reboot the cluster. Currently recovery from a running apiserver, an external running etcd cluster, or an etcd backup taken from the self hosted etcd cluster are the methods.
 
-To see available options, run:
-
-```
-bootkube recover --help
-```
-
-Recover from an external running etcd cluster:
-
-```
-bootkube recover --asset-dir=recovered --etcd-servers=http://127.0.0.1:2379 --kubeconfig=/etc/kubernetes/kubeconfig
-```
-
-Recover from a running apiserver (i.e. if the scheduler pods are all down):
-
-```
-bootkube recover --asset-dir=recovered --kubeconfig=/etc/kubernetes/kubeconfig
-```
-
-Recover from an etcd backup when self hosted etcd is enabled:
-
-```
-bootkube recover --asset-dir=recovered --etcd-backup-file=backup --kubeconfig=/etc/kubernetes/kubeconfig
-```
-
-For a complete recovery example please see the [hack/multi-node/bootkube-test-recovery](hack/multi-node/bootkube-test-recovery) and the [hack/multi-node/bootkube-test-recovery-self-hosted-etcd](hack/multi-node/bootkube-test-recovery-self-hosted-etcd) scripts.
+For more details and examples see [disaster recovery documentation](Documentation/disaster-recovery.md).
 
 ## Building