Overview

Following an OpenShift Container Platform upgrade, it may be desirable in extreme cases to downgrade your cluster to a previous version. The following sections outline the required steps for each system in a cluster to perform such a downgrade for the OpenShift Container Platform 3.5 to 3.4 downgrade path.

These steps are currently only supported for RPM-based installations of OpenShift Container Platform and assumes downtime of the entire cluster.

Verifying Backups

The Ansible playbook used during the upgrade process should have created a backup of the master-config.yaml file and the etcd data directory. Ensure these exist on your masters and etcd members:

/etc/origin/master/master-config.yaml.<timestamp>
/var/lib/origin/etcd-backup-<timestamp>

Also, back up the node-config.yaml file on each node (including masters, which have the node component on them) with a timestamp:

/etc/origin/node/node-config.yaml.<timestamp>

If you are using an external etcd cluster (versus the single embedded etcd), the backup is likely created on all etcd members, though only one is required for the recovery process.

The RPM downgrade process in a later step should create .rpmsave backups of the following files, but it may be a good idea to keep a separate copy regardless:

/etc/sysconfig/atomic-openshift-master
/etc/etcd/etcd.conf (1)
1 Only required if using external etcd.

Shutting Down the Cluster

On all masters, nodes, and etcd members (if using an external etcd cluster), ensure the relevant services are stopped.

On the master in a single master cluster:

# systemctl stop atomic-openshift-master

On each master in a multi-master cluster:

# systemctl stop atomic-openshift-master-api
# systemctl stop atomic-openshift-master-controllers

On all master and node hosts:

# systemctl stop atomic-openshift-node

On any external etcd hosts:

# systemctl stop etcd

Removing RPMs

  1. The *-excluder packages add entries to the exclude directive in the host’s /etc/yum.conf file when installed. Run the following command on each host to remove the atomic-openshift-* and docker packages from the exclude list:

    # atomic-openshift-excluder unexclude
    # atomic-openshift-docker-excluder unexclude
  2. On all masters, nodes, and etcd members (if using an external etcd cluster), remove the following packages:

    # yum remove atomic-openshift \
        atomic-openshift-clients \
        atomic-openshift-node \
        atomic-openshift-master \
        openvswitch \
        atomic-openshift-sdn-ovs \
        tuned-profiles-atomic-openshift-node\
        atomic-openshift-excluder\
        atomic-openshift-docker-excluder
  3. If you are using external etcd, also remove the etcd package:

    # yum remove etcd

    If using the embedded etcd, leave the etcd package installed. It is required for running the etcdctl command to issue operations in later steps.

Downgrading Docker

Both OpenShift Container Platform 3.4 and 3.5 require Docker 1.12, so Docker does not need to be downgraded.

Reinstalling RPMs

Disable the OpenShift Container Platform 3.5 repositories, and re-enable the 3.4 repositories:

# subscription-manager repos \
    --disable=rhel-7-server-ose-3.5-rpms \
    --enable=rhel-7-server-ose-3.4-rpms

On each master, install the following packages:

# yum install atomic-openshift \
    atomic-openshift-clients \
    atomic-openshift-node \
    atomic-openshift-master \
    openvswitch \
    atomic-openshift-sdn-ovs \
    tuned-profiles-atomic-openshift-node \
    atomic-openshift-excluder \
    atomic-openshift-docker-excluder

On each node, install the following packages:

# yum install atomic-openshift \
    atomic-openshift-node \
    openvswitch \
    atomic-openshift-sdn-ovs \
    tuned-profiles-atomic-openshift-node \
    atomic-openshift-excluder \
    atomic-openshift-docker-excluder

If using an external etcd cluster, install the following package on each etcd member:

# yum install etcd

Restoring etcd

Bringing OpenShift Container Platform Services Back Online

Verifying the Downgrade

  1. To verify the downgrade, first check that all nodes are marked as Ready:

    # oc get nodes
    NAME                        STATUS                     AGE
    master.example.com          Ready,SchedulingDisabled   165d
    node1.example.com           Ready                      165d
    node2.example.com           Ready                      165d
  2. Then, verify that you are running the expected versions of the docker-registry and router images, if deployed:

    # oc get -n default dc/docker-registry -o json | grep \"image\"
        "image": "openshift3/ose-docker-registry:v3.4.1.37-2",
    # oc get -n default dc/router -o json | grep \"image\"
        "image": "openshift3/ose-haproxy-router:v3.4.1.37-2",
  3. You can use the diagnostics tool on the master to look for common issues and provide suggestions:

    # oc adm diagnostics
    ...
    [Note] Summary of diagnostics execution:
    [Note] Completed with no errors or warnings seen.