Restoring your cluster | Cluster Administration | OpenShift Container Platform 3.9

Overview
Restoring a cluster
Restoring a master host backup
Restoring a node host backup
Restoring etcd
- Restoring etcd v2 & v3 data
- Restoring etcd for v3
Adding an etcd node
- Adding a new etcd host using Ansible
- Manually adding a new etcd host
Bringing OpenShift Container Platform services back online
Restoring a project
Restoring application data
Restoring Persistent Volume Claims
- Restoring files to an existing PVC
- Restoring data to a new PVC

Overview

In OpenShift Container Platform, you can restore your cluster and its components by recreating cluster elements, including nodes and applications, from separate storage.

To restore a cluster, you must first back it up.

The following process describes a generic way of restoring applications and the OpenShift Container Platform cluster. It cannot take into account custom requirements. You might need to take additional actions to restore your cluster.

Restoring a cluster

To restore a cluster, first reinstall OpenShift Container Platform.

Procedure

Reinstall OpenShift Container Platform in the same way that you originally installed OpenShift Container Platform.
Run all of your custom post-installation steps, such as changing services outside of the control of OpenShift Container Platform or installing extra services like monitoring agents.

Restoring a master host backup

After creating a backup of important master host files, if they become corrupted or accidentally removed, you can restore the files by copying the files back to master, ensuring they contain the proper content, and restarting the affected services.

Procedure

Restore the /etc/origin/master/master-config.yaml file:

# MYBACKUPDIR=*/backup/$(hostname)/$(date +%Y%m%d)*
# cp /etc/origin/master/master-config.yaml /etc/origin/master/master-config.yaml.old
# cp /backup/$(hostname)/$(date +%Y%m%d)/origin/master/master-config.yaml /etc/origin/master/master-config.yaml
# systemctl restart atomic-openshift-master-api
# systemctl restart atomic-openshift-master-controllers

Restarting the master services can lead to downtime. However, you can remove the master host from the highly available load balancer pool, then perform the restore operation. Once the service has been properly restored, you can add the master host back to the load balancer pool.

Perform a full reboot of the affected instance to restore the iptables configuration.

If you cannot restart OpenShift Container Platform because packages are missing, reinstall the packages.
1. Get the list of the current installed packages:
  $ rpm -qa | sort > /tmp/current_packages.txt
2. View the differences between the package lists:
  $ diff /tmp/current_packages.txt ${MYBACKUPDIR}/packages.txt > ansible-2.4.0.0-5.el7.noarch
3. Reinstall the missing packages:
  # yum reinstall -y <packages> (1)
  1 Replace <packages> with the packages that are different between the package lists.
Restore a system certificate by copying the certificate to the /etc/pki/ca-trust/source/anchors/ directory and execute the update-ca-trust:
```
$ MYBACKUPDIR=*/backup/$(hostname)/$(date +%Y%m%d)*
$ sudo cp ${MYBACKUPDIR}/external_certificates/my_company.crt /etc/pki/ca-trust/source/anchors/
$ sudo update-ca-trust
```
Always ensure the user ID and group ID are restored when the files are copied back, as well as the SELinux context.

Restoring a node host backup

After creating a backup of important node host files, if they become corrupted or accidentally removed, you can restore the file by copying back the file, ensuring it contains the proper content and restart the affected services.

Procedure

Restore the /etc/origin/node/node-config.yaml file:

# MYBACKUPDIR=/backup/$(hostname)/$(date +%Y%m%d)
# cp /etc/origin/node/node-config.yaml /etc/origin/node/node-config.yaml.old
# cp /backup/$(hostname)/$(date +%Y%m%d)/etc/origin/node/node-config.yaml /etc/origin/node/node-config.yaml
# systemctl restart atomic-openshift-node

Restarting the services can lead to downtime. See Node maintenance, for tips on how to ease the process.

Perform a full reboot of the affected instance to restore the iptables configuration.

If you cannot restart OpenShift Container Platform because packages are missing, reinstall the packages.
1. Get the list of the current installed packages:
  $ rpm -qa | sort > /tmp/current_packages.txt
2. View the differences between the package lists:
  $ diff /tmp/current_packages.txt ${MYBACKUPDIR}/packages.txt > ansible-2.4.0.0-5.el7.noarch
3. Reinstall the missing packages:
  # yum reinstall -y <packages> (1)
  1 Replace <packages> with the packages that are different between the package lists.
Restore a system certificate by copying the certificate to the /etc/pki/ca-trust/source/anchors/ directory and execute the update-ca-trust:
```
$ MYBACKUPDIR=*/backup/$(hostname)/$(date +%Y%m%d)*
$ sudo cp ${MYBACKUPDIR}/etc/pki/ca-trust/source/anchors/my_company.crt /etc/pki/ca-trust/source/anchors/
$ sudo update-ca-trust
```
Always ensure proper user ID and group ID are restored when the files are copied back, as well as the SELinux context.

Restoring etcd

The restore procedure for etcd configuration files replaces the appropriate files, then restarts the service.

If an etcd host has become corrupted and the /etc/etcd/etcd.conf file is lost, restore it using:

$ ssh master-0
# cp /backup/yesterday/master-0-files/etcd.conf /etc/etcd/etcd.conf
# restorecon -Rv /etc/etcd/etcd.conf
# systemctl restart etcd.service

In this example, the backup file is stored in the /backup/yesterday/master-0-files/etcd.conf path where it can be used as an external NFS share, S3 bucket, or other storage solution.

Restoring etcd v2 & v3 data

The following process restores healthy data files and starts the etcd cluster as a single node, then adds the rest of the nodes if an etcd cluster is required.

Procedure

Stop all etcd services:
```
# systemctl stop etcd.service
```
To ensure the proper backup is restored, delete the etcd directories:
- To back up the current etcd data before you delete the directory, run the following command:
  # mv /var/lib/etcd /var/lib/etcd.old # mkdir /var/lib/etcd # chown -R etcd.etcd /var/lib/etcd/ # restorecon -Rv /var/lib/etcd/
- Or, to delete the directory and the etcd, data, run the following command:
  # rm -Rf /var/lib/etcd/*
  In an all-in-one cluster, the etcd data directory is located in the /var/lib/origin/openshift.local.etcd directory.

Restore a healthy backup data file to each of the etcd nodes. Perform this step on all etcd hosts, including master hosts collocated with etcd.

# cp -R /backup/etcd-xxx/* /var/lib/etcd/
# mv /var/lib/etcd/db /var/lib/etcd/member/snap/db
# chcon -R --reference /backup/etcd-xxx/* /var/lib/etcd/
# chown -R etcd:etcd /var/lib/etcd/R

Run the etcd service on each host, forcing a new cluster.

This creates a custom file for the etcd service, which overwrites the execution command adding the --force-new-cluster option:

# mkdir -p /etc/systemd/system/etcd.service.d/
# echo "[Service]" > /etc/systemd/system/etcd.service.d/temp.conf
# echo "ExecStart=" >> /etc/systemd/system/etcd.service.d/temp.conf
# sed -n '/ExecStart/s/"$/ --force-new-cluster"/p' \
    /usr/lib/systemd/system/etcd.service \
    >> /etc/systemd/system/etcd.service.d/temp.conf

# systemctl daemon-reload
# systemctl restart etcd

Check for error messages:
```
$ journalctl -fu etcd.service
```

Check for health status:

# etcdctl2 cluster-health
member 5ee217d17301 is healthy: got healthy result from https://192.168.55.8:2379
cluster is healthy

Restart the etcd service in cluster mode:

# rm -f /etc/systemd/system/etcd.service.d/temp.conf
# systemctl daemon-reload
# systemctl restart etcd

Check for health status and member list:

# etcdctl2 cluster-health
member 5ee217d17301 is healthy: got healthy result from https://192.168.55.8:2379
cluster is healthy

# etcdctl2 member list
5ee217d17301: name=master-0.example.com peerURLs=http://localhost:2380 clientURLs=https://192.168.55.8:2379 isLeader=true

After the first instance is running, you can restore the rest of your etcd servers.

Fix the `peerURLS` parameter

After restoring the data and creating a new cluster, the peerURLs parameter shows localhost instead of the IP where etcd is listening for peer communication:

# etcdctl2 member list
5ee217d17301: name=master-0.example.com peerURLs=http://*localhost*:2380 clientURLs=https://192.168.55.8:2379 isLeader=true

Procedure

Get the member ID using etcdctl member list:
```
`etcdctl member list`
```
Get the IP where etcd listens for peer communication:
```
$ ss -l4n | grep 2380
```

Update the member information with that IP:

# etcdctl2 member update 5ee217d17301 https://192.168.55.8:2380
Updated member with ID 5ee217d17301 in cluster

To verify, check that the IP is in the member list:

$ etcdctl2 member list
5ee217d17301: name=master-0.example.com peerURLs=https://*192.168.55.8*:2380 clientURLs=https://192.168.55.8:2379 isLeader=true

Restoring etcd for v3

The restore procedure for v3 data is similar to the restore procedure for the v2 data.

Snapshot integrity may be optionally verified at restore time. If the snapshot is taken with etcdctl snapshot save, it will have an integrity hash that is checked by etcdctl snapshot restore. If the snapshot is copied from the data directory, there is no integrity hash and it will only restore by using --skip-hash-check.

The procedure to restore only the v3 data must be performed on a single etcd host. You can then add the rest of the nodes to the cluster.

Procedure

Stop all etcd services:
```
# systemctl stop etcd.service
```
Clear all old data, because etcdctl recreates it in the node where the restore procedure is going to be performed:
```
# rm -Rf /var/lib/etcd
```

Run the snapshot restore command, substituting the values from the /etc/etcd/etcd.conf file:

# etcdctl3 snapshot restore /backup/etcd-xxxxxx/backup.db \
  --data-dir /var/lib/etcd \
  --name master-0.example.com \
  --initial-cluster "master-0.example.com=https://192.168.55.8:2380" \ --initial-cluster-token "etcd-cluster-1" \
  --initial-advertise-peer-urls https://192.168.55.8:2380

2017-10-03 08:55:32.440779 I | mvcc: restore compact to 1041269
2017-10-03 08:55:32.468244 I | etcdserver/membership: added member 40bef1f6c79b3163 [https://192.168.55.8:2380] to cluster 26841ebcf610583c

Restore permissions and selinux context to the restored files:

# chown -R etcd.etcd /var/lib/etcd/
# restorecon -Rv /var/lib/etcd

Start the etcd service:
```
# systemctl start etcd
```
Check for any error messages:
```
$ journalctl -fu etcd.service
```

Adding an etcd node

After you restore etcd, you can add more etcd nodes to the cluster. You can either add an etcd host by using an Ansible playbook or by manual steps.

Adding a new etcd host using Ansible

Procedure

In the Ansible inventory file, create a new group named [new_etcd] and add the new host. Then, add the new_etcd group as a child of the [OSEv3] group:

[OSEv3:children]
masters
nodes
etcd
new_etcd (1)

... [OUTPUT ABBREVIATED] ...

[etcd]
master-0.example.com
master-1.example.com
master-2.example.com

[new_etcd] (1)
etcd0.example.com (1)

1	Add these lines.

From the host that installed OpenShift Container Platform and hosts the Ansible inventory file, run the etcd scaleup playbook:
```
$ ansible-playbook  /usr/share/ansible/openshift-ansible/playbooks/openshift-etcd/scaleup.yml
```

After the playbook runs, modify the inventory file to reflect the current status by moving the new etcd host from the [new_etcd] group to the [etcd] group:

[OSEv3:children]
masters
nodes
etcd
new_etcd

... [OUTPUT ABBREVIATED] ...

[etcd]
master-0.example.com
master-1.example.com
master-2.example.com
etcd0.example.com

If you use the service catalog, you must update its list of etcd servers:
```
$ oc edit ds apiserver -n kube-service-catalog
```
Add the FQDN for the new etcd node to the --etcd-servers argument. This argument contains a comma-separated list.
If you use Flannel, modify the flanneld service configuration on every OpenShift Container Platform host, located at /etc/sysconfig/flanneld, to include the new etcd host:
```
FLANNEL_ETCD_ENDPOINTS=https://master-0.example.com:2379,https://master-1.example.com:2379,https://master-2.example.com:2379,https://etcd0.example.com:2379
```
Restart the flanneld service:
```
# systemctl restart flanneld.service
```

Manually adding a new etcd host

Procedure

Modify the current etcd cluster

To create the etcd certificates, run the openssl command, replacing the values with those from your environment.

Create some environment variables:

export NEW_ETCD_HOSTNAME="*etcd0.example.com*"
export NEW_ETCD_IP="192.168.55.21"

export CN=$NEW_ETCD_HOSTNAME
export SAN="IP:${NEW_ETCD_IP}, DNS:${NEW_ETCD_HOSTNAME}"
export PREFIX="/etc/etcd/generated_certs/etcd-$CN/"
export OPENSSLCFG="/etc/etcd/ca/openssl.cnf"

The custom openssl extensions used as etcd_v3_ca_* include the $SAN environment variable as subjectAltName. See /etc/etcd/ca/openssl.cnf for more information.

Create the directory to store the configuration and certificates:
```
# mkdir -p ${PREFIX}
```

Create the server certificate request and sign it: (server.csr and server.crt)

# openssl req -new -config ${OPENSSLCFG} \
    -keyout ${PREFIX}server.key  \
    -out ${PREFIX}server.csr \
    -reqexts etcd_v3_req -batch -nodes \
    -subj /CN=$CN

# openssl ca -name etcd_ca -config ${OPENSSLCFG} \
    -out ${PREFIX}server.crt \
    -in ${PREFIX}server.csr \
    -extensions etcd_v3_ca_server -batch

Create the peer certificate request and sign it: (peer.csr and peer.crt)

# openssl req -new -config ${OPENSSLCFG} \
    -keyout ${PREFIX}peer.key \
    -out ${PREFIX}peer.csr \
    -reqexts etcd_v3_req -batch -nodes \
    -subj /CN=$CN

# openssl ca -name etcd_ca -config ${OPENSSLCFG} \
  -out ${PREFIX}peer.crt \
  -in ${PREFIX}peer.csr \
  -extensions etcd_v3_ca_peer -batch

Copy the current etcd configuration and ca.crt files from the current node as examples to modify later:
```
# cp /etc/etcd/etcd.conf ${PREFIX}
# cp /etc/etcd/ca.crt ${PREFIX}
```
While still on the surviving etcd host, add the new host to the cluster. To add additional etcd members to the cluster, you must first adjust the default localhost peer in the peerURLs value for the first member:
1. Get the member ID for the first member using the member list command:
  # etcdctl --cert-file=/etc/etcd/peer.crt \ --key-file=/etc/etcd/peer.key \ --ca-file=/etc/etcd/ca.crt \ --peers="https://172.18.1.18:2379,https://172.18.9.202:2379,https://172.18.0.75:2379" \ (1) member list
  1 Ensure that you specify the URLs of only active etcd members in the --peers parameter value.
2. Obtain the IP address where etcd listens for cluster peers:
  $ ss -l4n | grep 2380
3. Update the value of peerURLs using the etcdctl member update command by passing the member ID and IP address obtained from the previous steps:
  # etcdctl --cert-file=/etc/etcd/peer.crt \ --key-file=/etc/etcd/peer.key \ --ca-file=/etc/etcd/ca.crt \ --peers="https://172.18.1.18:2379,https://172.18.9.202:2379,https://172.18.0.75:2379" \ member update 511b7fb6cc0001 https://172.18.1.18:2380
4. Re-run the member list command and ensure the peer URLs no longer include localhost.

Add the new host to the etcd cluster. Note that the new host is not yet configured, so the status stays as unstarted until the you configure the new host.

You must add each member and bring it online one at a time. When you add each additional member to the cluster, you must adjust the peerURLs list for the current peers. The peerURLs list grows by one for each member added. The etcdctl member add command outputs the values that you must set in the etcd.conf file as you add each member, as described in the following instructions.

# etcdctl -C https://${CURRENT_ETCD_HOST}:2379 \
  --ca-file=/etc/etcd/ca.crt     \
  --cert-file=/etc/etcd/peer.crt     \
  --key-file=/etc/etcd/peer.key member add ${NEW_ETCD_HOSTNAME} https://${NEW_ETCD_IP}:2380 (1)

Added member named 10.3.9.222 with ID 4e1db163a21d7651 to cluster

ETCD_NAME="<NEW_ETCD_HOSTNAME>"
ETCD_INITIAL_CLUSTER="<NEW_ETCD_HOSTNAME>=https://<NEW_HOST_IP>:2380,<CLUSTERMEMBER1_NAME>=https:/<CLUSTERMEMBER2_IP>:2380,<CLUSTERMEMBER2_NAME>=https:/<CLUSTERMEMBER2_IP>:2380,<CLUSTERMEMBER3_NAME>=https:/<CLUSTERMEMBER3_IP>:2380"
ETCD_INITIAL_CLUSTER_STATE="existing"

1	In this line, `10.3.9.222` is a label for the etcd member. You can specify the host name, IP address, or a simple name.

Update the sample ${PREFIX}/etcd.conf file.
1. Replace the following values with the values generated in the previous step:
  - ETCD_NAME
  - ETCD_INITIAL_CLUSTER
  - ETCD_INITIAL_CLUSTER_STATE
2. Modify the following variables with the new host IP from the output of the previous step. You can use ${NEW_ETCD_IP} as the value.
  ETCD_LISTEN_PEER_URLS ETCD_LISTEN_CLIENT_URLS ETCD_INITIAL_ADVERTISE_PEER_URLS ETCD_ADVERTISE_CLIENT_URLS
3. If you previously used the member system as an etcd node, you must overwrite the current values in the /etc/etcd/etcd.conf file.
4. Check the file for syntax errors or missing IP addresses, otherwise the etcd service might fail:
  # vi ${PREFIX}/etcd.conf
On the node that hosts the installation files, update the [etcd] hosts group in the /etc/ansible/hosts inventory file. Remove the old etcd hosts and add the new ones.

Create a tgz file that contains the certificates, the sample configuration file, and the ca and copy it to the new host:

# tar -czvf /etc/etcd/generated_certs/${CN}.tgz -C ${PREFIX} .
# scp /etc/etcd/generated_certs/${CN}.tgz ${CN}:/tmp/

Modify the new etcd host

Install iptables-services to provide iptables utilities to open the required ports for etcd:
```
# yum install -y iptables-services
```
Create the OS_FIREWALL_ALLOW firewall rules to allow etcd to communicate:
- Port 2379/tcp for clients
- Port 2380/tcp for peer communication
  # systemctl enable iptables.service --now # iptables -N OS_FIREWALL_ALLOW # iptables -t filter -I INPUT -j OS_FIREWALL_ALLOW # iptables -A OS_FIREWALL_ALLOW -p tcp -m state --state NEW -m tcp --dport 2379 -j ACCEPT # iptables -A OS_FIREWALL_ALLOW -p tcp -m state --state NEW -m tcp --dport 2380 -j ACCEPT # iptables-save | tee /etc/sysconfig/iptables
  In this example, a new chain OS_FIREWALL_ALLOW is created, which is the standard naming the OpenShift Container Platform installer uses for firewall rules.
  
  If the environment is hosted in an IaaS environment, modify the security groups for the instance to allow incoming traffic to those ports as well.
Install etcd:
```
# yum install -y etcd
```
Ensure version etcd-2.3.7-4.el7.x86_64 or greater is installed,
Ensure the etcd service is not running:
```
# systemctl disable etcd --now
```

Remove any etcd configuration and data:

# rm -Rf /etc/etcd/*
# rm -Rf /var/lib/etcd/*

Extract the certificates and configuration files:

# tar xzvf /tmp/etcd0.example.com.tgz -C /etc/etcd/

Modify the file ownership permissions:

# chown -R etcd:etcd /etc/etcd/*
# chown -R etcd:etcd /var/lib/etcd/

Start etcd on the new host:
```
# systemctl enable etcd --now
```

Verify that the host is part of the cluster and the current cluster health:

If you use the v2 etcd api, run the following command:

# etcdctl --cert-file=/etc/etcd/peer.crt \
          --key-file=/etc/etcd/peer.key \
          --ca-file=/etc/etcd/ca.crt \
          --peers="https://*master-0.example.com*:2379,\
          https://*master-1.example.com*:2379,\
          https://*master-2.example.com*:2379,\
          https://*etcd0.example.com*:2379"\
          cluster-health
member 5ee217d19001 is healthy: got healthy result from https://192.168.55.12:2379
member 2a529ba1840722c0 is healthy: got healthy result from https://192.168.55.8:2379
member 8b8904727bf526a5 is healthy: got healthy result from https://192.168.55.21:2379
member ed4f0efd277d7599 is healthy: got healthy result from https://192.168.55.13:2379
cluster is healthy

If you use the v3 etcd api, run the following command:

# ETCDCTL_API=3 etcdctl --cert="/etc/etcd/peer.crt" \
          --key=/etc/etcd/peer.key \
          --cacert="/etc/etcd/ca.crt" \
          --endpoints="https://*master-0.example.com*:2379,\
            https://*master-1.example.com*:2379,\
            https://*master-2.example.com*:2379,\
            https://*etcd0.example.com*:2379"\
            endpoint health
https://master-0.example.com:2379 is healthy: successfully committed proposal: took = 5.011358ms
https://master-1.example.com:2379 is healthy: successfully committed proposal: took = 1.305173ms
https://master-2.example.com:2379 is healthy: successfully committed proposal: took = 1.388772ms
https://etcd0.example.com:2379 is healthy: successfully committed proposal: took = 1.498829ms

Modify each OpenShift Container Platform master

Modify the master configuration in the etcClientInfo section of the /etc/origin/master/master-config.yaml file on every master. Add the new etcd host to the list of the etcd servers OpenShift Container Platform uses to store the data, and remove any failed etcd hosts:

etcdClientInfo:
  ca: master.etcd-ca.crt
  certFile: master.etcd-client.crt
  keyFile: master.etcd-client.key
  urls:
    - https://master-0.example.com:2379
    - https://master-1.example.com:2379
    - https://master-2.example.com:2379
    - https://etcd0.example.com:2379

Restart the master API service:
- On every master:
  # systemctl restart atomic-openshift-master-api
- Or, on a single master cluster installation:
  # systemctl restart atomic-openshift-master
  The number of etcd nodes must be odd, so you must add at least two hosts.
If you use Flannel, modify the flanneld service configuration located at /etc/sysconfig/flanneld on every OpenShift Container Platform host to include the new etcd host:
```
FLANNEL_ETCD_ENDPOINTS=https://master-0.example.com:2379,https://master-1.example.com:2379,https://master-2.example.com:2379,https://etcd0.example.com:2379
```
Restart the flanneld service:
```
# systemctl restart flanneld.service
```

Bringing OpenShift Container Platform services back online

After you finish your changes, bring OpenShift Container Platform back online.

Procedure

On each OpenShift Container Platform master, restore your master and node configuration from backup and enable and restart all relevant services:

# cp ${MYBACKUPDIR}/etc/sysconfig/atomic-openshift-master-api /etc/sysconfig/atomic-openshift-master-api
# cp ${MYBACKUPDIR}/etc/sysconfig/atomic-openshift-master-controllers /etc/sysconfig/atomic-openshift-master-controllers
# cp ${MYBACKUPDIR}/etc/origin/master/master-config.yaml.<timestamp> /etc/origin/master/master-config.yaml
# cp ${MYBACKUPDIR}/etc/origin/node/node-config.yaml.<timestamp> /etc/origin/node/node-config.yaml
# cp ${MYBACKUPDIR}/etc/origin/master/scheduler.json.<timestamp> /etc/origin/master/scheduler.json
# systemctl enable atomic-openshift-master-api
# systemctl enable atomic-openshift-master-controllers
# systemctl enable atomic-openshift-node
# systemctl start atomic-openshift-master-api
# systemctl start atomic-openshift-master-controllers
# systemctl start atomic-openshift-node

On each OpenShift Container Platform node, restore your node-config.yaml file from backup and enable and restart the atomic-openshift-node service:

# cp /etc/origin/node/node-config.yaml.<timestamp> /etc/origin/node/node-config.yaml
# systemctl enable atomic-openshift-node
# systemctl start atomic-openshift-node

Restoring a project

To restore a project, create the new project, then restore any exported files by running oc create -f pods.json. However, restoring a project from scratch requires a specific order because some objects depend on others. For example, you must create the configmaps before you create any pods.

Procedure

If the project was exported as a single file, import it by running the following commands:

$ oc new-project <projectname>
$ oc create -f project.yaml
$ oc create -f secret.yaml
$ oc create -f serviceaccount.yaml
$ oc create -f pvc.yaml
$ oc create -f rolebindings.yaml

Some resources, such as pods and default service accounts, can fail to be created.

Restoring application data

You can restore application data by using the oc rsync command, assuming rsync is installed within the container image. The Red Hat rhel7 base image contains rsync. Therefore, all images that are based on rhel7 contain it as well. See Troubleshooting and Debugging CLI Operations - rsync.

This is a generic restoration of application data and does not take into account application-specific backup procedures, for example, special export and import procedures for database systems.

Other means of restoration might exist depending on the type of the persistent volume you use, for example, Cinder, NFS, or Gluster.

Procedure

Example of restoring a Jenkins deployment’s application data

Verify the backup:

$ ls -la /tmp/jenkins-backup/
total 8
drwxrwxr-x.  3 user     user   20 Sep  6 11:14 .
drwxrwxrwt. 17 root     root 4096 Sep  6 11:16 ..
drwxrwsrwx. 12 user     user 4096 Sep  6 11:14 jenkins

Use the oc rsync tool to copy the data into the running pod:
```
$ oc rsync /tmp/jenkins-backup/jenkins jenkins-1-37nux:/var/lib
```
Depending on the application, you may be required to restart the application.
Optionally, restart the application with new data:
```
$ oc delete pod jenkins-1-37nux
```
Alternatively, you can scale down the deployment to 0, and then up again:
```
$ oc scale --replicas=0 dc/jenkins
$ oc scale --replicas=1 dc/jenkins
```

Restoring Persistent Volume Claims

This topic describes two methods for restoring data. The first involves deleting the file, then placing the file back in the expected location. The second example shows migrating persistent volume claims. The migration would occur in the event that the storage needs to be moved or in a disaster scenario when the backend storage no longer exists.

Check with the restore procedures for the specific application on any steps required to restore data to the application.

Restoring files to an existing PVC

Procedure

Delete the file:

$ oc rsh demo-2-fxx6d
sh-4.2$ ls */opt/app-root/src/uploaded/*
lost+found  ocp_sop.txt
sh-4.2$ *rm -rf /opt/app-root/src/uploaded/ocp_sop.txt*
sh-4.2$ *ls /opt/app-root/src/uploaded/*
lost+found

Replace the file from the server that contains the rsync backup of the files that were in the pvc:
```
$ oc rsync uploaded demo-2-fxx6d:/opt/app-root/src/
```
Validate that the file is back on the pod by using oc rsh to connect to the pod and view the contents of the directory:
```
$ oc rsh demo-2-fxx6d
sh-4.2$ *ls /opt/app-root/src/uploaded/*
lost+found  ocp_sop.txt
```

Restoring data to a new PVC

The following steps assume that a new pvc has been created.

Procedure

Overwrite the currently defined claim-name:

$ oc volume dc/demo --add --name=persistent-volume \
		--type=persistentVolumeClaim --claim-name=filestore \ --mount-path=/opt/app-root/src/uploaded --overwrite

Validate that the pod is using the new PVC:

$ oc describe dc/demo
Name:		demo
Namespace:	test
Created:	3 hours ago
Labels:		app=demo
Annotations:	openshift.io/generated-by=OpenShiftNewApp
Latest Version:	3
Selector:	app=demo,deploymentconfig=demo
Replicas:	1
Triggers:	Config, Image(demo@latest, auto=true)
Strategy:	Rolling
Template:
  Labels:	app=demo
		deploymentconfig=demo
  Annotations:	openshift.io/container.demo.image.entrypoint=["container-entrypoint","/bin/sh","-c","$STI_SCRIPTS_PATH/usage"]
		openshift.io/generated-by=OpenShiftNewApp
  Containers:
   demo:
    Image:	docker-registry.default.svc:5000/test/demo@sha256:0a9f2487a0d95d51511e49d20dc9ff6f350436f935968b0c83fcb98a7a8c381a
    Port:	8080/TCP
    Volume Mounts:
      /opt/app-root/src/uploaded from persistent-volume (rw)
    Environment Variables:	<none>
  Volumes:
   persistent-volume:
    Type:	PersistentVolumeClaim (a reference to a PersistentVolumeClaim in the same namespace)
    *ClaimName:	filestore*
    ReadOnly:	false
...omitted...

Now that the deployement configuration uses the new pvc, run oc rsync to place the files onto the new pvc:

$ oc rsync uploaded demo-3-2b8gs:/opt/app-root/src/
sending incremental file list
uploaded/
uploaded/ocp_sop.txt
uploaded/lost+found/

sent 181 bytes  received 39 bytes  146.67 bytes/sec
total size is 32  speedup is 0.15

Validate that the file is back on the pod by using oc rsh to connect to the pod and view the contents of the directory:
```
$ oc rsh demo-3-2b8gs
sh-4.2$ ls /opt/app-root/src/uploaded/
lost+found  ocp_sop.txt
```

Restoring OpenShift Container Platform components

Overview

Restoring a cluster

Procedure

Restoring a master host backup

Procedure

Restoring a node host backup

Procedure

Restoring etcd

Restoring etcd v2 & v3 data

Procedure

Fix the peerURLS parameter

Procedure

Restoring etcd for v3

Procedure

Adding an etcd node

Adding a new etcd host using Ansible

Procedure

Manually adding a new etcd host

Procedure

Modify the current etcd cluster

Modify the new etcd host

Modify each OpenShift Container Platform master

Bringing OpenShift Container Platform services back online

Procedure

Restoring a project

Procedure

Restoring application data

Procedure

Restoring Persistent Volume Claims

Restoring files to an existing PVC

Procedure

Restoring data to a new PVC

Procedure

Fix the `peerURLS` parameter