OpenShift 3.6 Generic Guest Template: Difference between revisions

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==Docker Storage Setup==
==Docker Storage Setup==
Set up docker storage using Option A) described in the documentation: use an additional block device. In this case, the additional block device is provisioned as a dedicate volume group and exposed to the guest as the /dev/vdb block device.


/etc/sysconfig/docker-storage-setup:
/etc/sysconfig/docker-storage-setup:

Revision as of 05:07, 8 November 2017

Internal

Clone the Basic Template

Use the basic template as a base image, and clone it, as described here:

Cloning a Guest

The particular sequence follows:

virsh shutdown ocp36.basic-template
virsh dumpxml ocp36.basic-template > /root/environments/ocp36/ocp36.basic-template.xml

cp ocp36.basic-template.xml ocp36.generic-template.xml

Adjust the configuration as described here.

Clone the virtual machine image and create the new disk volumes, as described in Cloning a Guest.

virsh define /root/environments/ocp36/ocp36.generic-template.xml
virsh start --console ocp36.generic-template

Then reconfigure Linux VM Guest Image.

Install OpenShift Binaries

Attach the Node to the OpenShift Subscription

https://docs.openshift.com/container-platform/3.6/install_config/install/host_preparation.html#host-registration

More details about subscription management:

RedHat Subscription Manager

The node, being based on the basic template, should have been already registered with the subscription manager:

subscription-manager status
subscription-manager identity
subscription-manager list --available --matches '*OpenShift*'

Identify the OpenShift pool ID:

subscription-manager attach --pool=<pool-id>

Manage Repositories and Install Utilities

Once attached to the pool, all repositories must be first disabled, and then only select repositories are re-enabled:

subscription-manager repos --disable="*"
subscription-manager repos --list-enabled
yum repolist

If there are any enabled repositories, disable them with:

yum-config-manager --disable <repo_id>

Enable only the repositories required by OpenShift Container Platform 3.6:

subscription-manager repos --enable="rhel-7-server-rpms" --enable="rhel-7-server-extras-rpms" --enable="rhel-7-server-ose-3.6-rpms" --enable="rhel-7-fast-datapath-rpms"
subscription-manager repos --list-enabled
yum repolist
yum update -y

Install atomic-openshift-utils, which contains OpenShift installer utilities and other tools required by the installation process:

yum install atomic-openshift-utils

At this point, no OpenShift binaries, except installation utilities, are installed. The advanced installer knows how to override this and it will install the binaries as expected, without any further intervention.

Install Docker

https://docs.openshift.com/container-platform/3.6/install_config/install/host_preparation.html#installing-docker

Install Docker on the generic template. On the support host, it will simply not be activated. Docker is also required on masters too, but the image storage allocated to it can be made much smaller than on the nodes and infranodes. The binaries must be installed from the rhel-7-server-ose-3.*-rpms repository and have it running before installing OpenShift.

OpenShift 3.6 requires Docker 1.12.

yum install docker
docker version

Docker Storage Setup

Set up docker storage using Option A) described in the documentation: use an additional block device. In this case, the additional block device is provisioned as a dedicate volume group and exposed to the guest as the /dev/vdb block device.

/etc/sysconfig/docker-storage-setup:

CONTAINER_THINPOOL=docker-pool
STORAGE_DRIVER=devicemapper
DEVS=/dev/vdb
CONTAINER_THINPOOL=container-thinpool
VG=docker_vg
ROOT_SIZE=50G
DATA_SIZE=100%FREE
MIN_DATA_SIZE=2G
#POOL_META_SIZE=16M
CHUNK_SIZE=512K
GROWPART=false
AUTO_EXTEND_POOL=yes
POOL_AUTOEXTEND_THRESHOLD=60
POOL_AUTOEXTEND_PERCENT=20
DEVICE_WAIT_TIMEOUT=60
WIPE_SIGNATURES=true
CONTAINER_ROOT_LV_SIZE=100%FREE
# CONTAINER_ROOT_LV_MOUNT_PATH="/var/lib/containers/container-runtime"
docker-storage-setup
INFO: Volume group backing root filesystem could not be determined
INFO: Device node /dev/vdb1 exists.
 Physical volume "/dev/vdb1" successfully created.
 Volume group "docker_vg" successfully created
 Using default stripesize 64.00 KiB.
 Rounding up size to full physical extent 52.00 MiB
 Thin pool volume with chunk size 512.00 KiB can address at most 126.50 TiB of data.
 Logical volume "container-thinpool" created.
 Logical volume docker_vg/container-thinpool changed.



The advanced installation procedure is supposed to update /etc/sysconfig/docker on nodes with OpenShift-specific configuration. The documentation says that the advanced installation procedure will add an "--insecure-registry" option, but that does not seem to be the case, so we add it manually in /etc/sysconfig/docker:

INSECURE_REGISTRY='--insecure-registry 172.30.0.0/16'

The subnet value used to configure the insecure registry corresponds to the default value of the services subnet.

Provision storage for the Docker server. The default loopback storage is not appropriate for production, it should be replaced by a thin-pool logical volume. Follow https://docs.openshift.com/container-platform/3.5/install_config/install/host_preparation.html#configuring-docker-storage. Used Option A) "an additional block device". On VirtualBox or KVM, provision a new virtual disk and install it. At this stage, the size it is not important, as it will replaced with the actual storage when the nodes are built. Use 100 MB for the template.

KVM example (the template VM must be shut down prior to attaching the storage):

 virsh vol-create-as --pool main-storage-pool --name template-docker.raw --capacity 1024M
 virsh vol-list --pool main-storage-pool
 virsh attach-disk template /main-storage-pool/template-docker.raw vdb --config

Restart the template VM, the new storage should be available as /dev/vdb.

Then execute /usr/bin/docker-storage-setup with the base configuration read from /usr/lib/docker-storage-setup/docker-storage-setup and custom configuration specified in /etc/sysconfig/docker-storage-setup, similarly to:

STORAGE_DRIVER=devicemapper
DEVS=/dev/vdb
VG=docker_vg
# set to a little bit less than maximum amount of space available
DATA_SIZE=1023M
MIN_DATA_SIZE=1M

Setting DATA_SIZE too small caused nodes not being able to start and OpenShift OutOfDisk events.

Execute:

 /usr/bin/docker-storage-setup

Under some circumstances, /usr/bin/docker-storage-setup fails with:

[...]
end of partition 1 has impossible value for cylinders: 65 (should be in 0-64)
sfdisk: I don't like these partitions - nothing changed.
(If you really want this, use the --force option.)

If this happens, use the patched docker-storage-setup available here: https://github.com/NovaOrdis/playground/blob/master/openshift/3.5/patches/node/usr/bin/docker-storage-setup

Before running it, remove any logical volume, volume group and physical volume that may have been created and leave an empty /dev/vdb1 partition. Then run

 /usr/bin/docker-storage-setup --force

After the script completes successfully, it creates a logical volume with an XFS filesystem mounted on docker root directory /var/lib/docker and the Docker storage configuration file /etc/sysconfig/docker-storage. The thin pool to be used by Docker should be visible in lvs:

# lvs

  LV          VG        Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  docker-pool docker_vg twi-a-t--- 500.00m             0.00   0.88
  root        main_vg   -wi-ao----   7.00g

Alternatively, you can follow the manual procedure of provisioning Docker storage on a dedicated block device:

Provision Docker Storage on a Dedicated Block Device

Disable docker-storage-setup, is not needed, storage already setup.

 systemctl disable docker-storage-setup
 systemctl is-enabled docker-storage-setup

Enable Docker at boot and start it.

 systemctl enable docker
 systemctl start docker
 
 systemctl status docker

Reboot the system and then check Docker Server Runtime.

TODO: parse and NOKB this: https://docs.openshift.com/container-platform/3.5/scaling_performance/optimizing_storage.html#optimizing-storage

Generic Docker installation instructions Docker Installation.