OpenShift 3.6 Generic Guest Template
Internal
Overview
The generic template contains all an OpenShift master or regular node, as well as the support node, need to function. It is built in top of the basic template.
Clone the Basic Template
Use the basic template as a base image, and clone it, as described here:
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. When creating logical volumes, follow the storage volume naming conventions. For VirtualBox, the procedure of creating and installing a new virtual disk is available here.
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
More details about subscription management:
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
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
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. 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 50GB 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"
Setting DATA_SIZE too small caused nodes not being able to start and OpenShift OutOfDisk events.
Execute:
/usr/bin/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.
lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert container-thinpool docker_vg twi-a-t--- 49.89g 0.00 0.11
After setup, disable docker-storage-setup at startup, is not needed, storage already setup.
systemctl disable docker-storage-setup systemctl is-enabled docker-storage-setup
Optimizing Docker Storage
Enable Docker at Boot
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.
Docker and OpenShift Installation
The OpenShift 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.