Installing Docker on Centos 7

Step 1: Install the required prerequisite packages.

[root@localhost ~]# yum install yum-utils device-mapper-persistent-data, lvm2, firewalld
[root@localhost ~]# systemctl enable firewalld
[root@localhost ~]# systemctl start firewalld

Step 2: Use the following command to set up the stable repository.

[root@localhost ~]# yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

Step 3: Update the yum package index and install the latest version of Docker CE.

[root@localhost ~]# yum makecache fast
[root@localhost ~]# yum install docker-ce

Step 4: Create a directory called "docker" to store a new file called daemon.json. Create it and add the following contents.

[root@localhost ~]# mkdir /etc/docker
[root@localhost ~]# vi /etc/docker/daemon.json

{
  "storage-driver": "devicemapper"
}

Step 5: Add the following contents to the sysctl.conf file.

[root@localhost ~]# vi /etc/sysctl.conf

net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1

Step 6: Enable the Docker service to start at boot and manually start the Docker service.

[root@localhost ~]# systemctl enable docker
[root@localhost ~]# systemctl start docker

Step 7: Before adding any disk to the VM log on to the Linux VM, run the below command, and make note of the sdx entries.

[root@localhost ~]# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sda2

Step 8: Add a new disk to the VM, and reboot. Run the previous command again and make note of the new sdx entries. In our use case we added “/dev/sdb”.

[root@localhost ~]# ls /dev/sd*
/dev/sda  /dev/sda1  /dev/sda2 /dev/sdb

Step 9: Create a physical volume on your block device.

[root@localhost ~]# pvcreate /dev/sdb

Step 10: Create a volume group using the raw disk.

[root@localhost ~]# vgcreate docker /dev/sdb
Volume group "docker" successfully created

Step 11: Create two logical volumes for Docker to use.

[root@localhost ~]# lvcreate --wipesignatures y -n thinpool docker -l 95%VG
 Logical volume "thinpool" created.
[root@localhost ~]# lvcreate --wipesignatures y -n thinpoolmeta docker -l 1%VG
 Logical volume "thinpoolmeta" created.

Step 12: Convert the volumes to a thin pool and a storage location for metadata for the thin pool.

[root@localhost ~]# lvconvert -y \
 --zero n \
 -c 512K \
 --thinpool docker/thinpool \
 --poolmetadata docker/thinpoolmeta

 WARNING: Converting logical volume docker/thinpool and docker/thinpoolmeta to thin pool's data and metadata volumes with metadata wiping.
 THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.)
 Converted docker/thinpool to thin pool.

Step 13: Create a autoextension of thin pools via an lvm profile. The example below will add 20% more capacity when the disk usage reaches 80%.

[root@localhost ~]# vi /etc/lvm/profile/docker-thinpool.profile

activation {
  thin_pool_autoextend_threshold=80
  thin_pool_autoextend_percent=20
}

Step 14: Apply the LVM profile, using the lvchange command.

[root@localhost ~]# lvchange --metadataprofile docker-thinpool docker/thinpool
 Logical volume docker/thinpool changed.

Step 15: Enable monitoring for logical volumes on your host. Without this step, automatic extension will not occur even in the presence of the LVM profile.

[root@localhost ~]# lvs -o+seg_monitor
 LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert Monitor
 root centos -wi-ao---- 13.87g
 swap centos -wi-ao---- 1.60g
 thinpool docker twi-a-t--- 475.00g 0.00 0.01 monitored

Step 16: Since we have run Docker on this host before, stop Docker and move the contents of /var/lib/docker/ so that Docker can use the new LVM pool to store the contents of image and containers.

[root@localhost ~]# systemctl stop docker
[root@localhost ~]# mkdir /var/lib/docker.bk
[root@localhost ~]# mv /var/lib/docker/* /var/lib/docker.bk

Step 17: Edit /etc/docker/daemon.json and configure the options needed for the devicemapper storage driver. The file should now contain the below contents.

[root@localhost ~]# vi /etc/docker/daemon.json

{
    "storage-driver": "devicemapper",
    "storage-opts": [
    "dm.thinpooldev=/dev/mapper/docker-thinpool",
    "dm.use_deferred_removal=true",
    "dm.use_deferred_deletion=true"
    ]
}

NOTE: If you use Docker RHEL, CentOS, or Oracle Linux, you must use the devicemapper storage driver.

Step 18: Start the Docker service.

[root@localhost ~]# systemctl start docker