Overview
In order to properly support the environment, one set of images will be retrieved from the Red Hat OpenShift reference site for Debian, Ubuntu, and CentOS. These images will then be modified in order to support the necessary installations. Based on the requirements, an image will be created to provide sufficient space for the deployed product to operate efficiently.
This document will provide instructions on how to make changes to such images in order to prepare them for use.
Preparing Access
The Cloud images don’t have credentials by default. The intention is to use the cloud-init process to inject the account information for the service account, which then permits access to the image. Because the images aren’t configured to use the Linux Volume Manager (LVM), we’ll need to extend the file systems the old fashioned way. The tool to use is guestfish. It permits access to the image and the ability to mount a file system which can then be edited. In this case, we’ll want to either create a password for the root user or copy your credentials from the local system. In addition, in order for root to be able to log in, you may need to edit the /etc/ssh/sshd_config file and edit the PermitRootLogin option to be yes. With those two changes, you can then log in to the image to make any updates. Example session below.
# guestfish -a centos8.qcow2
Welcome to guestfish, the guest filesystem shell for
editing virtual machine filesystems and disk images.
Type: ‘help’ for help on commands
‘man’ to read the manual
‘quit’ to quit the shell
><fs> run
><fs> list-filesystems
/dev/sda1: xfs
><fs> mount /dev/sda1 /
><fs> vi /etc/shadow
><fs> vi /etc/ssh/sshd_config
><fs> quit
Don’t forget to use guestfish to access the image and replace the password with an asterisk.
Extending Images
There are multiple products being deployed and all have different disk space requirements. You’ll use the following command to access the consoles and create the necessary images. In preparation, copy each of the images to a specific disk size based on the requirements. If we have consistencies and the product has no underlying Operating System requirements, keep the changes to a minimum.
The sizes below are based on a reasonable base size of 20 Gigabytes and then a review of the existing environment, both as configured and the current utilization.
- DNS Server – 20 Gigabytes, Any Operating System
- FreeSwitch Server – 20 Gigabytes, Debian 10 Operating System
- NFS Server – 50 Gigabytes, Any Operating System
- MongoDB Server – 75 Gigabytes, XFS requirement for the WiredTiger Storage Engine mandating using the CentOS Operating System
- HAProxy Server – 20 Gigabytes, Any Operating System
- Provisioning Server – 50 Gigabytes, Any Operating System
- OpenShift Boot Node – 20 Gigabytes, CoreOS Operating System
- OpenShift Master Node – 100 Gigabytes, CoreOS Operating System
- OpenShift Worker Node – 100 Gigabytes, CoreOS Operating System
You’ll use the qemu-img command to extend the images as noted above.
# qemu-img resize debian10.qcow2 20G
Accessing a Debian Console
By default, grub on a Debian 9 and 10 Cloud image has console access disabled. This is a security measure for OpenShift to prevent Out of Band (OOB) access to an image. This does mean you have to have the ability to run an X Server on your laptop. Personally I use cygwin for my Windows laptops and XCode for the Mac. Once prepared, bring up a terminal window and run startx. This should bring up the X Server and a graphical terminal console. From there, you’ll need to use Secure Shell and a specific switch in order to access the target server. ssh -Y (target server). You can verify successful access by checking your DISPLAY variable (echo $DISPLAY). If it is set, you should then be able to access the Debian image. Don’t forget to change the image flag to Spice or VNC when opening the console.
Copy the retrieved debian10.qcow2 image into a common location where you’ll make the necessary changes such as /var/lib/libvirt/images/debian10/. Run the following command to bring up a graphical console session. Note that the –graphics flag is spice.
# virt-install \
--memory 2048 \
--vcpus 2 \
--name dbtst \
--disk /var/lib/libvirt/images/debian10/debian10.qcow2,device=disk \
--os-type Linux \
--os-variant debian10 \
--virt-type kvm \
--graphics spice \
--network default \
--import
Once the terminal is up, edit the /etc/default/grub file and uncomment the GRUB_TERMINAL=console line. Save it and run the update-grub command. Once that is done, you will be able to bring up a text console in the future to troubleshoot any issues. In this case, you will continue the disk space modifications through the graphical console.
Accessing the CentOS and Ubuntu Consoles
For the CentOS and Ubuntu images, copy the centos8.qcow2 and ubuntu18.img image into the image directory, in this example the /var/lib/libvirt/images/centos8|ubuntu18/ directory. You’ll need to give it a unique name when starting it as noted in the examples below. Once in the image, you can make the necessary changes, such as increasing the available disk space, then shut the image down.
For CentOS
# virt-install \
--memory 2048 \
--vcpus 2 \
--name cotst \
--disk /var/lib/libvirt/images/centos8/centos8.qcow2,device=disk \
--os-type Linux \
--os-variant centos8 \
--virt-type kvm \
--graphics none \
--network default \
--import
And for Ubuntu
# virt-install \
--memory 2048 \
--vcpus 2 \
--name ubtst \
--disk /var/lib/libvirt/images/ubuntu18/ubuntu18.img,device=disk \
--os-type Linux \
--os-variant ubuntu18.04 \
--virt-type kvm \
--graphics none \
--network default \
--import
Extending Debian EXT4 File System
By default the Debian image is 2 Gigs in size. This process extends the file system as required. Start the console and log in. This is an EXT4 file system so you’ll use the fdisk tools and partprobe and resize2fs to update the partition.
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
udev 1014152 0 1014152 0% /dev
tmpfs 204548 2948 201600 2% /run
/dev/vda1 2030416 991160 918068 52% /
tmpfs 1022720 0 1022720 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 1022720 0 1022720 0% /sys/fs/cgroup
tmpfs 204544 0 204544 0% /run/user/0
Run fdisk to see that 20 Gigs is available to the system now.
# fdisk -l
Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe5c3b0d8
Device Boot Start End Sectors Size Id Type
/dev/vda1 * 2048 4194303 4192256 2G 83 Linux
For an EXT4 file system, you’ll need to delete the partition and add it back in at the full available size.
# fdisk /dev/vda
Welcome to fdisk (util-linux 2.33.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe5c3b0d8
Device Boot Start End Sectors Size Id Type
/dev/vda1 * 2048 4194303 4192256 2G 83 Linux
Command (m for help): d
Selected partition 1
Partition 1 has been deleted.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-41943039, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-41943039, default 41943039):
Created a new partition 1 of type 'Linux' and of size 20 GiB.
Partition #1 contains a ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: n
Command (m for help): p
Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xe5c3b0d8
Device Boot Start End Sectors Size Id Type
/dev/vda1 2048 41943039 41940992 20G 83 Linux
Command (m for help): w
The partition table has been altered.
Syncing disks.
Unfortunately, partprobe isn’t part of the Debian installation. Simply install the parted package and partprobe will be installed in /sbin.
# aptitude install parted
The following NEW packages will be installed:
libparted2{a} parted
0 packages upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 473 kB of archives. After unpacking 809 kB will be used.
Do you want to continue? [Y/n/?] y
Get: 1 http://deb.debian.org/debian buster/main amd64 libparted2 amd64 3.2-25 [277 kB]
Get: 2 http://deb.debian.org/debian buster/main amd64 parted amd64 3.2-25 [196 kB]
Fetched 473 kB in 1s (458 kB/s)
Selecting previously unselected package libparted2:amd64.
(Reading database ... 27035 files and directories currently installed.)
Preparing to unpack .../libparted2_3.2-25_amd64.deb ...
Unpacking libparted2:amd64 (3.2-25) ...
Selecting previously unselected package parted.
Preparing to unpack .../parted_3.2-25_amd64.deb ...
Unpacking parted (3.2-25) ...
Setting up libparted2:amd64 (3.2-25) ...
Setting up parted (3.2-25) ...
Processing triggers for libc-bin (2.28-10) ...
Now run partprobe to register the new partition in the kernel.
# partprobe
Finally use resize2fs to extend the filesystem.
# resize2fs /dev/vda1
resize2fs 1.44.5 (15-Dec-2018)
Filesystem at /dev/vda1 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 3
[ 4014.025845] EXT4-fs (vda1): resizing filesystem from 524032 to 5242624 blocks
[ 4014.172547] EXT4-fs (vda1): resized filesystem to 5242624
And we’re now at 20 Gigs.
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
udev 1014152 0 1014152 0% /dev
tmpfs 204548 2948 201600 2% /run
/dev/vda1 20608592 1008764 18723724 6% /
tmpfs 1022720 0 1022720 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 1022720 0 1022720 0% /sys/fs/cgroup
tmpfs 204544 0 204544 0% /run/user/0
Extending CentOS XFS File System
By default, the cloud image for CentOS 8 is 8 Gigs. The file system is XFS and not EXT4 so you’ll use the XFS tools.
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 897776 0 897776 0% /dev
tmpfs 930128 0 930128 0% /dev/shm
tmpfs 930128 16856 913272 2% /run
tmpfs 930128 0 930128 0% /sys/fs/cgroup
/dev/vda1 8181760 1404372 6777388 18% /
tmpfs 186024 0 186024 0% /run/user/0
When running fdisk, you’ll see the current /dev/vda1 partition size of 16,384,000 sectors and the available sectors at 41,943,040 sectors.
# fdisk -l
Disk /dev/vda: 20 GiB, 21474836480 bytes, 41943040 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xada233c8
Device Boot Start End Sectors Size Id Type
/dev/vda1 * 2048 16386047 16384000 7.8G 83 Linux
Grow the partition to the available size.
# growpart /dev/vda 1
CHANGED: partition=1 start=2048 old: size=16384000 end=16386047 new: size=41940992 end=41943039
And then extend the file system to use the entire partition.
# xfs_growfs -d /dev/vda1
meta-data=/dev/vda1 isize=512 agcount=4, agsize=512000 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=1, sparse=1, rmapbt=0
= reflink=1
data = bsize=4096 blocks=2048000, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0, ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 2048000 to 5242624
When done, the partition is now the new size.
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
devtmpfs 897776 0 897776 0% /dev
tmpfs 930128 0 930128 0% /dev/shm
tmpfs 930128 16856 913272 2% /run
tmpfs 930128 0 930128 0% /sys/fs/cgroup
/dev/vda1 20960256 1493912 19466344 8% /
tmpfs 186024 0 186024 0% /run/user/0
Extending Ubuntu GPT File System
The default Ubuntu image is only 2 Gigs in size. You’ll need to use the gdisk command in the console vs the fdisk one as fdisk doesn’t work on GPT partitions. The process is similar though.
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
udev 1007580 0 1007580 0% /dev
tmpfs 204072 680 203392 1% /run
/dev/vda1 2058100 1072008 969708 53% /
tmpfs 1020348 0 1020348 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 1020348 0 1020348 0% /sys/fs/cgroup
/dev/vda15 106858 3696 103162 4% /boot/efi
tmpfs 204068 0 204068 0% /run/user/0
In gdisk, you’ll need to delete the existing partition and recreate it to the new size.
# gdisk /dev/vda
GPT fdisk (gdisk) version 1.0.3
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Command (? for help): p
Disk /dev/vda: 41943040 sectors, 20.0 GiB
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): E1A6C9DD-012D-4943-8697-0FE02F412F36
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 41943006
Partitions will be aligned on 2048-sector boundaries
Total free space is 37332958 sectors (17.8 GiB)
Number Start (sector) End (sector) Size Code Name
1 227328 4612062 2.1 GiB 8300
14 2048 10239 4.0 MiB EF02
15 10240 227327 106.0 MiB EF00
Command (? for help): d
Partition number (1-15): 1
Command (? for help): n
Partition number (1-128, default 1): 1
First sector (34-41943006, default = 227328) or {+-}size{KMGTP}:
Last sector (227328-41943006, default = 41943006) or {+-}size{KMGTP}:
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300):
Changed type of partition to 'Linux filesystem'
Command (? for help): p
Disk /dev/vda: 41943040 sectors, 20.0 GiB
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): E1A6C9DD-012D-4943-8697-0FE02F412F36
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 41943006
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)
Number Start (sector) End (sector) Size Code Name
1 227328 41943006 19.9 GiB 8300 Linux filesystem
14 2048 10239 4.0 MiB EF02
15 10240 227327 106.0 MiB EF00
Command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/vda.
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot or after you
run partprobe(8) or kpartx(8)
The operation has completed successfully.
You’ll need to refresh the partition table in the kernel by running the partprobe command.
# partprobe
With the partition recognized, we now need to resize the file system to the new partition table.
# resize2fs /dev/vda1
resize2fs 1.44.1 (24-Mar-2018)
Filesystem at /dev/vda1 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 3
The filesystem on /dev/vda1 is now 5214459 (4k) blocks long.
And we’re at 20 Gigs.
# df -k
Filesystem 1K-blocks Used Available Use% Mounted on
udev 1007580 0 1007580 0% /dev
tmpfs 204072 680 203392 1% /run
/dev/vda1 20145724 1077020 19052320 6% /
tmpfs 1020348 0 1020348 0% /dev/shm
tmpfs 5120 0 5120 0% /run/lock
tmpfs 1020348 0 1020348 0% /sys/fs/cgroup
/dev/vda15 106858 3696 103162 4% /boot/efi
tmpfs 204068 0 204068 0% /run/user/0
