My notes on getting these bootstrapped.
Get image onto SD card
- Example is for centos 7.6, released 2018-10 (1810)
- centos docs
img=CentOS-Userland-7-armv7hl-RaspberryPI-Minimal-1810-sda.raw
unxz ${img}.xz
sudo dd if=./${img} of=/dev/mmcblk1 status=progress bs=8192 ; sudo sync
At time of writing, this was a Centos 7.6 image, and by default had a 1.4gb ext4 root partition with 421mb free, a vfat boot partition. It also has a 500mb swap partition.
Reset root password
defaults to ‘centos’
passwd root
ssh key
ssh-copy-id root@<ip>
Set hostname
hostnamectl set-hostname foo.domain
Disable wifi
echo 'blacklist brcmfmac' > /etc/modprobe.d/brcmfmac.conf
/tmp tmpfs
systemctl enable tmp.mount
patch
yum update
Grow root partition
The procedure on the internet is to amend the partition table with fdisk, and then grow the filesystem. I subsequently tracked down the command to do this on the faq page
/usr/bin/rootfs-expand
That’s the easiest way to grow root to the entire disk.
I generally don’t ..
fdisk seems to be displaying in blocks of 1kb; we have a 1.4gb partition. sfdisk is using 512byte sectors.
# fdisk -l /dev/mmcblk0 Disk /dev/mmcblk0: 15.5 GB, 15489564672 bytes, 30253056 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 Disk label type: dos Disk identifier: 0x000cc7a5 Device Boot Start End Blocks Id System /dev/mmcblk0p1 * 2048 1370111 684032 c W95 FAT32 (LBA) /dev/mmcblk0p2 1370112 2369535 499712 82 Linux swap / Solaris /dev/mmcblk0p3 2369536 5298175 1464320 83 Linux
# sfdisk -d /dev/mmcblk0 | tee -a /root/mmcblk0_sfdisk_orig # partition table of /dev/mmcblk0 unit: sectors /dev/mmcblk0p1 : start= 2048, size= 1368064, Id= c, bootable /dev/mmcblk0p2 : start= 1370112, size= 999424, Id=82 /dev/mmcblk0p3 : start= 2369536, size= 2928640, Id=83 /dev/mmcblk0p4 : start= 0, size= 0, Id= 0
Let us go with six gb or so.
# expr 6000 \* 1024 \* 2
12288000
# cat /root/mmcblk0_sfdisk_orig | \
sed 's~ 2928640~12288000~g' > /root/mmcblk0_sfdisk_new
# sfdisk -f /dev/mmcblk0 < /root/mmcblk0_sfdisk_new
# reboot
And assuming it comes back 🙂
# mount | grep 'on / ' /dev/mmcblk0p3 on / type ext4 (rw,noatime,seclabel,data=ordered) resize2fs /dev/mmcblk0p3
packages
I add these via my puppet baseline.
yum install wget which file lsof unzip
logical volume manager, /home
- also installs device-mapper
yum install lvm2
- prepare to add a fourth partition for LVM
# sfdisk -T | grep -i lvm 8e Linux LVM
# fdisk -l /dev/mmcblk0
Disk /dev/mmcblk0: 15.5 GB, 15489564672 bytes, 30253056 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
Disk label type: dos
Disk identifier: 0x000cc7a5
Device Boot Start End Blocks Id System
/dev/mmcblk0p1 * 2048 1370111 684032 c W95 FAT32 (LBA)
/dev/mmcblk0p2 1370112 2369535 499712 82 Linux swap / Solaris
/dev/mmcblk0p3 2369536 14657535 6144000 83 Linux
# egrep -v '^/dev/mmcblk0p4' /root/mmcblk0_sfdisk_new > /root/mmcblk0_sfdisk_lvm # p3end=14657535 # from partition 3 end sector # sectors=30253056 # from total sectors of device
# pstart=$(expr ${p3end} + 1)
# psize=$(expr ${sectors} - ${pstart} )
# echo "/dev/mmcblk0p4 : start= ${pstart}, size= ${psize}, Id=8e" >> /root/mmcblk0_sfdisk_lvm
check file; apply change
cat /root/mmcblk0_sfdisk_lvm sfdisk -f /dev/mmcblk0 < /root/mmcblk0_sfdisk_lvm reboot
Set up volume group, home filesystem.
vgcreate rootvg /dev/mmcblk0p4 lvcreate --name lv00hom00 --size 1G rootvg mkfs.xfs /dev/rootvg/lv00hom00 echo "/dev/rootvg/lv00hom00 /home xfs defaults,noatime 0 0" >> /etc/fstab mount /home
Puppet
Revisions
2019-04-10 added default root password, and changed /home from ext4 to xfs
thewatertower.org 