How to create alpine linux cloud image

Currently (27 April 2022) alpine linux does not provide cloud images for Openstack. Here is how to make it.

Step-by-step guide

The main thing is needed to build a simple openstack alpine image is to install cloud-init apk package! Optionally qemu-guest-agent for better integration with KVM and e2fsprogs-extra for resizing file system are installed, as well as sudo and acpi

• Download the latest alpine-virt iso

 wget https://dl-cdn.alpinelinux.org/alpine/v3.15/releases/x86_64/alpine-virt-3.15.4-x86_64.iso

• Create an empty 512MB image

 qemu-img create -f qcow2 alpine-virt-3.15.4-x86_64.qcow 512M

• Boot alpine from the iso file using QEMU (or anything else like VirtualBox or VMWare, in which case you may need to create an appropriate image as raw may not work)

 /usr/bin/qemu-system-x86_64 -drive file=alpine-virt-3.15.4-x86_64.qcow,if=virtio,cache=writeback,discard=ignore,format=qcow2 -drive file=alpine-virt-3.15.4-x86_64.iso,media=cdrom -boot once=d -vnc 0.0.0.0:15 -name alpine -machine type=pc,accel=tcg -netdev bridge,id=user.0,br=virbr0 -m 512M -device virtio-net,netdev=user.0 

• Connect to alpine VM with a VNC client to port 0.0.0.0:5915 if using QEMU.
• login with root (no password)
• run “setup-alpine” answering “us us” for keyboard, “alpine” for hostname, “dhcp” for eth0, “sda”, “sys” for disk drive, enable “openssh”, use “1” mirror for apk, reboot.
• If volumes are required, then for the disk drive choose “none” and run setup-disk but growpart won’t work in this case

 setup-disk -m sys -L

• Or with the answer file:

 setup-alpine -c answers
 sed -i -e 's/alpine-test/alpine/g' answers
 sed -i -e '/^PROXYOPTS/cPROXYOPTS="none"' answers
 sed -i -e '/^APKREPOSOPTS/s/-r/-1/' answers
 sed -i -e '/hostname/d' answers
 sed -i -e 's/openntpd/chrony/' answers
 #sed -i -e '/^DISKOPTS/cDISKOPTS="-m sys -L /dev/vda"' answers
 sed -i -e '/^DISKOPTS/cDISKOPTS="-m sys /dev/sda"' answers
 sed -i -e 's/^LBUOPTS/#LBUOPTS/' answers
 sed -i -e 's/^APKCACHEOPTS/#APKCACHEOPTS/' answers
 sed -i -e '/^DNSOPTS/cDSNOPTS="-m ${DOMAIN_NAME} 8.8.8.8"' answers
 setup-alpine -f answers
 reboot

• Then:

 . /etc/os-release
 VERSION=`echo ${VERSION_ID}|cut -f1-2 -d"."`

• Enable community apk repo

 sed -i -e "/\/v${VERSION}\/community$/s/^#//" /etc/apk/repositories

• Upgrade All Packages in OneShot

 apk upgrade --update-cache --available

• Install sudo, cloud-init, acpi, qemu-guest-agent and e2fsprogs-extra

 apk add sudo cloud-init acpi qemu-guest-agent e2fsprogs-extra

• Add cloud-init and qemu-guest-agent to startup

 setup-cloud-init
 rc-update add qemu-guest-agent

• prevent cloud-init config overwriting /etc/network/interfaces

 cat << EOF > /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg
 network:
   config: disabled
 EOF
   
 - add udhcpc staticroutes option to create a route for 169.254.169.254 Openstack datasource address 

 cat << EOF > /etc/network/interfaces
 auto lo
 iface lo inet loopback

 auto eth0
 iface eth0 inet dhcp
         udhcpc_opts -O staticroutes
 EOF

• allow ssh-rsa algorithm

 cat << EOF >> /etc/ssh/sshd_config
 PubkeyAuthentication yes
 PubkeyAcceptedAlgorithms ssh-rsa,rsa-sha2-256,rsa-sha2-512
 EOF

• Configure Openstack datasource and unlock alpine account setting lock_passwd to false and adding passwd line!

 vi /etc/cloud/cloud.cfg
 datasource:
   OpenStack:
     timeout: 5
     retries: 3
     #metadata_urls: ["http://169.254.169.254"]
     #max_wait: -1
     #apply_network_config: True

 system_info:
    distro: alpine
     default_user:
       lock_passwd: false
       passwd: $6$e.MLvnlNXAjBVtGV$LoeBb3B0c9fZ6TSAZvKnv0lLLJa61blgpJJUGyy5KIjRRdXK6xH8am7TckNEMW8bgd8IpcBC7BnebTO9PbYi00

• Update /etc/inittab to allow serial console on ttyS1 (serial1), serial0 is used for logging by kvm

 cat << EOF >> /etc/inittab 
 ttyS1::respawn:/sbin/getty -L 0 ttyS1 vt100  
 EOF

• Optionally update MOTD

 cat << EOF > /etc/motd
 Welcome to $PRETTY_NAME ($VERSION_ID)!
 Home URL: $HOME_URL
 EOF

• Poweroff

 poweroff

• Upload the alpine openstack image to glance

 openstack image create --public --file alpine-virt-3.15.4-x86_64.qcow --property hw_scsi_model=virtio-scsi --property hw_disk_bus=scsi --property hw_qemu_guest_agent=yes --property os_require_quiesce=yes alpine-virt-3.15.4-x86_64