How to run cloud-init locally

It’s very likely that you will want to test cloud-init locally before deploying it to the cloud. Fortunately, there are several different virtual machine (VM) and container tools that are ideal for this sort of local testing.

QEMU

QEMU is a general purpose computer hardware emulator that is capable of running virtual machines with hardware acceleration as well as emulating the instruction sets of different architectures than the host that you are running on.

The NoCloud datasource allows users to provide their own user data, metadata, or network configuration directly to an instance without running a network service. This is helpful for launching local cloud images with QEMU.

Create your configuration

We will leave the network-config and meta-data files empty, but populate user-data with a cloud-init configuration. You may edit the network-config and meta-data files if you have a config to provide.

$ touch network-config
$ touch meta-data
$ cat >user-data <<EOF
#cloud-config
password: password
chpasswd:
  expire: False
ssh_pwauth: True
EOF

Create an ISO disk

This disk is used to pass configuration to cloud-init. Create it with the genisoimage command:

genisoimage \
    -output seed.img \
    -volid cidata -rational-rock -joliet \
    user-data meta-data network-config

Download a cloud image

Download an Ubuntu image to run:

wget https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64.img

Note

This example uses emulated CPU instructions on non-x86 hosts, so it may be slow. To make it faster on non-x86 architectures, one can change the image type and qemu-system-<arch> command name to match the architecture of your host machine.

Boot the image with the ISO attached

Boot the cloud image with our configuration, seed.img, to QEMU:

$ qemu-system-x86_64 -m 1024 -net nic -net user \
    -drive file=jammy-server-cloudimg-amd64.img,index=0,format=qcow2,media=disk \
    -drive file=seed.img,index=1,media=cdrom \
    -machine accel=kvm:tcg

The now-booted image will allow for login using the password provided above.

For additional configuration, users can provide much more detailed configuration in the empty network-config and meta-data files.

Note

See the Networking config Version 2 page for details on the format and config of network configuration. To learn more about the possible values for metadata, check out the NoCloud page.

LXD

LXD offers a streamlined user experience for using Linux system containers. With LXD, the following command initialises a container with user data:

$ lxc init ubuntu-daily:jammy test-container
$ lxc config set test-container user.user-data - < userdata.yaml
$ lxc start test-container

To avoid the extra commands this can also be done at launch:

$ lxc launch ubuntu-daily:jammy test-container --config=user.user-data="$(cat userdata.yaml)"

Finally, a profile can be set up with the specific data if you need to launch this multiple times:

$ lxc profile create dev-user-data
$ lxc profile set dev-user-data user.user-data - < cloud-init-config.yaml
$ lxc launch ubuntu-daily:jammy test-container -p default -p dev-user-data

LXD configuration types

The above examples all show how to pass user data. To pass other types of configuration data use the configuration options specified below:

Data

Configuration option

user data

cloud-init.user-data

vendor data

cloud-init.vendor-data

network config

cloud-init.network-config

See the LXD Instance Configuration docs for more info about configuration values or the LXD Custom Network Configuration document for more about custom network config.

Libvirt

Libvirt is a tool for managing virtual machines and containers.

Create your configuration

We will leave the network-config and meta-data files empty, but populate user-data with a cloud-init configuration. You may edit the network-config and meta-data files if you have a config to provide.

$ touch network-config
$ touch meta-data
$ cat >user-data <<EOF
#cloud-config
password: password
chpasswd:
  expire: False
ssh_pwauth: True
EOF

Download a cloud image

Download an Ubuntu image to run:

wget https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64.img

Create an instance

virt-install --name cloud-init-001 --memory 4000 --noreboot \
    --os-variant detect=on,name=ubuntujammy \
    --disk=size=10,backing_store="$(pwd)/jammy-server-cloudimg-amd64.img" \
    --cloud-init user-data="$(pwd)/user-data,meta-data=$(pwd)/meta-data,network-config=$(pwd)/network-config"

Multipass

Multipass is a cross-platform tool for launching Ubuntu VMs across Linux, Windows, and macOS.

When a user launches a Multipass VM, user data can be passed by adding the --cloud-init flag and the appropriate YAML file containing the user data:

$ multipass launch bionic --name test-vm --cloud-init userdata.yaml

Multipass will validate the user-data cloud-config file before attempting to start the VM. This breaks all cloud-init configuration formats except user data cloud-config.