Configuration

Welcome to the Kairos configuration reference page. This page provides details on the fields available in the YAML file used for installing Kairos, a Linux distribution focused on running Kubernetes. This file, written in cloud-config format, allows you to enable Kairos features, configure k3s, and set various other options.

The structure of the configuration file is as follows:

#cloud-config

# Additional system users
users:
- name: "kairos"
  passwd: "kairos"
  lock_passwd: true
  groups: "admin"
  ssh_authorized_keys:
  # - github:mudler

# enable debug logging
debug: true
# Additional paths for look for cloud-init files
cloud-init-paths:
  - "/some/path"
# fail on cloud-init errors, defaults to false
strict: false

# The install block is to drive automatic installations without user interaction.
install:
  # Device for automated installs
  device: "/dev/sda"
  # Reboot after installation
  reboot: true
  # Power off after installation
  poweroff: true
  # Set to true when installing without Pairing
  auto: true

  # firmware to use ('efi|bios')
  # This is autodetected so only use this to force the installation to use a different one if needed.
  # NOTE: This can break your system boot if forced to the wrong value
  firmware: efi
  # Disk format ('gpt|msdos')
  # Defaults to gpt. We recommend not changing it to msdos unless it's needed for legacy hardware
  part-table: gpt

  # Override the grub entry name
  grub-entry-name: Kairos
  
  # partitions setup
  # setting a partition size key to 0 means that the partition will take over the rest of the free space on the disk
  # after creating the rest of the partitions
  # by default the persistent partition has a value of 0
  # if you want any of the extra partitions to fill the rest of the space, you will need to set the persistent partition
  # size to a different value, for example
  # partitions:
  #   persistent:
  #     size: 300

  # default partitions
  # only 'oem', 'recovery', 'state' and 'persistent' objects allowed
  # Only size and fs should be changed here
  # size in MiB
  partitions:
    oem:
      size: 60
      fs: ext4
    recovery:
      size: 4096
      fs: ext4
  # note: This can also be set with dot notation like the following examples for a more condensed view:
  # partitions.oem.size: 60
  # partitions.oem.fs: ext4
  # partitions.recovery.size: 4096
  # partitions.recovery.fs: ext4

  # extra partitions to create during install
  # only size, label and fs are used
  # name is used for the partition label, but it's not really used during the kairos lifecycle. No spaces allowed.
  # if no fs is given the partition will be created but not formatted
  # These partitions are not automounted only created and formatted
  extra-partitions:
    - Name: myPartition
      size: 100
      fs: ext4
      label: ONE_PARTITION
    - Name: myOtherPartition
      size: 200
      fs: ext4
      label: TWO_PARTITION
  
  # no-format: true skips any disk partitioning and formatting
  # If set to true installation procedure will error out if expected
  # partitions are not already present within the disk.
  no-format: false

  # if no-format is used and elemental is running over an existing deployment
  # force can be used to force installation.
  force: false

  # Creates these dirs in the rootfs during installation. As the rootfs is RO from boot, sometimes we find that we
  # some applications want to write to non-standard paths like /data
  # If that dir is not already in the rootfs it makes it difficult to create that path on an RO system
  # This allows to create some extra paths in the rootfs that then we count use for mounting or binding via
  # the cloud-config stages
  extra-dirs-rootfs:
    - /data
    - /src
  
  # Override image sizes for active/passive/recovery
  # Note that the active+passive images are stored in the state partition and
  # the recovery in the recovery partition, so they should be big enough to accommodate te images sizes set below
  # size in MiB
  system:
    size: 4096
  passive:
    size: 4096
  recovery-system:
    size: 5000
  # note: This can also be set with dot notation like the following examples for a more condensed view:
  # system.size: 4096
  # passive.size: 4096
  # recovery-system.size: 5000
  
  # Use a different container image for the installation
  image: "docker:.."
  # Add bundles in runtime
  bundles:
    - ...
  # Set grub options
  grub_options:
    # additional Kernel option cmdline to apply
    extra_cmdline: "config_url=http://"
    # Same, just for active
    extra_active_cmdline: ""
    # Same, just for passive
    extra_passive_cmdline: ""
    # Change GRUB menu entry
    default_menu_entry: ""
  # Environmental variable to set to the installer calls
  env:
  - foo=bar
  # custom user mounts
  # bind mounts, can be read and modified, changes persist reboots
  bind_mounts:
  - /mnt/bind1
  - /mnt/bind2
  # ephemeral mounts, can be read and modified, changed are discarded at reboot
  ephemeral_mounts:

# The reset block configures what happens when reset is called
reset:
  # Reboot after reset
  reboot: true
  # Power off after reset
  poweroff: true

  # Override the grub entry name
  grub-entry-name: Kairos

  # if set to true it will format persistent partitions ('oem 'and 'persistent')
  reset-persistent: true
  reset-oem: false

  # Creates these dirs in the rootfs during reset. As the rootfs is RO from boot, sometimes we find that we
  # some applications want to write to non-standard paths like /data
  # If that dir is not already in the rootfs it makes it difficult to create that path on an RO system
  # This allows to create some extra paths in the rootfs that then we count use for mounting or binding via
  # the cloud-config stages
  extra-dirs-rootfs:
    - /data
    - /src


# The upgrade block configures what happens when upgrade is called
upgrade:
  # Reboot after upgrade
  reboot: true
  # Power off after upgrade
  poweroff: true

  # Override the grub entry name
  grub-entry-name: Kairos

  # if set to true upgrade command will upgrade recovery system instead
  # of main active system
  recovery: false

  # Override image sizes for active/recovery
  # Note that the active+passive images are stored in the state partition and
  # the recovery in the recovery partition, so they should be big enough to accommodate te images sizes set below
  # size in MiB
  # During upgrade only the active or recovery image cna be resized as those are the ones that contain the upgrade
  # passive image is the current system, and that its untouched during the upgrade
  system:
    size: 4096
  recovery-system:
    size: 5000

  # Creates these dirs in the rootfs during upgrade. As the rootfs is RO from boot, sometimes we find that we
  # some applications want to write to non-standard paths like /data
  # If that dir is not already in the rootfs it makes it difficult to create that path on an RO system
  # This allows to create some extra paths in the rootfs that then we count use for mounting or binding via
  # the cloud-config stages
  extra-dirs-rootfs:
    - /data
    - /src


k3s:
  # Additional env/args for k3s server instances
  env:
    K3S_RESOLV_CONF: ""
    K3S_DATASTORE_ENDPOINT: "mysql://username:password@tcp(hostname:3306)/database-name"
  args:
    - --node-label ""
    - --data-dir ""
  # Enabling below it replaces args/env entirely
  # replace_env: true
  # replace_args: true

k3s-agent:
  # Additional env/args for k3s agent instances
  env:
    K3S_NODE_NAME: "foo"
  args:
    - --private-registry "..."
  # Enabling below it replaces args/env entirely
  # replace_env: true
  # replace_args: true

# The p2p block enables the p2p full-mesh functionalities.
# To disable, don't specify one.
p2p:
  # Manually set node role. Available: master, worker. Defaults auto (none). This is available
 role: "master"
  # User defined network-id. Can be used to have multiple clusters in the same network
 network_id: "dev"
  # Enable embedded DNS See also: https://mudler.github.io/edgevpn/docs/concepts/overview/dns/
 dns: true
 # Disabling DHT makes co-ordination to discover nodes only in the local network
 disable_dht: true #Enabled by default
 # Configures a VPN for the cluster nodes
 vpn:
   create: false # defaults to true
   use: false # defaults to true
   env:
    # EdgeVPN environment options
    DHCP: "true"
    # Disable DHT (for airgap)
    EDGEVPNDHT: "false"
    EDGEVPNMAXCONNS: "200"
    # If DHCP is false, it's required to be given a specific node IP. Can be arbitrary
    ADDRESS: "10.2.0.30/24"
    # See all EDGEVPN options:
    # - https://github.com/mudler/edgevpn/blob/master/cmd/util.go#L33
    # - https://github.com/mudler/edgevpn/blob/master/cmd/main.go#L48
 # Automatic cluster deployment configuration
 auto:
   # Enables Automatic node configuration (self-coordination)
   # for role assignment
   enable: true
   # HA enables automatic HA roles assignment.
   # A master cluster init is always required,
   # Any additional master_node is configured as part of the 
   # HA control plane.
   # If auto is disabled, HA has no effect.
   ha:
     # Enables HA control-plane
     enable: true
     # Number of HA additional master nodes.
     # A master node is always required for creating the cluster and is implied.
     # The setting below adds 2 additional master nodes, for a total of 3.
     master_nodes: 2
     # Use an External database for the HA control plane
     external_db: "external-db-string"
 # network_token is the shared secret used by the nodes to co-ordinate with p2p
 network_token: "YOUR_TOKEN_GOES_HERE"

## Sets the Elastic IP used in KubeVIP. Only valid with p2p
kubevip:
  eip: "192.168.1.110"
  # Specify a manifest URL for KubeVIP. Empty uses default
  manifest_url: ""
  # Enables KubeVIP
  enable: true
  # Specifies a KubeVIP Interface
  interface: "ens18"

# Additional cloud init syntax can be used here.
# See `stages` below.
stages:
  network:
    - name: "Setup users"
      authorized_keys:
        kairos:
          - github:mudler

# Standard cloud-init syntax, see: https://github.com/mudler/yip/tree/e688612df3b6f24dba8102f63a76e48db49606b2#compatibility-with-cloud-init-format
growpart:
 devices: ['/']


runcmd:
- foo
hostname: "bar"
write_files:
- encoding: b64
  content: CiMgVGhpcyBmaWxlIGNvbnRyb2xzIHRoZSBzdGF0ZSBvZiBTRUxpbnV4
  path: /foo/bar
  permissions: "0644"
  owner: "bar"

The p2p block is used to enable the p2p full-mesh functionalities of Kairos. If you do not want to use these functionalities, simply don’t specify a kairos block in your configuration file.

Inside the p2p block, you can specify the network_token field, which is used to establish the p2p full meshed network. If you do not want to use the full-mesh functionalities, don’t specify a network_token value.

The role field allows you to manually set the node role for your Kairos installation. The available options are master and worker, and the default value is auto (which means no role is set).

The network_id field allows you to set a user-defined network ID, which can be used to have multiple Kairos clusters on the same network.

Finally, the dns field allows you to enable embedded DNS for Kairos. For more information on DNS in Kairos, see the link provided in the YAML code above.

That’s a brief overview of the structure and fields available in the Kairos configuration file. For more detailed information on how to use these fields, see the examples and explanations provided in the sections below.

Syntax

Kairos supports a portion of the standard cloud-init syntax, and the extended syntax which is based on yip.

Examples using the extended notation for running K3s as agent or server can be found in the examples directory of the Kairos repository.

Here’s an example that shows how to set up DNS at the boot stage using the extended syntax:

#cloud-config

stages:
  boot:
    - name: "DNS settings"
      dns:
        path: /etc/resolv.conf
        nameservers:
          - 8.8.8.8

Note

Kairos does not use cloud-init. yip was created with the goal of being distro agnostic, and does not use Bash at all (with the exception of systemd configurations, which are assumed to be available). This makes it possible to run yip on minimal Linux distros that have been built from scratch.

The rationale behind using yip instead of cloud-init is that it allows Kairos to have very minimal requirements. The cloud-init implementation has dependencies, while yip does not, which keeps the dependency tree small. There is also a CoreOS implementation of cloud-init, but it makes assumptions about the layout of the system that are not always applicable to Kairos, making it less portable.

The extended syntax can also be used to pass commands through Kernel boot parameters. See the examples below for more details.

Test your cloud configs

Writing YAML files can be a tedious process, and it’s easy to make syntax or indentation errors. To make sure your configuration is correct, you can use the cloud-init commands to test your YAML files locally in a container.

Here’s an example of how to test your configurations on the initramfs stage using a Docker container:

# List the YAML files in your current directory
$ ls -liah
total 4,0K
9935 drwxr-xr-x.  2 itxaka itxaka  60 may 17 11:21 .
   1 drwxrwxrwt. 31 root   root   900 may 17 11:28 ..
9939 -rw-r--r--.  1 itxaka itxaka  59 may 17 11:21 00_test.yaml

$ cat 00_test.yaml
stages:
  initramfs:
    - commands:
      - echo "hello!"


# Run the cloud-init command on your YAML files in a Docker container
$ docker run -ti -v $PWD:/test --entrypoint /usr/bin/kairos-agent --rm quay.io/kairos/core-debian run-stage --cloud-init-paths /test initramfs

# Output from the run-stage command
INFO[2023-05-17T11:32:09+02:00] kairos-agent version 0.0.0                   
INFO[2023-05-17T11:32:09+02:00] Running stage: initramfs.before              
INFO[2023-05-17T11:32:09+02:00] Done executing stage 'initramfs.before'      
INFO[2023-05-17T11:32:09+02:00] Running stage: initramfs                     
INFO[2023-05-17T11:32:09+02:00] Processing stage step ''. ( commands: 1, files: 0, ... ) 
INFO[2023-05-17T11:32:09+02:00] Command output: hello!                       
INFO[2023-05-17T11:32:09+02:00] Done executing stage 'initramfs'             
INFO[2023-05-17T11:32:09+02:00] Running stage: initramfs.after               
INFO[2023-05-17T11:32:09+02:00] Done executing stage 'initramfs.after'       
INFO[2023-05-17T11:32:09+02:00] Running stage: initramfs.before              
INFO[2023-05-17T11:32:09+02:00] Done executing stage 'initramfs.before'      
INFO[2023-05-17T11:32:09+02:00] Running stage: initramfs                     
INFO[2023-05-17T11:32:09+02:00] Done executing stage 'initramfs'             
INFO[2023-05-17T11:32:09+02:00] Running stage: initramfs.after               
INFO[2023-05-17T11:32:09+02:00] Done executing stage 'initramfs.after'

Validate Your Cloud Config

Note

Validation of configuration is available on Kairos v1.6.0-rc1 and later. If you’re interested in the validation rules or want to build a tool based on it, you can access them online via https://kairos.io/RELEASE/cloud-config.json e.g. v1.6.0 cloud-config.json

You have two options to validate your Cloud Config, one is with the Kairos command line, and the other with the Web UI.

Configuration Validation via the Kairos Command Line

To validate a configuration using the command line, we have introduced the validate command. As an argument you need to pass a URL or local file to be validated, e.g.:

If you had the following cloud-config.yaml in the current working directory

#cloud-config
users:
  - name: 007

You could validate it as follows

kairos validate ./cloud-config.yaml
jsonschema: '/users/0/name' does not validate with file:///home/mauro/workspace/kairos/schema.json#/properties/users/items/$ref/properties/name/type: expected string, but got number

Configuration Validation via Web UI

The validation in the Web UI is automatic, all you need to do is copy/paste or type your configuration on the input.

Schema Validation Preview

Using templates

Fields in the Kairos cloud-init configuration can be templated, which allows for dynamic configuration. Node information is retrieved using the sysinfo library, and can be templated in the commands, file, and entity fields.

Here’s an example of how you can use templating in your Kairos configuration:

#cloud-config

stages:
  foo:
  - name: "echo"
    commands:
    - echo "{{.Values.node.hostname}}"

In addition to standard templating, sprig functions are also available for use in your Kairos configuration.

Automatic Hostname at scale

You can also use templating to automatically generate hostnames for a set of machines. For example, if you have a single cloud-init file that you want to use for multiple machines, you can use the machine ID (which is generated for each host) to automatically set the hostname for each machine.

Here’s an example of how you can do this:

#cloud-config

stages:
  initramfs:
    - name: "Setup hostname"
      hostname: "node-{{ trunc 4 .MachineID }}"

This will set the hostname for each machine based on the first 4 characters of the machine ID. For example, if the machine ID for a particular machine is abcdef123456, the hostname for that machine will be set to node-abcd.

K3s settings

The k3s and k3s-agent blocks in the Kairos configuration file allow you to customize the environment and argument settings for K3s.

Here’s an example of how to use these blocks in your Kairos configuration:

k3s:
  enabled: true
  # Additional env/args for k3s server instances
  env:
    K3S_RESOLV_CONF: ""
    K3S_DATASTORE_ENDPOINT: ""
  args:
    - ...

k3s-agent:
  enabled: true
  # Additional env/args for k3s server instances
  env:
    K3S_RESOLV_CONF: ""
    K3S_DATASTORE_ENDPOINT: ""
  args:
    -

For more examples of how to configure K3s manually, see the examples section or HA.

Grub options

The install.grub_options field in the Kairos configuration file allows you to set key/value pairs for GRUB options that will be set in the GRUB environment after installation.

Here’s an example of how you can use this field to set the panic=0 boot argument:

#cloud-config

install:
  grub_options:
    extra_cmdline: "panic=0"

The table below lists all the available options for the install.grub_options field:

Variable	Description
next_entry	Set the next reboot entry
saved_entry	Set the default boot entry
default_menu_entry	Set the name entries on the GRUB menu
extra_active_cmdline	Set additional boot commands when booting into active
extra_passive_cmdline	Set additional boot commands when booting into passive
extra_recovery_cmdline	Set additional boot commands when booting into recovery
extra_cmdline	Set additional boot commands for all entries
default_fallback	Sets default fallback logic

Kubernetes manifests

The k3s distribution of Kubernetes allows you to automatically deploy Helm charts or Kubernetes resources after deployment.

Here’s an example of how you can use the k3s configuration file to deploy Fleet out of the box:

name: "Deploy fleet out of the box"
stages:
  boot:
    - name: "Copy fleet deployment files"
      files:
        - path: /var/lib/rancher/k3s/server/manifests/fleet-config.yaml
          content: |
            apiVersion: v1
            kind: Namespace
            metadata:
              name: cattle-system
            ---
            apiVersion: helm.cattle.io/v1
            kind: HelmChart
            metadata:
              name: fleet-crd
              namespace: cattle-system
            spec:
              chart: https://github.com/rancher/fleet/releases/download/v0.3.8/fleet-crd-0.3.8.tgz
            ---
            apiVersion: helm.cattle.io/v1
            kind: HelmChart
            metadata:
              name: fleet
              namespace: cattle-system
            spec:
              chart: https://github.com/rancher/fleet/releases/download/v0.3.8/fleet-0.3.8.tgz

This configuration will automatically deploy the Fleet Helm chart in the cattle-system namespace after the deployment of k3s using the extended syntax.

Kernel boot parameters

All the configurations can be issued via Kernel boot parameters, for instance, consider to add an user from the boot menu:

stages.boot[0].authorized_keys.root[0]=github:mudler

Or to either load a config url from network:

config_url=http://...

Usually secret gists are used to share such config files.

Additional users

Kairos comes with the kairos user pre-configured, however, it is possible to configure additional users to the system via the cloud-init config mechanism

Add a user during first-install

Consider the following example cloud-config, which adds the testuser user to the system with admin access:

#cloud-config
install:
  device: /dev/sda
k3s:
  enabled: true

users:
- name: "kairos"
  passwd: "kairos"
  ssh_authorized_keys:
  - github:mudler
- name: "testuser"
  passwd: "testuser"
  ssh_authorized_keys:
  - github:mudler
  groups:
  - "admin"

Add a user to an existing install

To add an user to an existing installation you can simply add a /oem file for the new user. For instance, consider the following:

stages:
   initramfs:
     - name: "Set user and password"
       users:
        testuser:
          groups:
          - "admin"
          passwd: "mypassword"
          shell: /bin/bash
          homedir: "/home/testuser"

This configuration can be either manually copied over, or can be propagated also via Kubernetes using the system upgrade controller. See the after-install section for an example.

❯ ssh testuser@192.168.1.238
testuser@192.168.1.238's password:
Welcome to kairos!

Refer to https://kairos.io for documentation.
localhost:~$ sudo su -
localhost:~# whoami
root
localhost:~# exit
localhost:~$ whoami
testuser
localhost:~$

P2P configuration

P2P functionalities are experimental Kairos features and disabled by default. In order to enable them, just use the p2p configuration block.

`p2p.network_token`

This defines the network token used by peers to join the p2p virtual private network. You can generate it with the Kairos CLI with kairos generate-token. Check out the P2P section for more instructions.

`p2p.role`

Define a role for the node. Accepted: worker, master. Currently only one master is supported.

`p2p.network_id`

Define a custom ID for the Kubernetes cluster. This can be used to create multiple clusters in the same network segment by specifying the same id across nodes with the same network token. Accepted: any string.

`p2p.dns`

When the p2p.dns is set to true the embedded DNS is configured on the node. This allows to propagate custom records to the nodes by using the blockchain DNS server. For example, this is assuming kairosctl bridge is running in a separate terminal:

curl -X POST http://localhost:8080/api/dns --header "Content-Type: application/json" -d '{ "Regex": "foo.bar", "Records": { "A": "2.2.2.2" } }'

It will add the foo.bar domain with 2.2.2.2 as A response.

Every node with DNS enabled will be able to resolve the domain after the domain is correctly announced.

You can check out the DNS in the DNS page in the API, see also the EdgeVPN docs.

Furthermore, it is possible to tweak the DNS server which are used to forward requests for domain listed outside, and as well, it’s possible to lock down resolving only to nodes in the blockchain, by customizing the configuration file:

#cloud-config
p2p:
  network_token: "...."
  # Enable embedded DNS See also: https://mudler.github.io/edgevpn/docs/concepts/overview/dns/
  dns: true
  vpn:
    env:
      # Disable DNS forwarding
      DNSFORWARD: "false"
      # Set cache size
      DNSCACHESIZE: "200"
      # Set DNS forward server
      DNSFORWARDSERVER: "8.8.8.8:53"

Stages

The stages key is a map that allows to execute blocks of cloud-init directives during the lifecycle of the node stages.

A full example of a stage is the following:

#cloud-config

stages:
   # "boot" is the stage
   boot:
     - systemd_firstboot:
         keymap: us
     - files:
        - path: /tmp/bar
          content: |
                                        test
          permissions: 0777
          owner: 1000
          group: 100
       if: "[ ! -e /tmp/bar ]"
     - files:
        - path: /tmp/foo
          content: |
                                        test
          permissions: 0777
          owner: 1000
          group: 100
       commands:
        - echo "test"
       modules:
       - nvidia
       environment:
         FOO: "bar"
       systctl:
         debug.exception-trace: "0"
       hostname: "foo"
       systemctl:
         enable:
         - foo
         disable:
         - bar
         start:
         - baz
         mask:
         - foobar
       authorized_keys:
          user:
          - "github:mudler"
          - "ssh-rsa ...."
       dns:
         path: /etc/resolv.conf
         nameservers:
         - 8.8.8.8
       ensure_entities:
       -  path: /etc/passwd
          entity: |
                  kind: "user"
                  username: "foo"
                  password: "pass"
                  uid: 0
                  gid: 0
                  info: "Foo!"
                  homedir: "/home/foo"
                  shell: "/bin/bash"                  
       delete_entities:
       -  path: /etc/passwd
          entity: |
                  kind: "user"
                  username: "foo"
                  password: "pass"
                  uid: 0
                  gid: 0
                  info: "Foo!"
                  homedir: "/home/foo"
                  shell: "/bin/bash"                  
      datasource:
        providers:
          - "digitalocean"
          - "aws"
          - "gcp"
        path: "/usr/local/etc"

Note multiple stages can be specified, to execute blocks into different stages, consider:

#cloud-config

stages:
   boot:
   - commands:
     - echo "hello from the boot stage"
   initramfs:
   - commands:
     - echo "hello from the boot stage"
   - commands:
     - echo "so much wow, /foo/bar bar exists!"
     if: "[ -e /foo/bar ]"

Below you can find a list of all the supported fields. Mind to replace with the appropriate stage you want to hook into.

Filtering stages by node hostname

Stages can be filtered using the node key with a hostname value:

#cloud-config

stages:
  foo:
  - name: "echo"
    commands:
    - echo hello
    node: "the_node_hostname_here" # Node hostname

Filtering stages with if statement

Stages can be skipped based on if statements:

#cloud-config

stages:
  foo:
  - name: "echo"
    commands:
    - echo hello
    if: "cat /proc/cmdline | grep debug"

name: "Test yip!"

The expression inside the if will be evaluated in bash and, if specified, the stage gets executed only if the condition returns successfully (exit 0).

`name`

A description of the stage step. Used only when printing output to console.

`commands`

A list of arbitrary commands to run after file writes and directory creation.

#cloud-config

stages:
   boot:
     - name: "Setup something"
       commands:
         - echo 1 > /bar

`files`

A list of files to write to disk.

#cloud-config

stages:
   boot:
     - files:
        - path: /tmp/bar
          content: |
                    #!/bin/sh
                    echo "test"                    
          permissions: 0777
          owner: 1000
          group: 100

`directories`

A list of directories to be created on disk. Runs before files.

#cloud-config

stages:
   boot:
     - name: "Setup folders"
       directories:
       - path: "/etc/foo"
         permissions: 0600
         owner: 0
         group: 0

`dns`

A way to configure the /etc/resolv.conf file.

#cloud-config

stages:
   boot:
     - name: "Setup dns"
       dns:
         nameservers:
         - 8.8.8.8
         - 1.1.1.1
         search:
         - foo.bar
         options:
         - ..
         path: "/etc/resolv.conf.bak"

`hostname`

A string representing the machine hostname. It sets it in the running system, updates /etc/hostname and adds the new hostname to /etc/hosts. Templates can be used to allow dynamic configuration. For example in mass-install scenario it could be needed (and easier) to specify hostnames for multiple machines from a single cloud-init config file.

#cloud-config

stages:
   boot:
     - name: "Setup hostname"
       hostname: "node-{{ trunc 4 .MachineID }}"

`sysctl`

Kernel configuration. It sets /proc/sys/<key> accordingly, similarly to sysctl.

#cloud-config

stages:
   boot:
     - name: "Setup exception trace"
       systctl:
         debug.exception-trace: "0"

`authorized_keys`

A list of SSH authorized keys that should be added for each user. SSH keys can be obtained from GitHub user accounts by using the format github:${USERNAME}, similarly for GitLab with gitlab:${USERNAME}.

#cloud-config

stages:
   boot:
     - name: "Setup exception trace"
       authorized_keys:
         mudler:
         - "github:mudler"
         - "ssh-rsa: ..."

`node`

If defined, the node hostname where this stage has to run, otherwise it skips the execution. The node can also be a regexp in the Golang format.

#cloud-config

stages:
   boot:
     - name: "Setup logging"
       node: "bastion"

`users`

A map of users and user info to set. Passwords can also be encrypted.

The users parameter adds or modifies the specified list of users. Each user is an object which consists of the following fields. Each field is optional and of type string unless otherwise noted. In case the user already exists, only the password and ssh-authorized-keys are evaluated. The rest of the fields are ignored.

name: Required. Login name of user
gecos: GECOS comment of user
passwd: Hash of the password to use for this user. Unencrypted strings are supported too.
homedir: User’s home directory. Defaults to /home/name
no-create-home: Boolean. Skip home directory creation.
primary-group: Default group for the user. Defaults to a new group created named after the user.
groups: Add user to these additional groups
no-user-group: Boolean. Skip default group creation.
ssh-authorized-keys: List of public SSH keys to authorize for this user
system: Create the user as a system user. No home directory will be created.
no-log-init: Boolean. Skip initialization of lastlog and faillog databases.
shell: User’s login shell.

#cloud-config

stages:
   boot:
     - name: "Setup users"
       users: 
          bastion: 
            passwd: "strongpassword"
            homedir: "/home/foo

`ensure_entities`

A user or a group in the entity format to be configured in the system

#cloud-config

stages:
   boot:
     - name: "Setup users"
       ensure_entities:
       -  path: /etc/passwd
          entity: |
                  kind: "user"
                  username: "foo"
                  password: "x"
                  uid: 0
                  gid: 0
                  info: "Foo!"
                  homedir: "/home/foo"
                  shell: "/bin/bash"

`delete_entities`

A user or a group in the entity format to be pruned from the system

#cloud-config

stages:
   boot:
     - name: "Setup users"
       delete_entities:
       -  path: /etc/passwd
          entity: |
                  kind: "user"
                  username: "foo"
                  password: "x"
                  uid: 0
                  gid: 0
                  info: "Foo!"
                  homedir: "/home/foo"
                  shell: "/bin/bash"

`modules`

A list of kernel modules to load.

#cloud-config

stages:
   boot:
     - name: "Setup users"
       modules:
       - nvidia

`systemctl`

A list of systemd services to enable, disable, mask or start.

#cloud-config

stages:
   boot:
     - name: "Setup users"
       systemctl:
         enable:
          - systemd-timesyncd
          - cronie
         mask:
          - purge-kernels
         disable:
          - crond
         start:
          - cronie

`environment`

A map of variables to write in /etc/environment, or otherwise specified in environment_file

#cloud-config

stages:
   boot:
     - name: "Setup users"
       environment:
         FOO: "bar"

`environment_file`

A string to specify where to set the environment file

#cloud-config

stages:
   boot:
     - name: "Setup users"
       environment_file: "/home/user/.envrc"
       environment:
         FOO: "bar"

`timesyncd`

Sets the systemd-timesyncd daemon file (/etc/system/timesyncd.conf) file accordingly. The documentation for timesyncd and all the options can be found here.

#cloud-config

stages:
   boot:
     - name: "Setup NTP"
       systemctl:
         enable:
         - systemd-timesyncd
       timesyncd:
          NTP: "0.pool.org foo.pool.org"
          FallbackNTP: ""
          ...

`datasource`

Sets to fetch user data from the specified cloud providers. It populates provider specific data into /run/config folder and the custom user data is stored into the provided path.

#cloud-config

stages:
   boot:
     - name: "Fetch cloud provider's user data"
       datasource:
         providers:
         - "aws"
         - "digitalocean"
         path: "/etc/cloud-data"

`layout`

Sets additional partitions on disk free space, if any, and/or expands the last partition. All sizes are expressed in MiB only and default value of size: 0 means all available free space in disk. This plugin is useful to be used in oem images where the default partitions might not suit the actual disk geometry.

#cloud-config

stages:
   boot:
     - name: "Repart disk"
       layout:
         device:
           # It will partition a device including the given filesystem label
           # or partition label (filesystem label matches first) or the device
           # provided in 'path'. The label check has precedence over path when
           # both are provided.
           label: "COS_RECOVERY"
           path: "/dev/sda"
         # Only last partition can be expanded and it happens after all the other
         # partitions are created. size: 0 means all available free space
         expand_partition:
           size: 4096
         add_partitions:
           - fsLabel: "COS_STATE"
             size: 8192
             # No partition label is applied if omitted
             pLabel: "state"
           - fsLabel: "COS_PERSISTENT"
             # default filesystem is ext2 if omitted
             filesystem: "ext4"

You can also set custom partitions within the kairos-install.pre.before stage. In the following example we will do a custom partition in disk /dev/vda.

Warning

You’re responsible to make sure the sizes of the partitions fit properly within the disk. Issues of space will be highlighted by the agent, but they will not fail the installation process unless you pass the --strict flag.

Warning

In the case of multiple devices, make sure you don’t choose auto to determine on which device to install but instead to point the installation to the device where you are creating the custom partitions.

#cloud-config

install:
  # Make sure the installer won't delete our custom partitions
  no-format: true

stages:
  kairos-install.pre.before:
  - if:  '[ -e /dev/vda ]'
    name: "Create partitions"
    commands:
      - |
        parted --script --machine -- /dev/vda mklabel msdos
    layout:
      device:
        path: /dev/vda
      expand_partition:
        size: 0 # All available space
      add_partitions:
        # all sizes bellow are in MB
        - fsLabel: COS_OEM
          size: 64
          pLabel: oem
        - fsLabel: COS_RECOVERY
          size: 8500
          pLabel: recovery
        - fsLabel: COS_STATE
          size: 18000
          pLabel: state
        - fsLabel: COS_PERSISTENT
          pLabel: persistent
          size: 25000
          filesystem: "ext4"

`git`

Pull git repositories, using golang native git (no need of git in the host).

#cloud-config

stages:
   boot:
    - git:
       url: "git@gitlab.com:.....git"
       path: "/oem/cloud-config-files"
       branch: "main"
       auth:
         insecure: true
         private_key: |
          -----BEGIN RSA PRIVATE KEY-----
          -----END RSA PRIVATE KEY-----

`downloads`

Download files to specified locations

#cloud-config

stages:
   boot:
    - downloads:
      - path: /tmp/out
        url: "https://www...."
        permissions: 0700
        owner: 0
        group: 0
        timeout: 0
        owner_string: "root"
      - path: /tmp/out
        url: "https://www...."
        permissions: 0700
        owner: 0
        group: 0
        timeout: 0
        owner_string: "root"

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Last modified August 3, 2023: Update configuration.md (1c57672)