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module_reference.md

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Module reference and examples

Kernel parameter

Kernel parameters are configured using sysctl commands. For this example, you need to configure the following kernel parameters in the kubernetes nodes:

sysctl -w kernel.hostname=test-hostname

This configuration can be applied with the following CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  kernelParameters:
    parameters:
    - name: fs.file-max
      value: "54321"
    state: present
    priority: 90

You can add an optional priority key to set the priority for these parameters. Default priority is 50

Etc hosts

Hostname resolution can be configured locally in /etc/hosts. For this example, you need to add the following entries:

test.whitestack.com 10.0.0.1
test2.whitestack.com 10.0.0.2
test3.whitestack.com test4.whitestack.com 10.0.0.3

This configuration can be applied with the following CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  hosts:
    hosts:
    - hostname: "test.whitestack.com"
      ip: "10.0.0.1"
    - hostname: "test2.whitestack.com"
      ip: "10.0.0.2"
    - hostname: "test3.whitestack.com test4.whitestack.com"
      ip: "10.0.0.3"
    state: present

Systemd units

Note

This module requires that the managerConfig.hostfsEnabled option is set to true

New systemd units can be configured in /etc/systemd/system. For this example, you need to configure a service with name test-service and the following unit file:

[Unit]
Description=example systemd service unit file.

[Service]
ExecStart=/bin/bash /usr/sbin/example.sh

[Install]
WantedBy=multi-user.target

This configuration can be applied with the following CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  systemdUnits:
    units:
    - name: test-service
      file: |
        [Unit]
        Description=example systemd service unit file.

        [Service]
        ExecStart=/bin/bash /usr/sbin/example.sh

        [Install]
        WantedBy=multi-user.target
    state: present

Systemd overrides

Note

This module requires that the managerConfig.hostfsEnabled option is set to true

Systemd overrides will be written to /etc/systemd/system/<unit-name>.d. For example, if you want to change the Exec command to a running service you use the following CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  systemdOverrides:
    overrides:
    - name: getty@tty2.service
      file: |
        [Service]
        ExecStart=
        ExecStart=sleep 2000
      priority: 20
    state: present

You can add an optional priority key to set the priority for each override. Default priority is 50

Kernel modules

Kernel modules can be loaded with modprobe. For this example, you need to load the following kernel modules:

modprobe multipath
modprobe dm_multipath

This configuration can be applied with the following CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  kernelModules:
    modules:
    - multipath
    - dm_multipath
    state: present
    priority: 50

You can add an optional priority key to set the priority for these modules. Default priority is 50

Block in File

Note

This module requires that the managerConfig.hostfsEnabled option is set to true

This module adds a block in a new or existing file. For example for a file in /etc/test.test:

line0
line1

You can add a block to the end of the file:

line0
line1
# BEGIN MARKER
line11
line12
# END MARKER

With this CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  blockInFiles:
    blocks:
    - filename: "/etc/test.test"
      content: |
        line11
        line12
      beginMarker: "# BEGIN MARKER"
      endMarker: "# END MARKER"
    state: present

Certificates

Note

This module requires that the managerConfig.hostfsEnabled option is set to true

This module adds a text to a new or existing certificate file. For example for a file in /etc/ssl/certs/whitestack.crt:

With this CR:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  certificates:
    certificates:
    - filename: "whitestack.crt"
      content: |
        -----BEGIN CERTIFICATE-----
        MIIE0DCCA7igAwIBAgIBBzANBgkqhkiG9w0BAQsFADCBgzELMAkGA1UEBhMCVVMx
        EDAOBgNVBAgTB0FyaXpvbmExEzARBgNVBAcTClNjb3R0c2RhbGUxGjAYBgNVBAoT
        EUdvRGFkZHkuY29tLCBJbmMuMTEwLwYDVQQDEyhHbyBEYWRkeSBSb290IENlcnRp
        ZmljYXRlIEF1dGhvcml0eSAtIEcyMB4XDTExMDUwMzA3MDAwMFoXDTMxMDUwMzA3
        MDAwMFowgbQxCzAJBgNVBAYTAlVTMRAwDgYDVQQIEwdBcml6b25hMRMwEQYDVQQH
        EwpTY290dHNkYWxlMRowGAYDVQQKExFHb0RhZGR5LmNvbSwgSW5jLjEtMCsGA1UE
        CxMkaHR0cDovL2NlcnRzLmdvZGFkZHkuY29tL3JlcG9zaXRvcnkvMTMwMQYDVQQD
        EypHbyBEYWRkeSBTZWN1cmUgQ2VydGlmaWNhdGUgQXV0aG9yaXR5IC0gRzIwggEi
        MA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQC54MsQ1K92vdSTYuswZLiBCGzD
        BNliF44v/z5lz4/OYuY8UhzaFkVLVat4a2ODYpDOD2lsmcgaFItMzEUz6ojcnqOv
        K/6AYZ15V8TPLvQ/MDxdR/yaFrzDN5ZBUY4RS1T4KL7QjL7wMDge87Am+GZHY23e
        cSZHjzhHU9FGHbTj3ADqRay9vHHZqm8A29vNMDp5T19MR/gd71vCxJ1gO7GyQ5HY
        pDNO6rPWJ0+tJYqlxvTV0KaudAVkV4i1RFXULSo6Pvi4vekyCgKUZMQWOlDxSq7n
        eTOvDCAHf+jfBDnCaQJsY1L6d8EbyHSHyLmTGFBUNUtpTrw700kuH9zB0lL7AgMB
        AAGjggEaMIIBFjAPBgNVHRMBAf8EBTADAQH/MA4GA1UdDwEB/wQEAwIBBjAdBgNV
        HQ4EFgQUQMK9J47MNIMwojPX+2yz8LQsgM4wHwYDVR0jBBgwFoAUOpqFBxBnKLbv
        9r0FQW4gwZTaD94wNAYIKwYBBQUHAQEEKDAmMCQGCCsGAQUFBzABhhhodHRwOi8v
        b2NzcC5nb2RhZGR5LmNvbS8wNQYDVR0fBC4wLDAqoCigJoYkaHR0cDovL2NybC5n
        b2RhZGR5LmNvbS9nZHJvb3QtZzIuY3JsMEYGA1UdIAQ/MD0wOwYEVR0gADAzMDEG
        CCsGAQUFBwIBFiVodHRwczovL2NlcnRzLmdvZGFkZHkuY29tL3JlcG9zaXRvcnkv
        MA0GCSqGSIb3DQEBCwUAA4IBAQAIfmyTEMg4uJapkEv/oV9PBO9sPpyIBslQj6Zz
        91cxG7685C/b+LrTW+C05+Z5Yg4MotdqY3MxtfWoSKQ7CC2iXZDXtHwlTxFWMMS2
        RJ17LJ3lXubvDGGqv+QqG+6EnriDfcFDzkSnE3ANkR/0yBOtg2DZ2HKocyQetawi
        DsoXiWJYRBuriSUBAA/NxBti21G00w9RKpv0vHP8ds42pM3Z2Czqrpv1KrKQ0U11
        GIo/ikGQI31bS/6kA1ibRrLDYGCD+H1QQc7CoZDDu+8CL9IVVO5EFdkKrqeKM+2x
        LXY2JtwE65/3YR8V3Idv7kaWKK2hJn0KCacuBKONvPi8BDAB
        -----END CERTIFICATE-----
    state: present

You may include multiple certificates in a single file, and multiple files in a single custom resource.

Apt packages

Note

This module requires that the managerConfig.hostfsEnabled and managerConfig.aptEnabled options are set to true. Only works in Ubuntu servers

This module updates the apt's package lists and installs the packages defined in the CR, for example:

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-sample
spec:
  aptPackages:
    packages:
    - name: vim
    - name: ssh
      version: 1:9.6p1-3ubuntu13.5
    state: present

Will install the latest version of the vim package and the required version of the ssh package.

Crontabs

Crontab entries can be managed by creating or removing files in the /etc/cron.d directory. Each entry specifies a scheduled task to be executed under a specific user. For example, to schedule a daily backup script to run as the root user, you would create a crontab entry like this:

@daily root /usr/bin/backup.sh # daily-backup

This configuration can be applied using the following Custom Resource (CR):

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-crontab-sample
spec:
  crontabs:
    entries:
    - name: "daily-backup"
      special_time: "daily"
      job: "/usr/bin/backup.sh"
      user: "root"
    - name: "hourly-cleanup"
      minute: "0"
      hour: "*"
      dayOfMonth: "*"
      month: "*"
      dayOfWeek: "*"
      job: "/usr/bin/cleanup.sh"
      user: "root"
    state: "present"

Fiels:

  • name: A unique identifier for the cron job. This is used to generate the filename in /etc/cron.d.
  • special_time: (Optional) Specifies a predefined schedule such as @daily, @reboot, @weekly, etc.
  • minute , hour , dayOfMonth , month , dayOfWeek: (Optional) Define the schedule explicitly. Defaults to * if not specified.
  • job: The command or script to execute.
  • user: The user under which the task will run.

GRUB Kernel Config

The GRUB configuration can be managed by creating or removing files in the /etc/default/grub.d directory. This approach enables modular and idempotent management of GRUB settings, such as kernel command-line arguments and the default kernel version.

For example, to set specific kernel arguments and select a default kernel version, you would create a configuration file like this:

# BEGIN MARKER NCO GRUB CONFIG
GRUB_CMDLINE_LINUX="quiet splash"
GRUB_DEFAULT="Advanced options for Ubuntu>Ubuntu, with Linux 5.15.0-91-generic"
# END MARKER NCO GRUB CONFIG

This configuration can be applied using the following Custom Resource (CR):

apiVersion: configuration.whitestack.com/v1beta2
kind: NodeConfig
metadata:
  name: nodeconfig-grub-sample
spec:
  grubKernelConfig:
    kernelVersion: "5.15.0-91-generic"
    args:
      - "quiet"
      - "splash"
    state: "present"
    priority: 55

You can add an optional priority key to set the priority for this configuration. Default priority is 50

Fields:

  • kernelVersion: (Optional) Specifies the Linux kernel version to set as the default (e.g., "5.15.0-91-generic"). If not provided, the default kernel will remain unchanged.
  • args: (Optional) A list of kernel command-line arguments to be added to GRUB_CMDLINE_LINUX. If not specified, no changes will be made to the kernel command-line arguments.