Note

This is a lightweight documentation intended to get users started with defining test nodes. For more insight on what Nodepool can do, please refer to its upstream documentation.

Nodepool user documentation

Labels, providers and diskimage are defined in config/nodepool/. All the yaml files present in this directory are merged to create the final Nodepool configuration. It’s recommended to create a file per provider or project so that it’s easier to manage.

Below is an example of a cloud provider configuration and an associated diskimage/label based on CentOS:

---
diskimages:
  - name: centos7
    elements:
      - centos-minimal
      - nodepool-minimal
      - zuul-worker-user

labels:
  - name: centos7
    min-ready: 1

providers:
  - name: nodepool-provider
    cloud: default
    clean-floating-ips: true
    image-name-format: '{image_name}-{timestamp}'
    boot-timeout: 120
    rate: 10.0
    diskimages:
      - name: centos7
    pools:
      - name: main
        max-servers: 20
        networks:
           - workers
        labels:
          - name: centos7
            min-ram: 1024
            diskimage: centos7

Cloud provider tuning

Provider settings include:

• rate: the delay between each API call, set it to 1 or lower for fast operations.
• clean-floating-ips: automatically release all unused floating IP addresses.
• boot-timeout : the delay to wait for an instance to start, the default value is 60 seconds.

Labels settings include:

• boot-from-volume: Use a volume instead of an ephemeral disk.
• cloud-image: Use an externally managed image instead of DIB.

Adding extra labels or cloud-image to a provider

Using the “extra-labels” stanza, extra labels or cloud-image can be added to an existing provider using a dedicated file. For example:

labels:
  - name: custom-label
    min-ready: 1

extra-labels:
  - provider: default-cloud
    pool: main
    cloud-images:
      - name: c2094f1d-9549-4dc8-99f6-e711d7db1e58
        username: zuul
    labels:
      - name: custom-label
        cloud-image: c2094f1d-9549-4dc8-99f6-e711d7db1e58
        min-ram: 4096

Building Images Using Virt Customize

It’s also possible to use virt-customize instead of diskimage-builder with the virt-customize roles provided in the config repository. All the informations are in the config/nodepool/virt-images/ README. There is an example playbook to build a fedora rawhide image.

Note

Nested virtualization should be enabled on the nodepool-builder host.

Diskimage elements

Using extra elements

All diskimage-builder elements as well as sf-elements are available to define a nodepool image. For example you can:

• Replace centos7 by fedora, debian or gentoo to change the base OS
• Use selinux-permissive to set selinux in permissive mode
• Use pip-and-virtualenv to install packages from PyPI
• Use source-repositories to provision a git repository

Adding custom elements

To customize an image, new diskimage builder elements can be added to the nodepool/elements directory in the config repository. For example, to add python 3.4 to a CentOS-based system, you need to create this element:

mkdir nodepool/elements/python34-epel
echo -e 'epel\npackage-installs' > nodepool/elements/python34-epel/element-deps
echo 'python34:' > nodepool/elements/python34-epel/packages.yaml

Then you can add the ‘python34-epel’ element to an existing image.

Read more about diskimage builder elements here. Or look at examples from sf-elements.

Building RHEL images

To build a RHEL with DIB, you have to download a RHEL cloud image from https://access.redhat.com (login required) and ask an operator to put the image in a directory owned by the nodepool user (nodepool dib operator documentation). Then you have to provide the information for registration on the env-var statement (see rhel-common element documentation) to be able to install packages during the build. The registration password should be set by an operator on nodepool secure.conf file (nodepool dib operator documentation).

- name: dib-rhel-7
  formats:
    - raw
  elements:
    - rhel7
    - rhel-common
    - nodepool-minimal
    - zuul-worker-user
  env-vars:
    DIB_LOCAL_IMAGE: '/var/lib/nodepool/images/rhel-7.5.qcow2'
    REG_AUTO_ATTACH: true
    REG_USER: $registration_user
    REG_METHOD: portal