This is a lightweight documentation intended to get operators started with setting up the Nodepool service. For more insight on what Nodepool can do, please refer to its upstream documentation.

Operate nodepool

  • The configuration is located in /etc/nodepool
  • The logs are written to /var/log/nodepool



The nodepool-launcher component is required in the architecture file to enable nodepool.

Podman containers

A new minimal kubernetes driver using podman container is available through the hypervisor-k1s component.

To use the kubernetes container driver, add the hypervisor-k1s component to the architecture file or check the k1s manual setup below.


To manage custom images through the config repository, built using diskimage-builder (DIB), add the nodepool-builder component in the architecture file.


With diskimage-builder, Software Factory users can customize test images without the need for specific authorizations on the OpenStack project. And since custom images definitions are subject to reviews on the config repository, operators can choose to allow or reject these images.

DIB can build images from scratch using elements, and it is also possible to use a local image as a base and add elements on top of it (this is mandatory for RHEL image, check nodepool user documentation). The operator can store base images on the host where the nodepool-builder service is deployed in /var/lib/nodepool/images.

Accessing test resources on failure (autohold)

To get a persistent shell access to test resources, use the autohold feature:

  • From the zuul-scheduler host, run this command (the –change argument is optional):
zuul autohold --tenant <tenant-name> --project <project-name> --job <job-name> --reason "text-string" [--change <change-id>]
  • Check the hold is registered using zuul autohold-list
  • Wait for a job failure and get the node ip using nodepool list –detail | grep “text-string”
  • Connect to the instance using ssh -i ~zuul/.ssh/id_rsa <username>@<ip>, the username can be zuul or zuul-worker depending on how the label has been built. You can add more public keys and share the access.
  • Once you are done with the instance, run nodepool delete <nodeid>

Storing registration password to build RHEL image

To provide the password environment variable to the nodepool-builder service, you have add image name and registration password in /etc/software-factory/sfconfig.yaml:

    - image_name: rhel-7
      reg_password: rhsm_password

Then run sfconfig –skip-install to finish the configuration.

Add a cloud provider

To add a cloud provider, an OpenStack cloud account is required. It is highly recommended to use a project dedicated to Nodepool.

The worker instances inherit the project’s “default” security group for access rules. Therefore the project’s “default” security group must allow incoming SSH traffic (TCP/22) and incoming log stream port (TCP/19885) from the zuul-executor node. Please refer to OpenStack’s documentation to find out how to modify security groups.

In order to configure an OpenStack provider you need to copy the clouds.yaml file to /etc/software-factory/ and set this configuration in sfconfig.yaml:

  clouds_File: /etc/software-factory/clouds.yaml

To apply the configuration you need to run again the sfconfig script.

You should be able to validate the configuration via the nodepool client by checking if Nodepool is able to authenticate on the cloud account.

$ nodepool list
$ nodepool image-list

See the Nodepool user documentation for configuring additional settings on the providers as well as defining labels and diskimages.

As an administrator, it can be really useful to check /var/log/nodepool to debug the Nodepool configuration.

Setup a k1s provider using the hypervisor-k1s role

The role hypervisor-k1s can be added to the architecture file. This role will install the requirements and configure the node. This role must be installed on a Centos 7 instance.

Please refer to Extending the architecture for adding a node to the architecture, then run sfconfig.


The k1s provider doesn’t enforce network isolation and test containers need to run on a dedicated instance/network. sfconfig will refuse to install this role on a server where Software Factory services are running. Nevertheless you can bypass this protection by using the sfconfig’s option –enable-insecure-workers.


Note that config/nodepool/_local_hypervisor_k1s.yaml and config/nodepool/_pods.yaml will by automatically updated in the config repository, making the k1s provider(s) and the default pod (test container) available in Nodepool.

The zuul-executors hosts need to be allowed to connect to the k1s hosts via 9023/TCP.

Define and use container images with the k1s provider

A new container image must be stored in the config/containers/ directory. The filename must be Dockerfile.

You need to ensure that the following lines are part of the new Dockerfile:

RUN mv /etc/sudoers /etc/sudoers.d/zuul && grep includedir \
  /etc/sudoers.d/zuul > /etc/sudoers && sed -e 's/.*includedir.*//' -i \
  /etc/sudoers.d/zuul && chmod 440 /etc/sudoers
RUN echo "zuul:x:0:0:root:/root:/bin/bash" >> /etc/passwd

The config-update job builds the new container and publish the container image into the k1s hosts local registry.

[ config]# podman images | grep k1s
localhost/k1s/centos-7-alt   latest   b205360ccab6   2 hours ago    699 MB
localhost/k1s/centos-7       latest   c75f523a04de   2 hours ago    699 MB

The name of the container image is the directory name of the container.

To make the new container image available to Nodepool then a new label must be defined and linked to k1s providers.

For a new container images called centos-7-alt, edit config/nodepool/k1s-labels.yaml:

- name: pod-centos-7-alt
  min-ready: 1

  - provider: managed-k1s-provider-managesf
    pool: main
      - name: pod-centos-7-alt
        image: localhost/k1s/centos-7-alt
        python-path: /bin/python2

The config-update job updates the nodepool configuration. Once the job is done, the new label should appear in Zuul and one container should be ready.

Debug container creation failure

If for some reason containers fail to start, here are some tips to investigate the errors:

  • Look for failure in Nodepool logs: /var/log/nodepool/launcher.log
  • Look for failure in k1s logs: journalctl -u k1s
  • Inspect podman manually on the k1s host server:
podman images
podman ps -a

Restart Nodepool services

The nodepool_restart.yml playbook stop and restart Nodepool launcher services.

ansible-playbook /var/lib/software-factory/ansible/nodepool_restart.yml

Build a Nodepool image locally

If you want to build a custom image with diskimage-builder locally you can follow this process. The following commands run on fedora 30.


Using a dedicated virtual machine is recommended. You can delete everything after your tests.

We start by installing the required dependencies, and downloading elements we will need for our build.

sudo dnf install -y qemu kpartx yum-utils policycoreutils-python-utils
python3 -m pip install --user diskimage-builder
mkdir elements
git clone
git clone
cp -Rf config/nodepool/elements/* elements/
cp -Rf sf-elements/elements/* elements/
export ELEMENTS_PATH=~/elements
export PATH=$PATH:~/.local/bin
mkdir -p /etc/nodepool/scripts

Some elements can require some files during the build. Be sure those files are present on your host before you run the build.

i.e. zuul-user element requires /var/lib/nodepool/.ssh/ during the build. So create this file if you use zuul-user element in your image.

sudo mkdir -p /var/lib/nodepool/.ssh/
sudo touch /var/lib/nodepool/.ssh/

You can now build your image using disk-image-create and the nodepool elements you need

disk-image-create -o image_name [nodepool_elements ...]
disk-image-create -o test zuul-user

You can edit/debug your element and run the build again

vi elements/zuul-user/...
disk-image-create -o test zuul-user

Useful commands

List worker instances and their status (used, building …). Use the –detail* option to get the public IP of the instances:

$ nodepool list

Trigger an diskimage build. The image will be automatically uploaded on the provider(s) after a successful build:

$ nodepool image-build *image-name*

Build logs are available in /var/www/nodepool-log/ on the nodepool-builder node but also via

List nodepool instance images available on the configured providers and their status:

$ nodepool image-list

List instance diskimages built by Disk Image Builder (DIB) and their status:

$ nodepool dib-image-list