A Kubernetes Operator for Zuul
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zuul-operator/doc/source/index.rst

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Zuul Operator

This is a Kubernetes Operator for the Zuul Project Gating System.

Zuul has a number of components and depencencies, and this operator is designed to simplify creating and maintaining Zuul systems in Kubernetes.

Somewhat unusually, this operator offers the ability to completely manage Zuul's operational dependencies, to the point of even installing other operators upon which it relies. Be sure to read about deployment options if you want to perform some of these tasks yourself.

Simple Example

The quickest way to get a running Zuul is to allow the operator to manage all of the dependencies for you. In this case, the operator will:

  • Install cert-manager and set up a self-signed cluster issuer
  • Install the Percona XtraDB operator and create a three-node PXC database cluster
  • Create a three-node ZooKeeper cluster
  • And of course, create a Zuul system

Note

Installing other operators requires a high level of access, so when used in this manner, zuul-operator runs with cluster admin privileges. If you would like the operator to run with reduced privileges, see Managing Operator Dependencies.

From the root of the zuul-operator repo, run:

kubectl apply -f deploy/crds/zuul-ci_v1alpha1_zuul_crd.yaml
kubectl apply -f deploy/rbac-admin.yaml
kubectl apply -f deploy/operator.yaml

You probably want a namespace, so go ahead and create one with:

kubectl create namespace zuul

You will need to prepare two config files for Zuul: the Nodepool config file and the Zuul tenant config file. See the Zuul and Nodepool manuals for how to prepare those. When they are ready, add them to Kubernetes with commands like:

kubectl -n zuul create secret generic zuul-nodepool-config --from-file=nodepool.yaml
kubectl -n zuul create secret generic zuul-tenant-config --from-file=main.yaml

Then create a file called zuul.yaml which looks like:

---
apiVersion: operator.zuul-ci.org/v1alpha2
kind: Zuul
metadata:
  name: zuul
spec:
  executor:
    count: 1
    sshkey:
      secretName: gerrit-secrets
  scheduler:
    config:
      secretName: zuul-tenant-config
  launcher:
    config:
      secretName: zuul-nodepool-config
  web:
    count: 1
  connections:
    opendev:
      driver: git
      baseurl: https://opendev.org

This will create the most basic of Zuul installations, with one each of the zuul-executor, zuul-scheduler, and zuul-web processes. It will also create a Nodepool launcher for each of the providers listed in your nodepool.yaml. If your Zuul tenant config file requires more connections, be sure to add them here.

Managing Operator Dependencies

You may not want zuul-operator to install other operators (for example, if your cluster has other users and you don't want cert-manager or pxc-operator to be tied to a Zuul installation, or if you would prefer to avoid granting zuul-operator cluster admin privileges). In that case, you may install the other operators yourself and still allow zuul-operator to use those other operators. It can still create a PXC cluster for you as long as the pxc-operator is present.

To use this mode of operation, make sure the following dependencies are installed before using zuul-operator:

  • Cert-manager (at least version 1.2.0)
  • Percona-xtradb-cluster-operator (at least version 1.7.0)

With these installed, you may install zuul-operator with reduced privileges:

kubectl apply -f deploy/crds/zuul-ci_v1alpha1_zuul_crd.yaml
kubectl apply -f deploy/rbac.yaml
kubectl apply -f deploy/operator.yaml

After this point, usage is the same as other methods.

Externally Managed Zuul Dependencies

If you want zuul-operator to do even less work, you can have it avoid managing either ZooKeeper or the SQL database.

Externally Managed ZooKeeper

If you already have a ZooKeeper instance you would like Zuul to use, add the following to the Zuul spec:

---
apiVersion: operator.zuul-ci.org/v1alpha2
kind: Zuul
spec:
  zookeeper:
     connectionString: ...
     secretName: ...

The connectionString field should be a standard ZooKeeper connection string, and the secretName field should be a Kubernetes TLS secret with the client cert for Zuul to use when connecting to ZooKeeper. TLS is required.

Externally Managed Database

If you would like to use an existing database, add the following to the Zuul spec:

---
apiVersion: operator.zuul-ci.org/v1alpha2
kind: Zuul
spec:
  database:
     dburi: ...

The dburi field should contain a Python db-api URI; it corresponds to the dburi entry in zuul.conf.

Secrets

The operator uses Kubernetes secrets as input values for several aspects of operation. There are some general rules about how secrets are used:

  • For configuration files, secret keys are expected to be the typical filename (for example, nodepool.yaml for the Nodepool config file).
  • For Zuul connection entries, secret keys correspond to the configuration file attributes for that section (e.g., app_key for the github driver).

See the reference documentation for the specific secretName entry for details.

Specification Reference

This is a fully populated example (with the exception of connection entries which can contain zuul.conf attributes passed through verbatim):

apiVersion: zuul-ci.org/v1alpha2
kind: Zuul
spec:
  database:
    secretName: mariadbSecret
  zookeeper:
    hosts: zk.example.com:2282
    secretName: zookeeperTLS
  merger:
    count: 5
    git_user_email: zuul@example.org
    git_user_name: Example Zuul
  executor:
    count: 5
    manage_ansible: false
  web:
    count: 1
    status_url: https://zuul.example.org
  fingergw:
    count: 1
  scheduler:
    count: 1
  connections:
    gerrit:
      driver: gerrit
      server: gerrit.example.com
      secretName: gerritSecrets
      user: zuul
      baseurl: http://gerrit.example.com:8080
    github:
      driver: github
      secretName: githubSecrets
      rate_limit_logging: false
      app_id: 1234
  jobVolumes:
    - context: trusted
      access: ro
      path: /authdaemon/token
      volume:
        name: gcp-auth
        hostPath:
          path: /var/authdaemon/executor
          type: DirectoryOrCreate

Zuul

The Zuul kind is currently the only resource directly handled by the operator. It holds a complete description of a Zuul system (though at least partly via secrets referenced by this resource).

spec

imagePrefix

The prefix to use for images. The image names are fixed (zuul-executor, etc). However, changing the prefix will allow you to use custom images or private registries.

zuulImageVersion

The image tag to append to the Zuul images.

nodepoolImageVersion

The image tag to append to the Nodepool images.

database

This is not required unless you want to manage the database yourself. If you omit this section, zuul-operator will create a Percona XtraDB cluster for you.

You may add any attribute corresponding to the database section of zuul.conf here. The dburi attribute will come from the secret below.

secretName

The name of a secret containing connection information for the database.

The key name in the secret should be dburi.

zookeeper

This is not required unless you want to manage the ZooKeeper cluster yourself. If you omit this section, zuul-operator will create a ZooKeeper cluster for you

You may add any attribute corresponding to the zookeeper section of zuul.conf here. The hosts and TLS attributes will come from the secret below.

hosts

A standard ZooKeeper connection string.

secretName

The name of a secret containing a TLS client certificate and key for ZooKeeper. This should be (or the format should match) a standard Kubernetes TLS secret.

The key names in the secret should be:

  • ca.crt
  • tls.crt
  • tls.key

scheduler

config

secretName

The name of a secret containing the Zuul tenant config file.

The key name in the secret should be main.yaml.

launcher

config

secretName

The name of a secret containing the Nodepool config file.

The key name in the secret should be nodepool.yaml.

executor

count

How many executors to manage. This is a required component and should be at least 1.

sshkey

secretName

The name of a secret containing the SSH private key that executors should use when logging into Nodepool nodes. You will need to arrange for the public half of this key to be installed on those nodes via whatever mechanism provided by your cloud.

The key name in the secret should be sshkey.

merger

count

How many mergers to manage. Executors also act as mergers so this is not required. They may be useful on a busy system.

web

count

How many Zuul webservers to manage. This is a required component and should be at least 1.

fingergw

count

How many Zuul finger gateway servers to manage.

connections

This is a mapping designed to match the connections entries in the main Zuul config file (zuul.conf). Each key in the mapping is the name of a connection (this is the name you will use in the tenant config file), and the values are key/value pairs that are directly added to that connectien entry in zuul.conf. In the case of keys which are typically files (for example, SSH keys), the values will be written to disk for you (so you should include the full values here and not the path).

You may provide any of these values directly in this resource or using the secret described below. You may use both, and the values will be combined (for example, you may include all the values here except a private key which you include in a secret).

Example:

connections:
  opendev:
    driver: git
    baseurl: https://opendev.org
  gerrit:
    driver: git
    baseurl: https://gerrit.examplec.mo
    secretName: gerrit-secrets

<name>

The name of the connection. You will use this is the tenant config file. All of the attributes describing this connection should be included underneath this key.

secretName

The name of a secret describing this connection. All of the keys and values in this secret will be merged with the keys and values described in this connection entry. If you need to provide a file (for example, the sshkey attribute of a Gerrit connection), include the contents as the value of the sshkey attribute in the secret.

jobVolumes

A list of Kubernetes volumes to be bind mounted into the executor's execution context. These correspond to the trusted_ro_paths, untrusted_ro_paths, trusted_rw_paths, and untrusted_ro_paths entries in zuul.conf.

The first part of each entry describes how the volume should appear in the executor, and the volume attribute describes the Kubernetes volume.

context

One of the following values:

trusted

To be mounted in the trusted execution context.

untrusted

To be mounted in the untrusted execution context.

access

One of the following values:

rw

To be mounted read/write.

ro

To be mounted read-only.

path

The mount point within the execution context.

volume

A mapping corresponding to a Kubernetes volume.