Configuration

(required)

Configuration
All Zuul processes read the /etc/zuul/zuul.conf file (an alternate
location may be supplied on the command line) which uses an INI file
syntax.  Each component may have its own configuration file, though
you may find it simpler to use the same file for all components.
Zuul will interpolate environment variables starting with the
ZUUL_ prefix given in the config file escaped as python string
expansion.  foo=%(ZUUL_HOME)s will set the value of foo to the
same value as the environment variable named ZUUL_HOME.
An example zuul.conf:
[zookeeper]
hosts=zk1.example.com,zk2.example.com,zk3.example.com

[database]
dburi=<URI>

[keystore]
password=MY_SECRET_PASSWORD

[web]
status_url=https://zuul.example.com/status

[scheduler]
log_config=/etc/zuul/scheduler-logging.yaml

Common Options
The following sections of zuul.conf are used by all Zuul components:

Statsd

statsd

Information about the optional statsd server.  If the statsd
python module is installed and this section is configured,
statistics will be reported to statsd.  See Statsd reporting for more
information.

statsd.server

Hostname or IP address of the statsd server.

statsd.port
Default: 8125

The UDP port on which the statsd server is listening.

statsd.prefix

If present, this will be prefixed to all of the keys before
transmitting to the statsd server.

ZooKeeper

zookeeper

Client connection information for ZooKeeper.  TLS is required.

zookeeper.hosts (required)

A list of zookeeper hosts for Zuul to use when communicating
with Nodepool.

zookeeper.tls_cert (required)

The path to the PEM encoded certificate file.

zookeeper.tls_key (required)

The path to the PEM encoded key file.

zookeeper.tls_ca (required)

The path to the PEM encoded CA certificate file.

zookeeper.session_timeout
Default: 10.0

The ZooKeeper session timeout, in seconds.

Database

database

database.dburi (required)

Database connection information in the form of a URI understood
by SQLAlchemy.  See The SQLAlchemy manual
for more information.
The driver will automatically set up the database creating and managing
the necessary tables. Therefore the provided user should have sufficient
permissions to manage the database. For example:
GRANT ALL ON my_database TO 'my_user'@'%';

database.pool_recycle
Default: 1

Tune the pool_recycle value. See The SQLAlchemy manual on pooling
for more information.

database.table_prefix
Default: ''

The string to prefix the table names. This makes it possible to run
several zuul deployments against the same database. This can be useful
if you rely on external databases which are not under your control.
The default is to have no prefix.

Scheduler
The scheduler is the primary component of Zuul.  The scheduler is a
scalable component; one or more schedulers must be running at all
times for Zuul to be operational.  It receives events from any
connections to remote systems which have been configured, enqueues
items into pipelines, distributes jobs to executors, and reports
results.
The scheduler must be able to connect to the ZooKeeper cluster shared
by Zuul and Nodepool in order to request nodes.  It does not need to
connect directly to the nodes themselves, however – that function is
handled by the Executors.
It must also be able to connect to any services for which connections
are configured (Gerrit, GitHub, etc).
The following sections of zuul.conf are used by the scheduler:

web

web.root (required)

The root URL of the web service (e.g.,
https://zuul.example.com/).
See tenant.web-root for additional options for
whitelabeled tenant configuration.

web.status_url

URL that will be posted in Zuul comments made to changes when
starting jobs for a change.

keystore

keystore.password (required)

Encryption password for private data stored in Zookeeper.

scheduler

scheduler.command_socket
Default: /var/lib/zuul/scheduler.socket

Path to command socket file for the scheduler process.

scheduler.tenant_config

Path to Tenant Configuration file. This attribute
is exclusive with scheduler.tenant_config_script.

scheduler.tenant_config_script

Path to a script to execute and load the tenant
config from. This attribute is exclusive with
scheduler.tenant_config.

scheduler.default_ansible_version

Default ansible version to use for jobs that doesn’t specify a version.
See job.ansible-version for details.

scheduler.log_config

Path to log config file.

scheduler.pidfile
Default: /var/run/zuul/scheduler.pid

Path to PID lock file.

scheduler.relative_priority
Default: False

A boolean which indicates whether the scheduler should supply
relative priority information for node requests.
In all cases, each pipeline may specify a precedence value which
is used by Nodepool to satisfy requests from higher-precedence
pipelines first.  If relative_priority is set to True,
then Zuul will additionally group items in the same pipeline by
pipeline queue and weight each request by its position in that
project’s group.  A request for the first change in a given
queue will have the highest relative priority, and the second
change a lower relative priority.  The first change of each
queue in a pipeline has the same relative priority, regardless
of the order of submission or how many other changes are in the
pipeline.  This can be used to make node allocations complete
faster for projects with fewer changes in a system dominated by
projects with more changes.
After the first 10 changes, the relative priority becomes more
coarse (batching groups of 10 changes at the same priority).
Likewise, after 100 changes they are batchen in groups of 100.
This is to avoid causing additional load with unecessary
priority changes if queues are long.
If this value is False (the default), then node requests are
sorted by pipeline precedence followed by the order in which
they were submitted.  If this is True, they are sorted by
pipeline precedence, followed by relative priority, and finally
the order in which they were submitted.

scheduler.default_hold_expiration
Default: max_hold_expiration

The default value for held node expiration if not supplied. This
will default to the value of max_hold_expiration if not changed,
or if it is set to a higher value than the max.

scheduler.max_hold_expiration
Default: 0

Maximum number of seconds any nodes held for an autohold request
will remain available. A value of 0 disables this, and the nodes
will remain held until the autohold request is manually deleted.
If a value higher than max_hold_expiration is supplied during
hold request creation, it will be lowered to this value.

scheduler.prometheus_port

Set a TCP port to start the prometheus metrics client.

scheduler.prometheus_addr
Default: 0.0.0.0

The IPv4 addr to listen for prometheus metrics poll.
To use IPv6, python>3.8 is required issue24209.

Merger
Mergers are an optional Zuul service; they are not required for Zuul
to operate, but some high volume sites may benefit from running them.
Zuul performs quite a lot of git operations in the course of its work.
Each change that is to be tested must be speculatively merged with the
current state of its target branch to ensure that it can merge, and to
ensure that the tests that Zuul perform accurately represent the
outcome of merging the change.  Because Zuul’s configuration is stored
in the git repos it interacts with, and is dynamically evaluated, Zuul
often needs to perform a speculative merge in order to determine
whether it needs to perform any further actions.
All of these git operations add up, and while Zuul executors can also
perform them, large numbers may impact their ability to run jobs.
Therefore, administrators may wish to run standalone mergers in order
to reduce the load on executors.
Mergers need to be able to connect to the ZooKeeper cluster as well as
any services for which connections are configured (Gerrit, GitHub,
etc).
The following section of zuul.conf is used by the merger:

merger

merger.command_socket
Default: /var/lib/zuul/merger.socket

Path to command socket file for the merger process.

merger.git_dir
Default: /var/lib/zuul/merger-git

Directory in which Zuul should clone git repositories.

merger.git_http_low_speed_limit
Default: 1000

If the HTTP transfer speed is less then git_http_low_speed_limit for
longer then git_http_low_speed_time, the transfer is aborted.
Value in bytes, setting to 0 will disable.

merger.git_http_low_speed_time
Default: 30

If the HTTP transfer speed is less then git_http_low_speed_limit for
longer then git_http_low_speed_time, the transfer is aborted.
Value in seconds, setting to 0 will disable.

merger.git_timeout
Default: 300

Timeout for git clone and fetch operations. This can be useful when
dealing with large repos. Note that large timeouts can increase startup
and reconfiguration times if repos are not cached so be cautious when
increasing this value.
Value in seconds.

merger.git_user_email

Value to pass to git config user.email.

merger.git_user_name

Value to pass to git config user.name.

merger.log_config

Path to log config file for the merger process.

merger.pidfile
Default: /var/run/zuul/merger.pid

Path to PID lock file for the merger process.

Executor
Executors are responsible for running jobs.  At the start of each job,
an executor prepares an environment in which to run Ansible which
contains all of the git repositories specified by the job with all
dependent changes merged into their appropriate branches.  The branch
corresponding to the proposed change will be checked out (in all
projects, if it exists).  Any roles specified by the job will also be
present (also with dependent changes merged, if appropriate) and added
to the Ansible role path.  The executor also prepares an Ansible
inventory file with all of the nodes requested by the job.
The executor also contains a merger.  This is used by the executor to
prepare the git repositories used by jobs, but is also available to
perform any tasks normally performed by standalone mergers.  Because
the executor performs both roles, small Zuul installations may not
need to run standalone mergers.
Executors need to be able to connect to the ZooKeeper cluster, any
services for which connections are configured (Gerrit, GitHub, etc),
as well as directly to the hosts which Nodepool provides.

Trusted and Untrusted Playbooks
The executor runs playbooks in one of two execution contexts depending
on whether the project containing the playbook is a
config-project or an untrusted-project.  If the
playbook is in a config project, the executor runs the playbook in the
trusted execution context, otherwise, it is run in the untrusted
execution context.
Both execution contexts use bubblewrap [1] to create a namespace to
ensure that playbook executions are isolated and are unable to access
files outside of a restricted environment.  The administrator may
configure additional local directories on the executor to be made
available to the restricted environment.
The trusted execution context has access to all Ansible features,
including the ability to load custom Ansible modules.  Needless to
say, extra scrutiny should be given to code that runs in a trusted
context as it could be used to compromise other jobs running on the
executor, or the executor itself, especially if the administrator has
granted additional access through bubblewrap, or a method of escaping
the restricted environment created by bubblewrap is found.
Playbooks run in the untrusted execution context are not permitted to
load additional Ansible modules or access files outside of the
restricted environment prepared for them by the executor.  In addition
to the bubblewrap environment applied to both execution contexts, in
the untrusted context some standard Ansible modules are replaced with
versions which prohibit some actions, including attempts to access
files outside of the restricted execution context.  These redundant
protections are made as part of a defense-in-depth strategy.

[1]
bubblewrap is integral to securely operating Zuul.
If it is difficult for you to use it in your environment, we
encourage you to let us know via the zuul-discuss mailing
list.

Configuration
The following sections of zuul.conf are used by the executor:

executor

executor.command_socket
Default: /var/lib/zuul/executor.socket

Path to command socket file for the executor process.

executor.finger_port
Default: 7900

Port to use for finger log streamer.

executor.state_dir
Default: /var/lib/zuul

Path to directory in which Zuul should save its state.

executor.git_dir
Default: /var/lib/zuul/executor-git

Directory that Zuul should clone local git repositories to.  The
executor keeps a local copy of every git repository it works
with to speed operations and perform speculative merging.
This should be on the same filesystem as
executor.job_dir so that when git repos are cloned into
the job workspaces, they can be hard-linked to the local git
cache.

executor.job_dir
Default: /var/lib/zuul/builds

Directory that Zuul should use to hold temporary job directories.
When each job is run, a new entry will be created under this
directory to hold the configuration and scratch workspace for
that job.  It will be deleted at the end of the job (unless the
–keep-jobdir command line option is specified).
This should be on the same filesystem as executor.git_dir
so that when git repos are cloned into the job workspaces, they
can be hard-linked to the local git cache.

executor.log_config

Path to log config file for the executor process.

executor.pidfile
Default: /var/run/zuul/executor.pid

Path to PID lock file for the executor process.

executor.private_key_file
Default: ~/.ssh/id_rsa

SSH private key file to be used when logging into worker nodes.

Note
If you use an RSA key, ensure it is encoded in the PEM
format (use the -t rsa -m PEM arguments to
ssh-keygen).

executor.default_username
Default: zuul

Username to use when logging into worker nodes, if none is
supplied by Nodepool.

executor.winrm_cert_key_file
Default: ~/.winrm/winrm_client_cert.key

The private key file of the client certificate to use for winrm
connections to Windows nodes.

executor.winrm_cert_pem_file
Default: ~/.winrm/winrm_client_cert.pem

The certificate file of the client certificate to use for winrm
connections to Windows nodes.

Note
Currently certificate verification is disabled when
connecting to Windows nodes via winrm.

executor.winrm_operation_timeout_sec
Default: None. The Ansible default of 20 is used in this case.

The timeout for WinRM operations.

executor.winrm_read_timeout_sec
Default: None. The Ansible default of 30 is used in this case.

The timeout for WinRM read. Increase this if there are intermittent
network issues and read timeout errors keep occurring.

executor.variables

Path to an Ansible variables file to supply site-wide variables.
This should be a YAML-formatted file consisting of a single
dictionary.  The contents will be made available to all jobs as
Ansible variables.  These variables take precedence over all
other forms (job variables and secrets).  Care should be taken
when naming these variables to avoid potential collisions with
those used by jobs.  Prefixing variable names with a
site-specific identifier is recommended.  The default is not to
add any site-wide variables.  See the User’s Guide for more information.

executor.manage_ansible
Default: True

Specifies wether the zuul-executor should install the supported ansible
versions during startup or not. If this is True the zuul-executor
will install the ansible versions into executor.ansible_root.
It is recommended to set this to False and manually install Ansible
after the Zuul installation by running zuul-manage-ansible. This has
the advantage that possible errors during Ansible installation can be
spotted earlier. Further especially containerized deployments of Zuul
will have the advantage of predictable versions.

executor.ansible_root
Default: <state_dir>/ansible-bin

Specifies where the zuul-executor should look for its supported ansible
installations. By default it looks in the following directories and uses
the first which it can find.

<zuul_install_dir>/lib/zuul/ansible
<ansible_root>

The ansible_root setting allows you to override the second location
which is also used for installation if manage_ansible is True.

executor.ansible_setup_timeout
Default: 60

Timeout of the ansible setup playbook in seconds that runs before
the first playbook of the job.

executor.disk_limit_per_job
Default: 250

This integer is the maximum number of megabytes that any one job
is allowed to consume on disk while it is running. If a job’s
scratch space has more than this much space consumed, it will be
aborted. Set to -1 to disable the limit.

executor.trusted_ro_paths

List of paths, separated by : to read-only bind mount into
trusted bubblewrap contexts.

executor.trusted_rw_paths

List of paths, separated by : to read-write bind mount into
trusted bubblewrap contexts.

executor.untrusted_ro_paths

List of paths, separated by : to read-only bind mount into
untrusted bubblewrap contexts.

executor.untrusted_rw_paths

List of paths, separated by : to read-write bind mount into
untrusted bubblewrap contexts.

executor.load_multiplier
Default: 2.5

When an executor host gets too busy, the system may suffer
timeouts and other ill effects. The executor will stop accepting
more than 1 job at a time until load has lowered below a safe
level.  This level is determined by multiplying the number of
CPU’s by load_multiplier.
So for example, if the system has 2 CPUs, and load_multiplier
is 2.5, the safe load for the system is 5.00. Any time the
system load average is over 5.00, the executor will quit
accepting multiple jobs at one time.
The executor will observe system load and determine whether
to accept more jobs every 30 seconds.

executor.max_starting_builds
Default: None

An executor is accepting up to as many starting builds as defined by the
executor.load_multiplier on systems with more than four CPU cores,
and up to twice as many on systems with four or less CPU cores. For
example, on a system with two CPUs: 2 * 2.5 * 2 - up to ten starting
builds may run on such executor; on systems with eight CPUs: 2.5 * 8 - up
to twenty starting builds may run on such executor.
On systems with high CPU/vCPU count an executor may accept too many
starting builds. This can be overwritten using this option providing a
fixed number of maximum starting builds on an executor.

executor.min_avail_hdd
Default: 5.0

This is the minimum percentage of HDD storage available for the
executor.state_dir directory. The executor will stop accepting
more than 1 job at a time until more HDD storage is available. The
available HDD percentage is calculated from the total available
disk space divided by the total real storage capacity multiplied by
100.

executor.min_avail_mem
Default: 5.0

This is the minimum percentage of system RAM available. The
executor will stop accepting more than 1 job at a time until
more memory is available. The available memory percentage is
calculated from the total available memory divided by the
total real memory multiplied by 100. Buffers and cache are
considered available in the calculation.

executor.hostname
Default: hostname of the server

The executor needs to know its hostname under which it is reachable by
zuul-web. Otherwise live console log streaming doesn’t work. In most cases
This is automatically detected correctly. But when running in environments
where it cannot determine its hostname correctly this can be overridden
here.

executor.paused_on_start
Default: false

Whether the executor should start in a paused mode. Such executor will not
accept tasks until it is unpaused.

executor.zone
Default: None

Name of the nodepool executor-zone to exclusively execute all jobs that
have nodes with the specified executor-zone attribute.  As an example,
it is possible for nodepool nodes to exist in a cloud without public
accessable IP address. By adding an executor to a zone nodepool nodes
could be configured to use private ip addresses.
To enable this in nodepool, you’ll use the node-attributes setting in a
provider pool. For example:
pools:
  - name: main
    node-attributes:
      executor-zone: vpn

executor.allow_unzoned
Default: False

If executor.zone is set it by default only processes jobs with
nodes of that specific zone even if the nodes have no zone at all.
Enabling allow_unzoned lets the executor also take jobs with nodes
without zone.

executor.merge_jobs
Default: True

To disable global merge job, set it to false. This is useful for zoned
executors that are running on slow network where you don’t want them to
perform merge operations for any events. The executor will still perform
the merge operations required for the build they are executing.

executor.sigterm_method
Default: graceful

Determines how the executor responds to a SIGTERM signal.

graceful
Stop accepting new jobs and wait for all running jobs to
complete before exiting.

stop
Abort all running jobs and exit as soon as possible.

keystore

keystore.password (required)

Encryption password for private data stored in Zookeeper.

merger

merger.git_user_email

Value to pass to git config user.email.

merger.git_user_name

Value to pass to git config user.name.

ansible_callback "<name>""" title="Permalink to this definition">

To whitelist ansible callback <name>. Any attributes found is this section
will be added to the callback_<name> section in ansible.cfg.
An example of what configuring the builtin mail callback would look like.
The configuration in zuul.conf.
[ansible_callback "mail"]
to = user@example.org
sender = zuul@example.org

Would generate the following in ansible.cfg:
[defaults]
callback_whitelist = mail

[callback_mail]
to = user@example.org
sender = zuul@example.org

Web Server
The Zuul web server serves as the single process handling all HTTP
interactions with Zuul. This includes the websocket interface for live
log streaming, the REST API and the html/javascript dashboard. All three are
served as a holistic web application. For information on additional supported
deployment schemes, see Web Deployment.
Web servers need to be able to connect to the ZooKeeper cluster and
the SQL database.  If a GitHub, Gitlab, or Pagure connection is
configured, they need to be reachable so they may receive
notifications.
In addition to the common configuration sections, the following
sections of zuul.conf are used by the web server:

web

web.listen_address
Default: 127.0.0.1

IP address or domain name on which to listen.

web.log_config

Path to log config file for the web server process.

web.pidfile
Default: /var/run/zuul/web.pid

Path to PID lock file for the web server process.

web.port
Default: 9000

Port to use for web server process.

web.websocket_url

Base URL on which the websocket service is exposed, if different
than the base URL of the web app.

web.stats_url

Base URL from which statistics emitted via statsd can be queried.

web.stats_type
Default: graphite

Type of server hosting the statistics information. Currently only
‘graphite’ is supported by the dashboard.

web.static_path
Default: zuul/web/static

Path containing the static web assets.

web.static_cache_expiry
Default: 3600

The Cache-Control max-age response header value for static files served
by the zuul-web. Set to 0 during development to disable Cache-Control.

web.zone

The zone in which zuul-web is deployed. This is only needed if
there are executors with different zones in the environment and
not all executors are directly addressable from zuul-web. The
parameter specifies the zone where the executors are directly
adressable. Live log streaming will go directly to the executors
of the same zone and be routed to a finger gateway of the target
zone if the zones are different.
In a mixed system (with zoned and unzoned executors) there may
also be zoned and unzoned zuul-web services. Omit the zone
parameter for any unzoned zuul-web servers.
If this is used the finger gateways should be configured accordingly.

keystore

keystore.password (required)

Encryption password for private data stored in Zookeeper.

Authentication
A user can be granted access to protected REST API endpoints by providing a
valid JWT (JSON Web Token) as a bearer token when querying the API endpoints.
JWTs are signed and therefore Zuul must be configured so that signatures can be
verified. More information about the JWT standard can be found on the IETF’s
RFC page.
This optional section of zuul.conf, if present, will activate the
protected endpoints and configure JWT validation:

auth <authenticator name>

auth <authenticator name>.driver

The signing algorithm to use. Accepted values are HS256, RS256,
RS256withJWKS or OpenIDConnect. See below for driver-specific
configuration options.

auth <authenticator name>.allow_authz_override
Default: false

Allow a JWT to override predefined access rules. See the section on
JWT contents for more details on how to grant access
to tenants with a JWT.

auth <authenticator name>.realm

The authentication realm.

auth <authenticator name>.default
Default: false

If set to true, use this realm as the default authentication realm
when handling HTTP authentication errors.

auth <authenticator name>.client_id

The expected value of the “aud” claim in the JWT. This is required for
validation.

auth <authenticator name>.issuer_id

The expected value of the “iss” claim in the JWT. This is required for
validation.

auth <authenticator name>.uid_claim
Default: sub

The JWT claim that Zuul will use as a unique identifier for the bearer of
a token. This is “sub” by default, as it is usually the purpose of this
claim in a JWT. This identifier is used in audit logs.

auth <authenticator name>.max_validity_time

Optional value to ensure a JWT cannot be valid for more than this amount
of time in seconds. This is useful if the Zuul operator has no control
over the service issueing JWTs, and the tokens are too long-lived.

auth <authenticator name>.skew
Default: 0

Optional integer value to compensate for skew between Zuul’s and the
JWT emitter’s respective clocks. Use a negative value if Zuul’s clock
is running behind.

This section can be repeated as needed with different authenticators, allowing
access to privileged API actions from several JWT issuers.

Driver-specific attributes

HS256
This is a symmetrical encryption algorithm that only requires a shared secret
between the JWT issuer and the JWT consumer (ie Zuul). This driver should be
used in test deployments only, or in deployments where JWTs will be issued
manually.

secret

The shared secret used to sign JWTs and validate signatures.

RS256
This is an asymmetrical encryption algorithm that requires an RSA key pair. Only
the public key is needed by Zuul for signature validation.

public_key

The path to the public key of the RSA key pair. It must be readable by Zuul.

private_key

Optional. The path to the private key of the RSA key pair. It must be
readable by Zuul.

RS256withJWKS

Warning
This driver is deprecated, use OpenIDConnect instead.

Some Identity Providers use key sets (also known as JWKS), therefore the key to
use when verifying the Authentication Token’s signatures cannot be known in
advance; the key’s id is stored in the JWT’s header and the key must then be
found in the remote key set.
The key set is usually available at a specific URL that can be found in the
“well-known” configuration of an OpenID Connect Identity Provider.

keys_url

The URL where the Identity Provider’s key set can be found. For example, for
Google’s OAuth service: https://www.googleapis.com/oauth2/v3/certs

OpenIDConnect
Use a third-party Identity Provider implementing the OpenID Connect protocol.
The issuer ID should be an URI, from which the “well-known” configuration URI
of the Identity Provider can be inferred. This is intended to be used for
authentication on Zuul’s web user interface.

scope
Default: openid profile

The scope(s) to use when requesting access to a user’s details. This attribute
can be multivalued (values must be separated by a space). Most OpenID Connect
Identity Providers support the default scopes “openid profile”. A full list
of supported scopes can be found in the well-known configuration of the
Identity Provider under the key “scopes_supported”.

keys_url

Optional. The URL where the Identity Provider’s key set can be found.
For example, for Google’s OAuth service: https://www.googleapis.com/oauth2/v3/certs
The well-known configuration of the Identity Provider should provide this URL
under the key “jwks_uri”, therefore this attribute is usually not necessary.

Some providers may not conform to the JWT specification and further
configuration may be necessary.  In these cases, the following
additional values may be used:

authority
Default: issuer_id

If the authority in the token response is not the same as the
issuer_id in the request, it may be explicitly set here.

audience
Default: client_id

If the audience in the token response is not the same as the
issuer_id in the request, it may be explicitly set here.

load_user_info
Default: true

If the web UI should skip accessing the “UserInfo” endpoint and
instead rely only on the information returned in the token, set
this to false.

Client
Zuul’s command line client may be configured to make calls to Zuul’s web
server. The client will then look for a zuul.conf file with a webclient
section to set up the connection over HTTP.

webclient

webclient.url

The root URL of Zuul’s web server.

webclient.verify_ssl
Default: true

Enforce SSL verification when sending requests over to Zuul’s web server.
This should only be disabled when working with test servers.

Finger Gateway
The Zuul finger gateway listens on the standard finger port (79) for
finger requests specifying a build UUID for which it should stream log
results. The gateway will determine which executor is currently running that
build and query that executor for the log stream.
This is intended to be used with the standard finger command line client.
For example:
finger UUID@zuul.example.com

The above would stream the logs for the build identified by UUID.
Finger gateway servers need to be able to connect to the ZooKeeper
cluster, as well as the console streaming port on the executors
(usually 7900).
Finger gateways are optional.  They may be run for either or both of
the following purposes:

Allowing end-users to connect to the finger port to stream logs.
Providing an accessible log streaming port for remote zoned
executors which are otherwise inacessible.
In this case, log streaming requests from finger gateways or
zuul-web will route to the executors via finger gateways in the same
zone.

In addition to the common configuration sections, the following
sections of zuul.conf are used by the finger gateway:

fingergw

fingergw.command_socket
Default: /var/lib/zuul/fingergw.socket

Path to command socket file for the executor process.

fingergw.listen_address
Default: all addresses

IP address or domain name on which to listen.

fingergw.log_config

Path to log config file for the finger gateway process.

fingergw.pidfile
Default: /var/run/zuul/fingergw.pid

Path to PID lock file for the finger gateway process.

fingergw.port
Default: 79

Port to use for the finger gateway. Note that since command line
finger clients cannot usually specify the port, leaving this set to
the default value is highly recommended.

fingergw.user

User ID for the zuul-fingergw process. In normal operation as a
daemon, the finger gateway should be started as the root
user, but if this option is set, it will drop privileges to this
user during startup.  It is recommended to set this option to an
unprivileged user.

fingergw.hostname
Default: hostname of the server

When running finger gateways in a multi-zone configuration, the
gateway needs to know its hostname under which it is reachable
by zuul-web. Otherwise live console log streaming doesn’t
work. In most cases This is automatically detected
correctly. But when running in environments where it cannot
determine its hostname correctly this can be overridden here.

fingergw.zone

The zone where the finger gateway is located. This is only needed for
live log streaming if the zuul deployment is spread over multiple
zones without the ability to directly connect to all executors from
zuul-web. See executor.zone for further information.
In a mixed system (with zoned and unzoned executors) there may
also be zoned and unzoned finger gateway services. Omit the zone
parameter for any unzoned finger gateway servers.

If the Zuul installation spans an untrusted network (for example, if
there are remote executor zones), it may be necessary to use TLS
between the components that handle log streaming (zuul-executor,
zuul-fingergw, and zuul-web).  If so, set the following options.
Note that this section is also read by zuul-web in order to load a
client certificate to use when connecting to a finger gateway which
requires TLS, and it is also read by zuul-executor to load a server
certificate for its console streaming port.
If any of these are present, all three certificate options must be
provided.

fingergw.tls_cert

The path to the PEM encoded certificate file.

fingergw.tls_key

The path to the PEM encoded key file.

fingergw.tls_ca

The path to the PEM encoded CA certificate file.

fingergw.tls_verify_hostnames
Default: true

In the case of a private CA it may be both safe and convenient
to disable hostname checks.  However, if the certificates are
issued by a public CA, hostname verification should be enabled.

fingergw.tls_client_only
Default: false

In order to provide a finger gateway which can reach remote
finger gateways and executors which use TLS, but does not itself
serve end-users via TLS (i.e., it runs within a protected
network and users access it directly via the finger port), set
this to true and the finger gateway will not listen on TLS,
but will still use the supplied certificate to make remote TLS
connections.

Connections
Most of Zuul’s configuration is contained in the git repositories upon
which Zuul operates, however, some configuration outside of git
repositories is still required to bootstrap the system.  This includes
information on connections between Zuul and other systems, as well as
identifying the projects Zuul uses.
In order to interact with external systems, Zuul must have a
connection to that system configured.  Zuul includes a number of
drivers, each of which implements the functionality
necessary to connect to a system.  Each connection in Zuul is
associated with a driver.
To configure a connection in Zuul, select a unique name for the
connection and add a section to zuul.conf with the form
[connection NAME].  For example, a connection to a gerrit server
may appear as:
[connection mygerritserver]
driver=gerrit
server=review.example.com

Zuul needs to use a single connection to look up information about
changes hosted by a given system.  When it looks up changes, it will
do so using the first connection it finds that matches the server name
it’s looking for.  It’s generally best to use only a single connection
for a given server, however, if you need more than one (for example,
to satisfy unique reporting requirements) be sure to list the primary
connection first as that is what Zuul will use to look up all changes
for that server.