:title: Operation .. _operation: Operation ========= You can run any zuul process with the **-f** option to make it not daemonize and stay in the foreground, logging to your terminal. It's a good idea at first to check for issues with your configuration. There's also a **-d** option to engage verbose debug logging, but be careful in busy deployments as this can generate very large logs. To start, simply run:: zuul-scheduler Before Zuul can run any jobs, it needs to load its configuration, most of which is in the git repositories that Zuul operates on. Start an executor to allow zuul to do that:: zuul-executor Zuul should now be able to read its configuration from the configured repo and process any jobs defined therein. Scheduler --------- Operation ~~~~~~~~~ To start the scheduler, run ``zuul-scheduler``. To stop it, run ``zuul-scheduler stop``. .. _reconfiguration: Reconfiguration ~~~~~~~~~~~~~~~ Most of Zuul's configuration is automatically updated as changes to the repositories which contain it are merged. However, Zuul must be explicitly notified of changes to the tenant config file, since it is not read from a git repository. Zuul supports two kinds of reconfigurations. The full reconfiguration refetches and reloads the configuration of all tenants. To do so, run ``zuul-scheduler full-reconfigure``. For example this can be used to fix eventual configuration inconsistencies after connection problems with the code hosting system. To perform the same actions as a full reconfiguration but for a single tenant, use ``zuul-scheduler tenant-reconfigure TENANT`` (where ``TENANT`` is the name of the tenant to reconfigure). The smart reconfiguration reloads only the tenants that changed their configuration in the tenant config file. To do so, run ``zuul-scheduler smart-reconfigure``. In multi tenant systems this can be much faster than the full reconfiguration so it is recommended to use the smart reconfiguration after changing the tenant configuration file. The ``tenant-reconfigure`` and ``smart-reconfigure`` commands should only be run on a single scheduler. Other schedulers will see any changes to the configuration stored in ZooKeeper and automatically update their configuration in the background without interrupting processing. .. _backup: Backup and Restoration ~~~~~~~~~~~~~~~~~~~~~~ While all of Zuul's component services are designed to be run in a resilient active-active clustered deployment, a good disaster recovery plan should include backing up critical data. At a minimum, the randomly-generated project keys used for encryption of job secrets and SSH access should be backed up, as they **cannot be recreated** if lost. Zuul stores these keys in a keystore in ZooKeeper which is inconvenient to back up directly, but provides an administrative tool to :ref:`export ` these keys to and :ref:`import ` them from a local directory. It's highly recommended to set up periodic automation for dumping such an export to a secure location (for example, on the filesystem of each Zuul Scheduler) for use in a disaster where all ZooKeeper content is lost. You may also consider configuring a safe remote backup of these files with the tool of your choice, but be aware that they are potentially sensitive since anyone who gains access to them could decrypt job secrets or access protected systems which have been instructed to trust those keys. Note that the exported keys are symmetrically encrypted with the same :ref:`keystore.password ` which is used for encrypting and decrypting the copy of them in ZooKeeper, because its the encrypted versions of the keys which are exported and imported. Someone with access to the keys would also need a copy of the keystore.password from Zuul's configuration, so for security-sensitive environments you may not want to back them up together. Conversely, if you lose the keystore.password then you also lose the use of the project keys in the keystore and any exports, so you will likely want to make sure you keep a secured copy of it somewhere as well in the event your server configuration is lost. Merger ------ Operation ~~~~~~~~~ To start the merger, run ``zuul-merger``. In order to stop the merger and under normal circumstances it is best to pause and wait for all currently running tasks to finish before stopping it. To do so run ``zuul-merger pause``. To stop the merger, run ``zuul-merger stop``. This will wait for any currently running merge task to complete before exiting. As a result this is always a graceful way to stop the merger. ``zuul-merger graceful`` is an alias for ``zuul-merger stop`` to make this consistent with the executor. Executor -------- Operation ~~~~~~~~~ To start the executor, run ``zuul-executor``. There are several commands which can be run to control the executor's behavior once it is running. To pause the executor and prevent it from running new jobs you can run ``zuul-executor pause``. To cause the executor to stop accepting new jobs and exit when all running jobs have finished you can run ``zuul-executor graceful``. Under most circumstances this will be the best way to stop Zuul. To stop the executor immediately, run ``zuul-executor stop``. Jobs that were running on the stopped executor will be rescheduled on other executors. The executor normally responds to a ``SIGTERM`` signal in the same way as the ``graceful`` command, however you can change this behavior to match ``stop`` with the :attr:`executor.sigterm_method` setting. To enable or disable running Ansible in verbose mode (with the ``-vvv`` argument to ansible-playbook) run ``zuul-executor verbose`` and ``zuul-executor unverbose``. .. _ansible-and-python-3: Ansible and Python 3 ~~~~~~~~~~~~~~~~~~~~ As noted above, the executor runs Ansible playbooks against the remote node(s) allocated for the job. Since part of executing playbooks on remote hosts is running Python scripts on them, Ansible needs to know what Python interpreter to use on the remote host. With older distributions, ``/usr/bin/python2`` was a generally sensible choice. However, over time a heterogeneous Python ecosystem has evolved where older distributions may only provide Python 2, most provide a mixed 2/3 environment and newer distributions may only provide Python 3 (and then others like RHEL8 may even have separate "system" Python versions to add to confusion!). Ansible's ``ansible_python_interpreter`` variable configures the path to the remote Python interpreter to use during playbook execution. This value is set by Zuul from the ``python-path`` specified for the node by Nodepool; see the `nodepool configuration documentation `__. This defaults to ``auto``, where Ansible will automatically discover the interpreter available on the remote host. However, this setting only became available in Ansible >=2.8, so Zuul will translate ``auto`` into the old default of ``/usr/bin/python2`` when configured to use older Ansible versions. Thus for modern Python 3-only hosts no further configuration is needed when using Ansible >=2.8 (e.g. Fedora, Bionic onwards). If using earlier Ansible versions you may need to explicitly set the ``python-path`` if ``/usr/bin/python2`` is not available on the node. Ansible roles/modules which include Python code are generally Python 3 safe now, but there is still a small possibility of incompatibility. See also the Ansible `Python 3 support page `__. .. _nodepool_console_streaming: Log streaming ~~~~~~~~~~~~~ The log streaming service enables Zuul to show the live status of long-running ``shell`` or ``command`` tasks. The server side is setup by the ``zuul_console:`` task built-in to Zuul's Ansible installation. The executor requires the ability to communicate with this server on the job nodes via port ``19885`` for this to work. The log streaming service spools command output via files on the job node in the format ``/tmp/console---.log``. By default, it will clean these files up automatically. Occasionally, a streaming file may be left if a job is interrupted. These may be safely removed after a short period of inactivity with a command such as .. code-block:: shell find /tmp -maxdepth 1 -name 'console-*-*-.log' -mtime +2 -delete If the executor is unable to reach port ``19885`` (for example due to firewall rules), or the ``zuul_console`` daemon can not be run for some other reason, the command to clean these spool files will not be processed and they may be left behind; on an ephemeral node this is not usually a problem, but on a static node these files will persist. In this situation, Zuul can be instructed to not to create any spool files for ``shell`` and ``command`` tasks via setting ``zuul_console_disabled: True`` (usually via a global host variable in inventory). Live streaming of ``shell`` and ``command`` calls will of course be unavailable in this case, but no spool files will be created. For Kubernetes-based job nodes the connection from the executor to the ``zuul_console`` daemon is established by using ``kubectl port-forward`` to forward a local port to the appropriate port on the pod containing the job node. If the Kubernetes user is not bound to a role that has authorization for port-forwarding, this will prevent connection to the ``zuul_console`` daemon. Web Server ---------- Operation ~~~~~~~~~ To start the web server, run ``zuul-web``. To stop it, kill the PID which was saved in the pidfile specified in the configuration. Finger Gateway -------------- Operation ~~~~~~~~~ To start the finger gateway, run ``zuul-fingergw``. To stop it, kill the PID which was saved in the pidfile specified in the configuration.