Architecture¶

Pulp’s architecture has three components to it: a REST API, a content serving application, and the tasking system. Each component can be horizontally scaled for both high availability and/or additional capacity for that part of the architecture.

REST API¶

Pulp’s REST API is a Django application that runs under any WSGI server. It serves the following things:

The REST API hosted at /pulp/api/v3/
The browse-able documentation at /pulp/api/v3/docs/
Any viewsets or views provided by plugins
Static content used by Django, e.g. images used by the browse-able API. This is not Pulp content.

Note

A simple, but limited way to run the REST API as a standalone service using the built-in Django runserver. The pulpcore-manager command is manage.py configured with the DJANGO_SETTINGS_MODULE="pulpcore.app.settings". Run the simple webserver with:

$ pulpcore-manager runserver 24817

The REST API can be deployed with any any WSGI webserver like a normal Django application. See the Django deployment docs for more information.

Content Serving Application¶

An aiohttp.server based application that serves content to clients. The content could be Artifacts already downloaded and saved in Pulp, or on-demand content units. When serving on-demand content units the downloading also happens from within this component as well.

Note

Pulp installs a script that lets you run the content serving app as a standalone service as follows::

$ pulp-content

The content serving application can be deployed like any aiohttp.server application. See the aiohttp Deployment docs for more information.

Availability¶

Ensuring the REST API and the content server is healthy and alive: * REST API: GET request to ${API_ROOT}api/v3/status/ see API_ROOT * Content Server: HEAD request to /pulp/content/ or CONTENT_PATH_PREFIX

Distributed Tasking System¶

Pulp’s tasking system consists of a single pulpcore-worker component consequently, and can be scaled by increasing the number of worker processes to provide more concurrency. Each worker can handle one task at a time, and idle workers will lookup waiting and ready tasks in a distributed manner. If no ready tasks were found a worker enters a sleep state to be notified, once new tasks are available or resources are released. Workers auto-name and are auto-discovered, so they can be started and stopped without notifying Pulp.

Note

Pulp serializes tasks that are unsafe to run in parallel, e.g. a sync and publish operation on the same repo should not run in parallel. Generally tasks are serialized at the “resource” level, so if you start N workers you can process N repo sync/modify/publish operations concurrently.

All necessary information about tasks is stored in Pulp’s Postgres database as a single source of truth. In case your tasking system get’s jammed, there is a guide to help :ref:debugging_tasks.

Static Content¶

When browsing the REST API or the browsable documentation with a web browser, for a good experience, you’ll need static content to be served.

In Development¶

If using the built-in Django webserver and your settings.yaml has DEBUG: True then static content is automatically served for you.

In Production¶

Collect all of the static content into place using the collectstatic command. The pulpcore-manager command is manage.py configured with the DJANGO_SETTINGS_MODULE="pulpcore.app.settings". Run collectstatic as follows:

$ pulpcore-manager collectstatic

Analytics Collection¶

By default, Pulp installations post anonymous analytics data every 24 hours which is summarized on https://analytics.pulpproject.org/ and aids in project decision making. This is enabled by default but can be disabled by setting ANALYTICS=False in your settings.

Here is the list of exactly what is collected along with an example below:

The version of Pulp components installed
The number of worker processes and number of hosts (not hostnames) those workers run on
The number of content app processes and number of hosts (not hostnames) those content apps run on

An example payload:

{
    "systemId": "a6d91458-32e8-4528-b608-b2222ede994e",
    "onlineContentApps": {
        "processes": 2,
        "hosts": 1
    },
    "onlineWorkers": {
        "processes": 2,
        "hosts": 1
        },
    "components": [{
        "name": "core",
        "version": "3.21.0"
        }, {
        "name": "file",
        "version": "1.12.0"
    }],
    "postgresqlVersion": 90200
}