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(Resources: Add Mitaka Summit Notes)
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=== Mitaka ===
* [https://wiki.openstack.org/wiki/Design_Summit/Mitaka/Etherpads#Oslo Mitaka Summit Planning etherpads]
=== Liberty ===
=== Liberty ===

Revision as of 14:50, 9 November 2015

Official Title: OpenStack Common Libraries

PTL: Davanum Srinivas <davanum@gmail.com>

Mission Statement:
To produce a set of python libraries containing code shared by OpenStack projects. The APIs provided by these libraries should be high quality, stable, consistent, documented and generally applicable.

The Oslo Team

The Oslo program brings together generalist code reviewers and specialist API maintainers. They share a common interest in tackling copy-and-paste technical debt across the OpenStack project.

Generalist Code Reviewers

Oslo's core reviewers take on a generalist role on the project. They are folks with good taste in Python code, provide constructive input in their reviews and make time to review any patches submitted to the project, irrespective of the area which a given patch targets.

Specialist API Maintainers

Each incubating API has one or more specialist maintainers who have responsibility for evolving the API in question. They work to ensure the API meets the needs of all OpenStack projects, and once the API is stable they help graduate the code to a library so it can be adopted by projects needing the functionality.

Each library has its own core team, which can include specialists in the area of the library who are not general Oslo cores. Because the scope of the Oslo project has grown so large, these library-specific cores are critical to the long-term health of the projects and anyone with an interest in a library is encouraged to get involved.

Project Meetings

See Meetings/Oslo.

Getting in Touch

We use the openstack-dev@lists.openstack.org mailing list for discussions and we all hang out in #openstack-oslo and #openstack-dev on freenode.

Each project also designates a liaison for handling integration issues. See Oslo/ProjectLiaisons.


The following libraries are currently published by the Oslo program. Where we felt that a library had real potential for widespread use outside OpenStack, we chose not to include them in the oslo namespace.

New libraries need to be careful to avoid introducing circular dependencies. See Oslo/Dependencies.

Specialized libraries have their own core-review team with members who may not be part of the main Oslo core team. Unless otherwise indicated below, an Oslo library is maintained by oslo-core.



automaton is a framework for building state machines.

Please file bugs in the automaton project in launchpad.


cliff is a framework for building command line programs.

Core review team: cliff-core

Documentation: [1]

Please file bugs in the python-cliff project in launchpad.



cookiecutter Cookiecutter is a project that creates a skeleton OpenStack project from a set of templates.

Please file bugs in the oslo project in launchpad.



debtcollector A collection of python patterns that help you collect your technical debt in a non-destructive manner (following deprecation patterns and strategies and so-on).

Please file bugs in the debtcollector project in launchpad.



futurist A collection of async functionality and additions from the future.

Please file bugs in the futurist project in launchpad.


A library for caching based on dogpile.

Please file bugs in the oslo.cache project in launchpad.


A library for managing external processes and task synchronization.

Please file bugs in the oslo.concurrency project in launchpad.


oslo.context has helpers to maintain useful information about a request context

Please file bugs in the oslo.context project in launchpad.

See this historical blueprint describing the initial requirements for the API.


oslo.config is a library for parsing configuration files and command line arguments.

Please file bugs in the oslo.config project in launchpad.

See this historical blueprint describing the initial requirements for the API.


cookiecutter oslo-cookiecutter creates a skeleton Oslo library from a set of templates.

Please file bugs in the oslo-cookiecutter project in launchpad.


oslo.db is an Oslo database handling library.

Core review team: oslo-db-core

Please file bugs in the oslo.db project in launchpad.


oslo.i18n is a wrapper around Python's gettext module for string translation and other internationalization features.

Please file bugs in the oslo.i18n project in launchpad


oslo.log is a logging configuration library.

Please file bugs and blueprints in the oslo.log project in launchpad.


The oslo.messaging provides a messaging API which supports RPC and notifications over a number of different messaging transports.

Bugs and blueprints should be filed using the oslo.messaging launchpad project.

Core review team: oslo-messaging-core

This etherpad captures the latest status and background to this project.


A collection of WSGI middleware for web service development

Please file bugs in the oslo.middleware project in launchpad.


Rules engine for enforcing policy

Please file bugs in the oslo.policy project in launchpad.


oslo.privsep is a mechanism for running selected python code with elevated privileges

Please file bugs in the oslo.privsep project in launchpad.

Core review team: oslo-privsep-core


oslo.reports allows projects to generate Guru Meditation Reports for debugging the current state of OpenStack processes. It can also be used to generating general reports on the fly that are serializable as plain text, JSON, or XML.

Please file bugs in the oslo.reports project in launchpad.


oslo.rootwrap Rootwrap allows fine filtering of shell commands to run as root from OpenStack services.

Please file bugs in the oslo.rootwrap project in launchpad

Core review team: oslo-rootwrap-core


oslo.serialization provides serialization functionality with special handling for some common types used in OpenStack.

Please file bugs in the oslo.serialization project in launchpad.


oslo.service provides functionality for running OpenStack services.

Please file bugs in the oslo.service project in launchpad.


oslosphinx provides theme and extension support for Sphinx documentation from the OpenStack project. It is maintained by Doug Hellmann.

Please file bugs in the oslosphinx project in launchpad.


oslotest provide base classes and fixtures for creating unit and functional tests.

Please file bugs in the oslotest project in launchpad.


A library of various low-level utility modules.

Please file bugs in the oslo.utils project in launchpad.


oslo.versionedobjects deals with DB schema being at different versions than the code expects, allowing services to be operated safely during upgrades.

Please file bugs in the oslo.versionedobjects project in launchpad.



oslo.version handles getting the version for an installed piece of software from the python metadata that already exists. It is maintained by Monty Taylor.

Please file bugs in the oslo project in launchpad.


Code common to the VMware drivers in several projects.

Please file bugs in the oslo.vmware project in launchpad.


Inter-process lock management library

Please file bugs in the pylockfile project in launchpad.


hacking is a set of tools for enforcing coding style guidelines. It is maintained by Joe Gordon and Sean Dague.

Please file bugs in the hacking project in launchpad.

Core review team: oslo-vmware-core


pbr (or Python Build Reasonableness) is a set of sensible default setuptools behaviours. It is maintained by Monty Taylor.

Please file bugs in the pbr project in launchpad.

Core review team: pbr-core


pyCADF is a python implementation of the DMTF Cloud Audit (CADF) data model.

Please file bugs in the pycadf project in launchpad.

Core review team: pycadf-core


stevedore is a library for managing plugins for Python applications.

Please file bugs in the python-stevedore project in launchpad.

Core review team: stevedore-core


taskflow is a library that helps create applications that handle state/failures... in a reasonable manner. It is maintained by taskflow-dev

More details can be found at: https://wiki.openstack.org/TaskFlow

Please file bugs in the taskflow project in launchpad.

Core review team: taskflow-core


tooz is a library that aims at centralizing the most common distributed primitives like group membership protocol, lock service and leader election by providing a coordination API helping developers to build distributed applications.

Please file bugs in the python-tooz project in launchpad.

Core review team: [2]


APIs included in Oslo should reflect a rough consensus across the project on the requirements and design for that use case. New OpenStack projects should be able to use an Oslo API safe in the knowledge that, by doing so, the project is being a good OpenStack citizen and building upon established best practice.

To that end, we keep a number of principles in mind when designing and evolving Oslo APIs:

  1. The API should be generally useful and a "good fit" - e.g. it shouldn't encode any assumptions specific to the project it originated from, it should follow a style consistent with other Oslo APIs and should fit generally in a theme like error handling, configuration options, time and date, notifications, WSGI, etc.
  2. The API should already be in use by a number of OpenStack projects
  3. There should be a commitment to adopt the API in all other OpenStack projects (where appropriate) and there should be no known major blockers to that adoption
  4. The API should represents the "rough consensus" across OpenStack projects
  5. There should be no other API in OpenStack competing for this "rough consensus"
  6. It should be possible for the API to evolve while continuing to maintain backwards compatibility with older versions for a reasonable period - e.g. compatibility with an API deprecated in release N may only be removed in release N+2


Refer to The Oslo Incubator in the Oslo policies for details.

Using an Oslo Library

See Oslo/UsingALibrary for steps for successfully introducing an Oslo library to a project.


Code in the incubator is expected to move out to its own repository to be packaged as a standalone library or project.

See the Graduation section of the team policy guide for more details.

See Oslo/CreatingANewLibrary for the steps involved.


Why aren't alpha releases of oslo.config published to PyPI?

See Choosing Version Numbers for the current policies related to versioning and releases.

Why does oslo.config have a CONF object? Global object SUCK!

Indeed. Well, it's a long story and well documented in mailing list archives if anyone cares to dig up some links.

Around the time of the Folsom Design Summit, an attempt was made to remove our dependence on a global object like this. There was massive debate and, in the end, the rough consensus was to stick with using this approach.

Nova, through its use of the gflags library, used this approach from commit zero. Some OpenStack projects didn't initially use this approach, but most now do. The idea is that having all projects use the same approach is more important than the objections to the approach. Sharing code between projects is great, but by also having projects use the same idioms for stuff like this it makes it much easier for people to work on multiple projects.

This debate will probably never completely go away, though. See this latest discussion in August, 2014.

Why does Oslo observe feature freeze

Feature freeze is a time to stabilize all of the new features that were added during a development cycle, but since Oslo projects don't necessarily release on the same six month schedule as the other OpenStack projects (or at all in the case of oslo-incubator) it might seem odd that Oslo observes feature freeze.

For the graduated libraries this serves the same purpose as for any of the other projects - it's a time for focusing on bug fixes and stability.

For oslo-incubator, the primary motivation is making last-minute fixes needed by other projects easier to sync. If a new feature lands in oslo-incubator and an unrelated bug is discovered by one of the consuming projects, it becomes a problem to sync just the bug fix to the project. When 11th hour bug fixes are needed it's best if the sync is as simple and small as possible. To avoid problems, oslo-incubator respects the feature freeze period just like any other project.

How does Oslo manage versions?

See Oslo/VersioningPolicy.


Review policies

These overlay the regular review rules for OpenStack as a whole.

  • Automated changes - patches from 'openstack proposal bot' and 'transifex' which have passed CI checks can be +2+A by a single core reviewer

Review Links

(See http://git.openstack.org/cgit/openstack/oslo-incubator/tree/dashboards for the source files to create these links)

Security Team

In addition to OpenStack's Vulnerability Management team, some members of the Oslo team have indicated their willingness to help with security related issues in Oslo code. See Oslo/Security for the current list.

Design Proposals

We use the oslo-specs repo to track design proposals across all Oslo projects.

See the Spec Approval policy for details.

The blueprints on launchpad detail the changes currently underway to implement these specs.

Approved Specs are published separately.

Release Instructions






Juno Etherpads

Icehouse Etherpads

Etherpads from sessions at the Icehouse Design summit.

Messaging Related Work in Havana

During the Havana cycle, work is going on to re-design our messaging APIs and to add signatures and encryption to our messages.

See this etherpad for yet more details.

Havana Etherpads

Etherpads from sessions at the Havana Design summit.

Grizzly Etherpads

Etherpads from sessions at the Grizzly Design summit.

Folsom Etherpads

Etherpads from sessions at the Folsom Design summit.