Ansible is a radically simple IT automation platform that makes your applications and systems easier to deploy. Avoid writing scripts or custom code to deploy and update your applications — automate in a language that approaches plain English, using SSH, with no agents to install on remote systems. https://docs.ansible.com/ansible/
6e82df451a
This change is motivated by an ssh oddity: when ControlPersist is
enabled, the first (i.e. master) connection goes into the background; we
see EOF on its stdout and the process exits, but we never see EOF on its
stderr. So if we ran a command like this:
ANSIBLE_SSH_PIPELINING=1 ansible -T 30 -vvv somehost -u someuser -m command -a whoami
We would first do select([stdout,stderr], timeout) and read the command
module output, then select([stdout,stderr], timeout) again and read EOF
on stdout, then select([stderr], timeout) AGAIN (though the process has
exited), and select() would wait for the full timeout before returning
rfd=[], and then we would exit. The use of a very short timeout in the
code masked the underlying problem (that we don't see EOF on stderr).
It's always preferable to call select() with a long timeout so that the
process doesn't use any CPU until one of the events it's interested in
happens (and then select will return independent of elapsed time).
(A long timeout value means "if nothing happens, sleep for up to <x>";
omitting the timeout value means "if nothing happens, sleep forever";
specifying a zero timeout means "don't sleep at all", i.e. poll for
events and return immediately.)
This commit uses a long timeout, but explicitly detects the condition
where we've seen EOF on stdout and the process has exited, but we have
not seen EOF on stderr. If and only if that happens, it reruns select()
with a short timeout (in practice it could just exit at that point, but
I chose to be extra cautious). As a result, we end up calling select()
far less often, and use less CPU while waiting, but don't sleep for a
long time waiting for something that will never happen.
Note that we don't omit the timeout to select() altogether because if
we're waiting for an escalation prompt, we DO want to give up with an
error after some time. We also don't set exceptfds, because we're not
actually acting on any notifications of exceptional conditions.
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| bin | ||
| contrib | ||
| docs/man | ||
| docsite | ||
| examples | ||
| hacking | ||
| lib/ansible | ||
| packaging | ||
| samples | ||
| test | ||
| ticket_stubs | ||
| .coveragerc | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .travis.yml | ||
| CHANGELOG.md | ||
| CODING_GUIDELINES.md | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| ISSUE_TEMPLATE.md | ||
| Makefile | ||
| MANIFEST.in | ||
| README.md | ||
| RELEASES.txt | ||
| setup.py | ||
| test-requirements.txt | ||
| tox.ini | ||
| VERSION | ||
Ansible
Ansible is a radically simple IT automation system. It handles configuration-management, application deployment, cloud provisioning, ad-hoc task-execution, and multinode orchestration - including trivializing things like zero downtime rolling updates with load balancers.
Read the documentation and more at http://ansible.com/
Many users run straight from the development branch (it's generally fine to do so), but you might also wish to consume a release.
You can find instructions here for a variety of platforms. If you decide to go with the development branch, be sure to run git submodule update --init --recursive after doing a checkout.
If you want to download a tarball of a release, go to releases.ansible.com, though most users use yum (using the EPEL instructions linked above), apt (using the PPA instructions linked above), or pip install ansible.
Design Principles
- Have a dead simple setup process and a minimal learning curve
- Manage machines very quickly and in parallel
- Avoid custom-agents and additional open ports, be agentless by leveraging the existing SSH daemon
- Describe infrastructure in a language that is both machine and human friendly
- Focus on security and easy auditability/review/rewriting of content
- Manage new remote machines instantly, without bootstrapping any software
- Allow module development in any dynamic language, not just Python
- Be usable as non-root
- Be the easiest IT automation system to use, ever.
Get Involved
- Read Community Information for all kinds of ways to contribute to and interact with the project, including mailing list information and how to submit bug reports and code to Ansible.
- All code submissions are done through pull requests. Take care to make sure no merge commits are in the submission, and use
git rebasevsgit mergefor this reason. If submitting a large code change (other than modules), it's probably a good idea to join ansible-devel and talk about what you would like to do or add first and to avoid duplicate efforts. This not only helps everyone know what's going on, it also helps save time and effort if we decide some changes are needed. - Users list: ansible-project
- Development list: ansible-devel
- Announcement list: ansible-announce - read only
- irc.freenode.net: #ansible
Branch Info
- Releases are named after Van Halen songs.
- The devel branch corresponds to the release actively under development.
- As of 1.8, modules are kept in different repos, you'll want to follow core and extras
- Various release-X.Y branches exist for previous releases.
- We'd love to have your contributions, read Community Information for notes on how to get started.
Authors
Ansible was created by Michael DeHaan (michael.dehaan/gmail/com) and has contributions from over 1000 users (and growing). Thanks everyone!
Ansible is sponsored by Ansible, Inc