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docs: more marketing, add lots of drama bold.

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David Wilson 2018-02-18 12:22:01 +05:45
parent 5933723d70
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docs/ansible.rst
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@ -7,8 +7,8 @@ Ansible Extension
An experimental extension to `Ansible`_ is included that implements host
connections over Mitogen, replacing embedded shell invocations with pure-Python
equivalents invoked over SSH via highly efficient remote procedure calls. No
changes are required to the target hosts.
equivalents invoked via highly efficient remote procedure calls tunnelled over
SSH. No changes are required to the target hosts.
The extension isn't nearly in a generally dependable state yet, however it
already works well enough for testing against real-world playbooks. `Bug
@ -23,29 +23,30 @@ significant testing will prove the extension's soundness.
Overview
--------
You should expect a general speedup ranging from 1.5x to 5x depending on
network conditions, the specific modules executed, and time spent by the target
host already doing useful work. Mitogen cannot speed up a module once it is
You should **expect a speedup between 1.5x and 5x** depending on network
conditions, the specific modules executed, and time spent by the target host
already doing useful work. Mitogen cannot speed up a module once it is
executing, it can only ensure the module executes as quickly as possible.
* A single SSH connection is used for each target host, in addition to one sudo
invocation per distinct user account. Subsequent playbook steps always reuse
the same connection. This is much better than SSH multiplexing combined with
pipelining, as significant state can be maintained in RAM between steps, and
the system logs aren't filled with spam from repeat SSH and sudo invocations.
* **A single SSH connection is used for each target host**, in addition to one
sudo invocation per distinct user account. Subsequent playbook steps always
reuse the same connection. This is much better than SSH multiplexing combined
with pipelining, as significant state can be maintained in RAM between steps,
and the system logs aren't filled with spam from repeat SSH and sudo
invocations.
* A single Python interpreter is used per host and sudo account combination for
the duration of the run, avoiding the repeat cost of invoking multiple
* **A single Python interpreter is used** per host and sudo account combination
for the duration of the run, avoiding the repeat cost of invoking multiple
interpreters and recompiling imports, saving 300-1000 ms for every playbook
step.
* Remote interpreters reuse Mitogen's module import mechanism, caching uploaded
dependencies between steps at the host and user account level. As a
consequence, bandwidth usage is consistently an order of magnitude lower
consequence, **bandwidth usage is consistently an order of magnitude lower**
compared to SSH pipelining, and around 5x fewer frames are required to
traverse the wire for a run to complete successfully.
* No writes to the target host's filesystem occur, unless explicitly
* **No writes to the target host's filesystem occur**, unless explicitly
triggered by a playbook step. In all typical configurations, Ansible
repeatedly rewrites and extracts ZIP files to multiple temporary directories
on the target host. Since no temporary files are used, security issues
@ -104,7 +105,8 @@ Local VM connection
This demonstrates Mitogen vs. connection pipelining to a local VM, executing
the 100 simple repeated steps of ``run_hostname_100_times.yml`` from the
examples directory. Mitogen uses 43x less bandwidth and 4.25x less time.
examples directory. Mitogen requires **43x less bandwidth and 4.25x less
time**.
.. image:: images/ansible/run_hostname_100_times.png