Also fixes tox env for py38-consul tests
Update zuul script to use consul 1.7.4 (2020) vs 0.6.3 (2016)

Adds ACL tokens to all session management calls.

Change-Id: Iaddf21f14c434129541e7c9ec7134e0661f7be52

The __future__ module [1] was used in this context to ensure compatibility
between python 2 and python 3.

We previously dropped the support of python 2.7 [2] and now we only support
python 3 so we don't need to continue to use this module and the imports
listed below.

Imports commonly used and their related PEPs:
- `division` is related to PEP 238 [3]
- `print_function` is related to PEP 3105 [4]
- `unicode_literals` is related to PEP 3112 [5]
- `with_statement` is related to PEP 343 [6]
- `absolute_import` is related to PEP 328 [7]

[1] https://docs.python.org/3/library/__future__.html
[2] https://governance.openstack.org/tc/goals/selected/ussuri/drop-py27.html
[3] https://www.python.org/dev/peps/pep-0238
[4] https://www.python.org/dev/peps/pep-3105
[5] https://www.python.org/dev/peps/pep-3112
[6] https://www.python.org/dev/peps/pep-0343
[7] https://www.python.org/dev/peps/pep-0328

Change-Id: I95809cf4035a6bc487b24f9e91aaa715921ad842

When running Consul with ACLs enabled, the best practice is to
default deny all. In order to support applying a policy to the
tooz coordination KV store path, passing through an ACL is needed.

Closes-Bug: #1752205
Change-Id: I98fc96468b21368ce66365e3fc38c495b1f2918a

Change-Id: Ie22e944e270dfd37988724f76823f6fd38d19b21
Closes-Bug: #1752225

If you're not intimately familiar with RFC 1808 it can be a bit tricky to
write tooz connection strings. In addition, some drivers do not document the
options that they recognize in a connection string. This can force a user to
read the driver code in order to figure out how to configure tooz to use said
driver, which should not be the case.

This change more explicitly documents the format of the connection string,
including which parts of an RFC 1808 URI it recognizes, and the options that
can be passed. It also clarifies which parts of the connection string are
optional (possibly because they have defaults) and which must always be
included.

Note that not every possible configuration is documented. For example, the
postgres driver supports multiple methods of configuring the connection host
and port. For consistency, I only documented the one that matches the other
drivers. This should be sufficient to allow a user to write a working
connection string.

This change also wires the etcd3 and etcd3gw drivers into the doc index since
they were missing before.

Change-Id: I66e54433115f27fb54badc2173f8f6044c49aacb

Change-Id: I364b0ca5a6361a818a084bbcb83c9e7855cb3583

Change-Id: I98d7790fdc74a86a067fdbc0665fbd1abd7de77c

There was a typo in pifpaf call where the prefix for the variable name should
be prefixed by using the -e option and not -g.

Change-Id: I5a97e0a0ffc5ba675914bb0881520ddc9693fa1b

Currently each driver in tooz only support exclusive lock, it is
inefficient in some scenarios which only need shared lock.

This patch adds shared lock in file driver.

Change-Id: I55a528977e74b27da736f421d2eee28c7aae8aa3
Implements: blueprint support-shared-lock
Co-Authored-By: Julien Danjou <julien@danjou.info>

Any coordinator that implements (and they all should) group membership
needs a member_id field and copy it to self. Just do that by default for
all driver at __init__ time.

Change-Id: I66d82815afd4c6e9354212e5ab3fba17931c1bbc