Add etcd API v3 implementation

[MKLeb]

What does this PR do?

Adds an implementation for etcd API v3.

Notes: The libraries are completely incompatible out of the box, the names for similar queries are completely different (which, albeit, is expected). However, etcd v2 and v3 are fundamentally incompatible with each other. Their structures are different: v2 has a hierarchical construction, meaning it essentially reads like a file system; v3 has no directories, and thus no hierarchy (by design) - its keys are simply interpreted as strings.

This PR allows the use of both APIs, but there are certainly some improvements that could be made (not done here due to time constraints). Right now, we have a base superclass sitting underneath both API "adapters". However, the ideal way to do this would be to have the base construction (and all common code) factored out to the top level, using the adapter pattern underneath for all of the fundamental functionality and ensuring they return consistent output to the higher-level object. Basically, we want the adapters to only implement the CRUD functionality of etcd (and also the watch idea). Then, the single higher-level object would assume their results follow a consistent pattern and would be able to use common code refactored out to do the rest of the processing.

What issues does this PR fix or reference?

Fixes: #60325 and all sub-issues of it

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

[waynew]

I think this is probably mostly good, got a few questions, and also would like to poke at this

[Ch3LL]

@waynew can you re-review this PR please

[waynew]

I haven't checked it out and banged on it a bit, so it's entirely possible that I'm missing something else there, I did catch a couple of things from a visual inspection - otherwise this mostly looks 👍

[waynew]

Okay, leaving this mostly as a note to self - all identified code changes look like they've been resolved, I'm checking out now and gonna bang on things a bit 👍

[waynew]

okay, this took me a while to actually get setup and running on my new system, but I was able to give it a cursory glance and it's looking good. I want to spend a bit more time banging on it tomorrow before I 👍 it

[waynew]

Okay, finally getting to bang on this a bit and I think that something
is off, but I'm not entirely sure if it's my expectation or something else
😂

I'm starting with this docker container:

docker run --rm -it -e ALLOW_NONE_AUTHENTICATION=yes -e ETCD_ENABLE_V2=true --publish 2379:2379 --publish 2380:2380 bitnami/etcd:3

Then I have the following pillar data:

top

base:
  'kevin':
    - 61911_etcd

61911_etcd.sls

some_etcd_config:
  etcd.host: 127.0.0.1
  etcd.port: 2379
  etcd.require_v2: True

And the following states:

top

base:
  'kevin':
    - 61911/base

61911/base.sls

{% if salt['config.get']('some_etcd_config:etcd.require_v2') %}
make with a directory:
  etcd.directory:
    - name: some cool dirname/with some spaces/and a couple of things deep
    - profile: some_etcd_config
{%- endif %}

basic key set:
  etcd.set:
    - name: so_basic
    - value: vanilla ice
    - profile: some_etcd_config

set this key yo:
  etcd.set:
    - name: some/cool/key
    - value: more keys are keyful

some deleted watch:
  etcd.wait_rm:
    - name: del/taco
    - recurse: True

some set watch:
  etcd.wait_set:
    - name: buh/leeted
    - value: this should only set if watch'd

create a thing lulz:
  etcd.set:
    - name: del/taco/del/mar
    - value: goodbye
    - watch_in:
      - etcd: some deleted watch
      - etcd: some set watch

nope:
  etcd.rm:
    - name: del/taco
    - recurse: True

Now, when I have v2 enabled, I can run this with salt kevin state.apply and
all works. I can even run a couple of modules as well:

 salt kevin etcd.get so_basic
 salt kevin etcd.get some/cool/key
 salt kevin etcd.get "some cool dirname/with some spaces/and a couple of things deep"
 salt kevin etcd.ls /
 salt kevin etcd.ls /some/cool
 salt kevin etcd.ls /some/cool/key
 salt kevin etcd.tree /some
 salt kevin etcd.tree /some/cool

 salt kevin etcd.rm /some/cool/key
 salt kevin etcd.watch /some/cool/key timeout=5
 salt kevin etcd.watch /some/cool/key  # then re-run the states

 salt kevin etcd.watch /some/cool/key
 # then run this next one in a different window
 salt kevin etcd.update /some/cool/key awesome

And all of those work. Super swell!

However, when I swap to v3:

sed -i 's/True/False/' srv/pillar/61911_etcd.sls
docker run --rm -it -e ALLOW_NONE_AUTHENTICATION=yes -e ETCD_ENABLE_V2=false --publish 2379:2379 --publish 2380:2380 bitnami/etcd:3

Then running a state.apply fails with a bunch of etcd.EtcdException: Bad Response : 404 page not found. So there's definitely something going on here - not sure if it's just some misconfiguration on my part, but we probably shouldn't be showing that exception to the user anyway.

I can show you what I did tomorrow if that would be helpful 👍

[MKLeb]

re-run all