Using default compatibility tag can cause DNS name conflicts

[mr-cal]

Bug Description

The Base class can accept an optional compatibility_tag. If a compatibility_tag is not provided and craft-providers launches LXD instances for 2 different projects, LXD will fail because the two base instances have identical names.

Source: canonical/craft-application#139

Quick fix

craft-providers should log a warning if a compatibility tag is not provided:

Warning: Compatibilty tag not provided. This may cause a name collision when launching LXD instances.

Long term fix

As part of a major release, the compatibility_tag should be easier to use. It should be required and prepended to the base's compatibility tag.

This simply the usage from:

from craft_providers import bases

base = bases.BuilddBase(compatibility_tag=f"testcraft-{bases.BuildBase.compatibility_tag}", ...)

to:

from craft_providers import bases

base = bases.BuilddBase(compatibility_tag="testcraft", ...)

To Reproduce

#! /usr/bin/env python3

from pathlib import Path
import logging

from craft_providers import bases, lxd

logging.basicConfig(level="DEBUG")

provider_a = lxd.LXDProvider(lxd_project="project1")

provider_a.ensure_provider_is_available()

alias = bases.BuilddBaseAlias.JAMMY
my_base = bases.BuilddBase(alias=alias)

with provider_a.launched_environment(
    project_name = "hello-world",
    project_path = Path().absolute(),
    base_configuration=my_base,
    build_base=alias.value,
    instance_name = "test-instance",
) as instance:
    instance.execute_run(["ls"])


provider_b = lxd.LXDProvider(lxd_project="project2")

provider_b.ensure_provider_is_available()

alias = bases.BuilddBaseAlias.JAMMY
my_base = bases.BuilddBase(alias=alias)

with provider_b.launched_environment(
    project_name = "hello-world",
    project_path = Path().absolute(),
    base_configuration=my_base,
    build_base=alias.value,
    instance_name = "test-instance",
) as instance:
    instance.execute_run(["ls"])

part yaml

No response

Relevant log output

* Command standard error output: b'Error: Failed start validation for device "eth0": Instance DNS name "base-instance-buildd-base-v3-craft-comub-523148486bd0c6cc722c" already used on network\nTry `lxc info --show-log local:base-instance-buildd-base-v3-craft-comub-523148486bd0c6cc722c` for more info\n'