Raise error on pip install dbt

[jtcohen6]

resolves #4100

• Raise an explicit error on pip install dbt
• Include richer metadata for dbt-core (in core/setup.py)

As of v1.0.0, `pip install dbt` is no longer supported.
  Instead, please use either:
    - `pip install dbt-core`, for core functionality
    - `pip install dbt-<adapter>`, to use dbt with your database, platform, or query engine
  See full list: https://docs.getdbt.com/docs/available-adapters

What's good

• Simple, clear, to the point
• No need for circular-ish dependencies (dbt-core → dbt-snowflake → dbt)
• Rips off the band-aid

What's bad

• This will break production pipelines that depend on pip install dbt
• This will break any python programs that have unbounded dependencies on dbt (rather than dbt-core)
• Cloning this repo + pip install . will not work, it needs to be cloning this repo + pip install -r requirements.txt (what dbt Cloud HEAD does) or pip install -r editable-requirements.txt (what we tell contributors to do)
• pip install git+https://github.com/dbt-labs/dbt-core will not work, it needs to be git+https://github.com/dbt-labs/dbt.git#egg=dbt-core&subdirectory=core (we can document this)

Uncertainties

• Will PyPi metadata still work? Will we be able to push and recognize this package as dbt?
• I wasn't able to get clear deprecation warnings working, and I wasn't able to find very clear resources online, but that's not to say that it isn't possible

Checklist

• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have updated the CHANGELOG.md and added information about my change

[jtcohen6]

I'm pretty sure this change will break PyPi metadata, so we might need to hand-roll that instead. Maybe we could test by pushing a dbt==1.00b1 prerelease after merging?

[leahwicz]

@jtcohen6 we have the test PyPi account we can use to try this out

[jtcohen6]

@leahwicz ah really good thought!! I forgot all about that

[kwigley]

@jtcohen6 tested locally and ended up pushing a small change to setup.py (cf3089d).

In order for this to work as expected, we should only build a source distribution when publishing to PyPI (python setup.py sdist). Distributing a wheel file won't run the code to warn the user.

[jtcohen6]

@kwigley Thanks for the magic one-liner there. I did some reorg enabled by that, including some edits to build-dist. Let me know if I'm being too clever/fancy there. Yes, I was. Opting to keep it simple + duplicative.

Let's try building dbt=1.0.0-b1 and pushing to Test PyPi, before we go live-live with this

[jtcohen6]

Now that I've reenabled the source-only distribution of dbt, it looks like I need to update some more pieces of the main.py CI test to avoid trying to install it, since it will raise an error :)

[joellabes]

I'm not convinced that

• pip install dbt-core, for core functionality

fulfils the "clear" component of

Simple, clear, to the point.

Why? Because I don't understand it 😅 . I'm reading it as "to access the critical functionality of dbt", but I think you want me to read it as "access the functionality of the dbt core project". Is that right?

Who is the target market for dbt-core on its own? I assume it's people building things that integrate with the dbt ecosystem, as opposed to analytics engineers building a dbt project? As a generic end user, "connect to a database" is definitely "core critical functionality" so I wouldn't necessarily be warned off of trying to install it.

Noodling on some alternatives:

• pip install dbt-core, for core functionality without connecting to a database
• pip install dbt-core, for developers of dbt integrations

[jtcohen6]

pip install dbt-core, for developers of dbt integrations

I like this! I'll also move it so that it's after pip install dbt-<adapter>, which we expect to be relevant in 95%+ of cases.

Just opened: #4229