plain.dev

A single command that runs everything you need for local development.

Plain dev command example

The plain.dev package can be installed from PyPI, and does not need to be added to INSTALLED_PACKAGES.

plain dev
plain dev services
plain pre-commit
plain contrib
VS Code debugging

`plain dev`

The plain dev command does several things:

Sets PLAIN_CSRF_TRUSTED_ORIGINS to localhost by default
Runs plain preflight to check for any issues
Executes any pending model migrations
Starts gunicorn with --reload
Runs plain tailwind compile --watch, if plain.tailwind is installed
Any custom process defined in pyproject.toml at tool.plain.dev.run
Necessary services (ex. Postgres) defined in pyproject.toml at tool.plain.dev.services

Services

Use services to define databases or other processes that your app needs to be functional. The services will be started automatically in plain dev, but also in plain pre-commit (so preflight and tests have a database).

Ultimately, how you run your development database is up to you. But a recommended starting point is to use Docker:

# pyproject.toml
[tool.plain.dev.services]
postgres = {cmd = "docker run --name app-postgres --rm -p 54321:5432 -v $(pwd)/.plain/dev/pgdata:/var/lib/postgresql/data -e POSTGRES_PASSWORD=postgres postgres:15 postgres"}

Custom processes

Unlike services, custom processes are only run during plain dev. This is a good place to run something like ngrok or a Plain worker, which you might need to use your local site, but don't need running for executing tests, for example.

# pyproject.toml
[tool.plain.dev.run]
ngrok = {command = "ngrok http $PORT"}

`plain dev services`

Starts your services by themselves.

`plain pre-commit`

A built-in pre-commit hook that can be installed with plain pre-commit --install.

Runs:

Custom commands defined in pyproject.toml at tool.plain.pre-commit.run
plain code check, if plain.code is installed
poetry check --lock, if using Poetry
plain preflight --database default
plain migrate --check
plain makemigrations --dry-run --check
plain compile
plain test

VS Code debugging

Debug Plain with VS Code

Since plain dev runs multiple processes at once, the regular pdb debuggers don't quite work.

Instead, we include microsoft/debugpy and an attach function to make it even easier to use VS Code's debugger.

First, import and run the debug.attach() function:

class HomeView(TemplateView):
    template_name = "home.html"

    def get_template_context(self):
        context = super().get_template_context()

        # Make sure the debugger is attached (will need to be if runserver reloads)
        from plain.dev import debug; debug.attach()

        # Add a breakpoint (or use the gutter in VS Code to add one)
        breakpoint()

        return context

When you load the page, you'll see "Waiting for debugger to attach...".

You can then run the VS Code debugger and attach to an existing Python process, at localhost:5678.

Source

plain-dev

plain

dev

services.py

 1import os
 2import subprocess
 3import time
 4from importlib.util import find_spec
 5from pathlib import Path
 6
 7import click
 8import tomllib
 9
10from plain.runtime import APP_PATH
11
12from .pid import Pid
13from .poncho.manager import Manager as PonchoManager
14from .utils import has_pyproject_toml
15
16
17class Services:
18    @staticmethod
19    def get_services(root):
20        if not has_pyproject_toml(root):
21            return {}
22
23        with open(Path(root, "pyproject.toml"), "rb") as f:
24            pyproject = tomllib.load(f)
25
26        return (
27            pyproject.get("tool", {})
28            .get("plain", {})
29            .get("dev", {})
30            .get("services", {})
31        )
32
33    def __init__(self):
34        self.poncho = PonchoManager()
35
36    def run(self):
37        services = self.get_services(APP_PATH.parent)
38        for name, data in services.items():
39            env = {
40                **os.environ,
41                "PYTHONUNBUFFERED": "true",
42                **data.get("env", {}),
43            }
44            self.poncho.add_process(name, data["cmd"], env=env)
45
46        self.poncho.loop()
47
48    def __enter__(self):
49        if not self.get_services(APP_PATH.parent):
50            # No-op if no services are defined
51            return
52
53        if Pid().exists():
54            click.secho("Services already running in `plain dev` command", fg="yellow")
55            return
56
57        print("Starting `plain dev services`")
58        self._subprocess = subprocess.Popen(
59            ["plain", "dev", "services"], cwd=APP_PATH.parent
60        )
61
62        if find_spec("plain.models"):
63            time.sleep(0.5)  # Give it a chance to hit on the first try
64            subprocess.check_call(["plain", "models", "db-wait"], env=os.environ)
65        else:
66            # A bit of a hack to wait for the services to start
67            time.sleep(3)
68
69    def __exit__(self, *args):
70        if not hasattr(self, "_subprocess"):
71            return
72
73        self._subprocess.terminate()
74
75        # Flush the buffer so the output doesn't spill over
76        self._subprocess.communicate()