Merge pull request #8 from k2bd/feat/initial-cli

WIP CLI and tweaks

Author: k2bd

.gitignore

@@ -1,4 +1,5 @@
 venv/
+.vscode/
 
 # Byte-compiled / optimized / DLL files
 __pycache__/

README.md

@@ -34,12 +34,12 @@ Backends are loaded as plugins through Python's entry point system.
 This means that you can add a new backend by simply installing a package that provides the backend as a plugin.
 
 To create a new backend in your package, you need to subclass ``flux.MigrationBackend`` and implement its abstract methods.
-Then register that class under the ``flux.backends`` entry point group in your package setup.
+Then register that class under the ``flux.backend`` entry point group in your package setup.
 
 For example, in ``pyproject.toml``:
 
 ```toml
-[project.entry-points."flux.backends"]
+[project.entry-points."flux.backend"]
 cooldb = "my_package.my_module:CoolDbBackend"
 ```
 

poetry.lock

@@ -6,10 +6,18 @@ authors = ["Kevin Duff <[email protected]>"]
 readme = "README.md"
 packages = [{include = "flux", from = "src"}]
 
+[tool.poetry.scripts]
+flux = "flux.cli:app"
+
+[tool.poetry.plugins."flux.backend"]
+postgres = "flux.builtins.postgres:FluxPostgresBackend"
+
 [tool.poetry.dependencies]
 python = "^3.10"
 typer = "^0.12.3"
 toml = "^0.10.2"
+aiopg = { version = "^1.4.0", optional = true }
+databases = { version = "^0.9.0", optional = true }
 
 [tool.poetry.group.dev.dependencies]
 black = "^24.4.2"
@@ -20,8 +28,10 @@ poethepoet = "^0.26.1"
 pytest = "^8.2.0"
 pytest-cov = "^5.0.0"
 pytest-asyncio = "^0.23.6"
-aiopg = "^1.4.0"
-databases = "^0.9.0"
+
+[tool.poetry.extras]
+postgres = ["aiopg", "databases"]
+
 
 [tool.isort]
 profile = "black"

pyproject.toml

@@ -0,0 +1,4 @@
+from .cli import app
+
+if __name__ == "__main__":
+    app()

src/flux/__main__.py

@@ -9,7 +9,7 @@
 class MigrationBackend(ABC):
 
     @classmethod
-    def from_config(cls, config: FluxConfig) -> "MigrationBackend":
+    def from_config(cls, config: FluxConfig, connection_uri: str) -> "MigrationBackend":
         """
         Create a MigrationBackend from a configuration
 
@@ -28,29 +28,27 @@ async def connection(self):
 
     @asynccontextmanager
     @abstractmethod
-    async def transaction(self):
+    async def migration_lock(self):
         """
-        Create a transaction that lasts as long as the context manager is
-        active.
-
-        The transaction is committed when the context manager exits.
+        Create a lock that prevents other migration processes from running
+        concurrently.
 
-        If an exception is raised inside the context manager, the transaction
-        is rolled back.
+        This lock should last as long as the context manager and should operate
+        will be within ``connection`` but outside of ``transaction``.
         """
         yield
 
     @asynccontextmanager
     @abstractmethod
-    async def migration_lock(self):
+    async def transaction(self):
         """
-        Create a lock that prevents other migration processes from running
-        concurrently.
+        Create a transaction that lasts as long as the context manager is
+        active.
+
+        The transaction is committed when the context manager exits.
 
-        The acceptable unlock conditions are:
-        - The context manager exits
-        - The transaction ends
-        - The connection ends
+        If an exception is raised inside the context manager, the transaction
+        is rolled back.
         """
         yield
 

src/flux/backend/base.py

@@ -2,8 +2,13 @@
 from contextlib import asynccontextmanager
 from dataclasses import dataclass, field
 
-from databases import Database
-from databases.core import Connection, Transaction
+try:
+    from databases import Database
+    from databases.core import Connection, Transaction
+except ImportError as e:
+    raise ImportError(
+        "Please install the postgres dependency group of flux-migrations to use the builtin Postgres backend. For example: pip install 'flux-migrations[postgres]'"  # noqa: E501
+    ) from e
 
 from flux.backend.applied_migration import AppliedMigration
 from flux.backend.base import MigrationBackend
@@ -18,7 +23,7 @@
 
 
 @dataclass
-class ExamplePostgresBackend(MigrationBackend):
+class FluxPostgresBackend(MigrationBackend):
     database_url: str
     migrations_table: str = DEFAULT_MIGRATIONS_TABLE
     migrations_schema: str = DEFAULT_MIGRATIONS_SCHEMA
@@ -33,15 +38,14 @@ def qualified_migrations_table(self) -> str:
         return f"{self.migrations_schema}.{self.migrations_table}"
 
     @classmethod
-    def from_config(cls, config: FluxConfig) -> "ExamplePostgresBackend":
+    def from_config(
+        cls, config: FluxConfig, connection_uri: str
+    ) -> "FluxPostgresBackend":
         """
         Create a MigrationBackend from a configuration
 
         This config appears in the config.toml file in the "backend" section.
         """
-        database_url = config.backend_config.get("database_url")
-        if not database_url:
-            raise ValueError("No database_url provided.")
         migrations_table = config.backend_config.get(
             "migrations_table", DEFAULT_MIGRATIONS_TABLE
         )
@@ -54,7 +58,7 @@ def from_config(cls, config: FluxConfig) -> "ExamplePostgresBackend":
             "migrations_schema", DEFAULT_MIGRATIONS_SCHEMA
         )
         return cls(
-            database_url=database_url,
+            database_url=connection_uri,
             migrations_table=migrations_table,
             migrations_lock_id=migrations_lock_id,
             migrations_schema=migrations_schema,