feat(bot): automerge Dependabot PRs by dependency type

bot/kodiak/dependencies.py

@@ -1,6 +1,11 @@
+from __future__ import annotations
+
 import re
 from typing import List, Optional, Sequence, Tuple, TypeVar
 
+import pydantic
+import yaml
+from pydantic import Field
 from typing_extensions import Literal
 
 title_regex = re.compile(r"from (?P<old_version>\S+) to (?P<new_version>\S+)")
@@ -81,3 +86,43 @@ def dep_version_from_title(x: str) -> Optional[Literal["major", "minor", "patch"
         return None
     old_version, new_version = res
     return _compare_versions(old_version, new_version)
+
+
+class DependabotUpdate(pydantic.BaseModel):
+    dependency_name: str = Field(default=..., alias="dependency-name")
+    dependency_type: str = Field(default=..., alias="dependency-type")
+    update_type: str = Field(default=..., alias="update-type")
+
+    class Config:
+        allow_population_by_field_name = True
+
+
+_dependency_regex = re.compile(
+    r"^-{3}\n(?P<dependencies>(.|\n)*)^\.{3}\n", flags=re.MULTILINE
+)
+
+
+class _ParsedMetadata(pydantic.BaseModel):
+    updated_dependencies: List[DependabotUpdate] = Field(
+        default=..., alias="updated-dependencies"
+    )
+
+
+def parse_dependabot_metadata(commit_message: str) -> list[DependabotUpdate]:
+    """
+    Parse Dependabot update metadata from commit message.
+
+    Dependabot writes structured data about the dependency upgrades as YAML
+    within the commit message. We can parse this information.
+    """
+    match = _dependency_regex.search(commit_message)
+    if match is None:
+        return []
+    dependencies = match.groupdict().get("dependencies")
+    if dependencies is None:
+        return []
+    metadata_dict = yaml.safe_load(dependencies)
+    try:
+        return _ParsedMetadata.parse_obj(metadata_dict).updated_dependencies
+    except pydantic.ValidationError:
+        return []

bot/kodiak/test_dependencies.py

@@ -1,7 +1,9 @@
 from kodiak.dependencies import (
+    DependabotUpdate,
     _compare_versions,
     _extract_versions,
     dep_version_from_title,
+    parse_dependabot_metadata,
 )
 
 
@@ -51,3 +53,61 @@ def test_compare_versions() -> None:
             _compare_versions(old_version=old_version, new_version=new_version)
             == change
         )
+
+
+def test_parse_dependabot_metadata_success() -> None:
+    EXAMPLE_COMMIT_MESSAGE = """\
+Bump rollup from 2.50.1 to 2.50.6
+Bumps [rollup](https://github.com/rollup/rollup) from 2.50.1 to 2.50.6.
+- [Release notes](https://github.com/rollup/rollup/releases)
+- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
+- [Commits](rollup/[email protected])
+
+---
+updated-dependencies:
+- dependency-name: rollup
+  dependency-type: direct:development
+  update-type: version-update:semver-patch
+...
+
+Signed-off-by: dependabot[bot] <[email protected]>
+"""
+    assert parse_dependabot_metadata(EXAMPLE_COMMIT_MESSAGE) == [
+        DependabotUpdate(
+            dependency_name="rollup",
+            dependency_type="direct:development",
+            update_type="version-update:semver-patch",
+        )
+    ]
+
+
+def test_parse_dependabot_metadata_invalid_metadata() -> None:
+    EXAMPLE_COMMIT_MESSAGE = """\
+Bump rollup from 2.50.1 to 2.50.6
+Bumps [rollup](https://github.com/rollup/rollup) from 2.50.1 to 2.50.6.
+- [Release notes](https://github.com/rollup/rollup/releases)
+- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
+- [Commits](rollup/[email protected])
+
+---
+updated-dependencies:
+
+...
+
+Signed-off-by: dependabot[bot] <[email protected]>
+"""
+    assert parse_dependabot_metadata(EXAMPLE_COMMIT_MESSAGE) == []
+
+
+def test_parse_dependabot_metadata_missing() -> None:
+    EXAMPLE_COMMIT_MESSAGE = """\
+Bump rollup from 2.50.1 to 2.50.6
+Bumps [rollup](https://github.com/rollup/rollup) from 2.50.1 to 2.50.6.
+- [Release notes](https://github.com/rollup/rollup/releases)
+- [Changelog](https://github.com/rollup/rollup/blob/master/CHANGELOG.md)
+- [Commits](rollup/[email protected])
+
+
+Signed-off-by: dependabot[bot] <[email protected]>
+"""
+    assert parse_dependabot_metadata(EXAMPLE_COMMIT_MESSAGE) == []

bot/pyproject.toml

@@ -23,6 +23,7 @@ requests = "^2.22"
 rure = "^0.2.2"
 zstandard = "^0.13.0"
 httpx = "^0.18.1"
+pyyaml = "^5.4"
 
 [tool.poetry.scripts]
 kodiak = 'kodiak.cli:cli'