config: allow to override pulse parameter via env

Author: shtrom

README.md

@@ -42,6 +42,23 @@ $ echo '{"payload": {"type": "push", "repo_url": "bla", "branches": [ "main" ],
 The RabbitMQ management interface is available at http://localhost:15672/, and
 the login and password are `guest` (don't do this at home, or in prod).
 
+## Configuration
+
+An example configuration file can be found in `config.toml.example`. A different
+configuration file can be specified with the `--config` (`-c`) option.
+
+In addition, Pulse parameters can be overridden via the following environment
+variables:
+
+- PULSE_EXCHANGE
+- PULSE_HOST
+- PULSE_PASSWORD
+- PULSE_PORT (needs to be an integer)
+- PULSE_QUEUE
+- PULSE_ROUTING_KEY
+- PULSE_SSL (needs to be an empty string to be False, otherwise True)
+- PULSE_USERID
+
 ## Build and test
 
 Format and test/lint code:

git_hg_sync/__main__.py

@@ -53,6 +53,8 @@ def start_app(
 
     queue = get_queue(pulse_config)
 
+    logger.info(f"Reading messages from {connection}/{queue.name} ...")
+
     synchronizers = {
         tracked_repo.url: RepoSynchronizer(
             config.clones.directory / tracked_repo.name, tracked_repo.url

git_hg_sync/config.py

@@ -1,3 +1,4 @@
+import os
 import pathlib
 from typing import Self
 
@@ -43,6 +44,12 @@ class Config(pydantic.BaseModel):
     def verify_all_mappings_reference_tracked_repositories(
         self,
     ) -> Self:
+        # Allow to override Pulse parameters via environment.
+        for config in self.pulse.model_fields:
+            env_var = f"PULSE_{config}".upper()
+            if value := os.getenv(env_var):
+                setattr(self.pulse, config, value)
+
         tracked_urls = [tracked_repo.url for tracked_repo in self.tracked_repositories]
         for mapping in self.branch_mappings:
             if mapping.source_url not in tracked_urls:

tests/test_config.py

@@ -8,4 +8,28 @@
 def test_load_config() -> None:
     config = Config.from_file(HERE / "data" / "config.toml")
     assert not config.pulse.ssl
+    assert config.pulse.host == "pulse"
     assert config.branch_mappings[0].destination_branch == "default"
+
+
+def test_load_config_env_override(monkeypatch) -> None:
+    pulse_env = {
+        "exchange": "overridden exchange",
+        "host": "overridden host",
+        "password": "overridden password",
+        "port": "overridden port",
+        "queue": "overridden queue",
+        "routing_key": "overridden routing_key",
+        "ssl": "false",
+        "userid": "overridden userid",
+    }
+
+    for key in pulse_env:  # noqa: PLC0206 We want the key only here...
+        monkeypatch.setenv(f"PULSE_{key}".upper(), pulse_env[key])
+
+    config = Config.from_file(HERE / "data" / "config.toml")
+
+    for key in pulse_env:  # noqa: PLC0206
+        assert (
+            getattr(config.pulse, key) == pulse_env[key]
+        ), f"Pulse configuration not overridden for {key}"