feat: improve config validation (#21)

* feat: improve config validation

* Update fastpubsub/config.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* test: add test for config validation

* Update fastpubsub/config.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update fastpubsub/config.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* test: fix test

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: allisson

fastpubsub/config.py

@@ -1,37 +1,63 @@
+from enum import StrEnum
+
+from pydantic import Field, field_validator, model_validator
+from pydantic.networks import IPvAnyAddress
 from pydantic_settings import BaseSettings, SettingsConfigDict
 
 
+class LogLevel(StrEnum):
+    debug = "debug"
+    info = "info"
+    warning = "warning"
+    error = "error"
+    critical = "critical"
+
+
 class Settings(BaseSettings):
     # database
     database_url: str
     database_echo: bool = False
-    database_pool_size: int = 5
-    database_max_overflow: int = 10
+    database_pool_size: int = Field(default=5, ge=1)
+    database_max_overflow: int = Field(default=10, ge=1)
     database_pool_pre_ping: bool = True
 
     # log
     log_formatter: str = (
         "asctime=%(asctime)s level=%(levelname)s pathname=%(pathname)s line=%(lineno)s message=%(message)s"
     )
-    log_level: str = "info"
+    log_level: LogLevel = LogLevel.info
 
     # subscription defaults
-    subscription_max_attempts: int = 5
-    subscription_backoff_min_seconds: int = 5
-    subscription_backoff_max_seconds: int = 300
+    subscription_max_attempts: int = Field(default=5, ge=1)
+    subscription_backoff_min_seconds: int = Field(default=5, ge=1)
+    subscription_backoff_max_seconds: int = Field(default=300, ge=1)
 
     # api
     api_debug: bool = False
-    api_host: str = "0.0.0.0"
-    api_port: int = 8000
-    api_num_workers: int = 1
+    api_host: IPvAnyAddress = Field(default="0.0.0.0")
+    api_port: int = Field(default=8000, ge=1)
+    api_num_workers: int = Field(default=1, ge=1)
 
     # workers
-    cleanup_acked_messages_older_than_seconds: int = 3600
-    cleanup_stuck_messages_lock_timeout_seconds: int = 60
+    cleanup_acked_messages_older_than_seconds: int = Field(default=3600, ge=1)
+    cleanup_stuck_messages_lock_timeout_seconds: int = Field(default=60, ge=1)
 
     # load .env
     model_config = SettingsConfigDict(env_file=".env", env_prefix="fastpubsub_")
 
+    @field_validator("database_url")
+    def validate_database_url_format(cls, v: str):
+        if not v.startswith("postgresql+psycopg://"):
+            raise ValueError("must start with 'postgresql+psycopg://'")
+        return v
+
+    @model_validator(mode="after")
+    def check_subscription_backoff_order(self) -> "Settings":
+        if self.subscription_backoff_max_seconds < self.subscription_backoff_min_seconds:
+            raise ValueError(
+                "subscription_backoff_max_seconds must be greater than or equal to subscription_backoff_min_seconds"
+            )
+        return self
+
 
 settings = Settings()

tests/test_config.py

@@ -0,0 +1,25 @@
+import pytest
+from pydantic import ValidationError
+
+from fastpubsub.config import Settings
+
+
+def test_settings_log_level():
+    with pytest.raises(ValidationError) as excinfo:
+        Settings(log_level="invalid")
+    assert "Input should be 'debug', 'info', 'warning', 'error' or 'critical'" in str(excinfo.value)
+
+
+def test_settings_database_url_format():
+    with pytest.raises(ValidationError) as excinfo:
+        Settings(database_url="postgresql://fastpubsub:fastpubsub@localhost:5432/fastpubsub")
+    assert "must start with 'postgresql+psycopg://'" in str(excinfo.value)
+
+
+def test_settings_subscription_backoff_order():
+    with pytest.raises(ValidationError) as excinfo:
+        Settings(subscription_backoff_min_seconds=5, subscription_backoff_max_seconds=4)
+    assert (
+        "subscription_backoff_max_seconds must be greater than or equal to subscription_backoff_min_seconds"
+        in str(excinfo.value)
+    )