Prevent FIREWHALE_RELOAD_INTERVAL from being negative

celsiusnarhwal · Jul 17, 2024 · 92a20b7 · 92a20b7
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diff --git a/README.md b/README.md
@@ -176,13 +176,13 @@ Firewhale supports all versions of the Docker API that are also supported by Doc
 
 Some aspects of Firewhale can be configured via environment variables.
 
-| **Environment Variable**     | **Description**                                                                                                                                                                                                                                                                                               | **Default** |
-|------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
-| `FIREWHALE_PORT`             | The port on which Firewhale should listen. Firewhale will be accessible at `http://firewhale:${FIREWHALE_PORT}`. Must be an integer between 0 and 65535 and different than `FIREWHALE_CADDY_API_PORT`.                                                                                                        | 2375        |
-| `FIREWHALE_CADDY_API_PORT`   | The port on which Caddy's [admin API](https://caddyserver.com/docs/api) should listen. The Caddy API will be accessible at `localhost:${FIREWHALE_CADDY_API_PORT}` within Firewhale's container. Must be an integer between 0 and 65535 and different than `FIREWHALE_PORT`.                                  | 2019        |
-| `FIREWHALE_HTTP_STATUS_CODE` | The [HTTP status code](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status) Firewhale should respond with when it receives a request it has not been configured to allow. Must be an integer between 100 and 599.                                                                                        | 403         |
-| `FIREWHALE_RELOAD_INTERVAL`  | The interval at which Firewhale will query Docker for any changes to your services' labels and update its rules accordingly. Must be in the format of a [Go duration string](https://pkg.go.dev/time#ParseDuration), except you can also use `d` for day, `w` for week, `mm` for month, and `y` for year.[^1] | `30s`       |
-| `FIREWHALE_LABEL_PREFIX`     | The prefix with which Firewhale labels should begin. Socket access will be configurable using the `${LABEL_PREFIX}.read` and `${LABEL_PREFIX}.write` labels.                                                                                                                                                  | `firewhale` |
+| **Environment Variable**     | **Description**                                                                                                                                                                                                                                                                                                                                                | **Default** |
+|------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| `FIREWHALE_PORT`             | The port on which Firewhale should listen. Firewhale will be accessible at `http://firewhale:${FIREWHALE_PORT}`. Must be an integer between 0 and 65535 and different than `FIREWHALE_CADDY_API_PORT`.                                                                                                                                                         | 2375        |
+| `FIREWHALE_CADDY_API_PORT`   | The port on which Caddy's [admin API](https://caddyserver.com/docs/api) should listen. The Caddy API will be accessible at `localhost:${FIREWHALE_CADDY_API_PORT}` within Firewhale's container. Must be an integer between 0 and 65535 and different than `FIREWHALE_PORT`.                                                                                   | 2019        |
+| `FIREWHALE_HTTP_STATUS_CODE` | The [HTTP status code](https://developer.mozilla.org/en-US/docs/Web/HTTP/Status) Firewhale should respond with when it receives a request it has not been configured to allow. Must be an integer between 100 and 599.                                                                                                                                         | 403         |
+| `FIREWHALE_RELOAD_INTERVAL`  | The interval at which Firewhale will query Docker for any changes to your services' labels and update its rules accordingly. Must be in the format of a [Go duration string](https://pkg.go.dev/time#ParseDuration) (except you can also use `d` for day, `w` for week, `mm` for month, and `y` for year[^1]) that represents a non-negative value in seconds. | `30s`       |
+| `FIREWHALE_LABEL_PREFIX`     | The prefix with which Firewhale labels should begin. Socket access will be configurable using the `${LABEL_PREFIX}.read` and `${LABEL_PREFIX}.write` labels.                                                                                                                                                                                                   | `firewhale` |
 
 ## Considerations
 

diff --git a/firewhale/settings.py b/firewhale/settings.py
@@ -28,13 +28,16 @@ def validate_ports(self):
     @field_validator("reload_interval")
     def validate_reload_interval(cls, v):
         try:
-            durationpy.from_str(v)
+            interval = durationpy.from_str(v)
         except ValueError:
             raise ValueError(
                 "FIREWHALE_RELOAD_INTERVAL must be in the format of a Go duration string. "
                 "https://pkg.go.dev/time#ParseDuration"
             ) from None
 
+        if interval.total_seconds() < 0:
+            raise ValueError(f"FIREWHALE_RELOAD_INTERVAL may not be negative ({v} = {interval.total_seconds()}).")
+
         return v
 
     @property