Empty UTOPIA_MIGRATION_URL env breaks startup: Some("") defeats the database_url fallback

[realestate-aistudio]

Problem

Fresh deploy via docker compose --profile app up -d (image ghcr.io/deeplethe/utopia:0.1.0-rc5) exits immediately with:

Error: error with configuration: relative URL without a base

Root cause

docker-compose.yml sets:

UTOPIA_MIGRATION_URL: ${UTOPIA_MIGRATION_URL:-}

When the variable is unset, Compose passes an empty string into the container. Figment's Env::prefixed("UTOPIA_") deserializes that as Some("") instead of None, so AppConfig::migration_url() (self.migration_url.as_deref().unwrap_or(&self.database_url)) returns "" and the fallback to database_url never fires. sqlx then fails parsing the empty URL.

Verified: setting UTOPIA_MIGRATION_URL explicitly to the same value as UTOPIA_DATABASE_URL makes the app start normally (HTTP 200, migrations run).

Suggested fix

Treat empty as unset, e.g. in migration_url():

self.migration_url.as_deref().filter(|s| !s.trim().is_empty()).unwrap_or(&self.database_url)

(same pattern already used for secret_key empty-string handling in main.rs), or drop the always-empty env line from docker-compose.yml.

[WaylandYang]

Thank you — this is an unusually good report. You found the root cause, the fix, and verified it by setting the variable explicitly, which is what made the empty-string path obvious.

Fixed in #344, one layer up from your suggestion: blank UTOPIA_* variables are now treated as unset when config is loaded, so every field falls back to its default instead of just migration_url. The same empty string was quietly replacing data_dir and web_dist as well, and turning UTOPIA_COOKIE_SECURE= into a startup type error that never mentions the variable.

The compose line stays, though — .env feeds interpolation rather than the container, so removing it would break the deployments that do use a separate migration role.

Thanks again for taking the time to write it up so precisely.