modifying-service-configs - SKILL.md Agent Skill

name: modifying-service-configs description: "Modifying service configuration types or defaults. Use when changing config structs, adding config fields, or updating default values for any Golem service."

Modifying Service Configs

Golem services use a configuration system built on Figment via a custom ConfigLoader. Configuration defaults are serialized to TOML and env-var reference files that are checked into the repository and validated in CI.

How Configuration Works

Each service has a configuration struct that implements:

Default — provides default values
Serialize / Deserialize — for TOML and env-var serialization
SafeDisplay — for logging without exposing secrets

Services load config by merging (in order): defaults → TOML file → environment variables.

Service Config Locations

Service	Config struct	File
Worker Executor	`GolemConfig`	`golem-worker-executor/src/services/golem_config.rs`
Worker Service	`WorkerServiceConfig`	`golem-worker-service/src/config.rs`
Registry Service	`RegistryServiceConfig`	`golem-registry-service/src/config.rs`
Shard Manager	`ShardManagerConfig`	`golem-shard-manager/src/shard_manager_config.rs`
Compilation Service	`ServerConfig`	`golem-component-compilation-service/src/config.rs`

The all-in-one golem binary has its own merged config that combines multiple service configs.

Modifying a Config

Step 1: Edit the config struct

Add, remove, or modify fields in the appropriate config struct. Update the Default implementation if default values change.

Step 2: Regenerate config files

cargo make generate-configs

This builds the service binaries and runs them with --dump-config-default-toml and --dump-config-default-env-var flags, producing reference files that reflect the current Default implementation.

Step 3: Verify

cargo make build

Step 4: Check configs match

CI runs cargo make check-configs which regenerates configs and diffs them against committed files. If this fails, you forgot to run cargo make generate-configs.

Adding a New Config Field

Add the field to the config struct with a serde attribute if needed
Set its default value in the Default impl
Run cargo make generate-configs to update reference files
If the field requires a new environment variable, the env-var mapping is derived automatically from the field path

Removing a Config Field

Remove the field from the struct and Default impl
Run cargo make generate-configs
Check for any code that references the removed field

Nested Config Types

Many config structs compose sub-configs (e.g., GolemConfig contains WorkersServiceConfig, BlobStoreServiceConfig, etc.). When modifying a sub-config type that's shared across services, regenerate configs for all affected services — cargo make generate-configs handles this automatically.

Checklist

Config struct modified with appropriate serde attributes
Default implementation updated
cargo make generate-configs run
Generated TOML and env-var files committed
cargo make build succeeds
cargo make check-configs passes (CI validation)
cargo make fix run before PR