golem-add-config-rust

name	golem-add-config-rust
description	Adding typed configuration to a Rust Golem agent. Use when the user asks about agent config, Config<T>, ConfigSchema, #[agent_config], or passing configuration values to agents.

Adding Typed Configuration to an Agent (Rust)

Golem agents can receive typed configuration via Config<T> from golem_rust::agentic::Config. Configuration values are validated against a schema derived from your Rust struct.

1. Define a Config Struct

Derive ConfigSchema on a struct whose fields become config keys:

use golem_rust::ConfigSchema;

#[derive(ConfigSchema)]
pub struct MyAgentConfig {
    pub foo: i32,
    pub bar: String,
    #[config_schema(nested)]
    pub nested: NestedConfig,
}

#[derive(ConfigSchema)]
pub struct NestedConfig {
    pub a: bool,
    pub b: Vec<i32>,
}

• All fields must implement the ConfigSchema trait.
• Nested structs require the #[config_schema(nested)] annotation.
• Option<T> fields are optional and default to None if not provided.

2. Add Config<T> to the Agent Constructor

Annotate the config parameter with #[agent_config]:

use golem_rust::{agent_definition, agent_implementation};
use golem_rust::agentic::Config;

#[agent_definition]
pub trait MyAgent {
    fn new(name: String, #[agent_config] config: Config<MyAgentConfig>) -> Self;
    fn get_foo(&self) -> i32;
}

struct MyAgentImpl {
    config: Config<MyAgentConfig>,
}

#[agent_implementation]
impl MyAgent for MyAgentImpl {
    fn new(_name: String, #[agent_config] config: Config<MyAgentConfig>) -> Self {
        Self { config }
    }

    fn get_foo(&self) -> i32 {
        self.config.get().foo
    }
}

• The #[agent_config] annotation is required on the Config<T> parameter.
• Do not call Config::new() yourself in user code. Config<T> metadata is discovered from the #[agent_config] constructor parameter, and manual construction bypasses that registration path.
• Config is loaded lazily when .get() is called.

3. Set Config in golem.yaml

Provide default values under agents.<Name>.config (or components.<Name>.config):

agents:
  MyAgent:
    config:
      foo: 42
      bar: "hello"
      nested:
        a: true
        b: [1, 2, 3]

Config values in golem.yaml use camelCase keys — Rust snake_case fields are converted automatically.

4. Pass Config via CLI

Override or supply config when creating an agent instance:

golem agent new my-ns:my-component/my-agent-1 \
  --config foo=42 \
  --config bar=hello \
  --config nested.a=true \
  --config nested.b="[1, 2, 3]"

Dot-separated keys address nested struct fields.

5. RPC Config Overrides

When calling an agent via RPC, use the generated *ConfigRpc type and get_with_config to override config at call time:

let agent = MyAgentConfigRpc::get_with_config(name, config_overrides);

Config Cascade

Config values follow the same cascade as environment variables:

componentTemplates → components → agents → presets

• Values in golem.yaml act as defaults.
• Values passed via golem agent new --config or RPC get_with_config override those defaults.
• If the config includes Secret<T> fields, also use golem-add-secret-rust for secret-specific declaration and CLI guidance.