Adding Secrets to a MoonBit Agent

Overview

Secrets are sensitive configuration values (API keys, passwords, tokens) stored per-environment and accessed at runtime via @config.Secret[T] from the Golem MoonBit SDK. Unlike regular config fields, the config value carries an opaque secret handle and plaintext is revealed only when agent code calls .get!(). Secrets are not stored in golem.yaml (which is checked into source control). They are managed via the CLI or through secretDefaults for local development.

Declaring Secrets in a Config Struct

Use @config.Secret[T] for secret fields inside a #derive.config struct:

#derive.config
pub(all) struct MyAgentConfig {
  name : String
  api_key : @config.Secret[String]
  db : DbConfig
}

#derive.config
pub(all) struct DbConfig {
  host : String
  port : UInt
  password : @config.Secret[String]
}

Wiring Secrets Into The Agent Constructor

Secrets use the same typed config mechanism as regular agent config. Receive the config via @config.Config[T] in the constructor:

#derive.config
pub(all) struct MyAgentConfig {
  api_key : @config.Secret[String]
}

#derive.agent
struct MyAgent {
  config : @config.Config[MyAgentConfig]
}

fn MyAgent::new(config : @config.Config[MyAgentConfig]) -> MyAgent {
  { config, }
}

pub fn MyAgent::connect(self : Self) -> String {
  let api_key = self.config.value.api_key.get!()
  "using \{api_key}"
}

• The @config.Config[T] parameter in the constructor is detected automatically by the SDK tooling to embed config and secret declarations into the component metadata.

Reading Secrets at Runtime

Call .get!() on a Secret[T] to explicitly reveal the value. Secrets are lazily loaded, so a fresh .get!() call can observe updated values after the update is visible:

pub fn MyAgent::connect(self : Self) -> String {
  let config = self.config.value
  let api_key = config.api_key.get!()
  let db_password = config.db.password.get!()
  "Connecting to \{config.db.host}:\{config.db.port} with key \{api_key}"
}

Managing Secrets via CLI

Secrets are environment-scoped — each deployment environment has its own set of secret values.

# Create secrets in the current environment
golem secret create apiKey --secret-type String --secret-value "sk-abc123"
golem secret create db.password --secret-type String --secret-value "s3cret"

# List all secrets
golem secret list

# Update a secret value
golem secret update-value apiKey --secret-value "new-value"

# Delete a secret
golem secret delete apiKey

Note: For update-value and delete, you can also use --id <uuid> instead of the positional path.

Secret Defaults in golem.yaml

For local development convenience, set defaults under secretDefaults. These are not used in production environments:

secretDefaults:
  local:
    apiKey: "dev-key-123"
    db:
      password: "dev-password"

Key Points

• Secrets use the same @config.Config[T] constructor injection mechanism as regular typed config
• If the agent also needs non-secret typed config guidance, use golem-add-config-moonbit alongside this skill
• Secret paths are normalized to camelCase by the platform — MoonBit snake_case field names like api_key become apiKey in the CLI and manifest (e.g., golem secret create apiKey ...)
• The --secret-type argument accepts type names using the project's language syntax (e.g., String, UInt, Bool) or JSON-encoded analysed types as a fallback
• Secrets are stored per-environment, not per-agent-instance
• Missing required secrets cause agent creation/deployment to fail
• Secrets are revealed on .get!(), and each reveal pins the resolved secret revision for deterministic retries and replay
• Fresh .get!() calls can observe runtime updates without restarting the agent
• .get!() raises @common.AgentError — use MoonBit's error handling (! or try) accordingly
• Never edit generated files — golem_reexports.mbt, golem_agents.mbt, and golem_derive.mbt are auto-generated by golem build