Config

Configuration management for Telo applications: declare where values come from, which keys are accessible, and how to expose them to other modules.

Why use this

• Single source of truth — a Config.EnvironmentVariableStore declares the full key set; only declared keys are readable.
• Variables and secrets split — Config.Variables for plain values, Config.Secrets for sensitive ones (redacted in logs and errors).
• CEL composition — compose multiple keys into a single value with ${{ ... }} expressions inside any map value.
• Fail-fast on missing keys — missing required values are a hard boot-time error, never a silent undefined.
• One-shot shortcut — Config.Env collapses store + variables + secrets into a single resource for small apps.

Kinds

| Kind | Purpose | | --- | --- | | Config.EnvironmentVariableStore | Provider that exposes a declared set of environment-variable keys. | | Config.Variables | Map a subset of store keys to named application values. | | Config.Secrets | Same as Config.Variables, but values are redacted in logs and errors. | | Config.Env | Compact one-resource shortcut combining store, variables, and secrets. |

Example

kind: Config.EnvironmentVariableStore
metadata:
  name: Env
schema:
  LOG_LEVEL: { type: string }
  DB_USERNAME: { type: string }
  DB_PASSWORD: { type: string }
  DB_HOST: { type: string }
  DB_PORT: { type: string }
  DB_NAME: { type: string }
  STRIPE_KEY: { type: string }
---
kind: Config.Variables
metadata:
  name: AppConfig
storeRef:
  name: Env
keys:
  logLevel: LOG_LEVEL
---
kind: Config.Secrets
metadata:
  name: AppSecrets
storeRef:
  name: Env
keys:
  stripeKey: STRIPE_KEY
  dbUrl: "${{ DB_USERNAME + ':' + DB_PASSWORD + '@' + DB_HOST + ':' + DB_PORT + '/' + DB_NAME }}"

Reference

• Config.Env — single-resource shortcut for small apps.

Concepts

Store — a backend that holds key/value pairs. Declares which keys are accessible via schema. Currently supported: Config.EnvironmentVariableStore.

Map — reads keys from a store and exposes them as named values. Supports direct key lookups and CEL expressions for composing multiple keys into one value. Use Config.Variables for plain config, Config.Secrets for sensitive values.

Missing keys — always a hard boot-time error for both Config.Variables and Config.Secrets.

CEL expressions in map values

Use ${{ }} in any map value to compose multiple store keys into one. All referenced keys must be declared in the store's schema:

keys:
  dbUrl: "${{ DB_USERNAME + ':' + DB_PASSWORD + '@' + DB_HOST + ':' + DB_PORT + '/' + DB_NAME }}"

CEL expressions and direct lookups can be freely mixed. Snapshot exposes resources.AppSecrets.stripeKey, resources.AppSecrets.dbUrl, etc.

Passing values into imports

kind: Telo.Import
metadata:
  name: Config
source: ./config
variables:
  logLevel: "${{ resources.AppConfig.logLevel }}"
  dbUrl: "${{ resources.AppSecrets.dbUrl }}"
  stripeKey: "${{ resources.AppSecrets.stripeKey }}"

Config.Env shortcut

A compact shortcut that collapses store, variables, and secrets into a single resource — useful for small apps and examples where the three-piece layout is overkill.

kind: Config.Env
metadata:
  name: AppConfig
variables:
  port:
    env: PORT
    type: integer
    default: 3000
  logLevel:
    env: LOG_LEVEL
    type: string
    default: info
secrets:
  dbConnection:
    env: DB_CONNECTION
    type: string
  apiKey:
    env: STRIPE_KEY
    type: string

Downstream resources reference values the same way as with Config.Variables / Config.Secrets:

connectionString: "${{ resources.AppConfig.dbConnection }}"
port: "${{ resources.AppConfig.port }}"

Types supported: string, integer, number, boolean. Missing variables without a default are a hard boot-time error — identical to the store/map split. Values declared under secrets are redacted in logs and error messages.

Pick Config.Env for a single-module app that reads the environment directly. Pick the store + map split when multiple maps share a store, when you need CEL composition across keys, or when different key groups are imported into different child modules.

Notes

• A key not listed in the store's schema cannot be read, even in a CEL expression — it will fail at init time.
• Multiple maps can reference the same store.
• CEL expressions have access only to the keys declared in the referenced store.