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Configuration

Go Micro follows a progressive configuration model so you can start with zero setup and layer in complexity only when needed.

Levels of Configuration

  1. Zero Config (Defaults)
    • mDNS registry, HTTP transport, in-memory broker/store
  2. Environment Variables
    • Override core components without code changes
  3. Code Options
    • Fine-grained control via functional options
  4. External Sources (Future / Plugins)
    • Configuration loaded from files, vaults, or remote services

Core Environment Variables

Component Variable Example Purpose
Registry MICRO_REGISTRY MICRO_REGISTRY=consul Select registry implementation
Registry Address MICRO_REGISTRY_ADDRESS MICRO_REGISTRY_ADDRESS=127.0.0.1:8500 Point to registry service
Broker MICRO_BROKER MICRO_BROKER=nats Select broker implementation
Broker Address MICRO_BROKER_ADDRESS MICRO_BROKER_ADDRESS=nats://localhost:4222 Broker endpoint
Transport MICRO_TRANSPORT MICRO_TRANSPORT=nats Select transport implementation
Transport Address MICRO_TRANSPORT_ADDRESS MICRO_TRANSPORT_ADDRESS=nats://localhost:4222 Transport endpoint
Store MICRO_STORE MICRO_STORE=postgres Select store implementation
Store Database MICRO_STORE_DATABASE MICRO_STORE_DATABASE=app Logical database name
Store Table MICRO_STORE_TABLE MICRO_STORE_TABLE=records Default table/collection
Store Address MICRO_STORE_ADDRESS MICRO_STORE_ADDRESS=postgres://user:pass@localhost:5432/app?sslmode=disable Connection string
Server Address MICRO_SERVER_ADDRESS MICRO_SERVER_ADDRESS=:8080 Bind address for RPC server

Example: Switching Components via Env Vars

# Use NATS for broker and transport, Consul for registry
export MICRO_BROKER=nats
export MICRO_TRANSPORT=nats
export MICRO_REGISTRY=consul
export MICRO_REGISTRY_ADDRESS=127.0.0.1:8500

# Run your service
go run main.go

No code changes required. The framework internally wires the selected implementations.

Equivalent Code Configuration

service := micro.NewService(
    micro.Name("helloworld"),
    micro.Broker(nats.NewBroker()),
    micro.Transport(natstransport.NewTransport()),
    micro.Registry(consul.NewRegistry(registry.Addrs("127.0.0.1:8500"))),
)
service.Init()

Use env vars for deployment level overrides; use code options for explicit control or when composing advanced setups.

Precedence Rules

  1. Explicit code options always win
  2. If not set in code, env vars are applied
  3. If neither code nor env vars set, defaults are used

Discoverability Strategy

Defaults allow local development with zero friction. As teams scale:

Validating Configuration

Enable debug logging to confirm selected components:

MICRO_LOG_LEVEL=debug go run main.go

You will see lines like:

Registry [consul] Initialised
Broker [nats] Connected
Transport [nats] Listening on nats://localhost:4222
Store [postgres] Connected to app/records

Patterns

Twelve-Factor Alignment

Environment variables map directly to deploy-time configuration. Avoid hardcoding component choices so services remain portable.

Multi-Environment Setup

Use a simple env file per environment:

# .env.staging
MICRO_REGISTRY=consul
MICRO_REGISTRY_ADDRESS=consul.staging.internal:8500
MICRO_BROKER=nats
MICRO_BROKER_ADDRESS=nats.staging.internal:4222
MICRO_STORE=postgres
MICRO_STORE_ADDRESS=postgres://staging:pass@pg.staging.internal:5432/app?sslmode=disable

Load with your process manager or container orchestrator.

Troubleshooting

Symptom Cause Fix
Service starts with memory store unexpectedly Env vars not exported env | grep MICRO_STORE to verify
Consul errors about connection refused Wrong address/port Check MICRO_REGISTRY_ADDRESS value
NATS connection timeout Server not running Start NATS or change address
Postgres SSL errors Missing sslmode param Append ?sslmode=disable locally
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