Go Microservices Example

Small, runnable example of Go microservices with:

• HTTP frontend
• gRPC service-to-service calls
• OpenTelemetry tracing to Jaeger
• Docker and non-Docker local workflows

What This Repo Demonstrates

• Service boundaries (frontend, search, profile, geo, rate)
• End-user HTTP API (/hotels)
• Internal gRPC composition (search fans out to geo + rate)
• Basic operational surface (/healthz, /readyz, traces)

Architecture

flowchart LR
  B["Browser"] --> F["frontend (HTTP :5001)"]
  F --> S["search (gRPC :8084)"]
  F --> P["profile (gRPC :8083)"]
  S --> G["geo (gRPC :8081)"]
  S --> R["rate (gRPC :8082)"]
  F --> J["Jaeger/OTLP (:4317, UI :16686)"]
  S --> J
  P --> J
  G --> J
  R --> J

Prerequisites

• Go (version from go.mod)
• Docker + Docker Compose (optional, for containerized stack)
• protoc + codegen tools (only for regenerating protobuf stubs)
• go-bindata (only for regenerating embedded JSON assets)

Install codegen tooling:

go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
go install github.com/go-bindata/go-bindata/...@latest

Golden Path (Local, No Docker)

1. Start all services:

make run-local

2. Open UI:

• http://localhost:5001/

3. Hit API directly:

curl "http://localhost:5001/hotels?inDate=2015-04-09&outDate=2015-04-10"

4. Check health/readiness:

• http://localhost:5001/healthz
• http://localhost:5001/readyz

5. View traces:

• http://localhost:16686/search

Docker Stack

make run

The frontend is available at http://localhost:5001/.

HTTP API Contract

GET /hotels

Required query params:

• inDate (YYYY-MM-DD)
• outDate (YYYY-MM-DD, must be after inDate, max range 30 days)

Example:

curl "http://localhost:5001/hotels?inDate=2015-04-09&outDate=2015-04-10"

Success response shape:

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "id": "hotel-id",
      "properties": {
        "name": "Hotel Name",
        "address_line": "123 Main St, San Francisco, CA, 94105",
        "description": "Hotel description",
        "rating": 4.7,
        "logo_url": "/logos/example.svg"
      },
      "geometry": {
        "type": "Point",
        "coordinates": [-122.4, 37.78]
      }
    }
  ]
}

Validation or upstream error shape:

{
  "error": {
    "code": "INVALID_ARGUMENT",
    "message": "invalid inDate format, expected YYYY-MM-DD"
  }
}

Failure Demo

To demonstrate readiness behavior when a dependency is down:

1. Stop search (local run: interrupt and restart without search, Docker run: docker-compose stop search).
2. Request readiness:

curl -i http://localhost:5001/readyz

Expected: 503 Service Unavailable with NOT_READY.

Developer Commands

Run all Go checks:

make check

Regenerate protobuf stubs:

make proto

Regenerate embedded data:

make data

Verify generated files are current:

make check-generated