Service-Context

Service Context runs as heart of our services, helps us manage components (such as Consumers, DB Connections, Configuration).

It offers:

• Logger component (using logrus).
• Manage ENV and Flag variables dynamically (with flagenv, godotenv).
• Output env and flag with .env formatted.
• Easily plug-and-play component (as plugin).

Examples

• Demo with simple GIN-HTTP
• Custom component
• Simple CLI (run service and output all env command)

How to use it

1. Install it with this cmd:

go get -u github.com/viettranx/service-context

2. Define your component:

Component can be anything but implements this interface:

type Component interface {
	ID() string
	InitFlags()
	Activate(ServiceContext) error
	Stop() error
}

Simple demo custom component:

package main

import (
	"flag"
	sctx "github.com/viettranx/service-context"
)

type simpleComponent struct {
	id    string
	value string
}

func NewSimpleComponent(id string) *simpleComponent {
	return &simpleComponent{id: id}
}

func (s *simpleComponent) ID() string {
	return s.id
}

func (s *simpleComponent) InitFlags() {
	flag.StringVar(&s.value, "simple-value", "demo", "Value in string")
}

func (s *simpleComponent) Activate(_ sctx.ServiceContext) error {
	return nil
}

func (s *simpleComponent) Stop() error {
	return nil
}

func (s *simpleComponent) GetValue() string {
	return s.value
}

3. Use the component with Service-Context:

package main

import (
	"github.com/viettranx/service-context"
	"log"
)

func main() {
	const compId = "foo" // identity your component

	// Init service-context, you can put components as much as you can
	serviceCtx := sctx.NewServiceContext(
		sctx.WithComponent(NewSimpleComponent(compId)),
	)

	// Load() will iterate registered components
	// It does parse flags and make some configurations if you defined
	// in Activate() method of the components
	if err := serviceCtx.Load(); err != nil {
		log.Fatal(err)
	}

	type CanGetValue interface {
		GetValue() string
	}

	// Get the component from ServiceContext by its ID
	comp := serviceCtx.MustGet(compId).(CanGetValue)

	log.Println(comp.GetValue())

	_ = serviceCtx.Stop() // can be omitted
}

4. Run your code with ENV

go build -o app
SIMPLE_VALUE="Hello World" ./app

You will see Hello World on your console.

Why should I use the ServiceContext?

When your service growths, a lot of components are required. More components more configurations and more ENVs to manage. That's why ServiceContext plays its role.

Service-Context also offers a helpful feature: output all ENV with dot-env (.env) formatted with: serviceContext.Outenv(). Please check this example.

Hope it helps and enjoy coding!