#Herald
Herald is a package intended to make your microservice compatible with multiple service discovery platforms throught the use of flags or environment variables.
Herald serves two functions.
Utilizing the service definition a service can declare its definition in a k/v store.
Currently supports etcd and consul.
Once again utilizing the service definition a system can become part of a pool of services for API routing.
Currently supports consul and vulcand
This package supports three flags and 3 environment variables. Flags take prescendence over environement variables and specificty takes prescedence over genrality.
--herald will set the declare and pool services to the same thing env (HERALD). Service must me both interface requirements.
--herald-p sets the pooling service only (HERALD_POOL)
--herald-d sets the declare service (HERALD_DECLARE)
Herald only acts if a pool or declaration or both have been set. Pool and declcarations are mutually independent so a user can mix and match services.
Herald has a registry of platforms currently supported and you can register all:
package main
import (
"github.com/duckbunny/herald/registry"
)
func init() {
registry.RegisterAll()
}Herald has two interfaces
###Pool
type Pool interface {
Start(*service.Service) error
Stop(*service.Service) error
Init() error
}New pool types can be created and registered utilizing the AddPool method.
my_new_pool = new(MyPoolStruct)
herald.AddPool("my_pool", my_new_pool)which can then be invoked from a flag or env variable.
###Declaration
type Declaration interface {
Declare(*service.Service) error
Get(*service.Service) error
Init() error
}New declaration types can be created and registered utilizing the AddDeclaration method.
my_new_declaration = new(MyDeclarationStruct)
herald.AddDeclaration("my_declaration", my_new_declaration)which can then be invoked from a flag or env variable.
-- import "github.com/duckbunny/herald"
The herald package is intended to provide the tools to make your microservice public to other declared microservices.
This tool facilitates two functions.
The pool interface allows the microservice to support many API routers through a pool registry.
The declaration interface allows the microservice to declare itself in a registry of services, so other services can consume that configuration and automate common actions. By utilizing a Declaration registry a microservice can support many systems.
A package can support one or both of the interfaces, and the interface to be used will be determined by environment variables or flags.
var DeclarationTypes map[string]Declaration = make(map[string]Declaration)DeclarationTypes are a collection of Declaration Interfaces identified by strings associated with a declaration mechanism.
var PoolTypes map[string]Pool = make(map[string]Pool)PoolTypes are a collection of Pool Interfaces identified by strings associated with a pooling mechanism.
func AddDeclaration(key string, d Declaration)Add a single declaration.
func AddDeclarations(ds map[string]Declaration)Add Multiple declarations at once.
func AddPool(key string, p Pool)Add a single pool.
func AddPools(ps map[string]Pool)Add Multiple pools at once.
type Declaration interface {
Declare(*service.Service) error
Get(*service.Service) error
Init() error
}Declaration defines an interface that will broadcast the microservice definition, for other services to digest.
type Herald struct {
Pool
Declaration
Service *service.Service
}Herald is a wrapper structure of the pooling and declaration interfaces that will be implemented based on flags or environement variables.
func This() (*Herald, error)Helper function to build herald for the currently running microservice.
func (h *Herald) Declare() errorDeclare this microservice definition.
func (h *Herald) Get(s *service.Service) errorGet a foreign microservice definition.
func (h *Herald) Init() errorWrapper to init Pool and Declare if they are set. This allows them to consume flags if necessary.
func (h *Herald) StartPool() errorAdd this service to pool of microservices.
func (h *Herald) StopPool() errorRemove this service from pool of microservices.
type Pool interface {
Start(*service.Service) error
Stop(*service.Service) error
Init() error
}Pool defines an interface that will add and remove a microservice to a pool of microservices.
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