martin-helmich/prometheus-nginxlog-exporter

package discovery

import (
    "github.com/hashicorp/consul/api"
    "github.com/martin-helmich/prometheus-nginxlog-exporter/pkg/config"
)

// ConsulRegistrator is a helper struct that handles Consul service registration
type ConsulRegistrator struct {
    config    *config.Config
    client    *api.Client
    serviceID string
}

func getDefault(a string, b string) string {
    if a == "" {
        return b
    }
    return a
}

// NewConsulRegistrator is a constructor function for building a new ConsulRegistrator
func NewConsulRegistrator(cfg *config.Config) (*ConsulRegistrator, error) {
    config := api.Config{
        Address:    getDefault(cfg.Consul.Address, "localhost:8500"),
        Datacenter: getDefault(cfg.Consul.Datacenter, "dc1"),
        Scheme:     getDefault(cfg.Consul.Scheme, "http"),
        Token:      cfg.Consul.Token,
    }

    client, err := api.NewClient(&config)
    if err != nil {
        return nil, err
    }

    name := getDefault(cfg.Consul.Service.Name, "nginx-exporter")
    serviceID := getDefault(cfg.Consul.Service.ID, name)

    return &ConsulRegistrator{
        config:    cfg,
        client:    client,
        serviceID: serviceID,
    }, nil
}

// RegisterConsul registers the exporter instance at Consul
func (r *ConsulRegistrator) RegisterConsul() error {
    registration := api.AgentServiceRegistration{
        ID:      r.serviceID,
        Address: r.config.Consul.Service.Address,
        Port:    r.config.Listen.Port,
        Name:    getDefault(r.config.Consul.Service.Name, "nginx-exporter"),
        Tags:    r.config.Consul.Service.Tags,
    }

    err := r.client.Agent().ServiceRegister(&registration)
    if err != nil {
        return err
    }

    return nil
}

// UnregisterConsul deregisters the exporter from Consul again
func (r *ConsulRegistrator) UnregisterConsul() error {
    return r.client.Agent().ServiceDeregister(r.serviceID)
}