Fetch current on call users from Pager Duty for a given schedule_id

main.go

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"time"

	"github.com/kelseyhightower/envconfig"
)

type AppConfig struct {
	ApiKey     string `envconfig:"API_KEY" required:"true"`
	ScheduleId string `envconfig:"SCHEDULE_ID" required:"true"`
}

type OncallDecoder struct {
	Oncalls []Oncall `json:"oncalls"`
}

type Oncall struct {
	User struct {
		Name string `json:"summary"`
	} `json:"user,omitempty"`
}

func main() {
	var (
		config   AppConfig
		decoder  OncallDecoder
		endpoint string
	)

	if err := envconfig.Process("oncall", &config); err != nil {
		log.Fatal(err.Error())
	}

	if err := buildEndpoint(&endpoint, config); err != nil {
		log.Fatal(err)
	}

	client := &http.Client{}

	req, _ := http.NewRequest(http.MethodGet, endpoint, nil)
	req.Header.Add("authorization", "Token token="+config.ApiKey)
	req.Header.Add("accept", "application/vnd.pagerduty+json;version=2")

	resp, err := client.Do(req)

	if err != nil {
		log.Fatal(err)
	}

	defer resp.Body.Close()

	if err := json.NewDecoder(resp.Body).Decode(&decoder); err != nil {
		log.Fatal(err)
	}

	fmt.Println("Users currently on call:")
	for _, oncall := range decoder.Oncalls {
		fmt.Println(oncall.User.Name)
	}
}

func buildEndpoint(endpoint *string, config AppConfig) error {
	uri, err := url.Parse("https://api.pagerduty.com/oncalls")

	if err != nil {
		return err
	}

	since := date()
	until := since

	query := uri.Query()
	query.Set("time_zone", "UTC")
	query.Set("since", since)
	query.Set("until", until)
	query.Set("schedule_ids[]", config.ScheduleId)

	uri.RawQuery = query.Encode()

	*endpoint = uri.String()

	return nil
}

func date() string {
	date := time.Now()
	date.AddDate(0, 0, 1)

	return date.Format("2006-01-02")
}