config.go

// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
// or more contributor license agreements. Licensed under the Elastic License 2.0;
// you may not use this file except in compliance with the Elastic License 2.0.

// Package loadgencfg contains configuration related code for load generator.
package loadgencfg

import (
	"flag"
	"fmt"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"
)

var Config struct {
	ServerURL                 *url.URL
	SecretToken               string
	APIKey                    string
	Secure                    bool
	EventRate                 RateFlag
	IgnoreErrors              bool
	RewriteIDs                bool
	RewriteTimestamps         bool
	RewriteServiceNames       bool
	RewriteServiceNodeNames   bool
	RewriteServiceTargetNames bool
	RewriteSpanNames          bool
	RewriteTransactionNames   bool
	RewriteTransactionTypes   bool
	Headers                   map[string]string
}

type RateFlag struct {
	Burst    int
	Interval time.Duration
}

func (f *RateFlag) String() string {
	return fmt.Sprintf("%d/%s", f.Burst, f.Interval)
}

func (f *RateFlag) Set(s string) error {
	before, after, ok := strings.Cut(s, "/")
	if !ok || before == "" || after == "" {
		return fmt.Errorf("invalid rate %q, expected format burst/duration", s)
	}

	burst, err := strconv.Atoi(before)
	if err != nil {
		return fmt.Errorf("invalid burst %s in event rate: %w", before, err)
	}

	if !(after[0] >= '0' && after[0] <= '9') {
		after = "1" + after
	}
	interval, err := time.ParseDuration(after)
	if err != nil {
		return fmt.Errorf("invalid interval %q in event rate: %w", after, err)
	}
	if interval <= 0 {
		return fmt.Errorf("invalid interval %q, must be positive", after)
	}

	f.Burst = burst
	f.Interval = interval
	return nil
}

func init() {
	// Server config
	flag.Func(
		"server",
		"server URL (default http://127.0.0.1:8200)",
		func(server string) (err error) {
			if server != "" {
				Config.ServerURL, err = url.Parse(server)
			}
			return
		})
	flag.StringVar(&Config.SecretToken, "secret-token", "", "secret token for APM Server")
	flag.StringVar(&Config.APIKey, "api-key", "", "API key for APM Server")
	flag.BoolVar(&Config.Secure, "secure", false, "validate the remote server TLS certificates")
	flag.BoolVar(
		&Config.RewriteTimestamps,
		"rewrite-timestamps",
		true,
		"rewrite event timestamps every iteration, maintaining relative offsets",
	)

	flag.BoolVar(
		&Config.RewriteIDs,
		"rewrite-ids",
		true,
		"rewrite event IDs every iteration, maintaining event relationships",
	)
	flag.Func("header",
		"extra headers to use when sending data to the server",
		func(s string) error {
			k, v, ok := strings.Cut(s, "=")
			if !ok {
				return fmt.Errorf("invalid header '%s': format must be key=value", s)
			}
			if len(Config.Headers) == 0 {
				Config.Headers = make(map[string]string)
			}
			Config.Headers[k] = v
			return nil
		},
	)
	flag.Var(&Config.EventRate, "event-rate", "Event rate in format of {burst}/{interval}. For example, 200/5s, <= 0 values evaluate to Inf (default 0/s)")
	flag.BoolVar(&Config.IgnoreErrors, "ignore-errors", false, "Ignore HTTP errors while sending events")

	rewriteNames := map[string]*bool{
		"service.name":        &Config.RewriteServiceNames,
		"service.node.name":   &Config.RewriteServiceNodeNames,
		"service.target.name": &Config.RewriteServiceTargetNames,
		"span.name":           &Config.RewriteSpanNames,
		"transaction.name":    &Config.RewriteTransactionNames,
		"transaction.type":    &Config.RewriteTransactionTypes,
	}
	for field, config := range rewriteNames {
		flag.BoolVar(
			config,
			fmt.Sprintf("rewrite-%ss", strings.Replace(field, ".", "-", -1)),
			false,
			fmt.Sprintf("replace `%s` in events", field),
		)
	}

	// For configs that can be set via environment variables, set the required
	// flags from env if they are not explicitly provided via command line
	setFlagsFromEnv()
}

func setFlagsFromEnv() {
	// value[0] is environment key
	// value[1] is default value
	flagEnvMap := map[string][]string{
		"server":       {"ELASTIC_APM_SERVER_URL", "http://127.0.0.1:8200"},
		"secret-token": {"ELASTIC_APM_SECRET_TOKEN", ""},
		"api-key":      {"ELASTIC_APM_API_KEY", ""},
		"secure":       {"ELASTIC_APM_VERIFY_SERVER_CERT", "false"},
	}

	for k, v := range flagEnvMap {
		flag.Set(k, getEnvOrDefault(v[0], v[1]))
	}
}

func getEnvOrDefault(name, defaultValue string) string {
	value := os.Getenv(name)
	if value != "" {
		return value
	}
	return defaultValue
}