add flag to allow user set dynamic concurrency

main.go

@@ -116,6 +116,13 @@ func main() {
 			Name:  "env-file",
 			Usage: "source env file",
 		},
+		cli.StringFlag{
+			Name:  "max-concurrency",
+			Usage: "customize number concurrent files to process",
+			Value: "100",
+			EnvVar: "PLUGIN_MAX_CONCURRENCY",
+
+		},
 	}
 
 	if err := app.Run(os.Args); err != nil {
@@ -145,6 +152,7 @@ func run(c *cli.Context) error {
 		Redirects:              c.Generic("redirects").(*MapFlag).Get(),
 		CloudFrontDistribution: c.String("cloudfront-distribution"),
 		DryRun:                 c.Bool("dry-run"),
+		MaxConcurrency:         c.String("max-concurrency"),
 	}
 
 	return plugin.Exec()

plugin.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"strconv"
 )
 
 type Plugin struct {
@@ -28,10 +29,9 @@ type Plugin struct {
 	PathStyle              bool
 	client                 AWS
 	jobs                   []job
+	MaxConcurrency         string
 }
 
-const maxConcurrent = 100
-
 type job struct {
 	local  string
 	remote string
@@ -156,7 +156,13 @@ func (p *Plugin) createInvalidateJob() {
 
 func (p *Plugin) runJobs() {
 	client := p.client
-	jobChan := make(chan struct{}, maxConcurrent)
+	maxConcurrency, err := strconv.Atoi(p.MaxConcurrency)
+	if err != nil {
+		fmt.Printf("ERROR: invalid input for max-concurrency")
+		os.Exit(1)
+	}
+
+	jobChan := make(chan struct{}, maxConcurrency)
 	results := make(chan *result, len(p.jobs))
 	var invalidateJob *job