Make queue name configurable

Author: ppai-plivo

README.md

@@ -1,3 +1,17 @@
 # sqscat
 
 Poll AWS SQS payloads for inspection.
+
+## Usage
+
+```sh
+$ ./sqscat --help
+Usage:
+  sqscat [OPTIONS] queue-name
+
+Application Options:
+  -c, --concurrency= Number of concurrent SQS pollers; Defaults to 10 x Num. of CPUs
+
+Help Options:
+  -h, --help         Show this help message
+```

go.mod

@@ -6,6 +6,7 @@ require (
 	github.com/aws/aws-sdk-go-v2 v1.9.1
 	github.com/aws/aws-sdk-go-v2/config v1.8.2
 	github.com/aws/aws-sdk-go-v2/service/sqs v1.9.1
+	github.com/jessevdk/go-flags v1.5.0
 )
 
 require (
@@ -16,4 +17,5 @@ require (
 	github.com/aws/aws-sdk-go-v2/service/sso v1.4.1 // indirect
 	github.com/aws/aws-sdk-go-v2/service/sts v1.7.1 // indirect
 	github.com/aws/smithy-go v1.8.0 // indirect
+	golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4 // indirect
 )

go.sum

@@ -22,10 +22,14 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/google/go-cmp v0.5.4/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.6 h1:BKbKCqvP6I+rmFHt06ZmyQtvB8xAkWdhFyr0ZUNZcxQ=
 github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/jessevdk/go-flags v1.5.0 h1:1jKYvbxEjfUl0fmqTCOfonvskHHXMjBySTLW4y9LFvc=
+github.com/jessevdk/go-flags v1.5.0/go.mod h1:Fw0T6WPc1dYxT4mKEZRfG5kJhaTDP9pj1c2EWnYs/m4=
 github.com/jmespath/go-jmespath v0.4.0/go.mod h1:T8mJZnbsbmF+m6zOOFylbeCJqk5+pHWvzYPziyZiYoo=
 github.com/jmespath/go-jmespath/internal/testify v1.5.1/go.mod h1:L3OGu8Wl2/fWfCI6z80xFu9LTZmf1ZRjMHUOPmWr69U=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4 h1:EZ2mChiOa8udjfp6rRmswTbtZN/QzUQp4ptM4rnjHvc=
+golang.org/x/sys v0.0.0-20210320140829-1e4c9ba3b0c4/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

main.go

@@ -6,65 +6,89 @@ import (
 	"log"
 	"os"
 	"os/signal"
+	"runtime"
 	"sync"
 
 	"github.com/aws/aws-sdk-go-v2/aws"
 	"github.com/aws/aws-sdk-go-v2/config"
 	"github.com/aws/aws-sdk-go-v2/service/sqs"
+	flags "github.com/jessevdk/go-flags"
 )
 
 const (
-	queueURL    = "https://sqs.us-east-1.amazonaws.com/xxxxxxxx/yyyyyyyyy"
-	concurrency = 10
+	maxNumberOfMessages = 10
+	waitTimeSeconds     = 20
 )
 
-var (
-	outputDelimiter = []byte("\n")
-)
+type opts struct {
+	Concurrency int `short:"c" long:"concurrency" description:"Number of concurrent SQS pollers; Defaults to 10 x Num. of CPUs"`
+	Positional  struct {
+		QueueName string `positional-arg-name:"queue-name"`
+	} `positional-args:"true" required:"true"`
+}
 
 func main() {
+	opts := opts{}
+	if _, err := flags.Parse(&opts); err != nil {
+		if e, ok := err.(*flags.Error); ok {
+			if e.Type == flags.ErrHelp {
+				os.Exit(0)
+			} else {
+				os.Exit(1)
+			}
+		}
+	}
+
 	awsCfg, err := config.LoadDefaultConfig(context.Background())
 	if err != nil {
 		log.Fatalf("config.LoadDefaultConfig() failed: %v", err)
 	}
+
 	sqsClient := sqs.NewFromConfig(awsCfg)
 
+	resp, err := sqsClient.GetQueueUrl(context.Background(), &sqs.GetQueueUrlInput{
+		QueueName: aws.String(opts.Positional.QueueName),
+	})
+	if err != nil {
+		log.Fatalf("sqsClient.GetQueueUrl(%s) failed: %v", opts.Positional.QueueName, err)
+	}
+
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer stop()
 
+	if opts.Concurrency <= 0 {
+		opts.Concurrency = 10 * runtime.NumCPU()
+	}
+
 	wg := &sync.WaitGroup{}
-	for i := 0; i < concurrency; i++ {
+	for i := 0; i < opts.Concurrency; i++ {
 		wg.Add(1)
-		go poll(ctx, sqsClient, os.Stdout, wg)
+		go poll(ctx, sqsClient, resp.QueueUrl, os.Stdout, wg)
 	}
 
 	wg.Wait()
 }
 
-func poll(ctx context.Context, sqsClient *sqs.Client, f *os.File, wg *sync.WaitGroup) {
+func poll(ctx context.Context, sqsClient *sqs.Client, queueURL *string, f *os.File, wg *sync.WaitGroup) {
 	defer wg.Done()
 
 	for {
 		select {
 		case <-ctx.Done():
-			log.Printf("poller exited")
 			return
 		default:
 			resp, err := sqsClient.ReceiveMessage(ctx, &sqs.ReceiveMessageInput{
-				QueueUrl:            aws.String(queueURL),
-				MaxNumberOfMessages: int32(10),
-				WaitTimeSeconds:     int32(20),
+				QueueUrl:            queueURL,
+				MaxNumberOfMessages: maxNumberOfMessages,
+				WaitTimeSeconds:     waitTimeSeconds,
 			})
 			if err != nil {
 				if errors.Is(err, context.Canceled) {
-					log.Printf("poller exited")
 					return
 				}
 				log.Fatalf("sqsClient.ReceiveMessage() failed: %v", err)
 			}
 
-			log.Printf("received messages; count = %d\n", len(resp.Messages))
-
 			for _, msg := range resp.Messages {
 				// sequential is ok, poller is concurrent
 				handleMessage(f, *msg.Body)
@@ -73,6 +97,8 @@ func poll(ctx context.Context, sqsClient *sqs.Client, f *os.File, wg *sync.WaitG
 	}
 }
 
+var outputDelimiter = []byte("\n")
+
 func handleMessage(f *os.File, body string) {
 	if _, err := f.WriteString(body); err != nil {
 		log.Fatalf("WriteString() failed: %v", err)