Make it more palatable for ECS environments

README.md

@@ -86,6 +86,9 @@ sudo dpkg -i <the_deb_name>
     # Watch production log group streams for api
     saw watch production --prefix api
 
+    # Watch recently changed streams for the production log group
+    saw watch production --recent
+
     # Watch production log group streams for api and filter for "error"
     saw watch production --prefix api --filter error
     ```

blade/blade.go

@@ -89,6 +89,25 @@ func (b *Blade) GetLogStreams() []*cloudwatchlogs.LogStream {
 	return streams
 }
 
+// GetTopLogStreams gets the recent log streams from AWS without prefix and limited to 100
+func (b *Blade) GetTopLogStreams() []*cloudwatchlogs.LogStream {
+	input := b.config.DescribeRecentLogStreamsInput()
+	streams := make([]*cloudwatchlogs.LogStream, 0)
+	b.cwl.DescribeLogStreamsPages(input, func(
+		out *cloudwatchlogs.DescribeLogStreamsOutput,
+		lastPage bool,
+	) bool {
+		for _, stream := range out.LogStreams {
+			streams = append(streams, stream)
+		}
+		if lastPage || len(streams) >= 100 {
+			return false
+		}
+		return true
+	})
+	return streams
+}
+
 // GetEvents gets events from AWS given the blade configuration
 func (b *Blade) GetEvents() {
 	formatter := b.output.Formatter()
@@ -150,6 +169,7 @@ func (b *Blade) StreamEvents() {
 		}
 		return !lastPage
 	}
+	fmt.Printf("starting to tail logs from %d streams ...\n", len(input.LogStreamNames))
 
 	for {
 		err := b.cwl.FilterLogEventsPages(input, handlePage)

cmd/watch.go

@@ -7,13 +7,15 @@ import (
 
 	"github.com/TylerBrock/saw/blade"
 	"github.com/TylerBrock/saw/config"
+	"github.com/aws/aws-sdk-go/service/cloudwatchlogs"
 	"github.com/spf13/cobra"
 )
 
 var watchConfig config.Configuration
 
 var watchOutputConfig config.OutputConfiguration
 
+var useRecent bool
 var watchCommand = &cobra.Command{
 	Use:   "watch <log group>",
 	Short: "Continuously stream log events",
@@ -27,8 +29,13 @@ var watchCommand = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 		watchConfig.Group = args[0]
 		b := blade.NewBlade(&watchConfig, &awsConfig, &watchOutputConfig)
-		if watchConfig.Prefix != "" {
-			streams := b.GetLogStreams()
+		if watchConfig.Prefix != "" || useRecent {
+			var streams []*cloudwatchlogs.LogStream
+			if useRecent {
+				streams = b.GetTopLogStreams()
+			} else {
+				streams = b.GetLogStreams()
+			}
 			if len(streams) == 0 {
 				fmt.Printf("No streams found in %s with prefix %s\n", watchConfig.Group, watchConfig.Prefix)
 				fmt.Printf("To view available streams: `saw streams %s`\n", watchConfig.Group)
@@ -41,6 +48,7 @@ var watchCommand = &cobra.Command{
 }
 
 func init() {
+	watchCommand.Flags().BoolVar(&useRecent, "recent", true, "Tails from recently changed streams")
 	watchCommand.Flags().StringVar(&watchConfig.Prefix, "prefix", "", "log stream prefix filter")
 	watchCommand.Flags().StringVar(&watchConfig.Filter, "filter", "", "event filter pattern")
 	watchCommand.Flags().BoolVar(&watchOutputConfig.Raw, "raw", false, "print raw log event without timestamp or stream prefix")

config/configuration.go

@@ -72,6 +72,14 @@ func (c *Configuration) DescribeLogStreamsInput() *cloudwatchlogs.DescribeLogStr
 	return &input
 }
 
+func (c *Configuration) DescribeRecentLogStreamsInput() *cloudwatchlogs.DescribeLogStreamsInput {
+	input := cloudwatchlogs.DescribeLogStreamsInput{}
+	input.SetLogGroupName(c.Group)
+	input.SetDescending(true)
+	input.SetOrderBy("LastEventTime")
+	return &input
+}
+
 func (c *Configuration) FilterLogEventsInput() *cloudwatchlogs.FilterLogEventsInput {
 	input := cloudwatchlogs.FilterLogEventsInput{}
 	input.SetInterleaved(true)