feat: introduce --silence-events flag on diff/sync commands

This patch also lays out code in a way to avoid duplication across
commands. decK's commands share significant amount of flags and a code
pattern like this can minimize the amount of code and number of code
paths that exist with flag parsing.

cmd/diff.go

@@ -32,7 +32,7 @@ that will be created or updated or deleted.
 			return errors.New("A state file with Kong's configuration " +
 				"must be specified using -s/--state flag.")
 		}
-		return nil
+		return preRunSilenceEventsFlag()
 	},
 }
 
@@ -61,4 +61,5 @@ func init() {
 		false, "return exit code 2 if there is a diff present,\n"+
 			"exit code 0 if no diff is found,\n"+
 			"and exit code 1 if an error occurs.")
+	addSilenceEventsFlag(diffCmd.Flags())
 }

cmd/konnect_diff.go

@@ -29,6 +29,9 @@ that will be created or updated or deleted.` + konnectAlphaState,
 		return syncKonnect(cmd.Context(), konnectDiffCmdKongStateFile, true,
 			konnectDiffCmdParallelism)
 	},
+	PreRunE: func(cmd *cobra.Command, args []string) error {
+		return preRunSilenceEventsFlag()
+	},
 }
 
 func init() {
@@ -45,4 +48,5 @@ func init() {
 		false, "return exit code 2 if there is a diff present,\n"+
 			"exit code 0 if no diff is found,\n"+
 			"and exit code 1 if an error occurs.")
+	addSilenceEventsFlag(konnectDiffCmd.Flags())
 }

cmd/konnect_sync.go

@@ -21,6 +21,9 @@ to get Konnect's state in sync with the input state.` + konnectAlphaState,
 		return syncKonnect(cmd.Context(), konnectDiffCmdKongStateFile, false,
 			konnectDiffCmdParallelism)
 	},
+	PreRunE: func(cmd *cobra.Command, args []string) error {
+		return preRunSilenceEventsFlag()
+	},
 }
 
 func init() {
@@ -33,4 +36,5 @@ func init() {
 			"with consumers")
 	konnectSyncCmd.Flags().IntVar(&konnectDiffCmdParallelism, "parallelism",
 		100, "Maximum number of concurrent operations")
+	addSilenceEventsFlag(konnectSyncCmd.Flags())
 }

cmd/sync.go

@@ -29,7 +29,7 @@ to get Kong's state in sync with the input state.`,
 			return errors.New("A state file with Kong's configuration " +
 				"must be specified using -s/--state flag.")
 		}
-		return nil
+		return preRunSilenceEventsFlag()
 	},
 }
 
@@ -58,4 +58,5 @@ func init() {
 		0, "aritificial delay in seconds that is injected between insert operations \n"+
 			"for related entities (usually for cassandra deployments).\n"+
 			"See 'db_update_propagation' in kong.conf.")
+	addSilenceEventsFlag(syncCmd.Flags())
 }

cmd/utils.go

@@ -2,7 +2,9 @@ package cmd
 
 import (
 	"github.com/fatih/color"
+	printPkg "github.com/kong/deck/print"
 	"github.com/kong/deck/solver"
+	"github.com/spf13/pflag"
 )
 
 func printStats(stats solver.Stats) {
@@ -14,3 +16,17 @@ func printStats(stats solver.Stats) {
 	printFn("  Updated: %v\n", stats.UpdateOps)
 	printFn("  Deleted: %v\n", stats.DeleteOps)
 }
+
+var (
+	silenceEvents bool
+)
+
+func preRunSilenceEventsFlag() error {
+	printPkg.DisableOutput = true
+	return nil
+}
+
+func addSilenceEventsFlag(set *pflag.FlagSet) {
+	set.BoolVar(&silenceEvents, "silence-events", false,
+		"disable printing events to stdout")
+}

go.mod

@@ -24,6 +24,7 @@ require (
 	github.com/spf13/cast v1.3.1 // indirect
 	github.com/spf13/cobra v0.0.7
 	github.com/spf13/jwalterweatherman v1.1.0 // indirect
+	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.7.1
 	github.com/stretchr/testify v1.7.0
 	github.com/xeipuuv/gojsonpointer v0.0.0-20190905194746-02993c407bfb // indirect