feat(apply): add deck gateway apply command

The `deck gateway apply` command allows you to apply partial
configuration to a running Gateway instance.

To do this, it runs a `sync` with the NoDeletes flag enabled.
This means that only new and existing resources are updated.
Existing resources that do not exist in the declarative
configuration file are left untouched.

cmd/common.go

@@ -131,7 +131,7 @@ func RemoveConsumerPlugins(targetContentPlugins []file.FPlugin) []file.FPlugin {
 }
 
 func syncMain(ctx context.Context, filenames []string, dry bool, parallelism,
-	delay int, workspace string, enableJSONOutput bool,
+	delay int, workspace string, enableJSONOutput bool, noDeletes bool,
 ) error {
 	// read target file
 	if enableJSONOutput {
@@ -373,7 +373,7 @@ func syncMain(ctx context.Context, filenames []string, dry bool, parallelism,
 	}
 
 	totalOps, err := performDiff(
-		ctx, currentState, targetState, dry, parallelism, delay, kongClient, mode == modeKonnect, enableJSONOutput)
+		ctx, currentState, targetState, dry, parallelism, delay, kongClient, mode == modeKonnect, enableJSONOutput, noDeletes)
 	if err != nil {
 		if enableJSONOutput {
 			var errs reconcilerUtils.ErrArray
@@ -502,7 +502,7 @@ func fetchCurrentState(ctx context.Context, client *kong.Client, dumpConfig dump
 
 func performDiff(ctx context.Context, currentState, targetState *state.KongState,
 	dry bool, parallelism int, delay int, client *kong.Client, isKonnect bool,
-	enableJSONOutput bool,
+	enableJSONOutput bool, noDeletes bool,
 ) (int, error) {
 	s, err := diff.NewSyncer(diff.SyncerOpts{
 		CurrentState:  currentState,
@@ -511,6 +511,7 @@ func performDiff(ctx context.Context, currentState, targetState *state.KongState
 		StageDelaySec: delay,
 		NoMaskValues:  noMaskValues,
 		IsKonnect:     isKonnect,
+		NoDeletes:     noDeletes,
 	})
 	if err != nil {
 		return 0, err

cmd/common_konnect.go

@@ -127,7 +127,7 @@ func resetKonnectV2(ctx context.Context) error {
 	if err != nil {
 		return err
 	}
-	_, err = performDiff(ctx, currentState, targetState, false, 10, 0, client, true, resetJSONOutput)
+	_, err = performDiff(ctx, currentState, targetState, false, 10, 0, client, true, resetJSONOutput, false)
 	if err != nil {
 		return err
 	}

cmd/gateway_apply.go

@@ -0,0 +1,55 @@
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+)
+
+var (
+	applyCmdParallelism   int
+	applyCmdDBUpdateDelay int
+	applyWorkspace        string
+	applyJSONOutput       bool
+)
+
+var applyCmdKongStateFile []string
+
+func executeApply(cmd *cobra.Command, _ []string) error {
+	return syncMain(cmd.Context(), applyCmdKongStateFile, false,
+		applyCmdParallelism, applyCmdDBUpdateDelay, applyWorkspace, applyJSONOutput, true)
+}
+
+func newApplyCmd() *cobra.Command {
+	short := "Apply configuration to Kong without deleting existing entities"
+	execute := executeApply
+
+	applyCmd := &cobra.Command{
+		Use:   "apply [flags] [kong-state-files...]",
+		Short: short,
+		Long:  `The apply command allows you to apply partial Kong configuration files without deleting existing entities.`,
+		Args:  cobra.MinimumNArgs(0),
+		RunE:  execute,
+		PreRunE: func(_ *cobra.Command, args []string) error {
+			applyCmdKongStateFile = args
+			if len(applyCmdKongStateFile) == 0 {
+				applyCmdKongStateFile = []string{"-"}
+			}
+			return preRunSilenceEventsFlag()
+		},
+	}
+
+	applyCmd.Flags().StringVarP(&applyWorkspace, "workspace", "w", "",
+		"Apply configuration to a specific workspace "+
+			"(Kong Enterprise only).\n"+
+			"This takes precedence over _workspace fields in state files.")
+	applyCmd.Flags().IntVar(&applyCmdParallelism, "parallelism",
+		10, "Maximum number of concurrent operations.")
+	applyCmd.Flags().IntVar(&applyCmdDBUpdateDelay, "db-update-propagation-delay",
+		0, "artificial 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.")
+	applyCmd.Flags().BoolVar(&syncJSONOutput, "json-output",
+		false, "generate command execution report in a JSON format")
+	addSilenceEventsFlag(applyCmd.Flags())
+
+	return applyCmd
+}

cmd/gateway_diff.go

@@ -17,7 +17,7 @@ var (
 
 func executeDiff(cmd *cobra.Command, _ []string) error {
 	return syncMain(cmd.Context(), diffCmdKongStateFile, true,
-		diffCmdParallelism, 0, diffWorkspace, diffJSONOutput)
+		diffCmdParallelism, 0, diffWorkspace, diffJSONOutput, false)
 }
 
 // newDiffCmd represents the diff command

cmd/gateway_reset.go

@@ -97,7 +97,7 @@ func executeReset(cmd *cobra.Command, _ []string) error {
 		if err != nil {
 			return err
 		}
-		_, err = performDiff(ctx, currentState, targetState, false, 10, 0, wsClient, false, resetJSONOutput)
+		_, err = performDiff(ctx, currentState, targetState, false, 10, 0, wsClient, false, resetJSONOutput, false)
 		if err != nil {
 			return err
 		}

cmd/gateway_sync.go

@@ -18,7 +18,7 @@ var syncCmdKongStateFile []string
 
 func executeSync(cmd *cobra.Command, _ []string) error {
 	return syncMain(cmd.Context(), syncCmdKongStateFile, false,
-		syncCmdParallelism, syncCmdDBUpdateDelay, syncWorkspace, syncJSONOutput)
+		syncCmdParallelism, syncCmdDBUpdateDelay, syncWorkspace, syncJSONOutput, false)
 }
 
 // newSyncCmd represents the sync command

cmd/root.go

@@ -237,6 +237,7 @@ It can be used to export, import, or sync entities to Kong.`,
 		gatewayCmd.AddCommand(newPingCmd(false))
 		gatewayCmd.AddCommand(newDumpCmd(false))
 		gatewayCmd.AddCommand(newDiffCmd(false))
+		gatewayCmd.AddCommand(newApplyCmd())
 	}
 	{
 		fileCmd := newFileSubCmd()