Add ChangeTabletTags RPC to vtctl, ChangeTags RPC to vttablet

changelog/21.0/21.0.0/summary.md

@@ -20,6 +20,7 @@
     - **[New VEXPLAIN Modes: TRACE and KEYS](#new-vexplain-modes)**
     - **[Errant GTID Detection on VTTablets](#errant-gtid-vttablet)**
     - **[Automatically Replace MySQL auto_increment Clauses with Vitess Sequences](#auto-replace-mysql-autoinc-with-seq)**
+    - **[vtctldclient ChangeTabletTags](#vtctldclient-changetablettags)**
 
 ## <a id="major-changes"/>Major Changes</a>
 
@@ -218,3 +219,22 @@ work automatically during the [`MoveTables`](https://vitess.io/docs/reference/vr
 [`--remove-sharded-auto-increment` boolean flag](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and you should begin using the new
 [`--sharded-auto-increment-handling` flag](https://vitess.io/docs/21.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) instead. Please see the new
 [`MoveTables` Auto Increment Handling](https://vitess.io/docs/21.0/reference/vreplication/movetables/#auto-increment-handling) documentation for additional details.
+
+### <a id="vtctldclient-changetablettags"/>`vtctldclient ChangeTabletTags` command and RPCs
+
+The `vtctldclient` command `ChangeTabletTags` was added to allow the tags of a tablet to be changed dynamically.
+
+This command allows one or many tablet tags to be defined using key=value format. The provided tags are merged with existing tags by default. The optional flag `--replace` causes the existing tags to be replaced with the provided tags. To support this, the VTCtld RPC `ChangeTabletTags` and the VTTablet RPC `ChangeTags` were added.
+
+Previous to this release the only way to define tablet tags was the `--init_tags` flag of `vttablet`, which requires a restart for a change to take effect.
+
+Example:
+```bash
+$ vtctldclient --server :15999 ChangeTabletTags --replace zone1-100 hello=world
+- []
++ [hello: "world"]
+$ vtctldclient --server :15999 GetTablet zone1-100 | jq .tags
+{
+  "hello": "world"
+}
+```

go/cmd/vtctldclient/cli/tablets.go

@@ -17,9 +17,11 @@ limitations under the License.
 package cli
 
 import (
-	"vitess.io/vitess/go/vt/topo/topoproto"
+	"fmt"
+	"strings"
 
 	topodatapb "vitess.io/vitess/go/vt/proto/topodata"
+	"vitess.io/vitess/go/vt/topo/topoproto"
 )
 
 // TabletAliasesFromPosArgs takes a list of positional (non-flag) arguments and
@@ -38,3 +40,22 @@ func TabletAliasesFromPosArgs(args []string) ([]*topodatapb.TabletAlias, error)
 
 	return aliases, nil
 }
+
+// TabletTagsFromPosArgs takes a list of positional (non-flag) arguements and
+// converts them to a map of tablet tags.
+func TabletTagsFromPosArgs(args []string) (map[string]string, error) {
+	if len(args) == 0 {
+		return nil, fmt.Errorf("no tablet tags specified")
+	}
+
+	tags := make(map[string]string, len(args))
+	for _, kvPair := range args {
+		if !strings.Contains(kvPair, "=") {
+			return nil, fmt.Errorf("invalid tablet tag %q specified. tablet tags must be specified in key=value format", kvPair)
+		}
+		fields := strings.SplitN(kvPair, "=", 2)
+		tags[fields[0]] = fields[1]
+	}
+
+	return tags, nil
+}

go/cmd/vtctldclient/cli/tablets_test.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2024 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+        http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cli
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestTabletTagsFromPosArgs(t *testing.T) {
+	t.Parallel()
+
+	{
+		tags, err := TabletTagsFromPosArgs([]string{"fail"})
+		assert.Error(t, err)
+		assert.Nil(t, tags)
+	}
+	{
+		tags, err := TabletTagsFromPosArgs([]string{"hello=world"})
+		assert.NoError(t, err)
+		assert.Equal(t, map[string]string{
+			"hello": "world",
+		}, tags)
+	}
+	{
+		tags, err := TabletTagsFromPosArgs([]string{"hello=world", "test=123"})
+		assert.NoError(t, err)
+		assert.Equal(t, map[string]string{
+			"hello": "world",
+			"test":  "123",
+		}, tags)
+	}
+}

go/cmd/vtctldclient/command/tablets.go

@@ -34,6 +34,17 @@ import (
 )
 
 var (
+	// ChangeTabletTags makes a ChangeTabletTags gRPC call to a vtctld.
+	ChangeTabletTags = &cobra.Command{
+		Use:   "ChangeTabletTags <alias> <tablet-tag> [ <tablet-tag> ... ]",
+		Short: "Changes the tablet tags for the specified tablet, if possible.",
+		Long: `Changes the tablet tags for the specified tablet, if possible.
+
+Tags must be specified as key=value pairs.`,
+		DisableFlagsInUseLine: true,
+		Args:                  cobra.MinimumNArgs(2),
+		RunE:                  commandChangeTabletTags,
+	}
 	// ChangeTabletType makes a ChangeTabletType gRPC call to a vtctld.
 	ChangeTabletType = &cobra.Command{
 		Use:   "ChangeTabletType [--dry-run] <alias> <tablet-type>",
@@ -212,6 +223,40 @@ Note that, in the SleepTablet implementation, the value should be positively-sig
 	}
 )
 
+var changeTabletTagsOptions = struct {
+	Replace bool
+}{}
+
+func commandChangeTabletTags(cmd *cobra.Command, args []string) error {
+	allArgs := cmd.Flags().Args()
+
+	alias, err := topoproto.ParseTabletAlias(allArgs[0])
+	if err != nil {
+		return err
+	}
+
+	tags, err := cli.TabletTagsFromPosArgs(allArgs[1:])
+	if err != nil {
+		return err
+	}
+
+	cli.FinishedParsing(cmd)
+
+	resp, err := client.ChangeTabletTags(commandCtx, &vtctldatapb.ChangeTabletTagsRequest{
+		TabletAlias: alias,
+		Tags:        tags,
+		Replace:     changeTabletTagsOptions.Replace,
+	})
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("- %v\n", cli.MarshalMapAWK(resp.BeforeTags))
+	fmt.Printf("+ %v\n", cli.MarshalMapAWK(resp.AfterTags))
+
+	return nil
+}
+
 var changeTabletTypeOptions = struct {
 	DryRun bool
 }{}
@@ -629,6 +674,9 @@ func commandStopReplication(cmd *cobra.Command, args []string) error {
 }
 
 func init() {
+	ChangeTabletTags.Flags().BoolVarP(&changeTabletTagsOptions.Replace, "replace", "r", false, "Replace all tablet tags with the tags provided. By default tags are merged/updated.")
+	Root.AddCommand(ChangeTabletTags)
+
 	ChangeTabletType.Flags().BoolVarP(&changeTabletTypeOptions.DryRun, "dry-run", "d", false, "Shows the proposed change without actually executing it.")
 	Root.AddCommand(ChangeTabletType)
 

go/flags/endtoend/vtctldclient.txt

@@ -18,6 +18,7 @@ Available Commands:
   ApplyVSchema                Applies the VTGate routing schema to the provided keyspace. Shows the result after application.
   Backup                      Uses the BackupStorage service on the given tablet to create and store a new backup.
   BackupShard                 Finds the most up-to-date REPLICA, RDONLY, or SPARE tablet in the given shard and uses the BackupStorage service on that tablet to create and store a new backup.
+  ChangeTabletTags            Changes the tablet tags for the specified tablet, if possible.
   ChangeTabletType            Changes the db type for the specified tablet, if possible.
   CheckThrottler              Issue a throttler check on the given tablet.
   CreateKeyspace              Creates the specified keyspace in the topology.