Support extra flags for mysqld_exporter

deploy/crds/planetscale.com_vitessclusters.yaml

@@ -1992,6 +1992,10 @@ spec:
                                             type: object
                                           mysqldExporter:
                                             properties:
+                                              extraFlags:
+                                                additionalProperties:
+                                                  type: string
+                                                type: object
                                               resources:
                                                 properties:
                                                   claims:
@@ -2025,8 +2029,6 @@ spec:
                                                       x-kubernetes-int-or-string: true
                                                     type: object
                                                 type: object
-                                            required:
-                                            - resources
                                             type: object
                                           name:
                                             default: ""
@@ -2433,6 +2435,10 @@ spec:
                                           type: object
                                         mysqldExporter:
                                           properties:
+                                            extraFlags:
+                                              additionalProperties:
+                                                type: string
+                                              type: object
                                             resources:
                                               properties:
                                                 claims:
@@ -2466,8 +2472,6 @@ spec:
                                                     x-kubernetes-int-or-string: true
                                                   type: object
                                               type: object
-                                          required:
-                                          - resources
                                           type: object
                                         name:
                                           default: ""

deploy/crds/planetscale.com_vitesskeyspaces.yaml

@@ -550,6 +550,10 @@ spec:
                                       type: object
                                     mysqldExporter:
                                       properties:
+                                        extraFlags:
+                                          additionalProperties:
+                                            type: string
+                                          type: object
                                         resources:
                                           properties:
                                             claims:
@@ -583,8 +587,6 @@ spec:
                                                 x-kubernetes-int-or-string: true
                                               type: object
                                           type: object
-                                      required:
-                                      - resources
                                       type: object
                                     name:
                                       default: ""
@@ -991,6 +993,10 @@ spec:
                                     type: object
                                   mysqldExporter:
                                     properties:
+                                      extraFlags:
+                                        additionalProperties:
+                                          type: string
+                                        type: object
                                       resources:
                                         properties:
                                           claims:
@@ -1024,8 +1030,6 @@ spec:
                                               x-kubernetes-int-or-string: true
                                             type: object
                                         type: object
-                                    required:
-                                    - resources
                                     type: object
                                   name:
                                     default: ""

deploy/crds/planetscale.com_vitessshards.yaml

@@ -533,6 +533,10 @@ spec:
                       type: object
                     mysqldExporter:
                       properties:
+                        extraFlags:
+                          additionalProperties:
+                            type: string
+                          type: object
                         resources:
                           properties:
                             claims:
@@ -566,8 +570,6 @@ spec:
                                 x-kubernetes-int-or-string: true
                               type: object
                           type: object
-                      required:
-                      - resources
                       type: object
                     name:
                       default: ""

docs/api.md

@@ -1536,6 +1536,22 @@ EtcdLockserverStatus
 <tbody>
 <tr>
 <td>
+<code>extraFlags</code><br>
+<em>
+map[string]string
+</em>
+</td>
+<td>
+<p>ExtraFlags can optionally be used to override default flags set by the
+operator, or pass additional flags to mysqld_exporter. All entries must be
+key-value string pairs of the form &ldquo;flag&rdquo;: &ldquo;value&rdquo;. The flag name should
+not have any prefix (just &ldquo;flag&rdquo;, not &ldquo;-flag&rdquo;). To set a boolean flag,
+set the string value to either &ldquo;true&rdquo; or &ldquo;false&rdquo;; the flag will be
+automatically converted to the format expected by mysqld_exporter.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>resources</code><br>
 <em>
 <a href="https://v1-18.docs.kubernetes.io/docs/reference/generated/kubernetes-api/v1.18/#resourcerequirements-v1-core">

docs/api/index.html

@@ -1538,6 +1538,22 @@ <h3 id="planetscale.com/v2.MysqldExporterSpec">MysqldExporterSpec
 <tbody>
 <tr>
 <td>
+<code>extraFlags</code><br>
+<em>
+map[string]string
+</em>
+</td>
+<td>
+<p>ExtraFlags can optionally be used to override default flags set by the
+operator, or pass additional flags to mysqld_exporter. All entries must be
+key-value string pairs of the form &ldquo;flag&rdquo;: &ldquo;value&rdquo;. The flag name should
+not have any prefix (just &ldquo;flag&rdquo;, not &ldquo;-flag&rdquo;). To set a boolean flag,
+set the string value to either &ldquo;true&rdquo; or &ldquo;false&rdquo;; the flag will be
+automatically converted to the format expected by mysqld_exporter.</p>
+</td>
+</tr>
+<tr>
+<td>
 <code>resources</code><br>
 <em>
 <a href="https://v1-18.docs.kubernetes.io/docs/reference/generated/kubernetes-api/v1.18/#resourcerequirements-v1-core">

pkg/apis/planetscale/v2/vitessshard_types.go

@@ -317,8 +317,16 @@ type MysqldSpec struct {
 
 // MysqldExporterSpec configures the local MySQL exporter within a tablet.
 type MysqldExporterSpec struct {
+	// ExtraFlags can optionally be used to override default flags set by the
+	// operator, or pass additional flags to mysqld_exporter. All entries must be
+	// key-value string pairs of the form "flag": "value". The flag name should
+	// not have any prefix (just "flag", not "-flag"). To set a boolean flag,
+	// set the string value to either "true" or "false"; the flag will be
+	// automatically converted to the format expected by mysqld_exporter.
+	ExtraFlags map[string]string `json:"extraFlags,omitempty"`
+
 	// Resources specify the compute resources to allocate for just the MySQL Exporter.
-	Resources corev1.ResourceRequirements `json:"resources"`
+	Resources corev1.ResourceRequirements `json:"resources,omitempty"`
 }
 
 // VitessTabletPoolType represents the tablet types for which it makes sense

pkg/operator/vitess/flags.go

@@ -19,6 +19,7 @@ package vitess
 import (
 	"fmt"
 	"sort"
+	"strings"
 )
 
 // Flags represents values for flags to be passed to Vitess binaries.
@@ -61,6 +62,44 @@ func (f Flags) FormatArgs() []string {
 	return args
 }
 
+// FormatArgsConvertBoolean returns the flags as a flattened list of
+// command-line args with boolean values formatted as `--flag` or `--no-flag`.
+// This format is used by some tools, like mysqld_exporter.
+// Method is based on FormatArgs().
+func (f Flags) FormatArgsConvertBoolean() []string {
+	// Sort flag names so the ordering is deterministic,
+	// which is important when diffing object specs.
+	// This also makes it easier for humans to find things.
+	keys := make([]string, 0, len(f))
+	for key := range f {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	// Make formatted args list.
+	args := make([]string, 0, len(f))
+	for _, key := range keys {
+		// These args are passed to the command as a string array,
+		// so we don't need to worry about quotes or escaping.
+		//
+		// We use two dashes (--) even though the standard flag parser
+		// accepts either one or two dashes, because some wrappers like
+		// pflags require two dashes.
+		//
+		// All boolean values are formatted as `--flag` or `--no-flag`.
+		value := f[key].(string)
+		switch value := strings.ToLower(value); value {
+		case "true":
+			args = append(args, fmt.Sprintf("--%v", key))
+		case "false":
+			args = append(args, fmt.Sprintf("--no-%v", key))
+		default:
+			args = append(args, fmt.Sprintf("--%v=%v", key, value))
+		}
+	}
+	return args
+}
+
 // Merge sets the given flags, overwriting duplicates.
 func (f Flags) Merge(flags Flags) Flags {
 	for key, value := range flags {

pkg/operator/vitess/flags_test.go

@@ -0,0 +1,165 @@
+/*
+Copyright 2024 PlanetScale Inc.
+
+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 vitess
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestFormatArgs tests the FormatArgs method of the Flags type.
+func TestFormatArgs(t *testing.T) {
+	tests := []struct {
+		name  string
+		flags Flags
+		want  []string
+	}{
+		{
+			name:  "empty flags",
+			flags: Flags{},
+			want:  []string{},
+		},
+		{
+			name: "single flag",
+			flags: Flags{
+				"flag1": "value1",
+			},
+			want: []string{"--flag1=value1"},
+		},
+		{
+			name: "multiple flags",
+			flags: Flags{
+				"flag2": "value2",
+				"flag3": "value3",
+			},
+			want: []string{"--flag2=value2", "--flag3=value3"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.flags.FormatArgs()
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+// TestFormatArgsConvertBoolean tests the FormatArgsConvertBoolean method of the Flags type.
+func TestFormatArgsConvertBoolean(t *testing.T) {
+	tests := []struct {
+		name  string
+		flags Flags
+		want  []string
+	}{
+		{
+			name:  "empty flags",
+			flags: Flags{},
+			want:  []string{},
+		},
+		{
+			name: "boolean flag true",
+			flags: Flags{
+				"flag1": "true",
+			},
+			want: []string{"--flag1"},
+		},
+		{
+			name: "boolean flag false",
+			flags: Flags{
+				"flag2": "false",
+			},
+			want: []string{"--no-flag2"},
+		},
+		{
+			name: "non-boolean flag",
+			flags: Flags{
+				"flag3": "value3",
+			},
+			want: []string{"--flag3=value3"},
+		},
+		{
+			name: "multiple flags",
+			flags: Flags{
+				"flag4": "true",
+				"flag5": "false",
+				"flag6": "value6",
+			},
+			want: []string{"--flag4", "--no-flag5", "--flag6=value6"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.flags.FormatArgsConvertBoolean()
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+// TestMerge tests the Merge method of the Flags type.
+func TestMerge(t *testing.T) {
+	tests := []struct {
+		name   string
+		flags  Flags
+		merge  Flags
+		result Flags
+	}{
+		{
+			name: "merge empty flags",
+			flags: Flags{
+				"flag1": "value1",
+			},
+			merge: Flags{},
+			result: Flags{
+				"flag1": "value1",
+			},
+		},
+		{
+			name: "merge non-empty flags",
+			flags: Flags{
+				"flag1": "value1",
+			},
+			merge: Flags{
+				"flag2": "value2",
+			},
+			result: Flags{
+				"flag1": "value1",
+				"flag2": "value2",
+			},
+		},
+		{
+			name: "merge duplicate flags",
+			flags: Flags{
+				"flag1": "value1",
+			},
+			merge: Flags{
+				"flag1": "value2",
+			},
+			result: Flags{
+				"flag1": "value2",
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.flags.Merge(tt.merge)
+			assert.Equal(t, tt.result, got)
+		})
+	}
+}