feat(config): Add framework for migrating deprecated plugins (#13377)

cmd/telegraf/cmd_config.go

@@ -0,0 +1,174 @@
+// Command handling for configuration "config" command
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net/url"
+	"os"
+	"path/filepath"
+
+	"github.com/influxdata/telegraf"
+	"github.com/influxdata/telegraf/config"
+	"github.com/influxdata/telegraf/logger"
+	"github.com/influxdata/telegraf/migrations"
+	"github.com/urfave/cli/v2"
+)
+
+func getConfigCommands(pluginFilterFlags []cli.Flag, outputBuffer io.Writer) []*cli.Command {
+	return []*cli.Command{
+		{
+			Name:  "config",
+			Usage: "commands for generating and migrating configurations",
+			Flags: pluginFilterFlags,
+			Action: func(cCtx *cli.Context) error {
+				// The sub_Filters are populated when the filter flags are set after the subcommand config
+				// e.g. telegraf config --section-filter inputs
+				filters := processFilterFlags(cCtx)
+
+				printSampleConfig(outputBuffer, filters)
+				return nil
+			},
+			Subcommands: []*cli.Command{
+				{
+					Name:  "create",
+					Usage: "create a full sample configuration and show it",
+					Description: `
+The 'create' produces a full configuration containing all plugins as an example
+and shows it on the console. You may apply 'section' or 'plugin' filtering
+to reduce the output to the plugins you need
+
+Create the full configuration
+
+> telegraf config create
+
+To produce a configuration only containing a Modbus input plugin and an
+InfluxDB v2 output plugin use
+
+> telegraf config create --section-filter "inputs:outputs" --input-filter "modbus" --output-filter "influxdb_v2"
+`,
+					Flags: pluginFilterFlags,
+					Action: func(cCtx *cli.Context) error {
+						filters := processFilterFlags(cCtx)
+
+						printSampleConfig(outputBuffer, filters)
+						return nil
+					},
+				},
+				{
+					Name:  "migrate",
+					Usage: "migrate deprecated plugins and options of the configuration(s)",
+					Description: `
+The 'migrate' command reads the configuration files specified via '--config' or
+'--config-directory' and tries to migrate plugins or options that are currently
+deprecated using the recommended replacements. If no configuration file is
+explicitly specified the command reads the default locations and uses those
+configuration files. Migrated files are stored with a '.migrated' suffix at the
+location of the  inputs. If you are migrating remote configurations the migrated
+configurations is stored in the current directory using the filename of the URL
+with a '.migrated' suffix.
+It is highly recommended to test those migrated configurations before using
+those files unattended!
+
+To migrate the file 'mysettings.conf' use
+
+> telegraf --config mysettings.conf config migrate
+`,
+					Flags: []cli.Flag{
+						&cli.BoolFlag{
+							Name:  "force",
+							Usage: "forces overwriting of an existing migration file",
+						},
+					},
+					Action: func(cCtx *cli.Context) error {
+						// Setup logging
+						telegraf.Debug = cCtx.Bool("debug")
+						logConfig := logger.LogConfig{Debug: telegraf.Debug}
+						if err := logger.SetupLogging(logConfig); err != nil {
+							return err
+						}
+
+						// Check if we have migrations at all. There might be
+						// none if you run a custom build without migrations
+						// enabled.
+						if len(migrations.PluginMigrations) == 0 {
+							return errors.New("no migrations available")
+						}
+						log.Printf("%d plugin migration(s) available", len(migrations.PluginMigrations))
+
+						// Collect the given configuration files
+						configFiles := cCtx.StringSlice("config")
+						configDir := cCtx.StringSlice("config-directory")
+						for _, fConfigDirectory := range configDir {
+							files, err := config.WalkDirectory(fConfigDirectory)
+							if err != nil {
+								return err
+							}
+							configFiles = append(configFiles, files...)
+						}
+
+						// If no "config" or "config-directory" flag(s) was
+						// provided we should load default configuration files
+						if len(configFiles) == 0 {
+							paths, err := config.GetDefaultConfigPath()
+							if err != nil {
+								return err
+							}
+							configFiles = paths
+						}
+
+						for _, fn := range configFiles {
+							log.Printf("D! Trying to migrate %q...", fn)
+
+							// Read and parse the config file
+							data, remote, err := config.LoadConfigFile(fn)
+							if err != nil {
+								return fmt.Errorf("opening input %q failed: %w", fn, err)
+							}
+
+							out, applied, err := config.ApplyMigrations(data)
+							if err != nil {
+								return err
+							}
+
+							// Do not write a migration file if nothing was done
+							if applied == 0 {
+								log.Printf("I! No migration applied for %q", fn)
+								continue
+							}
+
+							// Construct the output filename
+							// For remote locations we just save the filename
+							// with the migrated suffix.
+							outfn := fn + ".migrated"
+							if remote {
+								u, err := url.Parse(fn)
+								if err != nil {
+									return fmt.Errorf("parsing remote config URL %q failed: %w", fn, err)
+								}
+								outfn = filepath.Base(u.Path) + ".migrated"
+							}
+
+							log.Printf("I! %d migration applied for %q, writing result as %q", applied, fn, outfn)
+
+							// Make sure the file does not exist yet if we should not overwrite
+							if !cCtx.Bool("force") {
+								if _, err := os.Stat(outfn); !errors.Is(err, os.ErrNotExist) {
+									return fmt.Errorf("output file %q already exists", outfn)
+								}
+							}
+
+							// Write the output file
+							if err := os.WriteFile(outfn, out, 0640); err != nil {
+								return fmt.Errorf("writing output %q failed: %w", outfn, err)
+							}
+						}
+						return nil
+					},
+				},
+			},
+		},
+	}
+}

cmd/telegraf/cmd_secretstore.go

@@ -1,4 +1,4 @@
-// Command handling for secret-stores' "secret" command
+// Command handling for secret-stores' "secrets" command
 package main
 
 import (

cmd/telegraf/main.go

@@ -245,6 +245,11 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 		return m.Run()
 	}
 
+	commands := append(
+		getConfigCommands(pluginFilterFlags, outputBuffer),
+		getSecretStoreCommands(m)...,
+	)
+
 	app := &cli.App{
 		Name:   "Telegraf",
 		Usage:  "The plugin-driven server agent for collecting & reporting metrics.",
@@ -341,19 +346,6 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 			}, extraFlags...),
 		Action: action,
 		Commands: append([]*cli.Command{
-			{
-				Name:  "config",
-				Usage: "print out full sample configuration to stdout",
-				Flags: pluginFilterFlags,
-				Action: func(cCtx *cli.Context) error {
-					// The sub_Filters are populated when the filter flags are set after the subcommand config
-					// e.g. telegraf config --section-filter inputs
-					filters := processFilterFlags(cCtx)
-
-					printSampleConfig(outputBuffer, filters)
-					return nil
-				},
-			},
 			{
 				Name:  "version",
 				Usage: "print current version to stdout",
@@ -362,9 +354,7 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 					return nil
 				},
 			},
-		},
+		}, commands...),
-			getSecretStoreCommands(m)...,
-		),
 	}
 
 	// Make sure we safely erase secrets

config/config.go

@@ -376,7 +376,7 @@ func WalkDirectory(path string) ([]string, error) {
 //  1. $TELEGRAF_CONFIG_PATH
 //  2. $HOME/.telegraf/telegraf.conf
 //  3. /etc/telegraf/telegraf.conf and /etc/telegraf/telegraf.d/*.conf
-func getDefaultConfigPath() ([]string, error) {
+func GetDefaultConfigPath() ([]string, error) {
 	envfile := os.Getenv("TELEGRAF_CONFIG_PATH")
 	homefile := os.ExpandEnv("${HOME}/.telegraf/telegraf.conf")
 	etcfile := "/etc/telegraf/telegraf.conf"
@@ -434,7 +434,7 @@ func (c *Config) LoadConfig(path string) error {
 	paths := []string{}
 
 	if path == "" {
-		if paths, err = getDefaultConfigPath(); err != nil {
+		if paths, err = GetDefaultConfigPath(); err != nil {
 			return err
 		}
 	} else {
@@ -446,7 +446,7 @@ func (c *Config) LoadConfig(path string) error {
 			log.Printf("I! Loading config: %s", path)
 		}
 
-		data, err := LoadConfigFile(path)
+		data, _, err := LoadConfigFile(path)
 		if err != nil {
 			return fmt.Errorf("error loading config file %s: %w", path, err)
 		}
@@ -696,33 +696,37 @@ func trimBOM(f []byte) []byte {
 	return bytes.TrimPrefix(f, []byte("\xef\xbb\xbf"))
 }
 
-func LoadConfigFile(config string) ([]byte, error) {
+// LoadConfigFile loads the content of a configuration file and returns it
+// together with a flag denoting if the file is from a remote location such
+// as a web server.
+func LoadConfigFile(config string) ([]byte, bool, error) {
 	if fetchURLRe.MatchString(config) {
 		u, err := url.Parse(config)
 		if err != nil {
-			return nil, err
+			return nil, true, err
 		}
 
 		switch u.Scheme {
 		case "https", "http":
-			return fetchConfig(u)
+			data, err := fetchConfig(u)
+			return data, true, err
 		default:
-			return nil, fmt.Errorf("scheme %q not supported", u.Scheme)
+			return nil, true, fmt.Errorf("scheme %q not supported", u.Scheme)
 		}
 	}
 
 	// If it isn't a https scheme, try it as a file
 	buffer, err := os.ReadFile(config)
 	if err != nil {
-		return nil, err
+		return nil, false, err
 	}
 
 	mimeType := http.DetectContentType(buffer)
 	if !strings.Contains(mimeType, "text/plain") {
-		return nil, fmt.Errorf("provided config is not a TOML file: %s", config)
+		return nil, false, fmt.Errorf("provided config is not a TOML file: %s", config)
 	}
 
-	return buffer, nil
+	return buffer, false, nil
 }
 
 func fetchConfig(u *url.URL) ([]byte, error) {

config/config_test.go

@@ -3,6 +3,8 @@ package config_test
 import (
 	"bytes"
 	"fmt"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -441,6 +443,21 @@ func TestConfig_AzureMonitorNamespacePrefix(t *testing.T) {
 	}
 }
 
+func TestGetDefaultConfigPathFromEnvURL(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer ts.Close()
+
+	c := config.NewConfig()
+	t.Setenv("TELEGRAF_CONFIG_PATH", ts.URL)
+	configPath, err := config.GetDefaultConfigPath()
+	require.NoError(t, err)
+	require.Equal(t, []string{ts.URL}, configPath)
+	err = c.LoadConfig("")
+	require.NoError(t, err)
+}
+
 func TestConfig_URLLikeFileName(t *testing.T) {
 	c := config.NewConfig()
 	err := c.LoadConfig("http:##www.example.com.conf")

config/internal_test.go

@@ -135,18 +135,3 @@ func TestURLRetries3FailsThenPasses(t *testing.T) {
 	require.NoError(t, c.LoadConfig(ts.URL))
 	require.Equal(t, 4, responseCounter)
 }
-
-func TestConfig_getDefaultConfigPathFromEnvURL(t *testing.T) {
-	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		w.WriteHeader(http.StatusOK)
-	}))
-	defer ts.Close()
-
-	c := NewConfig()
-	t.Setenv("TELEGRAF_CONFIG_PATH", ts.URL)
-	configPath, err := getDefaultConfigPath()
-	require.NoError(t, err)
-	require.Equal(t, []string{ts.URL}, configPath)
-	err = c.LoadConfig("")
-	require.NoError(t, err)
-}

config/migration.go

@@ -0,0 +1,181 @@
+package config
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"sort"
+	"strings"
+
+	"github.com/influxdata/toml"
+	"github.com/influxdata/toml/ast"
+
+	"github.com/influxdata/telegraf/migrations"
+	_ "github.com/influxdata/telegraf/migrations/all" // register all migrations
+)
+
+type section struct {
+	name    string
+	begin   int
+	content *ast.Table
+	raw     *bytes.Buffer
+}
+
+func splitToSections(root *ast.Table) ([]section, error) {
+	var sections []section
+	for name, elements := range root.Fields {
+		switch name {
+		case "inputs", "outputs", "processors", "aggregators":
+			category, ok := elements.(*ast.Table)
+			if !ok {
+				return nil, fmt.Errorf("%q is not a table (%T)", name, category)
+			}
+
+			for plugin, elements := range category.Fields {
+				tbls, ok := elements.([]*ast.Table)
+				if !ok {
+					return nil, fmt.Errorf("elements of \"%s.%s\" is not a list of tables (%T)", name, plugin, elements)
+				}
+				for _, tbl := range tbls {
+					s := section{
+						name:    name + "." + tbl.Name,
+						begin:   tbl.Line,
+						content: tbl,
+						raw:     &bytes.Buffer{},
+					}
+					sections = append(sections, s)
+				}
+			}
+		default:
+			tbl, ok := elements.(*ast.Table)
+			if !ok {
+				return nil, fmt.Errorf("%q is not a table (%T)", name, elements)
+			}
+			s := section{
+				name:    name,
+				begin:   tbl.Line,
+				content: tbl,
+				raw:     &bytes.Buffer{},
+			}
+			sections = append(sections, s)
+		}
+	}
+
+	// Sort the TOML elements by begin (line-number)
+	sort.SliceStable(sections, func(i, j int) bool { return sections[i].begin < sections[j].begin })
+
+	return sections, nil
+}
+
+func assignTextToSections(data []byte, sections []section) ([]section, error) {
+	// Now assign the raw text to each section
+	if sections[0].begin > 0 {
+		sections = append([]section{{
+			name:  "header",
+			begin: 0,
+			raw:   &bytes.Buffer{},
+		}}, sections...)
+	}
+
+	var lineno int
+	scanner := bufio.NewScanner(bytes.NewBuffer(data))
+	for idx, next := range sections[1:] {
+		var buf bytes.Buffer
+		for lineno < next.begin-1 {
+			if !scanner.Scan() {
+				break
+			}
+			lineno++
+
+			line := strings.TrimSpace(scanner.Text())
+			if strings.HasPrefix(line, "#") {
+				_, _ = buf.Write(scanner.Bytes())
+				_, _ = buf.WriteString("\n")
+				continue
+			} else if buf.Len() > 0 {
+				if _, err := io.Copy(sections[idx].raw, &buf); err != nil {
+					return nil, fmt.Errorf("copying buffer failed: %w", err)
+				}
+				buf.Reset()
+			}
+
+			_, _ = sections[idx].raw.Write(scanner.Bytes())
+			_, _ = sections[idx].raw.WriteString("\n")
+		}
+		if err := scanner.Err(); err != nil {
+			return nil, fmt.Errorf("splitting by line failed: %w", err)
+		}
+
+		// If a comment is directly in front of the next section, without
+		// newline, the comment is assigned to the next section.
+		if buf.Len() > 0 {
+			if _, err := io.Copy(sections[idx+1].raw, &buf); err != nil {
+				return nil, fmt.Errorf("copying buffer failed: %w", err)
+			}
+			buf.Reset()
+		}
+	}
+	// Write the remaining to the last section
+	for scanner.Scan() {
+		_, _ = sections[len(sections)-1].raw.Write(scanner.Bytes())
+		_, _ = sections[len(sections)-1].raw.WriteString("\n")
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("splitting by line failed: %w", err)
+	}
+	return sections, nil
+}
+
+func ApplyMigrations(data []byte) ([]byte, uint64, error) {
+	root, err := toml.Parse(data)
+	if err != nil {
+		return nil, 0, fmt.Errorf("parsing failed: %w", err)
+	}
+
+	// Split the configuration into sections containing the location
+	// in the file.
+	sections, err := splitToSections(root)
+	if err != nil {
+		return nil, 0, fmt.Errorf("splitting to sections failed: %w", err)
+	}
+	if len(sections) == 0 {
+		return nil, 0, errors.New("no TOML configuration found")
+	}
+
+	// Assign the configuration text to the corresponding segments
+	sections, err = assignTextToSections(data, sections)
+	if err != nil {
+		return nil, 0, fmt.Errorf("assigning text failed: %w", err)
+	}
+
+	// Do the actual migration(s)
+	var applied uint64
+	for idx, s := range sections {
+		migrate, found := migrations.PluginMigrations[s.name]
+		if !found {
+			continue
+		}
+
+		log.Printf("D!   migrating plugin %q in line %d...", s.name, s.begin)
+		result, err := migrate(s.content)
+		if err != nil {
+			return nil, 0, fmt.Errorf("migrating %q (line %d) failed: %w", s.name, s.begin, err)
+		}
+		s.raw = bytes.NewBuffer(result)
+		sections[idx] = s
+		applied++
+	}
+
+	var buf bytes.Buffer
+	for _, s := range sections {
+		_, err = s.raw.WriteTo(&buf)
+		if err != nil {
+			return nil, applied, fmt.Errorf("joining output failed: %w", err)
+		}
+	}
+
+	return buf.Bytes(), applied, nil
+}

migrations/all/all.go

@@ -0,0 +1 @@
+package all

migrations/all/inputs_cassandra.go

@@ -0,0 +1,5 @@
+//go:build !custom || (migrations && (inputs || inputs.cassandra))
+
+package all
+
+import _ "github.com/influxdata/telegraf/migrations/inputs_cassandra" // register migration

migrations/common/filter_options.go

@@ -0,0 +1,15 @@
+package common
+
+type FilterOptions struct {
+	NamePass       []string            `toml:"namepass"`
+	NameDrop       []string            `toml:"namedrop"`
+	FieldPassOld   []string            `toml:"pass"`
+	FieldPass      []string            `toml:"fieldpass"`
+	FieldDropOld   []string            `toml:"drop"`
+	FieldDrop      []string            `toml:"fielddrop"`
+	TagPassFilters map[string][]string `toml:"tagpass"`
+	TagDropFilters map[string][]string `toml:"tagdrop"`
+	TagExclude     []string            `toml:"tagexclude"`
+	TagInclude     []string            `toml:"taginclude"`
+	MetricPass     string              `toml:"metricpass"`
+}

migrations/common/input_options.go

@@ -0,0 +1,14 @@
+package common
+
+type InputOptions struct {
+	Interval         string            `toml:"interval"`
+	Precision        string            `toml:"precision"`
+	CollectionJitter string            `toml:"collection_jitter"`
+	CollectionOffset string            `toml:"collection_offset"`
+	NamePrefix       string            `toml:"name_prefix"`
+	NameSuffix       string            `toml:"name_suffix"`
+	NameOverride     string            `toml:"name_override"`
+	Alias            string            `toml:"alias"`
+	Tags             map[string]string `toml:"tags"`
+	FilterOptions
+}

migrations/inputs_cassandra/migration.go

@@ -0,0 +1,247 @@
+package inputs_cassandra
+
+import (
+	"fmt"
+	"net/url"
+	"sort"
+	"strings"
+
+	"github.com/influxdata/toml"
+	"github.com/influxdata/toml/ast"
+
+	"github.com/influxdata/telegraf/migrations"
+	"github.com/influxdata/telegraf/migrations/common"
+)
+
+// Define "old" data structure
+type cassandra struct {
+	Context string   `toml:"context"`
+	Servers []string `toml:"servers"`
+	Metrics []string `toml:"metrics"`
+	common.InputOptions
+}
+
+// Define "new" data structure(s)
+type metricConfig struct {
+	Name        string   `toml:"name"`
+	Mbean       string   `toml:"mbean"`
+	FieldPrefix *string  `toml:"field_prefix,omitempty"`
+	TagKeys     []string `toml:"tag_keys,omitempty"`
+}
+
+type jolokiaAgent struct {
+	URLs     []string       `toml:"urls"`
+	Username string         `toml:"username,omitempty"`
+	Password string         `toml:"password,omitempty"`
+	Metrics  []metricConfig `toml:"metric"`
+
+	// Common options
+	Interval         string            `toml:"interval,omitempty"`
+	Precision        string            `toml:"precision,omitempty"`
+	CollectionJitter string            `toml:"collection_jitter,omitempty"`
+	CollectionOffset string            `toml:"collection_offset,omitempty"`
+	NamePrefix       string            `toml:"name_prefix,omitempty"`
+	NameSuffix       string            `toml:"name_suffix,omitempty"`
+	NameOverride     string            `toml:"name_override,omitempty"`
+	Alias            string            `toml:"alias,omitempty"`
+	Tags             map[string]string `toml:"tags,omitempty"`
+
+	NamePass       []string            `toml:"namepass,omitempty"`
+	NameDrop       []string            `toml:"namedrop,omitempty"`
+	FieldPass      []string            `toml:"fieldpass,omitempty"`
+	FieldDrop      []string            `toml:"fielddrop,omitempty"`
+	TagPassFilters map[string][]string `toml:"tagpass,omitempty"`
+	TagDropFilters map[string][]string `toml:"tagdrop,omitempty"`
+	TagExclude     []string            `toml:"tagexclude,omitempty"`
+	TagInclude     []string            `toml:"taginclude,omitempty"`
+	MetricPass     string              `toml:"metricpass,omitempty"`
+}
+
+// Migration function
+func migrate(tbl *ast.Table) ([]byte, error) {
+	// Decode the old data structure
+	var old cassandra
+	if err := toml.UnmarshalTable(tbl, &old); err != nil {
+		return nil, err
+	}
+
+	// Collect servers that use the same credentials
+	endpoints := make(map[string]jolokiaAgent)
+	for _, server := range old.Servers {
+		u, err := url.Parse("http://" + server)
+		if err != nil {
+			return nil, fmt.Errorf("invalid url %q: %w", server, err)
+		}
+		if u.Path != "" {
+			return nil, fmt.Errorf("unexpected path in %q: %w", server, err)
+		}
+		if u.Hostname() == "" {
+			u.Host = "localhost:" + u.Port()
+		}
+		user := u.User.Username()
+		passwd, _ := u.User.Password()
+		key := user + ":" + passwd
+
+		endpoint, found := endpoints[key]
+		if !found {
+			endpoint = jolokiaAgent{
+				Username: user,
+				Password: passwd,
+			}
+			endpoint.fillCommon(old.InputOptions)
+		}
+		u.User = nil
+		endpoint.URLs = append(endpoint.URLs, u.String())
+		endpoints[key] = endpoint
+	}
+
+	// Create new-style metrics according to the old config
+	var javaMetrics []metricConfig
+	var cassandraMetrics []metricConfig
+	for _, metric := range old.Metrics {
+		bean := strings.TrimPrefix(metric, "/")
+
+		params := make(map[string]string)
+		parts := strings.SplitN(bean, ":", 2)
+		for _, p := range strings.Split(parts[1], ",") {
+			x := strings.SplitN(p, "=", 2)
+			params[x[0]] = x[1]
+		}
+
+		name, found := params["type"]
+		if !found {
+			return nil, fmt.Errorf("cannot determine name for metric %q", metric)
+		}
+		name = strings.SplitN(name, "/", 2)[0]
+
+		var tagKeys []string
+		var prefix *string
+		for k := range params {
+			switch k {
+			case "name", "scope", "path", "keyspace":
+				tagKeys = append(tagKeys, k)
+			}
+		}
+		sort.Strings(tagKeys)
+		for i, k := range tagKeys {
+			if k == "name" {
+				p := fmt.Sprintf("$%d_", i+1)
+				prefix = &p
+				break
+			}
+		}
+
+		switch {
+		case strings.HasPrefix(bean, "java.lang:"):
+			javaMetrics = append(javaMetrics, metricConfig{
+				Name:        name,
+				Mbean:       bean,
+				TagKeys:     tagKeys,
+				FieldPrefix: prefix,
+			})
+		case strings.HasPrefix(bean, "org.apache.cassandra.metrics:"):
+			cassandraMetrics = append(cassandraMetrics, metricConfig{
+				Name:        name,
+				Mbean:       bean,
+				TagKeys:     tagKeys,
+				FieldPrefix: prefix,
+			})
+		default:
+			return nil, fmt.Errorf("unknown java metric %q", metric)
+		}
+	}
+
+	// Create the corresponding metric configurations
+	cfg := migrations.CreateTOMLStruct("inputs", "jolokia2_agent")
+	for _, endpoint := range endpoints {
+		if len(javaMetrics) > 0 {
+			plugin := jolokiaAgent{
+				URLs:     endpoint.URLs,
+				Username: endpoint.Username,
+				Password: endpoint.Password,
+				Metrics:  javaMetrics,
+			}
+			plugin.fillCommon(old.InputOptions)
+			plugin.NamePrefix = "java"
+			cfg.Add("inputs", "jolokia2_agent", plugin)
+		}
+		if len(cassandraMetrics) > 0 {
+			plugin := jolokiaAgent{
+				URLs:     endpoint.URLs,
+				Username: endpoint.Username,
+				Password: endpoint.Password,
+				Metrics:  cassandraMetrics,
+			}
+			plugin.fillCommon(old.InputOptions)
+			plugin.NamePrefix = "cassandra"
+
+			cfg.Add("inputs", "jolokia2_agent", plugin)
+		}
+	}
+
+	// Marshal the new configuration
+	buf, err := toml.Marshal(cfg)
+	if err != nil {
+		return nil, err
+	}
+	buf = append(buf, []byte("\n")...)
+
+	// Create the new content to output
+	return buf, nil
+}
+
+func (j *jolokiaAgent) fillCommon(o common.InputOptions) {
+	j.Interval = o.Interval
+	j.Precision = o.Precision
+	j.CollectionJitter = o.CollectionJitter
+	j.CollectionOffset = o.CollectionOffset
+	j.NamePrefix = o.NamePrefix
+	j.NameSuffix = o.NameSuffix
+	j.NameOverride = o.NameOverride
+	j.Alias = o.Alias
+	if len(o.Tags) > 0 {
+		j.Tags = make(map[string]string, len(o.Tags))
+		for k, v := range o.Tags {
+			j.Tags[k] = v
+		}
+	}
+
+	if len(o.NamePass) > 0 {
+		j.NamePass = append(j.NamePass, o.NamePass...)
+	}
+	if len(o.NameDrop) > 0 {
+		j.NameDrop = append(j.NameDrop, o.NameDrop...)
+	}
+	if len(o.FieldPass) > 0 || len(o.FieldDropOld) > 0 {
+		j.FieldPass = append(j.FieldPass, o.FieldPass...)
+		j.FieldPass = append(j.FieldPass, o.FieldPassOld...)
+	}
+	if len(o.FieldDrop) > 0 || len(o.FieldDropOld) > 0 {
+		j.FieldDrop = append(j.FieldDrop, o.FieldDrop...)
+		j.FieldDrop = append(j.FieldDrop, o.FieldDropOld...)
+	}
+	if len(o.TagPassFilters) > 0 {
+		j.TagPassFilters = make(map[string][]string, len(o.TagPassFilters))
+		for k, v := range o.TagPassFilters {
+			j.TagPassFilters[k] = v
+		}
+	}
+	if len(o.TagDropFilters) > 0 {
+		j.TagDropFilters = make(map[string][]string, len(o.TagDropFilters))
+		for k, v := range o.TagDropFilters {
+			j.TagDropFilters[k] = v
+		}
+	}
+	if len(o.TagExclude) > 0 {
+		j.TagExclude = append(j.TagExclude, o.TagExclude...)
+	}
+	if len(o.TagInclude) > 0 {
+		j.TagInclude = append(j.TagInclude, o.TagInclude...)
+	}
+	j.MetricPass = o.MetricPass
+}
+
+// Register the migration function for the plugin type
+func init() {
+	migrations.AddPluginMigration("inputs.cassandra", migrate)
+}

migrations/inputs_cassandra/migration_test.go

@@ -0,0 +1,61 @@
+package inputs_cassandra_test
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/influxdata/telegraf/config"
+	_ "github.com/influxdata/telegraf/migrations/inputs_cassandra"   // register migration
+	_ "github.com/influxdata/telegraf/plugins/inputs/jolokia2_agent" // register plugin
+)
+
+func TestCases(t *testing.T) {
+	// Get all directories in testdata
+	folders, err := os.ReadDir("testcases")
+	require.NoError(t, err)
+
+	for _, f := range folders {
+		// Only handle folders
+		if !f.IsDir() {
+			continue
+		}
+
+		t.Run(f.Name(), func(t *testing.T) {
+			testcasePath := filepath.Join("testcases", f.Name())
+			inputFile := filepath.Join(testcasePath, "telegraf.conf")
+			expectedFile := filepath.Join(testcasePath, "expected.conf")
+
+			// Read the expected output
+			expected := config.NewConfig()
+			require.NoError(t, expected.LoadConfig(expectedFile))
+			require.NotEmpty(t, expected.Inputs)
+
+			// Read the input data
+			input, remote, err := config.LoadConfigFile(inputFile)
+			require.NoError(t, err)
+			require.False(t, remote)
+			require.NotEmpty(t, input)
+
+			// Migrate
+			output, n, err := config.ApplyMigrations(input)
+			require.NoError(t, err)
+			require.NotEmpty(t, output)
+			require.GreaterOrEqual(t, n, uint64(1))
+			actual := config.NewConfig()
+			require.NoError(t, actual.LoadConfigData(output))
+
+			// Test the output
+			require.Len(t, actual.Inputs, len(expected.Inputs))
+			actualIDs := make([]string, 0, len(expected.Inputs))
+			expectedIDs := make([]string, 0, len(expected.Inputs))
+			for i := range actual.Inputs {
+				actualIDs = append(actualIDs, actual.Inputs[i].ID())
+				expectedIDs = append(expectedIDs, expected.Inputs[i].ID())
+			}
+			require.ElementsMatch(t, expectedIDs, actualIDs)
+		})
+	}
+}

migrations/inputs_cassandra/testcases/filter_options/expected.conf

@@ -0,0 +1,55 @@
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.1:8778"]
+username = "myuser"
+password = "mypassword"
+name_prefix = "java"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Memory"
+mbean = "java.lang:type=Memory/HeapMemoryUsage"
+
+[inputs.jolokia2_agent.tagdrop]
+app = ["myapp"]
+location = ["e*"]
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.1:8778"]
+username = "myuser"
+password = "mypassword"
+name_prefix = "cassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Table"
+mbean = "org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+field_prefix = "$2_"
+tag_keys = ["keyspace", "name", "scope"]
+
+[inputs.jolokia2_agent.tagdrop]
+app = ["myapp"]
+location = ["e*"]
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.2:8778", "http://localhost:8778"]
+name_prefix = "java"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Memory"
+mbean = "java.lang:type=Memory/HeapMemoryUsage"
+
+[inputs.jolokia2_agent.tagdrop]
+app = ["myapp"]
+location = ["e*"]
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.2:8778", "http://localhost:8778"]
+name_prefix = "cassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Table"
+mbean = "org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+field_prefix = "$2_"
+tag_keys = ["keyspace", "name", "scope"]
+
+[inputs.jolokia2_agent.tagdrop]
+app = ["myapp"]
+location = ["e*"]

migrations/inputs_cassandra/testcases/filter_options/telegraf.conf

@@ -0,0 +1,11 @@
+[[inputs.cassandra]]
+  context = "/jolokia/read"
+  servers = ["myuser:mypassword@10.10.10.1:8778","10.10.10.2:8778",":8778"]
+  metrics  = [
+    "/java.lang:type=Memory/HeapMemoryUsage",
+    "/org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+  ]
+
+  [inputs.cassandra.tagdrop]
+    app = ["myapp"]
+    location = ["e*"]

migrations/inputs_cassandra/testcases/general_options/expected.conf

@@ -0,0 +1,64 @@
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.1:8778"]
+username = "myuser"
+password = "mypassword"
+interval = "20s"
+name_prefix = "java"
+alias = "mycassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Memory"
+mbean = "java.lang:type=Memory/HeapMemoryUsage"
+
+[inputs.jolokia2_agent.tags]
+app = "myapp"
+location = "east"
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.1:8778"]
+username = "myuser"
+password = "mypassword"
+interval = "20s"
+name_prefix = "cassandra"
+alias = "mycassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Table"
+mbean = "org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+field_prefix = "$2_"
+tag_keys = ["keyspace", "name", "scope"]
+
+[inputs.jolokia2_agent.tags]
+app = "myapp"
+location = "east"
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.2:8778", "http://localhost:8778"]
+interval = "20s"
+name_prefix = "java"
+alias = "mycassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Memory"
+mbean = "java.lang:type=Memory/HeapMemoryUsage"
+
+[inputs.jolokia2_agent.tags]
+app = "myapp"
+location = "east"
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.2:8778", "http://localhost:8778"]
+interval = "20s"
+name_prefix = "cassandra"
+alias = "mycassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Table"
+mbean = "org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+field_prefix = "$2_"
+tag_keys = ["keyspace", "name", "scope"]
+
+[inputs.jolokia2_agent.tags]
+app = "myapp"
+location = "east"
+

migrations/inputs_cassandra/testcases/general_options/telegraf.conf

@@ -0,0 +1,13 @@
+[[inputs.cassandra]]
+  interval = "20s"
+  alias = "mycassandra"
+  context = "/jolokia/read"
+  servers = ["myuser:mypassword@10.10.10.1:8778","10.10.10.2:8778",":8778"]
+  metrics  = [
+    "/java.lang:type=Memory/HeapMemoryUsage",
+    "/org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+  ]
+
+  [inputs.cassandra.tags]
+    app = "myapp"
+    location = "east"

migrations/inputs_cassandra/testcases/simple/expected.conf

@@ -0,0 +1,40 @@
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.1:8778"]
+username = "myuser"
+password = "mypassword"
+name_prefix = "java"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Memory"
+mbean = "java.lang:type=Memory/HeapMemoryUsage"
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.1:8778"]
+username = "myuser"
+password = "mypassword"
+name_prefix = "cassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Table"
+mbean = "org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+field_prefix = "$2_"
+tag_keys = ["keyspace", "name", "scope"]
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.2:8778", "http://localhost:8778"]
+name_prefix = "java"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Memory"
+mbean = "java.lang:type=Memory/HeapMemoryUsage"
+
+[[inputs.jolokia2_agent]]
+urls = ["http://10.10.10.2:8778", "http://localhost:8778"]
+name_prefix = "cassandra"
+
+[[inputs.jolokia2_agent.metric]]
+name = "Table"
+mbean = "org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+field_prefix = "$2_"
+tag_keys = ["keyspace", "name", "scope"]
+

migrations/inputs_cassandra/testcases/simple/telegraf.conf

@@ -0,0 +1,14 @@
+[[inputs.cassandra]]
+  context = "/jolokia/read"
+  ## List of cassandra servers exposing jolokia read service
+  servers = ["myuser:mypassword@10.10.10.1:8778","10.10.10.2:8778",":8778"]
+  ## List of metrics collected on above servers
+  ## Each metric consists of a jmx path.
+  ## This will collect all heap memory usage metrics from the jvm and
+  ## ReadLatency metrics for all keyspaces and tables.
+  ## "type=Table" in the query works with Cassandra3.0. Older versions might
+  ## need to use "type=ColumnFamily"
+  metrics  = [
+    "/java.lang:type=Memory/HeapMemoryUsage",
+    "/org.apache.cassandra.metrics:type=Table,keyspace=*,scope=*,name=ReadLatency"
+  ]

migrations/registry.go

@@ -0,0 +1,33 @@
+package migrations
+
+import (
+	"fmt"
+
+	"github.com/influxdata/toml/ast"
+)
+
+type PluginMigrationFunc func(*ast.Table) ([]byte, error)
+
+var PluginMigrations = make(map[string]PluginMigrationFunc)
+
+func AddPluginMigration(name string, f PluginMigrationFunc) {
+	if _, found := PluginMigrations[name]; found {
+		panic(fmt.Errorf("plugin migration function already registered for %q", name))
+	}
+	PluginMigrations[name] = f
+}
+
+type pluginTOMLStruct map[string]map[string][]interface{}
+
+func CreateTOMLStruct(category, name string) pluginTOMLStruct {
+	return map[string]map[string][]interface{}{
+		category: {
+			name: make([]interface{}, 0),
+		},
+	}
+}
+
+func (p *pluginTOMLStruct) Add(category, name string, plugin interface{}) {
+	cfg := map[string]map[string][]interface{}(*p)
+	cfg[category][name] = append(cfg[category][name], plugin)
+}

tools/custom_builder/config.go

@@ -109,7 +109,7 @@ func (s *selection) Filter(p packageCollection) *packageCollection {
 
 func (s *selection) importFiles(configurations []string) error {
 	for _, cfg := range configurations {
-		buf, err := config.LoadConfigFile(cfg)
+		buf, _, err := config.LoadConfigFile(cfg)
 		if err != nil {
 			return fmt.Errorf("reading %q failed: %w", cfg, err)
 		}

tools/custom_builder/main.go

@@ -63,7 +63,7 @@ func usage() {
 }
 
 func main() {
-	var dryrun, showtags, quiet bool
+	var dryrun, showtags, migrations, quiet bool
 	var configFiles, configDirs []string
 
 	flag.Func("config",
@@ -82,6 +82,7 @@ func main() {
 	)
 	flag.BoolVar(&dryrun, "dry-run", false, "Skip the actual building step")
 	flag.BoolVar(&quiet, "quiet", false, "Print fewer log messages")
+	flag.BoolVar(&migrations, "migrations", false, "Include configuration migrations")
 	flag.BoolVar(&showtags, "tags", false, "Show build-tags used")
 
 	flag.Usage = usage
@@ -125,7 +126,11 @@ func main() {
 	if len(tagset) == 0 {
 		log.Fatalln("Nothing selected!")
 	}
-	tags := "custom," + strings.Join(tagset, ",")
+	tags := "custom,"
+	if migrations {
+		tags += "migrations,"
+	}
+	tags += strings.Join(tagset, ",")
 	if showtags {
 		fmt.Printf("Build tags: %s\n", tags)
 	}