fix(cli): Support old style of filtering sample configs (#11896)

cmd/telegraf/main.go

@@ -35,7 +35,41 @@ type Filters struct {
 	processor  []string
 }
 
-func processFilterFlags(section, input, output, aggregator, processor string) Filters {
+func appendFilter(a, b string) string {
+	if a != "" && b != "" {
+		return fmt.Sprintf("%s:%s", a, b)
+	}
+	if a != "" {
+		return a
+	}
+	return b
+}
+
+func processFilterFlags(ctx *cli.Context) Filters {
+	var section, input, output, aggregator, processor string
+
+	// Support defining filters before and after the command
+	// The old style was:
+	// ./telegraf --section-filter inputs --input-filter cpu config >test.conf
+	// The new style is:
+	// ./telegraf config --section-filter inputs --input-filter cpu >test.conf
+	// To support the old style, check if the parent context has the filter flags defined
+	if len(ctx.Lineage()) >= 2 {
+		parent := ctx.Lineage()[1] // ancestor contexts in order from child to parent
+		section = parent.String("section-filter")
+		input = parent.String("input-filter")
+		output = parent.String("output-filter")
+		aggregator = parent.String("aggregator-filter")
+		processor = parent.String("processor-filter")
+	}
+
+	// If both the parent and command filters are defined, append them together
+	section = appendFilter(section, ctx.String("section-filter"))
+	input = appendFilter(input, ctx.String("input-filter"))
+	output = appendFilter(output, ctx.String("output-filter"))
+	aggregator = appendFilter(aggregator, ctx.String("aggregator-filter"))
+	processor = appendFilter(processor, ctx.String("processor-filter"))
+
 	sectionFilters := deleteEmpty(strings.Split(section, ":"))
 	inputFilters := deleteEmpty(strings.Split(input, ":"))
 	outputFilters := deleteEmpty(strings.Split(output, ":"))
@@ -99,13 +133,7 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 		switch {
 		// print available input plugins
 		case cCtx.Bool("deprecation-list"):
-			filters := processFilterFlags(
+			filters := processFilterFlags(cCtx)
-				cCtx.String("section-filter"),
-				cCtx.String("input-filter"),
-				cCtx.String("output-filter"),
-				cCtx.String("aggregator-filter"),
-				cCtx.String("processor-filter"),
-			)
 			infos := c.CollectDeprecationInfos(
 				filters.input, filters.output, filters.aggregator, filters.processor,
 			)
@@ -156,13 +184,7 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 			return nil
 		// DEPRECATED
 		case cCtx.Bool("sample-config"):
-			filters := processFilterFlags(
+			filters := processFilterFlags(cCtx)
-				cCtx.String("section-filter"),
-				cCtx.String("input-filter"),
-				cCtx.String("output-filter"),
-				cCtx.String("aggregator-filter"),
-				cCtx.String("processor-filter"),
-			)
 
 			printSampleConfig(
 				outputBuffer,
@@ -179,13 +201,7 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 			pprof.Start(cCtx.String("pprof-addr"))
 		}
 
-		filters := processFilterFlags(
+		filters := processFilterFlags(cCtx)
-			cCtx.String("section-filter"),
-			cCtx.String("input-filter"),
-			cCtx.String("output-filter"),
-			cCtx.String("aggregator-filter"),
-			cCtx.String("processor-filter"),
-		)
 
 		g := GlobalFlags{
 			config:      cCtx.StringSlice("config"),
@@ -311,13 +327,7 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 				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(
+					filters := processFilterFlags(cCtx)
-						cCtx.String("section-filter"),
-						cCtx.String("input-filter"),
-						cCtx.String("output-filter"),
-						cCtx.String("aggregator-filter"),
-						cCtx.String("processor-filter"),
-					)
 
 					printSampleConfig(
 						outputBuffer,

cmd/telegraf/main_test.go

@@ -199,9 +199,8 @@ func TestCommandConfig(t *testing.T) {
 		expectedPlugins []string
 		removedPlugins  []string
 	}{
-		// Deprecated flag replaced with command "config"
 		{
-			name:     "no filters",
+			name:     "deprecated flag --sample-config",
 			commands: []string{"--sample-config"},
 			expectedHeaders: []string{
 				outputHeader,
@@ -290,6 +289,28 @@ func TestCommandConfig(t *testing.T) {
 				"[[aggregators.minmax]]",
 			},
 		},
+		{
+			name:     "test filters before config",
+			commands: []string{"--input-filter", "cpu:file", "config"},
+			expectedPlugins: []string{
+				"[[inputs.cpu]]",
+				"[[inputs.file]]",
+			},
+			removedPlugins: []string{
+				"[[inputs.disk]]",
+			},
+		},
+		{
+			name:     "test filters before and after config",
+			commands: []string{"--input-filter", "file", "config", "--input-filter", "cpu"},
+			expectedPlugins: []string{
+				"[[inputs.cpu]]",
+				"[[inputs.file]]",
+			},
+			removedPlugins: []string{
+				"[[inputs.disk]]",
+			},
+		},
 	}
 
 	for _, test := range tests {