fix(config): Restore old environment var behavior with option (#13457)

cmd/telegraf/main.go

@@ -226,6 +226,7 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 			pidFile:        cCtx.String("pidfile"),
 			plugindDir:     cCtx.String("plugin-directory"),
 			password:       cCtx.String("password"),
+			oldEnvBehavior: cCtx.Bool("old-env-behavior"),
 			test:           cCtx.Bool("test"),
 			debug:          cCtx.Bool("debug"),
 			once:           cCtx.Bool("once"),
@@ -294,6 +295,10 @@ func runApp(args []string, outputBuffer io.Writer, pprof Server, c TelegrafConfi
 				},
 				//
 				// Bool flags
+				&cli.BoolFlag{
+					Name:  "old-env-behavior",
+					Usage: "switch back to pre v1.27 environment replacement behavior",
+				},
 				&cli.BoolFlag{
 					Name:  "once",
 					Usage: "run one gather and exit",

cmd/telegraf/telegraf.go

@@ -39,6 +39,7 @@ type GlobalFlags struct {
 	pidFile        string
 	plugindDir     string
 	password       string
+	oldEnvBehavior bool
 	test           bool
 	debug          bool
 	once           bool
@@ -87,6 +88,9 @@ func (t *Telegraf) Init(pprofErr <-chan error, f Filters, g GlobalFlags, w Windo
 	if g.password != "" {
 		config.Password = config.NewSecret([]byte(g.password))
 	}
+
+	// Set environment replacement behavior
+	config.OldEnvVarReplacement = g.oldEnvBehavior
 }
 
 func (t *Telegraf) ListSecretStores() ([]string, error) {

config/config.go

@@ -40,12 +40,6 @@ import (
 	"github.com/influxdata/telegraf/plugins/serializers"
 )
 
-// envVarPattern is a regex to determine environment variables in the
-// config file for substitution. Those should start with a dollar signs.
-// Expression modified from
-// https://github.com/compose-spec/compose-go/blob/v1.14.0/template/template.go
-const envVarPattern = `\\(?P<escaped>\$)|\$(?i:(?P<named>[_a-z][_a-z0-9]*)|\${(?:(?P<braced>[_a-z][_a-z0-9]*(?::?[-+?](.*))?)}|(?P<invalid>)))`
-
 var (
 	httpLoadConfigRetryInterval = 10 * time.Second
 
@@ -53,8 +47,12 @@ var (
 	// be fetched from a remote or read from the filesystem.
 	fetchURLRe = regexp.MustCompile(`^\w+://`)
 
-	// envVarRe is the compiled regex of envVarPattern
+	// oldVarRe is a regex to reproduce pre v1.27.0 environment variable
-	envVarRe = regexp.MustCompile(envVarPattern)
+	// replacement behavior
+	oldVarRe = regexp.MustCompile(`\$(?i:(?P<named>[_a-z][_a-z0-9]*)|{(?:(?P<braced>[_a-z][_a-z0-9]*(?::?[-+?](.*))?)}|(?P<invalid>)))`)
+	// OldEnvVarReplacement is a switch to allow going back to pre v1.27.0
+	// environment variable replacement behavior
+	OldEnvVarReplacement = false
 
 	// Password specified via command-line
 	Password Secret
@@ -794,7 +792,7 @@ func parseConfig(contents []byte) (*ast.Table, error) {
 	if err != nil {
 		return nil, err
 	}
-	outputBytes, err := substituteEnvironment(contents)
+	outputBytes, err := substituteEnvironment(contents, OldEnvVarReplacement)
 	if err != nil {
 		return nil, err
 	}
@@ -857,19 +855,36 @@ func removeComments(contents []byte) ([]byte, error) {
 	return output.Bytes(), nil
 }
 
-func substituteEnvironment(contents []byte) ([]byte, error) {
+func substituteEnvironment(contents []byte, oldReplacementBehavior bool) ([]byte, error) {
+	options := []template.Option{
+		template.WithReplacementFunction(func(s string, m template.Mapping, cfg *template.Config) (string, error) {
+			result, err := template.DefaultReplacementFunc(s, m, cfg)
+			if err == nil && result == "" {
+				// Keep undeclared environment-variable patterns to reproduce
+				// pre-v1.27 behavior
+				return s, nil
+			}
+			if err != nil && strings.HasPrefix(err.Error(), "Invalid template:") {
+				// Keep invalid template patterns to ignore regexp substitutions
+				// like ${1}
+				return s, nil
+			}
+			return result, err
+		}),
+		template.WithoutLogging,
+	}
+	if oldReplacementBehavior {
+		options = append(options, template.WithPattern(oldVarRe))
+	}
+
 	envMap := utils.GetAsEqualsMap(os.Environ())
-	retVal, err := template.SubstituteWith(string(contents), func(k string) (string, bool) {
+	retVal, err := template.SubstituteWithOptions(string(contents), func(k string) (string, bool) {
 		if v, ok := envMap[k]; ok {
 			return v, ok
 		}
 		return "", false
-	}, envVarRe)
+	}, options...)
-	var invalidTmplError *template.InvalidTemplateError
+	return []byte(retVal), err
-	if err != nil && !errors.As(err, &invalidTmplError) {
-		return nil, err
-	}
-	return []byte(retVal), nil
 }
 
 func (c *Config) addAggregator(name string, table *ast.Table) error {

config/config_test.go

@@ -71,7 +71,7 @@ func TestConfig_LoadSingleInputWithEnvVars(t *testing.T) {
 
 	input := inputs.Inputs["memcached"]().(*MockupInputPlugin)
 	input.Servers = []string{"192.168.1.1"}
-	input.Command = `Raw command which may or may not contain # or ${var} in it
+	input.Command = `Raw command which may or may not contain # in it
 # is unique`
 
 	filter := models.Filter{

config/internal_test.go

@@ -25,17 +25,17 @@ func TestEnvironmentSubstitution(t *testing.T) {
 				t.Setenv("TEST_ENV1", "VALUE1")
 				t.Setenv("TEST_ENV2", "VALUE2")
 			},
-			contents: "A string with $${TEST_ENV1}, $TEST_ENV2 and $TEST_ENV1 as repeated",
+			contents: "A string with ${TEST_ENV1}, $TEST_ENV2 and $TEST_ENV1 as repeated",
 			expected: "A string with VALUE1, VALUE2 and VALUE1 as repeated",
 		},
 		{
 			name:     "Env not set",
-			contents: "Env variable $${NOT_SET} will be empty",
+			contents: "Env variable ${NOT_SET} will be empty",
-			expected: "Env variable  will be empty", // Two spaces present
+			expected: "Env variable ${NOT_SET} will be empty",
 		},
 		{
 			name:     "Env not set, fallback to default",
-			contents: "Env variable $${THIS_IS_ABSENT:-Fallback}",
+			contents: "Env variable ${THIS_IS_ABSENT:-Fallback}",
 			expected: "Env variable Fallback",
 		},
 		{
@@ -43,7 +43,7 @@ func TestEnvironmentSubstitution(t *testing.T) {
 			setEnv: func(t *testing.T) {
 				t.Setenv("MY_ENV1", "VALUE1")
 			},
-			contents: "Env variable $${MY_ENV1:-Fallback}",
+			contents: "Env variable ${MY_ENV1:-Fallback}",
 			expected: "Env variable VALUE1",
 		},
 		{
@@ -52,17 +52,17 @@ func TestEnvironmentSubstitution(t *testing.T) {
 				t.Setenv("MY_VAR", "VALUE")
 				t.Setenv("MY_VAR2", "VALUE2")
 			},
-			contents: "Env var $${MY_VAR} is set, with $MY_VAR syntax and default on this $${MY_VAR1:-Substituted}, no default on this $${MY_VAR2:-NoDefault}",
+			contents: "Env var ${MY_VAR} is set, with $MY_VAR syntax and default on this ${MY_VAR1:-Substituted}, no default on this ${MY_VAR2:-NoDefault}",
 			expected: "Env var VALUE is set, with VALUE syntax and default on this Substituted, no default on this VALUE2",
 		},
 		{
 			name:     "Default has special chars",
-			contents: `Not recommended but supported $${MY_VAR:-Default with special chars Supported#$\"}`,
+			contents: `Not recommended but supported ${MY_VAR:-Default with special chars Supported#$\"}`,
 			expected: `Not recommended but supported Default with special chars Supported#$\"`, // values are escaped
 		},
 		{
 			name:         "unset error",
-			contents:     "Contains $${THIS_IS_NOT_SET?unset-error}",
+			contents:     "Contains ${THIS_IS_NOT_SET?unset-error}",
 			wantErr:      true,
 			errSubstring: "unset-error",
 		},
@@ -71,7 +71,7 @@ func TestEnvironmentSubstitution(t *testing.T) {
 			setEnv: func(t *testing.T) {
 				t.Setenv("ENV_EMPTY", "")
 			},
-			contents:     "Contains $${ENV_EMPTY:?empty-error}",
+			contents:     "Contains ${ENV_EMPTY:?empty-error}",
 			wantErr:      true,
 			errSubstring: "empty-error",
 		},
@@ -80,33 +80,9 @@ func TestEnvironmentSubstitution(t *testing.T) {
 			setEnv: func(t *testing.T) {
 				t.Setenv("FALLBACK", "my-fallback")
 			},
-			contents: "Should output $${NOT_SET:-${FALLBACK}}",
+			contents: "Should output ${NOT_SET:-${FALLBACK}}",
 			expected: "Should output my-fallback",
 		},
-		{
-			name: "leave alone single dollar expressions #13432",
-			setEnv: func(t *testing.T) {
-				t.Setenv("MYVAR", "my-variable")
-			},
-			contents: "Should output ${MYVAR}",
-			expected: "Should output ${MYVAR}",
-		},
-		{
-			name: "leave alone escaped expressions (backslash)",
-			setEnv: func(t *testing.T) {
-				t.Setenv("MYVAR", "my-variable")
-			},
-			contents: `Should output \$MYVAR`,
-			expected: "Should output $MYVAR",
-		},
-		{
-			name: "double dollar no brackets",
-			setEnv: func(t *testing.T) {
-				t.Setenv("MYVAR", "my-variable")
-			},
-			contents: `Should output $$MYVAR`,
-			expected: "Should output $my-variable",
-		},
 	}
 
 	for _, tt := range tests {
@@ -114,7 +90,7 @@ func TestEnvironmentSubstitution(t *testing.T) {
 			if tt.setEnv != nil {
 				tt.setEnv(t)
 			}
-			actual, err := substituteEnvironment([]byte(tt.contents))
+			actual, err := substituteEnvironment([]byte(tt.contents), false)
 			if tt.wantErr {
 				require.ErrorContains(t, err, tt.errSubstring)
 				return
@@ -124,6 +100,194 @@ func TestEnvironmentSubstitution(t *testing.T) {
 	}
 }
 
+func TestEnvironmentSubstitutionOldBehavior(t *testing.T) {
+	tests := []struct {
+		name     string
+		contents string
+		expected string
+	}{
+		{
+			name:     "not defined no brackets",
+			contents: `my-da$tabase`,
+			expected: `my-da$tabase`,
+		},
+		{
+			name:     "not defined brackets",
+			contents: `my-da${ta}base`,
+			expected: `my-da${ta}base`,
+		},
+		{
+			name:     "not defined no brackets double dollar",
+			contents: `my-da$$tabase`,
+			expected: `my-da$$tabase`,
+		},
+		{
+			name:     "not defined no brackets backslash",
+			contents: `my-da\$tabase`,
+			expected: `my-da\$tabase`,
+		},
+		{
+			name:     "not defined brackets backslash",
+			contents: `my-da\${ta}base`,
+			expected: `my-da\${ta}base`,
+		},
+		{
+			name:     "no brackets and suffix",
+			contents: `my-da$VARbase`,
+			expected: `my-da$VARbase`,
+		},
+		{
+			name:     "no brackets",
+			contents: `my-da$VAR`,
+			expected: `my-dafoobar`,
+		},
+		{
+			name:     "brackets",
+			contents: `my-da${VAR}base`,
+			expected: `my-dafoobarbase`,
+		},
+		{
+			name:     "no brackets double dollar",
+			contents: `my-da$$VAR`,
+			expected: `my-da$foobar`,
+		},
+		{
+			name:     "brackets double dollar",
+			contents: `my-da$${VAR}`,
+			expected: `my-da$foobar`,
+		},
+		{
+			name:     "no brackets backslash",
+			contents: `my-da\$VAR`,
+			expected: `my-da\foobar`,
+		},
+		{
+			name:     "brackets backslash",
+			contents: `my-da\${VAR}base`,
+			expected: `my-da\foobarbase`,
+		},
+		{
+			name:     "fallback",
+			contents: `my-da${ta:-omg}base`,
+			expected: `my-daomgbase`,
+		},
+		{
+			name:     "fallback env",
+			contents: `my-da${ta:-${FALLBACK}}base`,
+			expected: `my-dadefaultbase`,
+		},
+		{
+			name:     "regex substitution",
+			contents: `${1}`,
+			expected: `${1}`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("VAR", "foobar")
+			t.Setenv("FALLBACK", "default")
+			actual, err := substituteEnvironment([]byte(tt.contents), true)
+			require.NoError(t, err)
+			require.EqualValues(t, tt.expected, string(actual))
+		})
+	}
+}
+
+func TestEnvironmentSubstitutionNewBehavior(t *testing.T) {
+	tests := []struct {
+		name     string
+		contents string
+		expected string
+	}{
+		{
+			name:     "not defined no brackets",
+			contents: `my-da$tabase`,
+			expected: `my-da$tabase`,
+		},
+		{
+			name:     "not defined brackets",
+			contents: `my-da${ta}base`,
+			expected: `my-da${ta}base`,
+		},
+		{
+			name:     "not defined no brackets double dollar",
+			contents: `my-da$$tabase`,
+			expected: `my-da$tabase`,
+		},
+		{
+			name:     "not defined no brackets backslash",
+			contents: `my-da\$tabase`,
+			expected: `my-da\$tabase`,
+		},
+		{
+			name:     "not defined brackets backslash",
+			contents: `my-da\${ta}base`,
+			expected: `my-da\${ta}base`,
+		},
+		{
+			name:     "no brackets and suffix",
+			contents: `my-da$VARbase`,
+			expected: `my-da$VARbase`,
+		},
+		{
+			name:     "no brackets",
+			contents: `my-da$VAR`,
+			expected: `my-dafoobar`,
+		},
+		{
+			name:     "brackets",
+			contents: `my-da${VAR}base`,
+			expected: `my-dafoobarbase`,
+		},
+		{
+			name:     "no brackets double dollar",
+			contents: `my-da$$VAR`,
+			expected: `my-da$VAR`,
+		},
+		{
+			name:     "brackets double dollar",
+			contents: `my-da$${VAR}`,
+			expected: `my-da${VAR}`,
+		},
+		{
+			name:     "no brackets backslash",
+			contents: `my-da\$VAR`,
+			expected: `my-da\foobar`,
+		},
+		{
+			name:     "brackets backslash",
+			contents: `my-da\${VAR}base`,
+			expected: `my-da\foobarbase`,
+		},
+		{
+			name:     "fallback",
+			contents: `my-da${ta:-omg}base`,
+			expected: `my-daomgbase`,
+		},
+		{
+			name:     "fallback env",
+			contents: `my-da${ta:-${FALLBACK}}base`,
+			expected: `my-dadefaultbase`,
+		},
+		{
+			name:     "regex substitution",
+			contents: `${1}`,
+			expected: `${1}`,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("VAR", "foobar")
+			t.Setenv("FALLBACK", "default")
+			actual, err := substituteEnvironment([]byte(tt.contents), false)
+			require.NoError(t, err)
+			require.EqualValues(t, tt.expected, string(actual))
+		})
+	}
+}
+
 func TestURLRetries3Fails(t *testing.T) {
 	httpLoadConfigRetryInterval = 0 * time.Second
 	responseCounter := 0

config/testdata/single_plugin_env_vars.toml

@@ -10,20 +10,20 @@
 # file would generate.
 #
 # Environment variables can be used anywhere in this config file, simply surround
-# them with $${}. For strings the variable must be within quotes (ie, "$${STR_VAR}"),
+# them with ${}. For strings the variable must be within quotes (ie, "${STR_VAR}"),
-# for numbers and booleans they should be plain (ie, $${INT_VAR}, $${BOOL_VAR})
+# for numbers and booleans they should be plain (ie, ${INT_VAR}, ${BOOL_VAR})
 
 [[inputs.memcached]]
   # this comment line will be ignored by the parser
   servers = ["$MY_TEST_SERVER"]
-  namepass = ["metricname1", "ip_$${MY_TEST_SERVER}_name"] # this comment will be ignored as well
+  namepass = ["metricname1", "ip_${MY_TEST_SERVER}_name"] # this comment will be ignored as well
   namedrop = ["metricname2"]
   fieldpass = ["some", "strings"]
   fielddrop = ["other", "stuff"]
   interval = "$TEST_INTERVAL"
    ##### this input is provided to test multiline strings
   command = """
-Raw command which may or may not contain # or ${var} in it
+Raw command which may or may not contain # in it
 # is unique""" # Multiline comment black starting with #
   [inputs.memcached.tagpass]
     goodtag = ["mytag", """tagwith#value""",

go.mod

@@ -55,7 +55,7 @@ require (
 	github.com/caio/go-tdigest v3.1.0+incompatible
 	github.com/cisco-ie/nx-telemetry-proto v0.0.0-20230117155933-f64c045c77df
 	github.com/clarify/clarify-go v0.2.4
-	github.com/compose-spec/compose-go v1.13.4
+	github.com/compose-spec/compose-go v1.15.0
 	github.com/coocood/freecache v1.2.3
 	github.com/coreos/go-semver v0.3.1
 	github.com/coreos/go-systemd v0.0.0-20190719114852-fd7a80b32e1f
@@ -188,7 +188,7 @@ require (
 	golang.org/x/mod v0.10.0
 	golang.org/x/net v0.10.0
 	golang.org/x/oauth2 v0.8.0
-	golang.org/x/sync v0.2.0
+	golang.org/x/sync v0.3.0
 	golang.org/x/sys v0.9.0
 	golang.org/x/term v0.9.0
 	golang.org/x/text v0.9.0
@@ -209,11 +209,6 @@ require (
 	modernc.org/sqlite v1.23.1
 )
 
-require (
-	google.golang.org/genproto v0.0.0-20230530153820-e85fd2cbaebc // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20230530153820-e85fd2cbaebc // indirect
-)
-
 require (
 	cloud.google.com/go v0.110.1 // indirect
 	cloud.google.com/go/compute v1.19.1 // indirect
@@ -335,7 +330,7 @@ require (
 	github.com/hashicorp/packer-plugin-sdk v0.3.1 // indirect
 	github.com/hashicorp/serf v0.10.1 // indirect
 	github.com/huandu/xstrings v1.3.2 // indirect
-	github.com/imdario/mergo v0.3.15 // indirect
+	github.com/imdario/mergo v0.3.16 // indirect
 	github.com/jackc/chunkreader/v2 v2.0.1 // indirect
 	github.com/jackc/pgpassfile v1.0.0 // indirect
 	github.com/jackc/pgproto3/v2 v2.3.2 // indirect
@@ -455,6 +450,8 @@ require (
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
 	golang.zx2c4.com/wireguard v0.0.0-20211209221555-9c9e7e272434 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/genproto v0.0.0-20230530153820-e85fd2cbaebc // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20230530153820-e85fd2cbaebc // indirect
 	gopkg.in/errgo.v1 v1.0.1 // indirect
 	gopkg.in/fatih/pool.v2 v2.0.0 // indirect
 	gopkg.in/fsnotify.v1 v1.4.7 // indirect

go.sum

@@ -409,8 +409,8 @@ github.com/cncf/xds/go v0.0.0-20211001041855-01bcc9b48dfe/go.mod h1:eXthEFrGJvWH
 github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cockroachdb/apd v1.1.0 h1:3LFP3629v+1aKXU5Q37mxmRxX/pIu1nijXydLShEq5I=
 github.com/cockroachdb/apd v1.1.0/go.mod h1:8Sl8LxpKi29FqWXR16WEFZRNSz3SoPzUzeMeY4+DwBQ=
-github.com/compose-spec/compose-go v1.13.4 h1:O6xAsPqaY1s9KXteiO7wRCDTJLahv1XP/z/eUO9EfbI=
+github.com/compose-spec/compose-go v1.15.0 h1:rv3TTgbS3U4Y8sRTngrcxDmpbz+fq26wTqHculSCi6s=
-github.com/compose-spec/compose-go v1.13.4/go.mod h1:rsiZ8uaOHJYJemDBzTe9UBpaq5ZFVEOO4TxM2G3SJxk=
+github.com/compose-spec/compose-go v1.15.0/go.mod h1:3yngGBGfls6FHGQsg4B1z6gz8ej9SOvmAJtxCwgbcnc=
 github.com/containerd/console v1.0.3/go.mod h1:7LqA/THxQ86k76b8c/EMSiaJ3h1eZkMkXar0TQ1gf3U=
 github.com/containerd/containerd v1.6.18 h1:qZbsLvmyu+Vlty0/Ex5xc0z2YtKpIsb5n45mAMI+2Ns=
 github.com/containerd/containerd v1.6.18/go.mod h1:1RdCUu95+gc2v9t3IL+zIlpClSmew7/0YS8O5eQZrOw=
@@ -839,8 +839,8 @@ github.com/hpcloud/tail v1.0.0/go.mod h1:ab1qPbhIpdTxEkNHXyeSf5vhxWSCs/tWer42PpO
 github.com/huandu/xstrings v1.3.2 h1:L18LIDzqlW6xN2rEkpdV8+oL/IXWJ1APd+vsdYy4Wdw=
 github.com/huandu/xstrings v1.3.2/go.mod h1:y5/lhBue+AyNmUVz9RLU9xbLR0o4KIIExikq4ovT0aE=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
-github.com/imdario/mergo v0.3.15 h1:M8XP7IuFNsqUx6VPK2P9OSmsYsI/YFaGil0uD21V3dM=
+github.com/imdario/mergo v0.3.16 h1:wwQJbIsHYGMUyLSPrEq1CT16AhnhNJQ51+4fdHUnCl4=
-github.com/imdario/mergo v0.3.15/go.mod h1:WBLT9ZmE3lPoWsEzCh9LPo3TiwVN+ZKEjmz+hD27ysY=
+github.com/imdario/mergo v0.3.16/go.mod h1:WBLT9ZmE3lPoWsEzCh9LPo3TiwVN+ZKEjmz+hD27ysY=
 github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/influxdata/go-syslog/v3 v3.0.0 h1:jichmjSZlYK0VMmlz+k4WeOQd7z745YLsvGMqwtYt4I=
 github.com/influxdata/go-syslog/v3 v3.0.0/go.mod h1:tulsOp+CecTAYC27u9miMgq21GqXRW6VdKbOG+QSP4Q=
@@ -1798,8 +1798,8 @@ golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20220722155255-886fb9371eb4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.2.0 h1:PUR+T4wwASmuSTYdKjYHI5TD22Wy5ogLU5qZCOLxBrI=
+golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
-golang.org/x/sync v0.2.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
 golang.org/x/sys v0.0.0-20180823144017-11551d06cbcc/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=