chore: Bump up to Go 1.19, minimum 1.18 (#4925)

23 files changed, 75 insertions, 83 deletions

diff --git a/modules/caddyhttp/app.go b/modules/caddyhttp/app.go
index 82e052c..24069eb 100644
--- a/modules/caddyhttp/app.go
+++ b/modules/caddyhttp/app.go
@@ -202,7 +202,7 @@ func (app *App) Provision(ctx caddy.Context) error {
 				return fmt.Errorf("loading listener wrapper modules: %v", err)
 			}
 			var hasTLSPlaceholder bool
-			for i, val := range vals.([]interface{}) {
+			for i, val := range vals.([]any) {
 				if _, ok := val.(*tlsPlaceholderWrapper); ok {
 					if i == 0 {
 						// putting the tls placeholder wrapper first is nonsensical because
diff --git a/modules/caddyhttp/caddyauth/caddyauth.go b/modules/caddyhttp/caddyauth/caddyauth.go
index 28b2e1b..ae30a08 100644
--- a/modules/caddyhttp/caddyauth/caddyauth.go
+++ b/modules/caddyhttp/caddyauth/caddyauth.go
@@ -62,7 +62,7 @@ func (a *Authentication) Provision(ctx caddy.Context) error {
 	if err != nil {
 		return fmt.Errorf("loading authentication providers: %v", err)
 	}
-	for modName, modIface := range mods.(map[string]interface{}) {
+	for modName, modIface := range mods.(map[string]any) {
 		a.Providers[modName] = modIface.(Authenticator)
 	}
 	return nil
diff --git a/modules/caddyhttp/celmatcher.go b/modules/caddyhttp/celmatcher.go
index 81fea70..e7067c3 100644
--- a/modules/caddyhttp/celmatcher.go
+++ b/modules/caddyhttp/celmatcher.go
@@ -218,7 +218,7 @@ var httpRequestCELType = types.NewTypeValue("http.Request", traits.ReceiverType)
 // drops allocation costs for CEL expression evaluations by roughly half.
 type celHTTPRequest struct{ *http.Request }
 
-func (cr celHTTPRequest) ResolveName(name string) (interface{}, bool) {
+func (cr celHTTPRequest) ResolveName(name string) (any, bool) {
 	if name == "request" {
 		return cr, true
 	}
@@ -229,7 +229,7 @@ func (cr celHTTPRequest) Parent() interpreter.Activation {
 	return nil
 }
 
-func (cr celHTTPRequest) ConvertToNative(typeDesc reflect.Type) (interface{}, error) {
+func (cr celHTTPRequest) ConvertToNative(typeDesc reflect.Type) (any, error) {
 	return cr.Request, nil
 }
 func (celHTTPRequest) ConvertToType(typeVal ref.Type) ref.Val {
@@ -241,8 +241,8 @@ func (cr celHTTPRequest) Equal(other ref.Val) ref.Val {
 	}
 	return types.ValOrErr(other, "%v is not comparable type", other)
 }
-func (celHTTPRequest) Type() ref.Type        { return httpRequestCELType }
-func (cr celHTTPRequest) Value() interface{} { return cr }
+func (celHTTPRequest) Type() ref.Type { return httpRequestCELType }
+func (cr celHTTPRequest) Value() any  { return cr }
 
 var pkixNameCELType = types.NewTypeValue("pkix.Name", traits.ReceiverType)
 
@@ -250,7 +250,7 @@ var pkixNameCELType = types.NewTypeValue("pkix.Name", traits.ReceiverType)
 // methods to satisfy the ref.Val interface.
 type celPkixName struct{ *pkix.Name }
 
-func (pn celPkixName) ConvertToNative(typeDesc reflect.Type) (interface{}, error) {
+func (pn celPkixName) ConvertToNative(typeDesc reflect.Type) (any, error) {
 	return pn.Name, nil
 }
 func (celPkixName) ConvertToType(typeVal ref.Type) ref.Val {
@@ -262,13 +262,13 @@ func (pn celPkixName) Equal(other ref.Val) ref.Val {
 	}
 	return types.ValOrErr(other, "%v is not comparable type", other)
 }
-func (celPkixName) Type() ref.Type        { return pkixNameCELType }
-func (pn celPkixName) Value() interface{} { return pn }
+func (celPkixName) Type() ref.Type { return pkixNameCELType }
+func (pn celPkixName) Value() any  { return pn }
 
 // celTypeAdapter can adapt our custom types to a CEL value.
 type celTypeAdapter struct{}
 
-func (celTypeAdapter) NativeToValue(value interface{}) ref.Val {
+func (celTypeAdapter) NativeToValue(value any) ref.Val {
 	switch v := value.(type) {
 	case celHTTPRequest:
 		return v
@@ -545,17 +545,17 @@ func celMatcherJSONMacroExpander(funcName string) parser.MacroExpander {
 // CELValueToMapStrList converts a CEL value to a map[string][]string
 //
 // Earlier validation stages should guarantee that the value has this type
-// at compile time, and that the runtime value type is map[string]interface{}.
+// at compile time, and that the runtime value type is map[string]any.
 // The reason for the slight difference in value type is that CEL allows for
 // map literals containing heterogeneous values, in this case string and list
 // of string.
 func CELValueToMapStrList(data ref.Val) (map[string][]string, error) {
-	mapStrType := reflect.TypeOf(map[string]interface{}{})
+	mapStrType := reflect.TypeOf(map[string]any{})
 	mapStrRaw, err := data.ConvertToNative(mapStrType)
 	if err != nil {
 		return nil, err
 	}
-	mapStrIface := mapStrRaw.(map[string]interface{})
+	mapStrIface := mapStrRaw.(map[string]any)
 	mapStrListStr := make(map[string][]string, len(mapStrIface))
 	for k, v := range mapStrIface {
 		switch val := v.(type) {
diff --git a/modules/caddyhttp/encode/encode.go b/modules/caddyhttp/encode/encode.go
index 8b49205..aae7280 100644
--- a/modules/caddyhttp/encode/encode.go
+++ b/modules/caddyhttp/encode/encode.go
@@ -71,7 +71,7 @@ func (enc *Encode) Provision(ctx caddy.Context) error {
 	if err != nil {
 		return fmt.Errorf("loading encoder modules: %v", err)
 	}
-	for modName, modIface := range mods.(map[string]interface{}) {
+	for modName, modIface := range mods.(map[string]any) {
 		err = enc.addEncoding(modIface.(Encoding))
 		if err != nil {
 			return fmt.Errorf("adding encoding %s: %v", modName, err)
@@ -142,7 +142,7 @@ func (enc *Encode) addEncoding(e Encoding) error {
 		enc.writerPools = make(map[string]*sync.Pool)
 	}
 	enc.writerPools[ae] = &sync.Pool{
-		New: func() interface{} {
+		New: func() any {
 			return e.NewEncoder()
 		},
 	}
@@ -418,7 +418,7 @@ type Precompressed interface {
 }
 
 var bufPool = sync.Pool{
-	New: func() interface{} {
+	New: func() any {
 		return new(bytes.Buffer)
 	},
 }
diff --git a/modules/caddyhttp/fileserver/browse.go b/modules/caddyhttp/fileserver/browse.go
index bdddc23..da97842 100644
--- a/modules/caddyhttp/fileserver/browse.go
+++ b/modules/caddyhttp/fileserver/browse.go
@@ -231,7 +231,7 @@ type templateContext struct {
 
 // bufPool is used to increase the efficiency of file listings.
 var bufPool = sync.Pool{
-	New: func() interface{} {
+	New: func() any {
 		return new(bytes.Buffer)
 	},
 }
diff --git a/modules/caddyhttp/fileserver/staticfiles.go b/modules/caddyhttp/fileserver/staticfiles.go
index 6bdb5af..93d529d 100644
--- a/modules/caddyhttp/fileserver/staticfiles.go
+++ b/modules/caddyhttp/fileserver/staticfiles.go
@@ -205,7 +205,7 @@ func (fsrv *FileServer) Provision(ctx caddy.Context) error {
 	if err != nil {
 		return fmt.Errorf("loading encoder modules: %v", err)
 	}
-	for modName, modIface := range mods.(map[string]interface{}) {
+	for modName, modIface := range mods.(map[string]any) {
 		p, ok := modIface.(encode.Precompressed)
 		if !ok {
 			return fmt.Errorf("module %s is not precompressor", modName)
diff --git a/modules/caddyhttp/map/caddyfile.go b/modules/caddyhttp/map/caddyfile.go
index f1ee468..f38aff7 100644
--- a/modules/caddyhttp/map/caddyfile.go
+++ b/modules/caddyhttp/map/caddyfile.go
@@ -78,7 +78,7 @@ func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error)
 
 			// every other line maps one input to one or more outputs
 			in := h.Val()
-			var outs []interface{}
+			var outs []any
 			for h.NextArg() {
 				val := h.ScalarVal()
 				if val == "-" {
diff --git a/modules/caddyhttp/map/map.go b/modules/caddyhttp/map/map.go
index 0a27aab..bbc1249 100644
--- a/modules/caddyhttp/map/map.go
+++ b/modules/caddyhttp/map/map.go
@@ -119,7 +119,7 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhtt
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
 
 	// defer work until a variable is actually evaluated by using replacer's Map callback
-	repl.Map(func(key string) (interface{}, bool) {
+	repl.Map(func(key string) (any, bool) {
 		// return early if the variable is not even a configured destination
 		destIdx := h.destinationIndex(key)
 		if destIdx < 0 {
@@ -187,7 +187,7 @@ type Mapping struct {
 	// Upon a match with the input, each output is positionally correlated
 	// with each destination of the parent handler. An output that is null
 	// (nil) will be treated as if it was not mapped at all.
-	Outputs []interface{} `json:"outputs,omitempty"`
+	Outputs []any `json:"outputs,omitempty"`
 
 	re *regexp.Regexp
 }
diff --git a/modules/caddyhttp/map/map_test.go b/modules/caddyhttp/map/map_test.go
index 26d6e85..fe233bf 100644
--- a/modules/caddyhttp/map/map_test.go
+++ b/modules/caddyhttp/map/map_test.go
@@ -15,7 +15,7 @@ func TestHandler(t *testing.T) {
 	for i, tc := range []struct {
 		handler Handler
 		reqURI  string
-		expect  map[string]interface{}
+		expect  map[string]any
 	}{
 		{
 			reqURI: "/foo",
@@ -25,11 +25,11 @@ func TestHandler(t *testing.T) {
 				Mappings: []Mapping{
 					{
 						Input:   "/foo",
-						Outputs: []interface{}{"FOO"},
+						Outputs: []any{"FOO"},
 					},
 				},
 			},
-			expect: map[string]interface{}{
+			expect: map[string]any{
 				"output": "FOO",
 			},
 		},
@@ -41,11 +41,11 @@ func TestHandler(t *testing.T) {
 				Mappings: []Mapping{
 					{
 						InputRegexp: "(/abc)",
-						Outputs:     []interface{}{"ABC"},
+						Outputs:     []any{"ABC"},
 					},
 				},
 			},
-			expect: map[string]interface{}{
+			expect: map[string]any{
 				"output": "ABC",
 			},
 		},
@@ -57,11 +57,11 @@ func TestHandler(t *testing.T) {
 				Mappings: []Mapping{
 					{
 						InputRegexp: "(xyz)",
-						Outputs:     []interface{}{"...${1}..."},
+						Outputs:     []any{"...${1}..."},
 					},
 				},
 			},
-			expect: map[string]interface{}{
+			expect: map[string]any{
 				"output": "...xyz...",
 			},
 		},
@@ -74,11 +74,11 @@ func TestHandler(t *testing.T) {
 				Mappings: []Mapping{
 					{
 						InputRegexp: "(?i)(\\^|`|<|>|%|\\\\|\\{|\\}|\\|)",
-						Outputs:     []interface{}{"3"},
+						Outputs:     []any{"3"},
 					},
 				},
 			},
-			expect: map[string]interface{}{
+			expect: map[string]any{
 				"output": "3",
 			},
 		},
@@ -90,11 +90,11 @@ func TestHandler(t *testing.T) {
 				Mappings: []Mapping{
 					{
 						Input:   "/foo",
-						Outputs: []interface{}{"{testvar}"},
+						Outputs: []any{"{testvar}"},
 					},
 				},
 			},
-			expect: map[string]interface{}{
+			expect: map[string]any{
 				"output": "testing",
 			},
 		},
diff --git a/modules/caddyhttp/matchers.go b/modules/caddyhttp/matchers.go
index 82972e5..2eedaca 100644
--- a/modules/caddyhttp/matchers.go
+++ b/modules/caddyhttp/matchers.go
@@ -1032,7 +1032,7 @@ func (m *MatchNot) Provision(ctx caddy.Context) error {
 	if err != nil {
 		return fmt.Errorf("loading matcher sets: %v", err)
 	}
-	for _, modMap := range matcherSets.([]map[string]interface{}) {
+	for _, modMap := range matcherSets.([]map[string]any) {
 		var ms MatcherSet
 		for _, modIface := range modMap {
 			ms = append(ms, modIface.(RequestMatcher))
diff --git a/modules/caddyhttp/matchers_test.go b/modules/caddyhttp/matchers_test.go
index f394921..bd4606b 100644
--- a/modules/caddyhttp/matchers_test.go
+++ b/modules/caddyhttp/matchers_test.go
@@ -807,7 +807,7 @@ func TestVarREMatcher(t *testing.T) {
 			req := &http.Request{URL: new(url.URL), Method: http.MethodGet}
 			repl := caddy.NewReplacer()
 			ctx := context.WithValue(req.Context(), caddy.ReplacerCtxKey, repl)
-			ctx = context.WithValue(ctx, VarsCtxKey, make(map[string]interface{}))
+			ctx = context.WithValue(ctx, VarsCtxKey, make(map[string]any))
 			req = req.WithContext(ctx)
 
 			addHTTPVarsToReplacer(repl, req, httptest.NewRecorder())
diff --git a/modules/caddyhttp/replacer.go b/modules/caddyhttp/replacer.go
index 2fa6517..bde58b7 100644
--- a/modules/caddyhttp/replacer.go
+++ b/modules/caddyhttp/replacer.go
@@ -57,7 +57,7 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 	SetVar(req.Context(), "start_time", time.Now())
 	SetVar(req.Context(), "uuid", new(requestID))
 
-	httpVars := func(key string) (interface{}, bool) {
+	httpVars := func(key string) (any, bool) {
 		if req != nil {
 			// query string parameters
 			if strings.HasPrefix(key, reqURIQueryReplPrefix) {
@@ -233,7 +233,7 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 			// middleware variables
 			if strings.HasPrefix(key, varsReplPrefix) {
 				varName := key[len(varsReplPrefix):]
-				tbl := req.Context().Value(VarsCtxKey).(map[string]interface{})
+				tbl := req.Context().Value(VarsCtxKey).(map[string]any)
 				raw := tbl[varName]
 				// variables can be dynamic, so always return true
 				// even when it may not be set; treat as empty then
@@ -258,7 +258,7 @@ func addHTTPVarsToReplacer(repl *caddy.Replacer, req *http.Request, w http.Respo
 	repl.Map(httpVars)
 }
 
-func getReqTLSReplacement(req *http.Request, key string) (interface{}, bool) {
+func getReqTLSReplacement(req *http.Request, key string) (any, bool) {
 	if req == nil || req.TLS == nil {
 		return nil, false
 	}
@@ -279,7 +279,7 @@ func getReqTLSReplacement(req *http.Request, key string) (interface{}, bool) {
 		if strings.HasPrefix(field, "client.san.") {
 			field = field[len("client.san."):]
 			var fieldName string
-			var fieldValue interface{}
+			var fieldValue any
 			switch {
 			case strings.HasPrefix(field, "dns_names"):
 				fieldName = "dns_names"
@@ -383,7 +383,7 @@ func getReqTLSReplacement(req *http.Request, key string) (interface{}, bool) {
 }
 
 // marshalPublicKey returns the byte encoding of pubKey.
-func marshalPublicKey(pubKey interface{}) ([]byte, error) {
+func marshalPublicKey(pubKey any) ([]byte, error) {
 	switch key := pubKey.(type) {
 	case *rsa.PublicKey:
 		return asn1.Marshal(key)
diff --git a/modules/caddyhttp/reverseproxy/admin.go b/modules/caddyhttp/reverseproxy/admin.go
index 771fa10..f64d1ec 100644
--- a/modules/caddyhttp/reverseproxy/admin.go
+++ b/modules/caddyhttp/reverseproxy/admin.go
@@ -76,7 +76,7 @@ func (adminUpstreams) handleUpstreams(w http.ResponseWriter, r *http.Request) er
 
 	// Iterate over the upstream pool (needs to be fast)
 	var rangeErr error
-	hosts.Range(func(key, val interface{}) bool {
+	hosts.Range(func(key, val any) bool {
 		address, ok := key.(string)
 		if !ok {
 			rangeErr = caddy.APIError{
diff --git a/modules/caddyhttp/reverseproxy/healthchecks.go b/modules/caddyhttp/reverseproxy/healthchecks.go
index 317b283..eb98638 100644
--- a/modules/caddyhttp/reverseproxy/healthchecks.go
+++ b/modules/caddyhttp/reverseproxy/healthchecks.go
@@ -269,7 +269,7 @@ func (h *Handler) doActiveHealthCheck(dialInfo DialInfo, hostAddr string, upstre
 	// attach dialing information to this request
 	ctx := h.ctx.Context
 	ctx = context.WithValue(ctx, caddy.ReplacerCtxKey, caddy.NewReplacer())
-	ctx = context.WithValue(ctx, caddyhttp.VarsCtxKey, map[string]interface{}{
+	ctx = context.WithValue(ctx, caddyhttp.VarsCtxKey, map[string]any{
 		dialInfoVarKey: dialInfo,
 	})
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
diff --git a/modules/caddyhttp/reverseproxy/reverseproxy.go b/modules/caddyhttp/reverseproxy/reverseproxy.go
index 7061275..c800b39 100644
--- a/modules/caddyhttp/reverseproxy/reverseproxy.go
+++ b/modules/caddyhttp/reverseproxy/reverseproxy.go
@@ -1317,7 +1317,7 @@ func (brc bodyReadCloser) Close() error {
 
 // bufPool is used for buffering requests and responses.
 var bufPool = sync.Pool{
-	New: func() interface{} {
+	New: func() any {
 		return new(bytes.Buffer)
 	},
 }
diff --git a/modules/caddyhttp/reverseproxy/streaming.go b/modules/caddyhttp/reverseproxy/streaming.go
index 6bd1af2..298ab58 100644
--- a/modules/caddyhttp/reverseproxy/streaming.go
+++ b/modules/caddyhttp/reverseproxy/streaming.go
@@ -279,7 +279,7 @@ func (c switchProtocolCopier) copyToBackend(errc chan<- error) {
 }
 
 var streamingBufPool = sync.Pool{
-	New: func() interface{} {
+	New: func() any {
 		// The Pool's New function should generally only return pointer
 		// types, since a pointer can be put into the return interface
 		// value without an allocation
diff --git a/modules/caddyhttp/rewrite/rewrite.go b/modules/caddyhttp/rewrite/rewrite.go
index da92269..ac8c4fc 100644
--- a/modules/caddyhttp/rewrite/rewrite.go
+++ b/modules/caddyhttp/rewrite/rewrite.go
@@ -283,7 +283,7 @@ func buildQueryString(qs string, repl *caddy.Replacer) string {
 
 		// consume the component and write the result
 		comp := qs[:end]
-		comp, _ = repl.ReplaceFunc(comp, func(name string, val interface{}) (interface{}, error) {
+		comp, _ = repl.ReplaceFunc(comp, func(name string, val any) (any, error) {
 			if name == "http.request.uri.query" && wroteVal {
 				return val, nil // already escaped
 			}
diff --git a/modules/caddyhttp/routes.go b/modules/caddyhttp/routes.go
index b8771db..45cbd80 100644
--- a/modules/caddyhttp/routes.go
+++ b/modules/caddyhttp/routes.go
@@ -151,7 +151,7 @@ func (routes RouteList) ProvisionHandlers(ctx caddy.Context) error {
 		if err != nil {
 			return fmt.Errorf("route %d: loading handler modules: %v", i, err)
 		}
-		for _, handler := range handlersIface.([]interface{}) {
+		for _, handler := range handlersIface.([]any) {
 			routes[i].Handlers = append(routes[i].Handlers, handler.(MiddlewareHandler))
 		}
 
@@ -315,9 +315,9 @@ func (ms MatcherSets) AnyMatch(req *http.Request) bool {
 	return len(ms) == 0
 }
 
-// FromInterface fills ms from an interface{} value obtained from LoadModule.
-func (ms *MatcherSets) FromInterface(matcherSets interface{}) error {
-	for _, matcherSetIfaces := range matcherSets.([]map[string]interface{}) {
+// FromInterface fills ms from an 'any' value obtained from LoadModule.
+func (ms *MatcherSets) FromInterface(matcherSets any) error {
+	for _, matcherSetIfaces := range matcherSets.([]map[string]any) {
 		var matcherSet MatcherSet
 		for _, matcher := range matcherSetIfaces {
 			reqMatcher, ok := matcher.(RequestMatcher)
diff --git a/modules/caddyhttp/server.go b/modules/caddyhttp/server.go
index 44a5888..c665e29 100644
--- a/modules/caddyhttp/server.go
+++ b/modules/caddyhttp/server.go
@@ -585,7 +585,7 @@ func PrepareRequest(r *http.Request, repl *caddy.Replacer, w http.ResponseWriter
 	// set up the context for the request
 	ctx := context.WithValue(r.Context(), caddy.ReplacerCtxKey, repl)
 	ctx = context.WithValue(ctx, ServerCtxKey, s)
-	ctx = context.WithValue(ctx, VarsCtxKey, make(map[string]interface{}))
+	ctx = context.WithValue(ctx, VarsCtxKey, make(map[string]any))
 	ctx = context.WithValue(ctx, routeGroupCtxKey, make(map[string]struct{}))
 	var url2 url.URL // avoid letting this escape to the heap
 	ctx = context.WithValue(ctx, OriginalRequestCtxKey, originalRequest(r, &url2))
diff --git a/modules/caddyhttp/staticresp.go b/modules/caddyhttp/staticresp.go
index 9e12bd5..f0aea03 100644
--- a/modules/caddyhttp/staticresp.go
+++ b/modules/caddyhttp/staticresp.go
@@ -283,7 +283,7 @@ func cmdRespond(fl caddycmd.Flags) (int, error) {
 	// build headers map
 	hdr := make(http.Header)
 	for i, h := range respondCmdHeaders {
-		key, val, found := cut(h, ":") // TODO: use strings.Cut() once Go 1.18 is our minimum
+		key, val, found := strings.Cut(h, ":")
 		key, val = strings.TrimSpace(key), strings.TrimSpace(val)
 		if !found || key == "" || val == "" {
 			return caddy.ExitCodeFailedStartup, fmt.Errorf("header %d: invalid format \"%s\" (expecting \"Field: value\")", i, h)
@@ -395,14 +395,6 @@ func cmdRespond(fl caddycmd.Flags) (int, error) {
 	select {}
 }
 
-// TODO: delete this and use strings.Cut() once Go 1.18 is our minimum
-func cut(s, sep string) (before, after string, found bool) {
-	if i := strings.Index(s, sep); i >= 0 {
-		return s[:i], s[i+len(sep):], true
-	}
-	return s, "", false
-}
-
 // respondCmdHeaders holds the parsed values from repeated use of the --header flag.
 var respondCmdHeaders caddycmd.StringSlice
 
diff --git a/modules/caddyhttp/templates/frontmatter.go b/modules/caddyhttp/templates/frontmatter.go
index 9031e13..3f7bd0c 100644
--- a/modules/caddyhttp/templates/frontmatter.go
+++ b/modules/caddyhttp/templates/frontmatter.go
@@ -10,7 +10,7 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
-func extractFrontMatter(input string) (map[string]interface{}, string, error) {
+func extractFrontMatter(input string) (map[string]any, string, error) {
 	// get the bounds of the first non-empty line
 	var firstLineStart, firstLineEnd int
 	lineEmpty := true
@@ -35,7 +35,7 @@ func extractFrontMatter(input string) (map[string]interface{}, string, error) {
 
 	// see what kind of front matter there is, if any
 	var closingFence []string
-	var fmParser func([]byte) (map[string]interface{}, error)
+	var fmParser func([]byte) (map[string]any, error)
 	for _, fmType := range supportedFrontMatterTypes {
 		if firstLine == fmType.FenceOpen {
 			closingFence = fmType.FenceClose
@@ -77,35 +77,35 @@ func extractFrontMatter(input string) (map[string]interface{}, string, error) {
 	return fm, body, nil
 }
 
-func yamlFrontMatter(input []byte) (map[string]interface{}, error) {
-	m := make(map[string]interface{})
+func yamlFrontMatter(input []byte) (map[string]any, error) {
+	m := make(map[string]any)
 	err := yaml.Unmarshal(input, &m)
 	return m, err
 }
 
-func tomlFrontMatter(input []byte) (map[string]interface{}, error) {
-	m := make(map[string]interface{})
+func tomlFrontMatter(input []byte) (map[string]any, error) {
+	m := make(map[string]any)
 	err := toml.Unmarshal(input, &m)
 	return m, err
 }
 
-func jsonFrontMatter(input []byte) (map[string]interface{}, error) {
+func jsonFrontMatter(input []byte) (map[string]any, error) {
 	input = append([]byte{'{'}, input...)
 	input = append(input, '}')
-	m := make(map[string]interface{})
+	m := make(map[string]any)
 	err := json.Unmarshal(input, &m)
 	return m, err
 }
 
 type parsedMarkdownDoc struct {
-	Meta map[string]interface{} `json:"meta,omitempty"`
-	Body string                 `json:"body,omitempty"`
+	Meta map[string]any `json:"meta,omitempty"`
+	Body string         `json:"body,omitempty"`
 }
 
 type frontMatterType struct {
 	FenceOpen  string
 	FenceClose []string
-	ParseFunc  func(input []byte) (map[string]interface{}, error)
+	ParseFunc  func(input []byte) (map[string]any, error)
 }
 
 var supportedFrontMatterTypes = []frontMatterType{
diff --git a/modules/caddyhttp/templates/tplcontext.go b/modules/caddyhttp/templates/tplcontext.go
index bae24ba..96a341c 100644
--- a/modules/caddyhttp/templates/tplcontext.go
+++ b/modules/caddyhttp/templates/tplcontext.go
@@ -44,7 +44,7 @@ import (
 type TemplateContext struct {
 	Root        http.FileSystem
 	Req         *http.Request
-	Args        []interface{} // defined by arguments to funcInclude
+	Args        []any // defined by arguments to funcInclude
 	RespHeader  WrappedHeader
 	CustomFuncs []template.FuncMap // functions added by plugins
 
@@ -99,7 +99,7 @@ func (c TemplateContext) OriginalReq() http.Request {
 // Note that included files are NOT escaped, so you should only include
 // trusted files. If it is not trusted, be sure to use escaping functions
 // in your template.
-func (c TemplateContext) funcInclude(filename string, args ...interface{}) (string, error) {
+func (c TemplateContext) funcInclude(filename string, args ...any) (string, error) {
 
 	bodyBuf := bufPool.Get().(*bytes.Buffer)
 	bodyBuf.Reset()
@@ -304,7 +304,7 @@ func (TemplateContext) funcStripHTML(s string) string {
 
 // funcMarkdown renders the markdown body as HTML. The resulting
 // HTML is NOT escaped so that it can be rendered as HTML.
-func (TemplateContext) funcMarkdown(input interface{}) (string, error) {
+func (TemplateContext) funcMarkdown(input any) (string, error) {
 	inputStr := toString(input)
 
 	md := goldmark.New(
@@ -340,7 +340,7 @@ func (TemplateContext) funcMarkdown(input interface{}) (string, error) {
 // splitFrontMatter parses front matter out from the beginning of input,
 // and returns the separated key-value pairs and the body/content. input
 // must be a "stringy" value.
-func (TemplateContext) funcSplitFrontMatter(input interface{}) (parsedMarkdownDoc, error) {
+func (TemplateContext) funcSplitFrontMatter(input any) (parsedMarkdownDoc, error) {
 	meta, body, err := extractFrontMatter(toString(input))
 	if err != nil {
 		return parsedMarkdownDoc{}, err
@@ -465,7 +465,7 @@ func (h WrappedHeader) Del(field string) string {
 	return ""
 }
 
-func toString(input interface{}) string {
+func toString(input any) string {
 	switch v := input.(type) {
 	case string:
 		return v
@@ -479,7 +479,7 @@ func toString(input interface{}) string {
 }
 
 var bufPool = sync.Pool{
-	New: func() interface{} {
+	New: func() any {
 		return new(bytes.Buffer)
 	},
 }
diff --git a/modules/caddyhttp/vars.go b/modules/caddyhttp/vars.go
index e7a7dbb..08f3e70 100644
--- a/modules/caddyhttp/vars.go
+++ b/modules/caddyhttp/vars.go
@@ -37,7 +37,7 @@ func init() {
 //
 // The key is the variable name, and the value is the value of the
 // variable. Both the name and value may use or contain placeholders.
-type VarsMiddleware map[string]interface{}
+type VarsMiddleware map[string]any
 
 // CaddyModule returns the Caddy module information.
 func (VarsMiddleware) CaddyModule() caddy.ModuleInfo {
@@ -48,7 +48,7 @@ func (VarsMiddleware) CaddyModule() caddy.ModuleInfo {
 }
 
 func (m VarsMiddleware) ServeHTTP(w http.ResponseWriter, r *http.Request, next Handler) error {
-	vars := r.Context().Value(VarsCtxKey).(map[string]interface{})
+	vars := r.Context().Value(VarsCtxKey).(map[string]any)
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
 	for k, v := range m {
 		keyExpanded := repl.ReplaceAll(k, "")
@@ -156,7 +156,7 @@ func (m VarsMatcher) Match(r *http.Request) bool {
 		return true
 	}
 
-	vars := r.Context().Value(VarsCtxKey).(map[string]interface{})
+	vars := r.Context().Value(VarsCtxKey).(map[string]any)
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
 
 	for key, vals := range m {
@@ -250,7 +250,7 @@ func (m MatchVarsRE) Provision(ctx caddy.Context) error {
 
 // Match returns true if r matches m.
 func (m MatchVarsRE) Match(r *http.Request) bool {
-	vars := r.Context().Value(VarsCtxKey).(map[string]interface{})
+	vars := r.Context().Value(VarsCtxKey).(map[string]any)
 	repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
 	for k, rm := range m {
 		var varStr string
@@ -290,8 +290,8 @@ func (m MatchVarsRE) Validate() error {
 
 // GetVar gets a value out of the context's variable table by key.
 // If the key does not exist, the return value will be nil.
-func GetVar(ctx context.Context, key string) interface{} {
-	varMap, ok := ctx.Value(VarsCtxKey).(map[string]interface{})
+func GetVar(ctx context.Context, key string) any {
+	varMap, ok := ctx.Value(VarsCtxKey).(map[string]any)
 	if !ok {
 		return nil
 	}
@@ -305,8 +305,8 @@ func GetVar(ctx context.Context, key string) interface{} {
 // If the value is nil (note: non-nil interface with nil
 // underlying value does not count) and the key exists in
 // the table, the key+value will be deleted from the table.
-func SetVar(ctx context.Context, key string, value interface{}) {
-	varMap, ok := ctx.Value(VarsCtxKey).(map[string]interface{})
+func SetVar(ctx context.Context, key string, value any) {
+	varMap, ok := ctx.Value(VarsCtxKey).(map[string]any)
 	if !ok {
 		return
 	}