diff --git a/terraform/addrs/resource.go b/terraform/addrs/resource.go
index 358eb1e93..6b2f71c42 100644
--- a/terraform/addrs/resource.go
+++ b/terraform/addrs/resource.go
@@ -51,8 +51,6 @@ func (r ResourceInstance) ContainingResource() Resource {
 // resource lifecycle has a slightly different address format.
 type ResourceMode rune
 
-//go:generate go run golang.org/x/tools/cmd/stringer -type ResourceMode
-
 const (
 	// InvalidResourceMode is the zero value of ResourceMode and is not
 	// a valid resource mode.
diff --git a/terraform/lang/funcs/datetime.go b/terraform/lang/funcs/datetime.go
index fbd7c0b27..373d12795 100644
--- a/terraform/lang/funcs/datetime.go
+++ b/terraform/lang/funcs/datetime.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package funcs
 
 import (
@@ -17,6 +20,16 @@ var TimestampFunc = function.New(&function.Spec{
 	},
 })
 
+// PlantimestampFunc constructs a function that returns the time of the plan.
+// TFLint always treats this value as unknown.
+var PlantimestampFunc = function.New(&function.Spec{
+	Params: []function.Parameter{},
+	Type:   function.StaticReturnType(cty.String),
+	Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+		return cty.UnknownVal(cty.String), nil
+	},
+})
+
 // TimeAddFunc constructs a function that adds a duration to a timestamp, returning a new timestamp.
 var TimeAddFunc = function.New(&function.Spec{
 	Params: []function.Parameter{
diff --git a/terraform/lang/funcs/string.go b/terraform/lang/funcs/string.go
index 9ef709c7f..ea7ada1be 100644
--- a/terraform/lang/funcs/string.go
+++ b/terraform/lang/funcs/string.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package funcs
 
 import (
@@ -103,3 +106,29 @@ var ReplaceFunc = function.New(&function.Spec{
 func Replace(str, substr, replace cty.Value) (cty.Value, error) {
 	return ReplaceFunc.Call([]cty.Value{str, substr, replace})
 }
+
+// StrContainsFunc searches a given string for another given substring,
+// if found the function returns true, otherwise returns false.
+var StrContainsFunc = function.New(&function.Spec{
+	Params: []function.Parameter{
+		{
+			Name: "str",
+			Type: cty.String,
+		},
+		{
+			Name: "substr",
+			Type: cty.String,
+		},
+	},
+	Type: function.StaticReturnType(cty.Bool),
+	Impl: func(args []cty.Value, retType cty.Type) (ret cty.Value, err error) {
+		str := args[0].AsString()
+		substr := args[1].AsString()
+
+		if strings.Contains(str, substr) {
+			return cty.True, nil
+		}
+
+		return cty.False, nil
+	},
+})
diff --git a/terraform/lang/funcs/string_test.go b/terraform/lang/funcs/string_test.go
index 7b44a2762..d5c5996d9 100644
--- a/terraform/lang/funcs/string_test.go
+++ b/terraform/lang/funcs/string_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package funcs
 
 import (
@@ -71,3 +74,66 @@ func TestReplace(t *testing.T) {
 		})
 	}
 }
+
+func TestStrContains(t *testing.T) {
+	tests := []struct {
+		String cty.Value
+		Substr cty.Value
+		Want   cty.Value
+		Err    bool
+	}{
+		{
+			cty.StringVal("hello"),
+			cty.StringVal("hel"),
+			cty.BoolVal(true),
+			false,
+		},
+		{
+			cty.StringVal("hello"),
+			cty.StringVal("lo"),
+			cty.BoolVal(true),
+			false,
+		},
+		{
+			cty.StringVal("hello1"),
+			cty.StringVal("1"),
+			cty.BoolVal(true),
+			false,
+		},
+		{
+			cty.StringVal("hello1"),
+			cty.StringVal("heo"),
+			cty.BoolVal(false),
+			false,
+		},
+		{
+			cty.StringVal("hello1"),
+			cty.NumberIntVal(1),
+			cty.UnknownVal(cty.Bool),
+			true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(fmt.Sprintf("includes(%#v, %#v)", test.String, test.Substr), func(t *testing.T) {
+			got, err := StrContains(test.String, test.Substr)
+
+			if test.Err {
+				if err == nil {
+					t.Fatal("succeeded; want error")
+				}
+				return
+			} else if err != nil {
+				t.Fatalf("unexpected error: %s", err)
+			}
+
+			if !got.RawEquals(test.Want) {
+				t.Errorf("wrong result\ngot:  %#v\nwant: %#v", got, test.Want)
+			}
+		})
+	}
+}
+
+func StrContains(str, substr cty.Value) (cty.Value, error) {
+	return StrContainsFunc.Call([]cty.Value{str, substr})
+}
diff --git a/terraform/lang/functions.go b/terraform/lang/functions.go
index ff029b3d6..c4a498beb 100644
--- a/terraform/lang/functions.go
+++ b/terraform/lang/functions.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lang
 
 import (
@@ -93,6 +96,7 @@ func (s *Scope) Functions() map[string]function.Function {
 			"one":              funcs.OneFunc,
 			"parseint":         stdlib.ParseIntFunc,
 			"pathexpand":       funcs.PathExpandFunc,
+			"plantimestamp":    funcs.PlantimestampFunc,
 			"pow":              stdlib.PowFunc,
 			"range":            stdlib.RangeFunc,
 			"regex":            stdlib.RegexFunc,
@@ -114,6 +118,7 @@ func (s *Scope) Functions() map[string]function.Function {
 			"sort":             stdlib.SortFunc,
 			"split":            stdlib.SplitFunc,
 			"startswith":       funcs.StartsWithFunc,
+			"strcontains":      funcs.StrContainsFunc,
 			"strrev":           stdlib.ReverseFunc,
 			"substr":           stdlib.SubstrFunc,
 			"sum":              funcs.SumFunc,
diff --git a/terraform/lang/functions_test.go b/terraform/lang/functions_test.go
index 726f747f1..280c98c15 100644
--- a/terraform/lang/functions_test.go
+++ b/terraform/lang/functions_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
 package lang
 
 import (
@@ -638,6 +641,13 @@ func TestFunctions(t *testing.T) {
 			},
 		},
 
+		"plantimestamp": {
+			{
+				`plantimestamp()`,
+				cty.UnknownVal(cty.String),
+			},
+		},
+
 		"pow": {
 			{
 				`pow(1,0)`,
@@ -837,6 +847,17 @@ func TestFunctions(t *testing.T) {
 			},
 		},
 
+		"strcontains": {
+			{
+				`strcontains("hello", "llo")`,
+				cty.BoolVal(true),
+			},
+			{
+				`strcontains("hello", "a")`,
+				cty.BoolVal(false),
+			},
+		},
+
 		"strrev": {
 			{
 				`strrev("hello world")`,