[Filebeat] Add URL Encode template function for httpjson input (#30962)

Add URL Encode template function for httpjson input.

CHANGELOG.next.asciidoc

@@ -95,7 +95,6 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...main[Check the HEAD dif
 
 - Add FIPS configuration option for all AWS API calls. {pull}28899[28899]
 - Add support for kafka message headers. {pull}29940[29940]
-- Add FIPS configuration option for all AWS API calls. {pull}[28899]
 - Add support for non-unique Kafka headers for output messages. {pull}30369[30369]
 - Add syslog parser and processor. {issue}30139[30139] {pull}30541[30541]
 - Add action_input_type for the .fleet-actions-results {pull}30562[30562]
@@ -118,6 +117,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...main[Check the HEAD dif
 - Improve recovery from corrupted registries. {issue}25135[25135] {pull}30994[30994]
 - Add support in httpjson input for chain calls. {pull}29816[29816]
 - checkpoint module: Add `network.transport` derived from IANA number. {pull}31076[31076]
+- Add URL Encode template function for httpjson input. {pull}30962[30962]
 
 *Auditbeat*
 

x-pack/filebeat/docs/inputs/input-httpjson.asciidoc

@@ -222,6 +222,7 @@ Some built-in helper functions are provided to work with the input state inside
 - `uuid`: returns a random UUID such as `a11e8780-e3e7-46d0-8e76-f66e75acf019`. Example: `[[ uuid ]]`
 - `userAgent`: generates the User Agent with optional additional values. If no arguments are provided, it will generate the default User Agent that is added to all requests by default. It is recommended to delete the existing User-Agent header before setting a new one. Example: `[[ userAgent "integration/1.2.3" ]]` would generate `Elastic-Filebeat/8.1.0 (darwin; amd64; 9b893e88cfe109e64638d65c58fd75c2ff695402; 2021-12-15 13:20:00 +0000 UTC; integration_name/1.2.3)`
 - `beatInfo`: returns a map containing information about the Beat.  Available keys in the map are `goos` (running operating system), `goarch` (running system architecture), `commit` (git commit of current build), `buildtime` (compile time of current build), `version` (version of current build). Example: `[[ beatInfo.version ]]` returns `{version}`.
+- `urlEncode`: URL encodes the supplied string. Example `[[urlEncode "string1"]]`. Example `[[urlEncode "<string1>"]]` will return `%3Cstring1%3E`.
 
 In addition to the provided functions, any of the native functions for https://golang.org/pkg/time/#Time[`time.Time`], https://golang.org/pkg/net/http/#Header[`http.Header`], and https://golang.org/pkg/net/url/#Values[`url.Values`] types can be used on the corresponding objects. Examples: `[[(now).Day]]`, `[[.last_response.header.Get "key"]]`
 

x-pack/filebeat/input/httpjson/value_tpl.go

@@ -14,6 +14,7 @@ import (
 	"errors"
 	"fmt"
 	"hash"
+	"net/url"
 	"reflect"
 	"regexp"
 	"runtime"
@@ -71,6 +72,7 @@ func (t *valueTpl) Unpack(in string) error {
 			"uuid":                uuidString,
 			"userAgent":           userAgentString,
 			"beatInfo":            beatInfo,
+			"urlEncode":           urlEncode,
 		}).
 		Delims(leftDelim, rightDelim).
 		Parse(in)
@@ -379,3 +381,10 @@ func beatInfo() map[string]string {
 		"version":   version.GetDefaultVersion(),
 	}
 }
+
+func urlEncode(value string) string {
+	if value == "" {
+		return ""
+	}
+	return url.QueryEscape(value)
+}

x-pack/filebeat/input/httpjson/value_tpl_test.go

@@ -460,6 +460,28 @@ func TestValueTpl(t *testing.T) {
 			paramTr:     transformable{},
 			expectedVal: version.GetDefaultVersion(),
 		},
+		{
+			name:          "func urlEncode blank",
+			value:         `[[urlEncode ""]]`,
+			paramCtx:      emptyTransformContext(),
+			paramTr:       transformable{},
+			expectedVal:   "",
+			expectedError: errEmptyTemplateResult.Error(),
+		},
+		{
+			name:        "func urlEncode URL Safe",
+			value:       `[[urlEncode "asdf"]]`,
+			paramCtx:    emptyTransformContext(),
+			paramTr:     transformable{},
+			expectedVal: "asdf",
+		},
+		{
+			name:        "func urlEncode URL Safe",
+			value:       `[[urlEncode "2022-02-17T04:37:10.406+0000"]]`,
+			paramCtx:    emptyTransformContext(),
+			paramTr:     transformable{},
+			expectedVal: "2022-02-17T04%3A37%3A10.406%2B0000",
+		},
 	}
 
 	for _, tc := range cases {