User Agent: Add a UserAgentLite function to display less information in the user_agent (#307)

* User Agent: Rearrange the user agent to prioritize displaying the most useful information.

* User Agent: Rearrange the user agent to prioritize displaying the most useful information.

* Add a new Lite function instead of changing the behavior of the existing one

* Switch to known parameters + validate user agent size

* Add AgentManagementMode and AgentUnprivilegedMode enums + now returning an error if length > 100 chars

Author: pierrehilbert

useragent/useragent.go

@@ -18,10 +18,48 @@
 package useragent
 
 import (
+	"errors"
 	"runtime"
 	"strings"
 )
 
+type AgentManagementMode int
+
+const (
+	// AgentManagementModeManaged indicates that the beat is managed by Fleet.
+	AgentManagementModeManaged AgentManagementMode = iota
+	// AgentManagementModeStandalone indicates that the beat is running in standalone mode.
+	AgentManagementModeStandalone
+)
+
+func (m AgentManagementMode) String() string {
+	switch m {
+	case AgentManagementModeManaged:
+		return "Managed"
+	case AgentManagementModeStandalone:
+		return "Standalone"
+	default:
+		return "Unknown"
+	}
+}
+
+// AgentUnprivilegedMode indicates whether the beat is running in unprivileged mode.
+type AgentUnprivilegedMode bool
+
+const (
+	// AgentUnprivilegedModeUnprivileged indicates that the beat is running in unprivileged mode.
+	AgentUnprivilegedModeUnprivileged AgentUnprivilegedMode = true
+	// AgentUnprivilegedModePrivileged indicates that the beat is running in privileged mode.
+	AgentUnprivilegedModePrivileged AgentUnprivilegedMode = false
+)
+
+func (m AgentUnprivilegedMode) String() string {
+	if m {
+		return "Unprivileged"
+	}
+	return "Privileged"
+}
+
 // UserAgent takes the capitalized name of the current beat and returns
 // an RFC compliant user agent string for that beat.
 func UserAgent(binaryNameCapitalized string, version, commit, buildTime string, additionalComments ...string) string {
@@ -43,3 +81,24 @@ func UserAgent(binaryNameCapitalized string, version, commit, buildTime string,
 	builder.WriteByte(')')
 	return builder.String()
 }
+
+func UserAgentWithBeatTelemetry(binaryNameCapitalized string, version string, mode AgentManagementMode, unprivileged AgentUnprivilegedMode) (string, error) {
+	var builder strings.Builder
+	builder.WriteString("Elastic-" + binaryNameCapitalized + "/" + version + " ")
+	uaValues := []string{
+		runtime.GOOS,
+		runtime.GOARCH,
+		mode.String(),
+		unprivileged.String(),
+	}
+	builder.WriteByte('(')
+	builder.WriteString(strings.Join(uaValues, "; "))
+	builder.WriteByte(')')
+
+	// Ensure the user agent string does not exceed 100 characters
+	userAgent := builder.String()
+	if len(userAgent) > 100 {
+		return userAgent, errors.New("user agent string exceeds 100 characters")
+	}
+	return userAgent, nil
+}

useragent/useragent_test.go

@@ -25,9 +25,11 @@ import (
 )
 
 const (
-	v         = "9.9.9"
-	commit    = "1234abcd"
-	buildTime = "20001212"
+	v            = "10.10.11"
+	commit       = "a408c834fe3674b21546885890da17be05c91a51"
+	buildTime    = "2024-11-21 16:41:00 +0000"
+	mode         = AgentManagementModeManaged
+	unprivileged = AgentUnprivilegedModeUnprivileged
 )
 
 func TestUserAgent(t *testing.T) {
@@ -37,3 +39,11 @@ func TestUserAgent(t *testing.T) {
 	ua2 := UserAgent("FakeBeat", v, commit, buildTime, "integration_name/1.2.3")
 	assert.Regexp(t, regexp.MustCompile(`; integration_name\/1\.2\.3\)$`), ua2)
 }
+
+func TestUserAgentWithBeatTelemetry(t *testing.T) {
+	ua2, err := UserAgentWithBeatTelemetry("FakeBeat", v, mode, unprivileged)
+	assert.Regexp(t, regexp.MustCompile(`^Elastic-FakeBeat`), ua2)
+	assert.Regexp(t, regexp.MustCompile(`; Managed; Unprivileged\)$`), ua2)
+	assert.LessOrEqual(t, len(ua2), 100, "User agent string should be less than 100 characters")
+	assert.NoError(t, err)
+}