add support for cyclic alias check

Author: sni

.golangci.yml

@@ -167,20 +167,12 @@ linters:
         text: variable name 'ok' is too short
       - path: (.+)\.go$
         text: Function 'setListenTLSConfig' has too many statements
-      - path: (.+)\.go$
-        text: Function 'ParseArgs' has too many statements
-      - path: (.+)\.go$
-        text: 'cyclomatic complexity 45 of func `.*\.parseArgs` is high'
-      - path: (.+)\.go$
-        text: Function 'parseArgs' has too many statements
       - path: (.+)\.go$
         text: Function 'parseAnyArg' has too many statements
       - path: (.+)\.go$
         text: complexity.*setListenTLSConfig
       - path: (.+)\.go$
         text: complexity.*checkFlags
-      - path: (.+)\.go$
-        text: complexity.*ParseArgs
       - path: (.+)\.go$
         text: Function 'readConfiguration' has too many statements
       - path: (.+)\.go$

Changes

@@ -3,6 +3,7 @@ This file documents the revision history for the SNClient agent.
 next
          - change minimum golang requirement to 1.25.5
          - add support for recursive `script path`
+         - add support for cyclic alias check
 
 0.39     Tue Nov 18 14:22:01 CET 2025
          - optionally send HSTS header in HTTP response

pkg/snclient/check_alias.go

@@ -42,7 +42,7 @@ func (a *CheckAlias) Check(ctx context.Context, snc *Agent, check *CheckData, _
 
 		log.Debugf("command after macros expanded: %s %s", a.command, replacedStr)
 	}
-	statusResult, _ := snc.runCheck(ctx, a.command, cmdArgs, check.timeout, nil, true)
+	statusResult, _ := snc.runCheck(ctx, a.command, cmdArgs, check.timeout, nil, true, true)
 
 	statusResult.ParsePerformanceDataFromOutputCond(a.command, a.config)
 

pkg/snclient/check_alias_test.go

@@ -13,6 +13,8 @@ CheckExternalScripts = enabled
 
 [/settings/external scripts/alias]
 alias_cpu = check_cpu warn=load=101 crit=load=102
+check_memory = check_memory -a type=physical warn="used > 100" crit="used > 100"
+check_uptime = check_uptime "warn=uptime > 3000d" "crit=uptime > 6000d"
 
 [/settings/external scripts/alias/alias_cpu2]
 command = check_cpu warn=load=101 crit=load=102
@@ -37,7 +39,7 @@ allow arguments = yes
 `
 	snc := StartTestAgent(t, config)
 
-	assert.Lenf(t, snc.runSet.cmdAliases, 6, "there should be one alias")
+	assert.Lenf(t, snc.runSet.cmdAliases, 8, "there should be 8 alias entries")
 
 	res := snc.RunCheck("alias_cpu", []string{})
 	assert.Equalf(t, CheckExitOK, res.State, "state OK")
@@ -84,5 +86,20 @@ allow arguments = yes
 	assert.Equalf(t, CheckExitOK, res.State, "state OK")
 	assert.Equalf(t, "test 123 456", string(res.BuildPluginOutput()), "plugin output matches")
 
+	// recursive memory check
+	res = snc.RunCheck("check_memory", []string{})
+	assert.Equalf(t, CheckExitOK, res.State, "state OK")
+	assert.Regexpf(t, `^OK - physical =`, string(res.BuildPluginOutput()), "output matches")
+
+	// help from aliased check
+	res = snc.RunCheck("check_memory", []string{"help"})
+	assert.Equalf(t, CheckExitUnknown, res.State, "state Unknown")
+	assert.Regexpf(t, `There are several types of memory that can be checked`, string(res.BuildPluginOutput()), "output matches")
+
+	// recursive uptime check
+	res = snc.RunCheck("check_uptime", []string{})
+	assert.Equalf(t, CheckExitOK, res.State, "state OK")
+	assert.Regexpf(t, `^OK - uptime:`, string(res.BuildPluginOutput()), "output matches")
+
 	StopTestAgent(t, snc)
 }

pkg/snclient/checkdata.go

@@ -599,6 +599,8 @@ func (cd *CheckData) parseStateString(state string) int64 {
 
 // parseArgs parses check arguments into the CheckData struct
 // and returns all unknown options
+//
+//nolint:funlen,gocyclo // it is not complex, it is just a long list of options
 func (cd *CheckData) parseArgs(args []string) (argList []Argument, err error) {
 	cd.rawArgs = args
 	cd.hasArgsSupplied = map[string]bool{}
@@ -730,6 +732,8 @@ func (cd *CheckData) parseArgs(args []string) (argList []Argument, err error) {
 				argList = append(argList, Argument{key: keyword, value: argValue})
 			case keyword == "-h", keyword == "--help":
 				cd.showHelp = PluginHelp
+			case keyword == "-a":
+				// ignore -a for legacy compatibility
 			default:
 				return nil, fmt.Errorf("unknown argument: %s", keyword)
 			}

pkg/snclient/inventory.go

@@ -111,7 +111,7 @@ func (snc *Agent) buildInventory(ctx context.Context, modules []string) *Invento
 	sort.Strings(keys)
 
 	for _, k := range keys {
-		check, _ := snc.getCheck(k)
+		check, _ := snc.getCheck(k, false)
 		handler := check.Handler()
 		meta := handler.Build()
 		if !meta.isImplemented(runtime.GOOS) {

pkg/snclient/listen_nrpe.go

@@ -116,7 +116,7 @@ func (l *HandlerNRPE) ServeTCP(snc *Agent, con net.Conn) {
 		cmd = "check_snclient_version"
 		args = []string{}
 	}
-	statusResult := snc.RunCheckWithContext(context.TODO(), cmd, args, 0, l.conf)
+	statusResult := snc.RunCheckWithContext(context.TODO(), cmd, args, 0, l.conf, false)
 
 	output := statusResult.BuildPluginOutput()
 	state, err2 := convert.UInt16E(statusResult.State)

pkg/snclient/listen_web.go

@@ -363,7 +363,7 @@ func (l *HandlerWeb) runCheck(req *http.Request, command string) (result *CheckR
 		}
 	}
 
-	return l.snc.RunCheckWithContext(req.Context(), command, args, timeoutSeconds, l.conf)
+	return l.snc.RunCheckWithContext(req.Context(), command, args, timeoutSeconds, l.conf, false)
 }
 
 type HandlerWebLegacy struct {

pkg/snclient/snclient.go

@@ -734,13 +734,13 @@ func (snc *Agent) logPanicRecover() {
 
 // RunCheck calls check by name and returns the check result.
 func (snc *Agent) RunCheck(name string, args []string) *CheckResult {
-	return snc.RunCheckWithContext(context.TODO(), name, args, 0, nil)
+	return snc.RunCheckWithContext(context.TODO(), name, args, 0, nil, false)
 }
 
 // RunCheckWithContext calls check by name and returns the check result.
 // secCon configuration section will be used to check for nasty characters and allowed arguments.
-func (snc *Agent) RunCheckWithContext(ctx context.Context, name string, args []string, timeoutOverride float64, transportConf *ConfigSection) *CheckResult {
-	res, chk := snc.runCheck(ctx, name, args, timeoutOverride, transportConf, false)
+func (snc *Agent) RunCheckWithContext(ctx context.Context, name string, args []string, timeoutOverride float64, transportConf *ConfigSection, skipAlias bool) *CheckResult {
+	res, chk := snc.runCheck(ctx, name, args, timeoutOverride, transportConf, false, skipAlias)
 	if res.Raw == nil || res.Raw.showHelp == 0 {
 		if chk != nil {
 			res.Finalize(chk.timezone)
@@ -752,13 +752,13 @@ func (snc *Agent) RunCheckWithContext(ctx context.Context, name string, args []s
 	return res
 }
 
-func (snc *Agent) runCheck(ctx context.Context, name string, args []string, timeoutOverride float64, transportConf *ConfigSection, skipAllowedCheck bool) (*CheckResult, *CheckData) {
+func (snc *Agent) runCheck(ctx context.Context, name string, args []string, timeoutOverride float64, transportConf *ConfigSection, skipAllowedCheck, skipAlias bool) (*CheckResult, *CheckData) {
 	log.Tracef("command: %s", name)
 	log.Tracef("args: %#v", args)
 	if deadline, ok := ctx.Deadline(); ok {
 		log.Tracef("ctx deadline: %s", time.Until(deadline).String())
 	}
-	check, ok := snc.getCheck(name)
+	check, ok := snc.getCheck(name, skipAlias)
 	if !ok {
 		return &CheckResult{
 			State:  CheckExitUnknown,
@@ -857,6 +857,12 @@ func (snc *Agent) runHelp(ctx context.Context, chk *CheckData, handler CheckHand
 	switch builtin := handler.(type) {
 	case *CheckBuiltin:
 		help = builtin.Help(ctx, snc, chk, chk.showHelp)
+	case *CheckAlias:
+		alias, ok := snc.getCheck(builtin.command, true)
+		if ok {
+			realChk := alias.Handler().Build()
+			help = realChk.Help(chk.showHelp)
+		}
 	default:
 		help = chk.Help(chk.showHelp)
 	}
@@ -868,10 +874,12 @@ func (snc *Agent) runHelp(ctx context.Context, chk *CheckData, handler CheckHand
 	}
 }
 
-func (snc *Agent) getCheck(name string) (_ *CheckEntry, ok bool) {
+func (snc *Agent) getCheck(name string, skipAlias bool) (_ *CheckEntry, ok bool) {
 	if snc.runSet != nil {
-		if chk, ok := snc.runSet.cmdAliases[name]; ok {
-			return &chk, ok
+		if !skipAlias {
+			if chk, ok := snc.runSet.cmdAliases[name]; ok {
+				return &chk, ok
+			}
 		}
 		if chk, ok := snc.runSet.cmdWraps[name]; ok {
 			return &chk, ok