Skip KUSTOMIZE_PLUGIN_CONFIG_* env variables when too large

Kustomize sets the legacy KUSTOMIZE_PLUGIN_CONFIG_STRING and
KUSTOMIZE_PLUGIN_CONFIG_ROOT environment variables. When these
environment variables exceed a hardcoded length (PAGE_SIZE * 32 on most
Linux systems), the kernel will return `argument list too long`. Given
that the environment variables are legacy, log a warning and do not set
them if they exceed 131071 bytes.

Reported-at: https://github.com/kubernetes-sigs/kustomize/issues/5480
Signed-off-by: Andreas Karis <ak.karis@gmail.com>

api/internal/plugins/execplugin/execplugin.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/google/shlex"
+	"k8s.io/klog"
 
 	"sigs.k8s.io/kustomize/api/internal/plugins/utils"
 	"sigs.k8s.io/kustomize/api/resmap"
@@ -21,6 +22,7 @@ import (
 
 const (
 	tmpConfigFilePrefix = "kust-plugin-config-"
+	maxArgStringLength  = 131071
 )
 
 // ExecPlugin record the name and args of an executable
@@ -184,8 +186,19 @@ func (p *ExecPlugin) invokePlugin(input []byte) ([]byte, error) {
 
 func (p *ExecPlugin) getEnv() []string {
 	env := os.Environ()
-	env = append(env,
-		"KUSTOMIZE_PLUGIN_CONFIG_STRING="+string(p.cfg),
-		"KUSTOMIZE_PLUGIN_CONFIG_ROOT="+p.h.Loader().Root())
+	pluginConfigString := "KUSTOMIZE_PLUGIN_CONFIG_STRING=" + string(p.cfg)
+	if len(pluginConfigString) <= maxArgStringLength {
+		env = append(env, pluginConfigString)
+	} else {
+		klog.Warningf("KUSTOMIZE_PLUGIN_CONFIG_STRING exceeds hard limit of %d characters, the environment variable "+
+			"will be omitted", maxArgStringLength)
+	}
+	pluginConfigRoot := "KUSTOMIZE_PLUGIN_CONFIG_ROOT=" + p.h.Loader().Root()
+	if len(pluginConfigRoot) <= maxArgStringLength {
+		env = append(env, pluginConfigRoot)
+	} else {
+		klog.Warningf("KUSTOMIZE_PLUGIN_CONFIG_ROOT exceeds hard limit of %d characters, the environment variable "+
+			"will be omitted", maxArgStringLength)
+	}
 	return env
 }