feat(apiserver): add flag to control the request size limit (#93431)

pkg/services/apiserver/standalone/options/options.go

@@ -1,6 +1,8 @@
 package options
 
 import (
+	"fmt"
+
 	"github.com/grafana/grafana/pkg/infra/log"
 	"github.com/grafana/grafana/pkg/services/apiserver/options"
 	"github.com/spf13/pflag"
@@ -41,6 +43,7 @@ func (o *Options) AddFlags(fs *pflag.FlagSet) {
 	o.MetricsOptions.AddFlags(fs)
 	o.ProfilingOptions.AddFlags(fs)
 	o.ServerRunOptions.AddUniversalFlags(fs)
+	o.internalFlags(fs)
 }
 
 func (o *Options) Validate() []error {
@@ -68,6 +71,10 @@ func (o *Options) Validate() []error {
 		return errs
 	}
 
+	if errs := o.internalFlagsValidate(); len(errs) != 0 {
+		return errs
+	}
+
 	// NOTE: we don't call validate on the top level recommended options as it doesn't like skipping etcd-servers
 	// the function is left here for troubleshooting any other config issues
 	// errors = append(errors, o.RecommendedOptions.Validate()...)
@@ -189,3 +196,21 @@ func (o *Options) ApplyTo(serverConfig *genericapiserver.RecommendedConfig) erro
 
 	return nil
 }
+
+func (o *Options) internalFlags(fs *pflag.FlagSet) {
+	// We also want to be able to set the MaxRequestSize by using flags. This is
+	// usually not exposed by k8s. The value is already set to the upstream default
+	// at this stage, so we can use it as the default.
+	// Reference: https://github.com/kubernetes/kubernetes/blob/v1.31.1/staging/src/k8s.io/apiserver/pkg/server/config.go#L453
+	fs.Int64Var(&o.ServerRunOptions.MaxRequestBodyBytes, "max-request-body-bytes",
+		o.ServerRunOptions.MaxRequestBodyBytes, ""+
+			"Specifies the maximum allowable size for a request payload sent to the API server in bytes."+
+			"The default is 3MB.")
+}
+
+func (o *Options) internalFlagsValidate() []error {
+	if o.ServerRunOptions.MaxRequestBodyBytes < 0 {
+		return []error{fmt.Errorf("--max-request-body-bytes can not be a negative value")}
+	}
+	return nil
+}