resource: support using Quantity as command line value

The Quantity type itself cannot be used because the Set method has the wrong signature. Embedding Quantity inside a new QuantityValue type makes it possible to inherit most of the methods while overriding the Set method.
ii · Oct 8, 2021 · 963d3c1 · 963d3c1
1 parent dd650bd
commit 963d3c1
Show file tree

Hide file tree

Showing 5 changed files with 138 additions and 16 deletions.
diff --git a/staging/src/k8s.io/apimachinery/pkg/api/resource/generated.pb.go b/staging/src/k8s.io/apimachinery/pkg/api/resource/generated.pb.go
diff --git a/staging/src/k8s.io/apimachinery/pkg/api/resource/generated.proto b/staging/src/k8s.io/apimachinery/pkg/api/resource/generated.proto
diff --git a/staging/src/k8s.io/apimachinery/pkg/api/resource/quantity.go b/staging/src/k8s.io/apimachinery/pkg/api/resource/quantity.go
@@ -764,3 +764,30 @@ func (q *Quantity) SetScaled(value int64, scale Scale) {
 	q.d.Dec = nil
 	q.i = int64Amount{value: value, scale: scale}
 }
+
+// QuantityValue makes it possible to use a Quantity as value for a command
+// line parameter.
+//
+// +protobuf=true
+// +protobuf.embed=string
+// +protobuf.options.marshal=false
+// +protobuf.options.(gogoproto.goproto_stringer)=false
+// +k8s:deepcopy-gen=true
+type QuantityValue struct {
+	Quantity
+}
+
+// Set implements pflag.Value.Set and Go flag.Value.Set.
+func (q *QuantityValue) Set(s string) error {
+	quantity, err := ParseQuantity(s)
+	if err != nil {
+		return err
+	}
+	q.Quantity = quantity
+	return nil
+}
+
+// Type implements pflag.Value.Type.
+func (q QuantityValue) Type() string {
+	return "quantity"
+}
diff --git a/staging/src/k8s.io/apimachinery/pkg/api/resource/quantity_test.go b/staging/src/k8s.io/apimachinery/pkg/api/resource/quantity_test.go
@@ -21,11 +21,13 @@ import (
 	"fmt"
 	"math"
 	"math/rand"
+	"os"
 	"strings"
 	"testing"
 	"unicode"
 
 	fuzz "github.com/google/gofuzz"
+	"github.com/spf13/pflag"
 
 	inf "gopkg.in/inf.v0"
 )
@@ -1475,3 +1477,42 @@ func BenchmarkQuantityAsApproximateFloat64(b *testing.B) {
 	}
 	b.StopTimer()
 }
+
+var _ pflag.Value = &QuantityValue{}
+
+func TestQuantityValueSet(t *testing.T) {
+	q := QuantityValue{}
+
+	if err := q.Set("invalid"); err == nil {
+
+		t.Error("'invalid' did not trigger a parse error")
+	}
+
+	if err := q.Set("1Mi"); err != nil {
+		t.Errorf("parsing 1Mi should have worked, got: %v", err)
+	}
+	if q.Value() != 1024*1024 {
+		t.Errorf("quantity should have been set to 1Mi, got: %v", q)
+	}
+
+	data, err := json.Marshal(q)
+	if err != nil {
+		t.Errorf("unexpected encoding error: %v", err)
+	}
+	expected := `"1Mi"`
+	if string(data) != expected {
+		t.Errorf("expected 1Mi value to be encoded as %q, got: %q", expected, string(data))
+	}
+}
+
+func ExampleQuantityValue() {
+	q := QuantityValue{
+		Quantity: MustParse("1Mi"),
+	}
+	fs := pflag.FlagSet{}
+	fs.SetOutput(os.Stdout)
+	fs.Var(&q, "mem", "sets amount of memory")
+	fs.PrintDefaults()
+	// Output:
+	// --mem quantity   sets amount of memory (default 1Mi)
+}
diff --git a/staging/src/k8s.io/apimachinery/pkg/api/resource/zz_generated.deepcopy.go b/staging/src/k8s.io/apimachinery/pkg/api/resource/zz_generated.deepcopy.go