Merge pull request #3645 from serathius/resource-size-deterministic

Make randomized data in pods deterministic to avoid pod recreation

Author: k8s-ci-robot

clusterloader2/pkg/config/template_functions.go

@@ -17,7 +17,10 @@ limitations under the License.
 package config
 
 import (
+	"crypto/sha256"
+	"encoding/binary"
 	"fmt"
+	"io"
 	"io/fs"
 	"io/ioutil"
 	"math"
@@ -34,8 +37,10 @@ import (
 	"k8s.io/klog/v2"
 )
 
+var globalRand *rand.Rand
+
 func init() {
-	rand.Seed(time.Now().UnixNano())
+	globalRand = rand.New(rand.NewSource(time.Now().UnixNano()))
 }
 
 // GetFuncs returns map of names to functions, that are supported by template provider.
@@ -60,6 +65,7 @@ func GetFuncs(fsys fs.FS) template.FuncMap {
 		"MultiplyFloat":    multiplyFloat,
 		"MultiplyInt":      multiplyInt,
 		"RandData":         randData,
+		"RandDataWithSeed": randDataWithSeed,
 		"RandInt":          randInt,
 		"RandIntRange":     randIntRange,
 		"Seq":              seq,
@@ -108,9 +114,29 @@ func toFloat64(val interface{}) float64 {
 
 // randData returns pseudo-random string of i length.
 func randData(i interface{}) string {
-	const alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
 	typedI := int(toFloat64(i))
-	b := make([]byte, typedI)
+	return randString(globalRand, typedI)
+}
+
+// randData returns pseudo-random string of i length with a provided seed to allow deterministic result.
+func randDataWithSeed(i, j interface{}) string {
+	typedI := int(toFloat64(i))
+	if typedI == 0 {
+		return ""
+	}
+	typedJ := j.(string)
+	h := sha256.New()
+	_, err := io.WriteString(h, typedJ)
+	if err != nil {
+		panic(fmt.Sprintf("failed to write %q to sha256 hash", typedJ))
+	}
+	seed := int64(binary.BigEndian.Uint64(h.Sum(nil)))
+	return randString(rand.New(rand.NewSource(seed)), typedI)
+}
+
+func randString(rand *rand.Rand, length int) string {
+	const alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	b := make([]byte, length)
 	for i := range b {
 		b[i] = alphabet[rand.Intn(len(alphabet))]
 	}
@@ -120,7 +146,7 @@ func randData(i interface{}) string {
 // randInt returns pseudo-random int in [0, i].
 func randInt(i interface{}) int {
 	typedI := int(toFloat64(i))
-	return rand.Intn(typedI + 1)
+	return globalRand.Intn(typedI + 1)
 }
 
 // randIntRange returns pseudo-random int in [i, j].
@@ -131,7 +157,7 @@ func randIntRange(i, j interface{}) int {
 	if typedI >= typedJ {
 		return typedI
 	}
-	return typedI + rand.Intn(typedJ-typedI+1)
+	return typedI + globalRand.Intn(typedJ-typedI+1)
 }
 
 func addInt(numbers ...interface{}) int {

clusterloader2/pkg/config/template_functions_test.go

@@ -39,3 +39,40 @@ func TestTemplateRandData(t *testing.T) {
 		}
 	}
 }
+
+func TestTemplateRandDataWithSeed(t *testing.T) {
+	tests := []struct {
+		length   int
+		seed     string
+		wantData string
+	}{
+		{
+			length:   0,
+			seed:     "test",
+			wantData: "",
+		},
+		{
+			length:   1,
+			seed:     "test-1",
+			wantData: "n",
+		},
+		{
+			length:   1,
+			seed:     "test-2",
+			wantData: "P",
+		},
+		{
+			length:   100,
+			seed:     "test",
+			wantData: "HlXm60Fjrvvp0pE3RK7lDhhhuQZpI6ECS18Gp0qqwFlOKjlZH4rFS3pk9pBkVRLzyqIWUv1Omfnmj7djTRjxL4bnp2kG7O5xD2Rf",
+		},
+	}
+
+	for i, tt := range tests {
+		data := randDataWithSeed(tt.length, tt.seed)
+
+		if tt.wantData != data {
+			t.Errorf("%d: wanted: %q, got: %q", i, tt.wantData, data)
+		}
+	}
+}

clusterloader2/testing/load/daemonset.yaml

@@ -35,7 +35,7 @@ spec:
           - name: TEST_ENV
             value: {{$Env}}
           - name: ENV_VAR
-            value: {{RandData $podPayloadSize}}
+            value: {{RandDataWithSeed $podPayloadSize .Name}}
         resources:
           # Keep the CpuRequest/MemoryRequest request equal percentage of 1-core, 4GB node.
           # For now we're setting it to 0.5%.

clusterloader2/testing/load/deployment.yaml

@@ -81,7 +81,7 @@ spec:
 {{end}}
         env:
         - name: ENV_VAR
-          value: {{RandData $podPayloadSize}}
+          value: {{RandDataWithSeed $podPayloadSize .Name}}
         resources:
           requests:
             cpu: {{$CpuRequest}}

clusterloader2/testing/load/job.yaml

@@ -1,6 +1,7 @@
 {{$HostNetworkMode := DefaultParam .CL2_USE_HOST_NETWORK_PODS false}}
 {{$RUN_ON_ARM_NODES := DefaultParam .CL2_RUN_ON_ARM_NODES false}}
 {{$Image := DefaultParam .Image "registry.k8s.io/pause:3.9"}}
+{{$podPayloadSize := DefaultParam .CL2_JOB_POD_PAYLOAD_SIZE 0}}
 
 apiVersion: batch/v1
 kind: Job
@@ -27,6 +28,9 @@ spec:
       - name: {{.Name}}
         # TODO(#799): We should test the "run-to-completion" workflow and hence don't use pause pods.
         image: {{$Image}}
+        env:
+        - name: ENV_VAR
+          value: {{RandDataWithSeed $podPayloadSize .Name}}
         resources:
           # Keep the CpuRequest/MemoryRequest request equal percentage of 1-core, 4GB node.
           # For now we're setting it to 0.5%.

clusterloader2/testing/load/simple-deployment.yaml

@@ -31,7 +31,7 @@ spec:
       containers:
       - env:
         - name: ENV_VAR
-          value: {{RandData $podPayloadSize}}
+          value: {{RandDataWithSeed $podPayloadSize .Name}}
         image: {{$Image}}
         imagePullPolicy: IfNotPresent
         name: {{.Name}}

clusterloader2/testing/load/statefulset.yaml

@@ -30,7 +30,7 @@ spec:
         image: {{$Image}}
         env:
         - name: ENV_VAR
-          value: {{RandData $podPayloadSize}}
+          value: {{RandDataWithSeed $podPayloadSize .Name}}
         ports:
           - containerPort: 80
             name: web