From a0742aef7c383991577adafb7ad7fea839ca6d3b Mon Sep 17 00:00:00 2001
From: Amit Watve <amwat@google.com>
Date: Mon, 1 Mar 2021 16:27:59 -0800
Subject: [PATCH] use a identifiable uuid prefix as default

---
 kubetest2-gce/deployer/deployer.go      | 32 ++++++++++++---
 kubetest2-gce/deployer/deployer_test.go | 54 +++++++++++++++++++++++++
 2 files changed, 81 insertions(+), 5 deletions(-)
 create mode 100644 kubetest2-gce/deployer/deployer_test.go

diff --git a/kubetest2-gce/deployer/deployer.go b/kubetest2-gce/deployer/deployer.go
index ccaf4059..e427afc3 100644
--- a/kubetest2-gce/deployer/deployer.go
+++ b/kubetest2-gce/deployer/deployer.go
@@ -81,6 +81,27 @@ type deployer struct {
 	CreateCustomNetwork         bool   `desc:"Sets the environment variable CREATE_CUSTOM_NETWORK=true during deployment."`
 }
 
+// pseudoUniqueSubstring returns a substring of a UUID
+// that can be reasonably used in resource names
+// where length is constrained
+// e.g https://cloud.google.com/compute/docs/naming-resources
+// but still retain as much uniqueness as possible
+// also easily lets us tie it back to a run
+func pseudoUniqueSubstring(uuid string) string {
+	// both KUBETEST2_RUN_ID and PROW_JOB_ID uuids are generated
+	// following RFC 4122 https://tools.ietf.org/html/rfc4122
+	// e.g. 09a2565a-7ac6-11eb-a603-2218f636630c
+	// extract the first 13 characters (09a2565a-7ac6) as they are the ones that depend on
+	// timestamp and has the best avalanche effect (https://en.wikipedia.org/wiki/Avalanche_effect)
+	// as compared to the other bytes
+	// 13 characters is also <= the no. of character being used previously
+	const maxResourceNamePrefixLength = 13
+	if len(uuid) <= maxResourceNamePrefixLength {
+		return uuid
+	}
+	return uuid[:maxResourceNamePrefixLength]
+}
+
 // New implements deployer.New for gce
 func New(opts types.Options) (types.Deployer, *pflag.FlagSet) {
 	d := &deployer{
@@ -92,11 +113,12 @@ func New(opts types.Options) (types.Deployer, *pflag.FlagSet) {
 				Strategy: "make",
 			},
 		},
-		kubeconfigPath:              filepath.Join(opts.RunDir(), "kubetest2-kubeconfig"),
-		logsDir:                     filepath.Join(opts.RunDir(), "cluster-logs"),
-		boskosHeartbeatClose:        make(chan struct{}),
-		instancePrefix:              "kubetest2",
-		network:                     "default",
+		kubeconfigPath:       filepath.Join(opts.RunDir(), "kubetest2-kubeconfig"),
+		logsDir:              filepath.Join(opts.RunDir(), "cluster-logs"),
+		boskosHeartbeatClose: make(chan struct{}),
+		// names need to start with an alphabet
+		instancePrefix:              "kt2-" + pseudoUniqueSubstring(opts.RunID()),
+		network:                     "kt2-" + pseudoUniqueSubstring(opts.RunID()),
 		BoskosAcquireTimeoutSeconds: 5 * 60,
 		BoskosLocation:              "http://boskos.test-pods.svc.cluster.local.",
 		NumNodes:                    3,
diff --git a/kubetest2-gce/deployer/deployer_test.go b/kubetest2-gce/deployer/deployer_test.go
new file mode 100644
index 00000000..f83cb28a
--- /dev/null
+++ b/kubetest2-gce/deployer/deployer_test.go
@@ -0,0 +1,54 @@
+/*
+Copyright 2020 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package deployer
+
+import "testing"
+
+func TestPseudoUniqueSubstring(t *testing.T) {
+	testCases := []struct {
+		name              string
+		uuid              string
+		expectedSubstring string
+	}{
+		{
+			name:              "actual uuid",
+			uuid:              "09a2565a-7ac6-11eb-a603-2218f636630c",
+			expectedSubstring: "09a2565a-7ac6",
+		},
+		{
+			name:              "<= 13 length uuid",
+			uuid:              "09a2565a-7ac6",
+			expectedSubstring: "09a2565a-7ac6",
+		},
+		{
+			name:              "empty string",
+			uuid:              "",
+			expectedSubstring: "",
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			actualSubstring := pseudoUniqueSubstring(tc.uuid)
+			if actualSubstring != tc.expectedSubstring {
+				t.Errorf("invalid substring: expected %s, but got %s", tc.expectedSubstring, actualSubstring)
+			}
+		})
+	}
+}