limit PVC name sizes by trimming generated names from the middle

go.mod

@@ -35,12 +35,14 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
 	golang.org/x/crypto v0.0.0-20210817164053-32db794688a5 // indirect
+	golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 // indirect
 	golang.org/x/net v0.0.0-20211209124913-491a49abca63 // indirect
 	golang.org/x/oauth2 v0.0.0-20210819190943-2bc19b11175f // indirect
 	golang.org/x/sys v0.0.0-20211029165221-6e7872819dc8 // indirect
 	golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac // indirect
+	golang.org/x/tools v0.1.5 // indirect
 	google.golang.org/appengine v1.6.7 // indirect
 	google.golang.org/protobuf v1.27.1 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect

go.sum

@@ -521,6 +521,7 @@ golang.org/x/lint v0.0.0-20191125180803-fdd1cda4f05f/go.mod h1:5qLYkcX4OjUUV8bRu
 golang.org/x/lint v0.0.0-20200130185559-910be7a94367/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/lint v0.0.0-20201208152925-83fdc39ff7b5/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
+golang.org/x/lint v0.0.0-20210508222113-6edffad5e616 h1:VLliZ0d+/avPrXXH+OakdXhpJuEoBZuwh1m2j7U6Iug=
 golang.org/x/lint v0.0.0-20210508222113-6edffad5e616/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
 golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
 golang.org/x/mobile v0.0.0-20190719004257-d2bd2a29d028/go.mod h1:E/iHnbuqvinMTCcRqshq8CkpyQDoeVncDDYHnLhea+o=
@@ -750,6 +751,7 @@ golang.org/x/tools v0.0.0-20210105154028-b0ab187a4818/go.mod h1:emZCQorbCU4vsT4f
 golang.org/x/tools v0.0.0-20210106214847-113979e3529a/go.mod h1:emZCQorbCU4vsT4fOWvOPXz4eW1wZW4PmDk9uLelYpA=
 golang.org/x/tools v0.1.0/go.mod h1:xkSsbof2nBLbhDlRMhhhyNLN/zl3eTqcnHD5viDpcZ0=
 golang.org/x/tools v0.1.2/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/tools v0.1.5 h1:ouewzE6p+/VEB31YYnTbEJdi8pFqKp4P4n85vwo3DHA=
 golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/tools v0.1.6-0.20210820212750-d4cc65f0b2ff/go.mod h1:YD9qOF0M9xpSpdWTBbzEl5e/RnCefISl8E5Noe10jFM=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

pkg/migrate/migrate.go

@@ -525,8 +525,21 @@ func validateStorageClasses(ctx context.Context, w *log.Logger, clientset k8scli
 	return nil
 }
 
+const nameSuffix = "-pvcmigrate"
+
+// if the length after adding the suffix is more than 63 characters, we need to reduce that to fit within k8s limits
+// pruning from the end runs the risk of dropping the '0'/'1'/etc of a statefulset's PVC name
+// pruning from the front runs the risk of making a-replica-... and b-replica-... collide
+// so this removes characters from the middle of the string
 func newPvcName(originalName string) string {
-	return originalName + "-pvcmigrate"
+	candidate := originalName + nameSuffix
+	if len(candidate) <= 63 {
+		return candidate
+	}
+
+	// remove characters from the middle of the string to reduce the total length to 63 characters
+	newCandidate := candidate[0:31] + candidate[len(candidate)-32:]
+	return newCandidate
 }
 
 // get a PV, apply the selected mutator to the PV, update the PV, use the supplied validator to wait for the update to show up

pkg/migrate/migrate_test.go

@@ -2210,3 +2210,34 @@ func Test_waitForDeletion(t *testing.T) {
 		})
 	}
 }
+
+func Test_newPvcName(t *testing.T) {
+	tests := []struct {
+		originalName string
+		want         string
+	}{
+		{
+			originalName: "abc",
+			want:         "abc-pvcmigrate",
+		},
+		{
+			originalName: "very very very long name test with a suffix that might be the only unique part of it 0",
+			want:         "very very very long name test wy unique part of it 0-pvcmigrate",
+		},
+		{
+			originalName: "0 very very very long name test with a prefix that might be the only unique part of it",
+			want:         "0 very very very long name testnly unique part of it-pvcmigrate",
+		},
+		{
+			originalName: "63 character (after suffix) name is untouched paddin",
+			want:         "63 character (after suffix) name is untouched paddin-pvcmigrate",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.originalName, func(t *testing.T) {
+			req := require.New(t)
+			got := newPvcName(tt.originalName)
+			req.Equal(tt.want, got)
+		})
+	}
+}