Use temp-directory that is covered by framework level cleanup

Prior to this PR, the e2e tests where creating dirs like:
```
/tmp/testname1.etcd030299846
/tmp/testname0.etcd039445123
/tmp/testname0.etcd206372065
```
and not cleaning them, that led to disk-space-exceeded flakes.

After the PR, the testing.TB tempdir mechanism is used and the names are
being cleaned and are more miningful:

```
../../bin/etcd --name test-TestCtlV3EndpointHashKV-2 --listen-client-urls http://localhost:20010 --advertise-client-urls http://localhost:20010 --listen-peer-urls https://localhost:20011 --initial-advertise-peer-urls https://localhost:20011 --initial-cluster-token new --data-dir /tmp/TestCtlV3EndpointHashKV429176179/003 --snapshot-count 100000 --experimental-initial-corrupt-check --peer-auto-tls --initial-cluster test-TestCtlV3EndpointHashKV-0=https://localhost:20001,test-TestCtlV3EndpointHashKV-1=https://localhost:20006,test-TestCtlV3EndpointHashKV-2=https://localhost:20011
```

test.sh

@@ -67,7 +67,7 @@ fi
 
 # This options make sense for cases where SUT (System Under Test) is compiled by test.
 COMMON_TEST_FLAGS=("${RACE}")
-if [[ ! -z "${CPU}" ]]; then
+if [[ -n "${CPU}" ]]; then
   COMMON_TEST_FLAGS+=("--cpu=${CPU}")
 fi 
 

tests/e2e/cluster_test.go

@@ -16,7 +16,6 @@ package e2e
 
 import (
 	"fmt"
-	"io/ioutil"
 	"net/url"
 	"os"
 	"strings"
@@ -171,7 +170,7 @@ type etcdProcessClusterConfig struct {
 func newEtcdProcessCluster(t testing.TB, cfg *etcdProcessClusterConfig) (*etcdProcessCluster, error) {
 	skipInShortMode(t)
 
-	etcdCfgs := cfg.etcdServerProcessConfigs()
+	etcdCfgs := cfg.etcdServerProcessConfigs(t)
 	epc := &etcdProcessCluster{
 		cfg:   cfg,
 		procs: make([]etcdProcess, cfg.clusterSize),
@@ -217,7 +216,7 @@ func (cfg *etcdProcessClusterConfig) peerScheme() string {
 	return peerScheme
 }
 
-func (cfg *etcdProcessClusterConfig) etcdServerProcessConfigs() []*etcdServerProcessConfig {
+func (cfg *etcdProcessClusterConfig) etcdServerProcessConfigs(tb testing.TB) []*etcdServerProcessConfig {
 	if cfg.basePort == 0 {
 		cfg.basePort = etcdProcessBasePort
 	}
@@ -247,14 +246,10 @@ func (cfg *etcdProcessClusterConfig) etcdServerProcessConfigs() []*etcdServerPro
 		}
 
 		purl := url.URL{Scheme: cfg.peerScheme(), Host: fmt.Sprintf("localhost:%d", port+1)}
-		name := fmt.Sprintf("testname%d", i)
+		name := fmt.Sprintf("test-%s-%d", tb.Name(), i)
 		dataDirPath := cfg.dataDirPath
 		if cfg.dataDirPath == "" {
-			var derr error
+			dataDirPath = tb.TempDir()
-			dataDirPath, derr = ioutil.TempDir("", name+".etcd")
-			if derr != nil {
-				panic(fmt.Sprintf("could not get tempdir for datadir: %s", derr))
-			}
 		}
 		initialCluster[i] = fmt.Sprintf("%s=%s", name, purl.String())
 

tests/e2e/ctl_v3_snapshot_test.go

@@ -18,7 +18,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"math/rand"
 	"os"
 	"path/filepath"
 	"strings"
@@ -32,13 +31,6 @@ import (
 
 func TestCtlV3Snapshot(t *testing.T) { testCtl(t, snapshotTest) }
 
-// TODO: Replace with testing.T.TestDir() in golang-1.15.
-func tempDir(tb testing.TB) string {
-	dir := filepath.Join(os.TempDir(), tb.Name(), fmt.Sprint(rand.Int()))
-	os.MkdirAll(dir, 0700)
-	return dir
-}
-
 func snapshotTest(cx ctlCtx) {
 	maintenanceInitKeys(cx)
 
@@ -50,7 +42,7 @@ func snapshotTest(cx ctlCtx) {
 		cx.t.Fatalf("snapshot: ctlV3Put error (%v)", err)
 	}
 
-	fpath := filepath.Join(tempDir(cx.t), "snapshot")
+	fpath := filepath.Join(cx.t.TempDir(), "snapshot")
 	defer os.RemoveAll(fpath)
 
 	if err = ctlV3SnapshotSave(cx, fpath); err != nil {
@@ -72,7 +64,7 @@ func snapshotTest(cx ctlCtx) {
 func TestCtlV3SnapshotCorrupt(t *testing.T) { testCtl(t, snapshotCorruptTest) }
 
 func snapshotCorruptTest(cx ctlCtx) {
-	fpath := filepath.Join(tempDir(cx.t), "snapshot")
+	fpath := filepath.Join(cx.t.TempDir(), "snapshot")
 	defer os.RemoveAll(fpath)
 
 	if err := ctlV3SnapshotSave(cx, fpath); err != nil {
@@ -89,7 +81,7 @@ func snapshotCorruptTest(cx ctlCtx) {
 	}
 	f.Close()
 
-	datadir := filepath.Join(tempDir(cx.t), "data")
+	datadir := cx.t.TempDir()
 	defer os.RemoveAll(datadir)
 
 	serr := spawnWithExpect(
@@ -107,7 +99,7 @@ func snapshotCorruptTest(cx ctlCtx) {
 func TestCtlV3SnapshotStatusBeforeRestore(t *testing.T) { testCtl(t, snapshotStatusBeforeRestoreTest) }
 
 func snapshotStatusBeforeRestoreTest(cx ctlCtx) {
-	fpath := filepath.Join(tempDir(cx.t), "snapshot")
+	fpath := filepath.Join(cx.t.TempDir(), "snapshot")
 	defer os.RemoveAll(fpath)
 
 	if err := ctlV3SnapshotSave(cx, fpath); err != nil {
@@ -120,7 +112,7 @@ func snapshotStatusBeforeRestoreTest(cx ctlCtx) {
 		cx.t.Fatalf("snapshotTest getSnapshotStatus error (%v)", err)
 	}
 
-	dataDir := filepath.Join(tempDir(cx.t), "data")
+	dataDir := cx.t.TempDir()
 	defer os.RemoveAll(dataDir)
 	serr := spawnWithExpect(
 		append(cx.PrefixArgs(), "snapshot", "restore",
@@ -201,7 +193,7 @@ func TestIssue6361(t *testing.T) {
 		}
 	}
 
-	fpath := filepath.Join(tempDir(t), "snapshot")
+	fpath := filepath.Join(t.TempDir(), "test.snapshot")
 	defer os.RemoveAll(fpath)
 
 	t.Log("etcdctl saving snapshot...")
@@ -214,7 +206,7 @@ func TestIssue6361(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	newDataDir := tempDir(t)
+	newDataDir := filepath.Join(t.TempDir(), "test.data")
 	defer os.RemoveAll(newDataDir)
 
 	t.Log("etcdctl restoring the snapshot...")
@@ -249,7 +241,7 @@ func TestIssue6361(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	newDataDir2 := filepath.Join(tempDir(t), "newdata")
+	newDataDir2 := t.TempDir()
 	defer os.RemoveAll(newDataDir2)
 
 	name2 := "infra2"