diff --git a/client/v2/client.go b/client/v2/client.go
index 7902b9c20a2..fda25988f6b 100644
--- a/client/v2/client.go
+++ b/client/v2/client.go
@@ -523,7 +523,7 @@ type simpleHTTPClient struct {
 
 // ErrNoRequest indicates that the HTTPRequest object could not be found
 // or was nil.  No processing could continue.
-var ErrNoRequest = errors.New("No HTTPRequest was available")
+var ErrNoRequest = errors.New("no HTTPRequest was available")
 
 func (c *simpleHTTPClient) Do(ctx context.Context, act httpAction) (*http.Response, []byte, error) {
 	req := act.HTTPRequest(c.endpoint)
diff --git a/client/v3/client.go b/client/v3/client.go
index 7f1f1322ec7..9442c9d1595 100644
--- a/client/v3/client.go
+++ b/client/v3/client.go
@@ -298,7 +298,7 @@ func (c *Client) credentialsForEndpoint(ep string) grpccredentials.TransportCred
 		}
 		return credentials.NewBundle(credentials.Config{}).TransportCredentials()
 	default:
-		panic(fmt.Errorf("Unsupported CredsRequirement: %v", r))
+		panic(fmt.Errorf("unsupported CredsRequirement: %v", r))
 	}
 }
 
diff --git a/client/v3/client_test.go b/client/v3/client_test.go
index 5e0f5844c63..159c2f3446f 100644
--- a/client/v3/client_test.go
+++ b/client/v3/client_test.go
@@ -140,13 +140,13 @@ func TestDialNoTimeout(t *testing.T) {
 }
 
 func TestIsHaltErr(t *testing.T) {
-	if !isHaltErr(nil, fmt.Errorf("etcdserver: some etcdserver error")) {
+	if !isHaltErr(context.TODO(), fmt.Errorf("etcdserver: some etcdserver error")) {
 		t.Errorf(`error prefixed with "etcdserver: " should be Halted by default`)
 	}
-	if isHaltErr(nil, rpctypes.ErrGRPCStopped) {
+	if isHaltErr(context.TODO(), rpctypes.ErrGRPCStopped) {
 		t.Errorf("error %v should not halt", rpctypes.ErrGRPCStopped)
 	}
-	if isHaltErr(nil, rpctypes.ErrGRPCNoLeader) {
+	if isHaltErr(context.TODO(), rpctypes.ErrGRPCNoLeader) {
 		t.Errorf("error %v should not halt", rpctypes.ErrGRPCNoLeader)
 	}
 	ctx, cancel := context.WithCancel(context.TODO())
diff --git a/client/v3/ctx_test.go b/client/v3/ctx_test.go
index c0e054341f9..8ba616b76a4 100644
--- a/client/v3/ctx_test.go
+++ b/client/v3/ctx_test.go
@@ -26,13 +26,13 @@ import (
 
 func TestMetadataWithRequireLeader(t *testing.T) {
 	ctx := context.TODO()
-	md, ok := metadata.FromOutgoingContext(ctx)
+	_, ok := metadata.FromOutgoingContext(ctx)
 	if ok {
 		t.Fatal("expected no outgoing metadata ctx key")
 	}
 
 	// add a conflicting key with some other value
-	md = metadata.Pairs(rpctypes.MetadataRequireLeaderKey, "invalid")
+	md := metadata.Pairs(rpctypes.MetadataRequireLeaderKey, "invalid")
 	// add a key, and expect not be overwritten
 	md.Set("hello", "1", "2")
 	ctx = metadata.NewOutgoingContext(ctx, md)
diff --git a/client/v3/internal/endpoint/endpoint.go b/client/v3/internal/endpoint/endpoint.go
index befe6022bbd..1d3f1a7a2c7 100644
--- a/client/v3/internal/endpoint/endpoint.go
+++ b/client/v3/internal/endpoint/endpoint.go
@@ -50,7 +50,7 @@ func extractHostFromPath(pathStr string) string {
 func mustSplit2(s, sep string) (string, string) {
 	spl := strings.SplitN(s, sep, 2)
 	if len(spl) < 2 {
-		panic(fmt.Errorf("Token '%v' expected to have separator sep: `%v`", s, sep))
+		panic(fmt.Errorf("token '%v' expected to have separator sep: `%v`", s, sep))
 	}
 	return spl[0], spl[1]
 }
diff --git a/client/v3/ordering/kv_test.go b/client/v3/ordering/kv_test.go
index 9b5c8ab2c2a..cc5c03bfa6b 100644
--- a/client/v3/ordering/kv_test.go
+++ b/client/v3/ordering/kv_test.go
@@ -77,7 +77,7 @@ func TestKvOrdering(t *testing.T) {
 			tt.prevRev,
 			sync.RWMutex{},
 		}
-		res, err := kv.Get(nil, "mockKey")
+		res, err := kv.Get(context.TODO(), "mockKey")
 		if err != nil {
 			t.Errorf("#%d: expected response %+v, got error %+v", i, tt.response, err)
 		}
diff --git a/client/v3/retry_interceptor.go b/client/v3/retry_interceptor.go
index 371c85800d3..1e0f20fd248 100644
--- a/client/v3/retry_interceptor.go
+++ b/client/v3/retry_interceptor.go
@@ -313,7 +313,7 @@ func isSafeRetry(lg *zap.Logger, err error, callOpts *options) bool {
 }
 
 func isContextError(err error) bool {
-	return grpc.Code(err) == codes.DeadlineExceeded || grpc.Code(err) == codes.Canceled
+	return status.Code(err) == codes.DeadlineExceeded || status.Code(err) == codes.Canceled
 }
 
 func contextErrToGrpcErr(err error) error {
diff --git a/client/v3/txn_test.go b/client/v3/txn_test.go
index 9101b04fa2a..0e755459fc2 100644
--- a/client/v3/txn_test.go
+++ b/client/v3/txn_test.go
@@ -15,6 +15,7 @@
 package clientv3
 
 import (
+	"context"
 	"testing"
 	"time"
 
@@ -44,7 +45,7 @@ func TestTxnPanics(t *testing.T) {
 		{
 			f: func() {
 				defer df()
-				kv.Txn(nil).If(cmp).If(cmp)
+				kv.Txn(context.TODO()).If(cmp).If(cmp)
 			},
 
 			err: "cannot call If twice!",
@@ -52,7 +53,7 @@ func TestTxnPanics(t *testing.T) {
 		{
 			f: func() {
 				defer df()
-				kv.Txn(nil).Then(op).If(cmp)
+				kv.Txn(context.TODO()).Then(op).If(cmp)
 			},
 
 			err: "cannot call If after Then!",
@@ -60,7 +61,7 @@ func TestTxnPanics(t *testing.T) {
 		{
 			f: func() {
 				defer df()
-				kv.Txn(nil).Else(op).If(cmp)
+				kv.Txn(context.TODO()).Else(op).If(cmp)
 			},
 
 			err: "cannot call If after Else!",
@@ -68,7 +69,7 @@ func TestTxnPanics(t *testing.T) {
 		{
 			f: func() {
 				defer df()
-				kv.Txn(nil).Then(op).Then(op)
+				kv.Txn(context.TODO()).Then(op).Then(op)
 			},
 
 			err: "cannot call Then twice!",
@@ -76,7 +77,7 @@ func TestTxnPanics(t *testing.T) {
 		{
 			f: func() {
 				defer df()
-				kv.Txn(nil).Else(op).Then(op)
+				kv.Txn(context.TODO()).Else(op).Then(op)
 			},
 
 			err: "cannot call Then after Else!",
@@ -84,7 +85,7 @@ func TestTxnPanics(t *testing.T) {
 		{
 			f: func() {
 				defer df()
-				kv.Txn(nil).Else(op).Else(op)
+				kv.Txn(context.TODO()).Else(op).Else(op)
 			},
 
 			err: "cannot call Else twice!",
diff --git a/etcdctl/ctlv2/command/exec_watch_command.go b/etcdctl/ctlv2/command/exec_watch_command.go
index 2bded023214..58f8b529fb3 100644
--- a/etcdctl/ctlv2/command/exec_watch_command.go
+++ b/etcdctl/ctlv2/command/exec_watch_command.go
@@ -109,7 +109,7 @@ func execWatchCommandFunc(c *cli.Context, ki client.KeysAPI) {
 		go func() {
 			err := cmd.Start()
 			if err != nil {
-				fmt.Fprintf(os.Stderr, err.Error())
+				fmt.Fprint(os.Stderr, err.Error())
 				os.Exit(1)
 			}
 			cmd.Wait()
diff --git a/etcdctl/ctlv3/command/ep_command.go b/etcdctl/ctlv3/command/ep_command.go
index 589a76aa77b..c286e896e06 100644
--- a/etcdctl/ctlv3/command/ep_command.go
+++ b/etcdctl/ctlv3/command/ep_command.go
@@ -133,7 +133,7 @@ func epHealthCommandFunc(cmd *cobra.Command, args []string) {
 				eh.Error = err.Error()
 			}
 
-			if eh.Health == true {
+			if eh.Health {
 				resp, err := cli.AlarmList(ctx)
 				if err == nil && len(resp.Alarms) > 0 {
 					eh.Health = false
diff --git a/etcdctl/ctlv3/command/printer_json.go b/etcdctl/ctlv3/command/printer_json.go
index 4d9732b95e4..22bc4f482c1 100644
--- a/etcdctl/ctlv3/command/printer_json.go
+++ b/etcdctl/ctlv3/command/printer_json.go
@@ -98,6 +98,6 @@ func printMemberListWithHexJSON(r clientv3.MemberListResponse) {
 		}
 	}
 	buffer.WriteString("}")
-	fmt.Println(string(buffer.Bytes()))
+	fmt.Println(buffer.String())
 
 }
diff --git a/etcdctl/ctlv3/command/watch_command.go b/etcdctl/ctlv3/command/watch_command.go
index 1697511f59c..1bfc479b149 100644
--- a/etcdctl/ctlv3/command/watch_command.go
+++ b/etcdctl/ctlv3/command/watch_command.go
@@ -98,7 +98,7 @@ func watchInteractiveFunc(cmd *cobra.Command, osArgs []string, envKey, envRange
 	for {
 		l, err := reader.ReadString('\n')
 		if err != nil {
-			ExitWithError(ExitInvalidInput, fmt.Errorf("Error reading watch request line: %v", err))
+			ExitWithError(ExitInvalidInput, fmt.Errorf("error reading watch request line: %v", err))
 		}
 		l = strings.TrimSuffix(l, "\n")
 
diff --git a/pkg/fileutil/fileutil.go b/pkg/fileutil/fileutil.go
index 657d5584163..f4b1986424d 100644
--- a/pkg/fileutil/fileutil.go
+++ b/pkg/fileutil/fileutil.go
@@ -121,7 +121,7 @@ func ZeroToEnd(f *os.File) error {
 // Returns error if dir is empty or exist with a different permission than specified.
 func CheckDirPermission(dir string, perm os.FileMode) error {
 	if !Exist(dir) {
-		return fmt.Errorf("directory %q empty, cannot check permission.", dir)
+		return fmt.Errorf("directory %q empty, cannot check permission", dir)
 	}
 	//check the existing permission on the directory
 	dirInfo, err := os.Stat(dir)
@@ -130,7 +130,7 @@ func CheckDirPermission(dir string, perm os.FileMode) error {
 	}
 	dirMode := dirInfo.Mode().Perm()
 	if dirMode != perm {
-		err = fmt.Errorf("directory %q exist, but the permission is %q. The recommended permission is %q to prevent possible unprivileged access to the data.", dir, dirInfo.Mode(), os.FileMode(PrivateDirMode))
+		err = fmt.Errorf("directory %q exist, but the permission is %q. The recommended permission is %q to prevent possible unprivileged access to the data", dir, dirInfo.Mode(), os.FileMode(PrivateDirMode))
 		return err
 	}
 	return nil
diff --git a/pkg/transport/transport.go b/pkg/transport/transport.go
index 4a7fe69d2e1..949610d46c1 100644
--- a/pkg/transport/transport.go
+++ b/pkg/transport/transport.go
@@ -41,10 +41,10 @@ func NewTransport(info TLSInfo, dialtimeoutd time.Duration) (*http.Transport, er
 		TLSClientConfig:     cfg,
 	}
 
-	dialer := (&net.Dialer{
+	dialer := &net.Dialer{
 		Timeout:   dialtimeoutd,
 		KeepAlive: 30 * time.Second,
-	})
+	}
 	dial := func(net, addr string) (net.Conn, error) {
 		return dialer.Dial("unix", addr)
 	}
diff --git a/raft/confchange/confchange.go b/raft/confchange/confchange.go
index 85689b44884..55e6830ce8a 100644
--- a/raft/confchange/confchange.go
+++ b/raft/confchange/confchange.go
@@ -188,7 +188,6 @@ func (c Changer) makeVoter(cfg *tracker.Config, prs tracker.ProgressMap, id uint
 	nilAwareDelete(&cfg.Learners, id)
 	nilAwareDelete(&cfg.LearnersNext, id)
 	incoming(cfg.Voters)[id] = struct{}{}
-	return
 }
 
 // makeLearner makes the given ID a learner or stages it to be a learner once
@@ -321,10 +320,10 @@ func checkInvariants(cfg tracker.Config, prs tracker.ProgressMap) error {
 	if !joint(cfg) {
 		// We enforce that empty maps are nil instead of zero.
 		if outgoing(cfg.Voters) != nil {
-			return fmt.Errorf("Voters[1] must be nil when not joint")
+			return fmt.Errorf("cfg.Voters[1] must be nil when not joint")
 		}
 		if cfg.LearnersNext != nil {
-			return fmt.Errorf("LearnersNext must be nil when not joint")
+			return fmt.Errorf("cfg.LearnersNext must be nil when not joint")
 		}
 		if cfg.AutoLeave {
 			return fmt.Errorf("AutoLeave must be false when not joint")
diff --git a/raft/quorum/datadriven_test.go b/raft/quorum/datadriven_test.go
index 50dbb25af62..b40eaa76c69 100644
--- a/raft/quorum/datadriven_test.go
+++ b/raft/quorum/datadriven_test.go
@@ -169,7 +169,7 @@ func TestDataDriven(t *testing.T) {
 				// test case.
 				if !joint {
 					idx := c.CommittedIndex(l)
-					fmt.Fprintf(&buf, c.Describe(l))
+					fmt.Fprint(&buf, c.Describe(l))
 					// These alternative computations should return the same
 					// result. If not, print to the output.
 					if aIdx := alternativeMajorityCommittedIndex(c, l); aIdx != idx {
@@ -213,7 +213,7 @@ func TestDataDriven(t *testing.T) {
 					fmt.Fprintf(&buf, "%s\n", idx)
 				} else {
 					cc := JointConfig([2]MajorityConfig{c, cj})
-					fmt.Fprintf(&buf, cc.Describe(l))
+					fmt.Fprint(&buf, cc.Describe(l))
 					idx := cc.CommittedIndex(l)
 					// Interchanging the majorities shouldn't make a difference. If it does, print.
 					if aIdx := JointConfig([2]MajorityConfig{cj, c}).CommittedIndex(l); aIdx != idx {
diff --git a/raft/quorum/quick_test.go b/raft/quorum/quick_test.go
index 45fb6b00a74..d838b54f8c3 100644
--- a/raft/quorum/quick_test.go
+++ b/raft/quorum/quick_test.go
@@ -44,10 +44,10 @@ func TestQuick(t *testing.T) {
 }
 
 // smallRandIdxMap returns a reasonably sized map of ids to commit indexes.
-func smallRandIdxMap(rand *rand.Rand, size int) map[uint64]Index {
+func smallRandIdxMap(rand *rand.Rand, _ int) map[uint64]Index {
 	// Hard-code a reasonably small size here (quick will hard-code 50, which
 	// is not useful here).
-	size = 10
+	size := 10
 
 	n := rand.Intn(size)
 	ids := rand.Perm(2 * n)[:n]
diff --git a/raft/rafttest/interaction_env_handler_log_level.go b/raft/rafttest/interaction_env_handler_log_level.go
index a61ba37cd89..2194c9ee1a1 100644
--- a/raft/rafttest/interaction_env_handler_log_level.go
+++ b/raft/rafttest/interaction_env_handler_log_level.go
@@ -28,7 +28,7 @@ func (env *InteractionEnv) handleLogLevel(t *testing.T, d datadriven.TestData) e
 
 func (env *InteractionEnv) LogLevel(name string) error {
 	for i, s := range lvlNames {
-		if strings.ToLower(s) == strings.ToLower(name) {
+		if strings.EqualFold(s, name) {
 			env.Output.Lvl = i
 			return nil
 		}
diff --git a/raft/rafttest/interaction_env_handler_process_ready.go b/raft/rafttest/interaction_env_handler_process_ready.go
index c0014d7e01b..d94ac60334f 100644
--- a/raft/rafttest/interaction_env_handler_process_ready.go
+++ b/raft/rafttest/interaction_env_handler_process_ready.go
@@ -99,9 +99,9 @@ func (env *InteractionEnv) ProcessReady(idx int) error {
 		snap.Metadata.ConfState = *cs
 		env.Nodes[idx].History = append(env.Nodes[idx].History, snap)
 	}
-	for _, msg := range rd.Messages {
-		env.Messages = append(env.Messages, msg)
-	}
+
+	env.Messages = append(env.Messages, rd.Messages...)
+
 	rn.Advance(rd)
 	return nil
 }
diff --git a/raft/rafttest/node.go b/raft/rafttest/node.go
index 2dfeca5307b..cb1a1241fcd 100644
--- a/raft/rafttest/node.go
+++ b/raft/rafttest/node.go
@@ -64,7 +64,7 @@ func startNode(id uint64, peers []raft.Peer, iface iface) *node {
 
 func (n *node) start() {
 	n.stopc = make(chan struct{})
-	ticker := time.Tick(5 * time.Millisecond)
+	ticker := time.NewTicker(5 * time.Millisecond).C
 
 	go func() {
 		for {
diff --git a/raft/rawnode_test.go b/raft/rawnode_test.go
index 0fe03512f91..898b0f12c3e 100644
--- a/raft/rawnode_test.go
+++ b/raft/rawnode_test.go
@@ -467,7 +467,7 @@ func TestRawNodeJointAutoLeave(t *testing.T) {
 			t.Fatalf("exp:\n%+v\nact:\n%+v", expCs, cs)
 		}
 
-		if 0 != rawNode.raft.pendingConfIndex {
+		if rawNode.raft.pendingConfIndex != 0 {
 			t.Fatalf("pendingConfIndex: expected %d, got %d", 0, rawNode.raft.pendingConfIndex)
 		}
 
diff --git a/raft/status.go b/raft/status.go
index d7c7a4fa7ae..acfb56c3915 100644
--- a/raft/status.go
+++ b/raft/status.go
@@ -44,8 +44,7 @@ type BasicStatus struct {
 func getProgressCopy(r *raft) map[uint64]tracker.Progress {
 	m := make(map[uint64]tracker.Progress)
 	r.prs.Visit(func(id uint64, pr *tracker.Progress) {
-		var p tracker.Progress
-		p = *pr
+		p := *pr
 		p.Inflights = pr.Inflights.Clone()
 		pr = nil
 
diff --git a/raft/tracker/tracker.go b/raft/tracker/tracker.go
index 13a0dc09465..72dcc73b866 100644
--- a/raft/tracker/tracker.go
+++ b/raft/tracker/tracker.go
@@ -194,7 +194,7 @@ func (p *ProgressTracker) Visit(f func(id uint64, pr *Progress)) {
 	// The optimization here mirrors that in `(MajorityConfig).CommittedIndex`,
 	// see there for details.
 	var sl [7]uint64
-	ids := sl[:]
+	var ids []uint64
 	if len(sl) >= n {
 		ids = sl[:n]
 	} else {