Fix local imports, add appropriate linter

Format all imports to have three groups:
1. Standard library packages.
2. Third-party packages.
3. Local packages (i.e. ones with github.com/google/cadvisor prefix).

Modify Makefile to do the same for format target. Note goimports does
the same thing as gofmt, plus imports sorting. It can't do what gofmt -s
does, but it was not done before (although checked according to
.golangci.yml), so it's left as is.

Finally, add goimports linter with proper configuration to check imports
formatting in CI.

NOTE we can't use $(pkgs) and $(cmd_pkgs) in Makefile's format target,
as we have to skip some auto-generated files (*.pb.go), so use find|grep
instead.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

.golangci.yml

@@ -7,6 +7,8 @@ run:
       min-confidence: 0
     gofmt:
       simplify: true
+    goimports:
+      local-prefixes: github.com/google/cadvisor
 linters:
   disable-all: true
   enable:
@@ -22,6 +24,7 @@ linters:
     - typecheck
     - golint
     - gofmt
+    - goimports
 issues:
   max-issues-per-linter: 0
   max-same-issues: 0

Makefile

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 GO := go
+GOFMT := goimports -w -local github.com/google/cadvisor
 pkgs     = $(shell $(GO) list ./... | grep -v vendor)
 cmd_pkgs = $(shell cd cmd && $(GO) list ./... | grep -v vendor)
 arch ?= $(shell go env GOARCH)
@@ -62,8 +63,10 @@ tidy:
 
 format:
 	@echo ">> formatting code"
-	@$(GO) fmt $(pkgs)
-	@cd cmd && $(GO) fmt $(cmd_pkgs)
+	@# Can't use $(pkgs) and $(cmd_pkgs) here as we need
+	@# to skip auto-generated files.
+	@find -name '*.go' | grep -Ev '^vendor/|.pb.go$$' | \
+		xargs goimports -w -local github.com/google/cadvisor
 
 vet:
 	@echo ">> vetting code"

accelerators/nvidia_test.go

@@ -14,12 +14,13 @@
 package accelerators
 
 import (
-	"github.com/google/cadvisor/stats"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
 
+	"github.com/google/cadvisor/stats"
+
 	"github.com/mindprince/gonvml"
 	"github.com/stretchr/testify/assert"
 )

client/client.go

@@ -28,7 +28,7 @@ import (
 	"path"
 	"strings"
 
-	"github.com/google/cadvisor/info/v1"
+	v1 "github.com/google/cadvisor/info/v1"
 
 	"k8s.io/klog/v2"
 )

client/v2/client.go

@@ -27,7 +27,7 @@ import (
 	"strings"
 
 	v1 "github.com/google/cadvisor/info/v1"
-	"github.com/google/cadvisor/info/v2"
+	v2 "github.com/google/cadvisor/info/v2"
 )
 
 // Client represents the base URL for a cAdvisor client.

client/v2/client_test.go

@@ -24,9 +24,10 @@ import (
 	"testing"
 	"time"
 
-	"github.com/google/cadvisor/info/v1"
-	"github.com/google/cadvisor/info/v2"
 	"github.com/stretchr/testify/assert"
+
+	v1 "github.com/google/cadvisor/info/v1"
+	v2 "github.com/google/cadvisor/info/v2"
 )
 
 func cadvisorTestClient(path string, expectedPostObj *v1.ContainerInfoRequest, replyObj interface{}, t *testing.T) (*Client, *httptest.Server, error) {

cmd/cadvisor_test.go

@@ -18,8 +18,9 @@ import (
 	"flag"
 	"testing"
 
-	"github.com/google/cadvisor/container"
 	"github.com/stretchr/testify/assert"
+
+	"github.com/google/cadvisor/container"
 )
 
 func TestTcpMetricsAreDisabledByDefault(t *testing.T) {

cmd/internal/container/mesos/client.go

@@ -16,6 +16,9 @@ package mesos
 
 import (
 	"fmt"
+	"net/url"
+	"sync"
+
 	"github.com/Rican7/retry"
 	"github.com/Rican7/retry/strategy"
 	mesos "github.com/mesos/mesos-go/api/v1/lib"
@@ -24,8 +27,6 @@ import (
 	mclient "github.com/mesos/mesos-go/api/v1/lib/client"
 	"github.com/mesos/mesos-go/api/v1/lib/encoding/codecs"
 	"github.com/mesos/mesos-go/api/v1/lib/httpcli"
-	"net/url"
-	"sync"
 )
 
 const (

cmd/internal/container/mesos/factory.go

@@ -22,12 +22,13 @@ import (
 	"strings"
 	"time"
 
+	"k8s.io/klog/v2"
+
 	"github.com/google/cadvisor/container"
 	"github.com/google/cadvisor/container/libcontainer"
 	"github.com/google/cadvisor/fs"
 	info "github.com/google/cadvisor/info/v1"
 	"github.com/google/cadvisor/watcher"
-	"k8s.io/klog/v2"
 )
 
 var MesosAgentAddress = flag.String("mesos_agent", "127.0.0.1:5051", "Mesos agent address")

cmd/internal/container/mesos/factory_test.go

@@ -15,10 +15,12 @@
 package mesos
 
 import (
-	containerlibcontainer "github.com/google/cadvisor/container/libcontainer"
+	"testing"
+
 	mesos "github.com/mesos/mesos-go/api/v1/lib"
 	"github.com/stretchr/testify/assert"
-	"testing"
+
+	containerlibcontainer "github.com/google/cadvisor/container/libcontainer"
 )
 
 func TestIsContainerName(t *testing.T) {

cmd/internal/container/mesos/handler_test.go

@@ -18,12 +18,13 @@ import (
 	"fmt"
 	"testing"
 
+	mesos "github.com/mesos/mesos-go/api/v1/lib"
+	"github.com/stretchr/testify/assert"
+
 	"github.com/google/cadvisor/container"
 	containerlibcontainer "github.com/google/cadvisor/container/libcontainer"
 	"github.com/google/cadvisor/fs"
 	info "github.com/google/cadvisor/info/v1"
-	mesos "github.com/mesos/mesos-go/api/v1/lib"
-	"github.com/stretchr/testify/assert"
 )
 
 func PopulateContainer() *mContainer {

cmd/internal/container/mesos/install/install.go

@@ -16,9 +16,10 @@
 package install
 
 import (
+	"k8s.io/klog/v2"
+
 	"github.com/google/cadvisor/cmd/internal/container/mesos"
 	"github.com/google/cadvisor/container"
-	"k8s.io/klog/v2"
 )
 
 func init() {

cmd/internal/container/mesos/mesos_agent.go

@@ -16,6 +16,7 @@ package mesos
 
 import (
 	"fmt"
+
 	mesos "github.com/mesos/mesos-go/api/v1/lib"
 	"github.com/mesos/mesos-go/api/v1/lib/agent"
 )

cmd/internal/container/mesos/mesos_agent_test.go

@@ -16,10 +16,11 @@ package mesos
 
 import (
 	"fmt"
+	"testing"
+
 	mesos "github.com/mesos/mesos-go/api/v1/lib"
 	"github.com/mesos/mesos-go/api/v1/lib/agent"
 	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 func PopulateFrameworks(fwID string) *agent.Response_GetFrameworks {

cmd/internal/storage/bigquery/client/example/example.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"github.com/SeanDolphin/bqschema"
+
 	"github.com/google/cadvisor/cmd/internal/storage/bigquery/client"
 )
 

collector/collector_manager.go

@@ -19,7 +19,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/google/cadvisor/info/v1"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 const metricLabelPrefix = "io.cadvisor.metric."

collector/collector_manager_test.go

@@ -18,9 +18,9 @@ import (
 	"testing"
 	"time"
 
-	"github.com/google/cadvisor/info/v1"
-
 	"github.com/stretchr/testify/assert"
+
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 type fakeCollector struct {

collector/config.go

@@ -18,7 +18,8 @@ import (
 	"time"
 
 	"encoding/json"
-	"github.com/google/cadvisor/info/v1"
+
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 type Config struct {

collector/fakes.go

@@ -17,7 +17,7 @@ package collector
 import (
 	"time"
 
-	"github.com/google/cadvisor/info/v1"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 type FakeCollectorManager struct {

collector/generic_collector.go

@@ -25,7 +25,7 @@ import (
 	"time"
 
 	"github.com/google/cadvisor/container"
-	"github.com/google/cadvisor/info/v1"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 type GenericCollector struct {

collector/generic_collector_test.go

@@ -22,10 +22,10 @@ import (
 	"os"
 	"testing"
 
-	"github.com/google/cadvisor/info/v1"
+	"github.com/stretchr/testify/assert"
 
 	containertest "github.com/google/cadvisor/container/testing"
-	"github.com/stretchr/testify/assert"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 func TestEmptyConfig(t *testing.T) {

collector/prometheus_collector.go

@@ -28,7 +28,7 @@ import (
 	"github.com/prometheus/common/model"
 
 	"github.com/google/cadvisor/container"
-	"github.com/google/cadvisor/info/v1"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 type PrometheusCollector struct {

collector/prometheus_collector_test.go

@@ -21,11 +21,11 @@ import (
 	"net/http/httptest"
 	"testing"
 
-	"github.com/google/cadvisor/info/v1"
-
-	containertest "github.com/google/cadvisor/container/testing"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+
+	containertest "github.com/google/cadvisor/container/testing"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 func TestPrometheus(t *testing.T) {

collector/types.go

@@ -17,7 +17,7 @@ package collector
 import (
 	"time"
 
-	"github.com/google/cadvisor/info/v1"
+	v1 "github.com/google/cadvisor/info/v1"
 )
 
 // TODO(vmarmol): Export to a custom metrics type when that is available.

container/common/helpers.go

@@ -24,14 +24,15 @@ import (
 	"strings"
 	"time"
 
-	"github.com/google/cadvisor/container"
-	info "github.com/google/cadvisor/info/v1"
-	"github.com/google/cadvisor/utils"
 	"github.com/karrick/godirwalk"
 	"github.com/opencontainers/runc/libcontainer/cgroups"
 	"github.com/pkg/errors"
 	"golang.org/x/sys/unix"
 
+	"github.com/google/cadvisor/container"
+	info "github.com/google/cadvisor/info/v1"
+	"github.com/google/cadvisor/utils"
+
 	"k8s.io/klog/v2"
 )
 

container/common/helpers_test.go

@@ -21,9 +21,10 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+
 	info "github.com/google/cadvisor/info/v1"
 	v2 "github.com/google/cadvisor/info/v2"
-	"github.com/stretchr/testify/assert"
 )
 
 func BenchmarkListDirectories(b *testing.B) {

container/containerd/client.go

@@ -30,9 +30,10 @@ import (
 	"github.com/containerd/containerd/errdefs"
 	"github.com/containerd/containerd/pkg/dialer"
 	ptypes "github.com/gogo/protobuf/types"
-	criapi "github.com/google/cadvisor/cri-api/pkg/apis/runtime/v1alpha2"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/backoff"
+
+	criapi "github.com/google/cadvisor/cri-api/pkg/apis/runtime/v1alpha2"
 )
 
 type client struct {

container/containerd/client_test.go

@@ -20,6 +20,7 @@ import (
 
 	types "github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/containers"
+
 	criapi "github.com/google/cadvisor/cri-api/pkg/apis/runtime/v1alpha2"
 )
 

container/containerd/handler.go

@@ -23,16 +23,18 @@ import (
 	"time"
 
 	"github.com/containerd/containerd/errdefs"
-	criapi "github.com/google/cadvisor/cri-api/pkg/apis/runtime/v1alpha2"
 	"golang.org/x/net/context"
 	"k8s.io/klog/v2"
 
+	criapi "github.com/google/cadvisor/cri-api/pkg/apis/runtime/v1alpha2"
+
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+
 	"github.com/google/cadvisor/container"
 	"github.com/google/cadvisor/container/common"
 	containerlibcontainer "github.com/google/cadvisor/container/libcontainer"
 	"github.com/google/cadvisor/fs"
 	info "github.com/google/cadvisor/info/v1"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
 )
 
 type fsUsageProvider struct {

container/containerd/handler_test.go

@@ -23,14 +23,15 @@ import (
 	types "github.com/containerd/containerd/api/types"
 	"github.com/containerd/containerd/containers"
 	"github.com/containerd/typeurl"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/stretchr/testify/assert"
+
 	"github.com/google/cadvisor/container"
 	containerlibcontainer "github.com/google/cadvisor/container/libcontainer"
 	criapi "github.com/google/cadvisor/cri-api/pkg/apis/runtime/v1alpha2"
 	"github.com/google/cadvisor/fs"
 	info "github.com/google/cadvisor/info/v1"
 	v1 "github.com/google/cadvisor/info/v1"
-	specs "github.com/opencontainers/runtime-spec/specs-go"
-	"github.com/stretchr/testify/assert"
 )
 
 const (

container/containerd/install/install.go

@@ -16,9 +16,10 @@
 package install
 
 import (
+	"k8s.io/klog/v2"
+
 	"github.com/google/cadvisor/container"
 	"github.com/google/cadvisor/container/containerd"
-	"k8s.io/klog/v2"
 )
 
 func init() {