Removed Version API from the public-api

This is a sibling PR to #5993, and it's the second step towards removing the `linkerd-controller` pod.

This one deals with a replacement for the `Version` API, fetching instead the `linkerd-config` CM and retrieving the `LinkerdVersion` value.

## Changes to the public-api

- Removal of the `publicPb.ApiClient` entry from the `Client` interface
- Removal of the `publicPb.ApiServer` entry from the `Server` interface
- Removal of the `Version` and related methods from `client.go`, `grpc_server.go` and `http_server.go`

## Changes to `linkerd version`

- Removal of all references to the public API.
- Call `healthcheck.GetServerVersion` to retrieve the version

## Changes to `linkerd check`

- Removal of the "can query the control API" check from the "linkerd-api" section
- Addition of a new "can retrieve the control plane version" check under the "control-plane-version" section

## Changes to `linkerd-web`

- The version is now retrieved from the `linkerd-config` CM instead of a public-API call.
- Removal of all references to the public API.
- Removal of the `data-go-version` global attribute on the dashboard, which wasn't being used.

## Other changes

- Added `ValuesFromConfigMap` function in `values.go` to convert the `linkerd-config` CM into a `*Values` struct instance
- Removal of the `public` protobuf

bin/protoc-go.sh

@@ -6,16 +6,14 @@ bindir=$( cd "${0%/*}" && pwd )
 
 go install -mod=readonly github.com/golang/protobuf/protoc-gen-go
 
-rm -rf controller/gen/common controller/gen/public controller/gen/config viz/metrics-api/gen viz/tap/gen
-mkdir -p controller/gen/common/net controller/gen/public viz/metrics-api/gen/viz viz/tap/gen/tap
+rm -rf controller/gen/common controller/gen/config viz/metrics-api/gen viz/tap/gen
+mkdir -p controller/gen/common/net viz/metrics-api/gen/viz viz/tap/gen/tap
 
 "$bindir"/protoc -I proto --go_out=plugins=grpc,paths=source_relative:controller/gen proto/common/net.proto
-"$bindir"/protoc -I proto --go_out=plugins=grpc,paths=source_relative:controller/gen proto/public.proto
 "$bindir"/protoc -I proto --go_out=plugins=grpc,paths=source_relative:controller/gen proto/config/config.proto
 "$bindir"/protoc -I proto -I viz/metrics-api/proto --go_out=plugins=grpc,paths=source_relative:viz/metrics-api/gen viz/metrics-api/proto/viz.proto
 "$bindir"/protoc -I proto -I viz/tap/proto -I viz/metrics-api/proto --go_out=plugins=grpc,paths=source_relative:viz/tap/gen viz/tap/proto/viz_tap.proto
 
 mv controller/gen/common/net.pb.go   controller/gen/common/net/
-mv controller/gen/public.pb.go controller/gen/public/
 mv viz/metrics-api/gen/viz.pb.go viz/metrics-api/gen/viz/viz.pb.go
 mv viz/tap/gen/viz_tap.pb.go viz/tap/gen/tap/viz_tap.pb.go

cli/cmd/version.go

@@ -7,10 +7,8 @@ import (
 	"os"
 	"time"
 
-	publicPb "github.com/linkerd/linkerd2/controller/gen/public"
 	"github.com/linkerd/linkerd2/pkg/healthcheck"
 	"github.com/linkerd/linkerd2/pkg/k8s"
-	api "github.com/linkerd/linkerd2/pkg/public"
 	"github.com/linkerd/linkerd2/pkg/version"
 	"github.com/spf13/cobra"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -51,7 +49,7 @@ func newCmdVersion() *cobra.Command {
 				}
 			}
 
-			configureAndRunVersion(cmd.Context(), k8sAPI, options, os.Stdout, api.RawPublicAPIClient)
+			configureAndRunVersion(k8sAPI, options, os.Stdout)
 			return nil
 		},
 	}
@@ -65,11 +63,9 @@ func newCmdVersion() *cobra.Command {
 }
 
 func configureAndRunVersion(
-	ctx context.Context,
 	k8sAPI *k8s.KubernetesAPI,
 	options *versionOptions,
 	stdout io.Writer,
-	mkPublicClient func(ctx context.Context, k8sAPI *k8s.KubernetesAPI, controlPlaneNamespace, apiAddr string) (publicPb.ApiClient, error),
 ) {
 	clientVersion := version.Version
 	if options.shortVersion {
@@ -79,16 +75,11 @@ func configureAndRunVersion(
 	}
 
 	if !options.onlyClientVersion {
-		serverVersion := defaultVersionString
-		publicClient, clientErr := mkPublicClient(ctx, k8sAPI, controlPlaneNamespace, apiAddr)
-		if clientErr == nil {
-			ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-			defer cancel()
-			var err error
-			serverVersion, err = healthcheck.GetServerVersion(ctx, publicClient)
-			if err != nil {
-				serverVersion = defaultVersionString
-			}
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		serverVersion, err := healthcheck.GetServerVersion(ctx, controlPlaneNamespace, k8sAPI)
+		if err != nil {
+			serverVersion = defaultVersionString
 		}
 
 		if options.shortVersion {

controller/api/public/client.go

@@ -1,7 +1,6 @@
 package public
 
 import (
-	"bufio"
 	"bytes"
 	"context"
 	"errors"
@@ -11,7 +10,6 @@ import (
 
 	"github.com/golang/protobuf/proto"
 	destinationPb "github.com/linkerd/linkerd2-proxy-api/go/destination"
-	publicPb "github.com/linkerd/linkerd2/controller/gen/public"
 	"github.com/linkerd/linkerd2/pkg/k8s"
 	"github.com/linkerd/linkerd2/pkg/protohttp"
 	log "github.com/sirupsen/logrus"
@@ -27,9 +25,8 @@ const (
 	apiDeployment = "linkerd-controller"
 )
 
-// Client wraps one gRPC client interface for publicPb.Api:
+// Client wraps one gRPC client interface for destination
 type Client interface {
-	publicPb.ApiClient
 	destinationPb.DestinationClient
 }
 
@@ -39,12 +36,6 @@ type grpcOverHTTPClient struct {
 	controlPlaneNamespace string
 }
 
-func (c *grpcOverHTTPClient) Version(ctx context.Context, req *publicPb.Empty, _ ...grpc.CallOption) (*publicPb.VersionInfo, error) {
-	var msg publicPb.VersionInfo
-	err := c.apiRequest(ctx, "Version", req, &msg)
-	return &msg, err
-}
-
 func (c *grpcOverHTTPClient) Get(ctx context.Context, req *destinationPb.GetDestination, _ ...grpc.CallOption) (destinationPb.Destination_GetClient, error) {
 	url := c.endpointNameToPublicAPIURL("DestinationGet")
 	httpRsp, err := c.post(ctx, url, req)
@@ -65,25 +56,6 @@ func (c *grpcOverHTTPClient) GetProfile(ctx context.Context, _ *destinationPb.Ge
 	return nil, errors.New("Not implemented")
 }
 
-func (c *grpcOverHTTPClient) apiRequest(ctx context.Context, endpoint string, req proto.Message, protoResponse proto.Message) error {
-	url := c.endpointNameToPublicAPIURL(endpoint)
-
-	log.Debugf("Making gRPC-over-HTTP call to [%s] [%+v]", url.String(), req)
-	httpRsp, err := c.post(ctx, url, req)
-	if err != nil {
-		return err
-	}
-	defer httpRsp.Body.Close()
-	log.Debugf("gRPC-over-HTTP call returned status [%s] and content length [%d]", httpRsp.Status, httpRsp.ContentLength)
-
-	if err := protohttp.CheckIfResponseHasError(httpRsp); err != nil {
-		return err
-	}
-
-	reader := bufio.NewReader(httpRsp.Body)
-	return protohttp.FromByteStreamToProtocolBuffers(reader, protoResponse)
-}
-
 func (c *grpcOverHTTPClient) post(ctx context.Context, url *url.URL, req proto.Message) (*http.Response, error) {
 	reqBytes, err := proto.Marshal(req)
 	if err != nil {

controller/api/public/client_test.go

@@ -3,85 +3,15 @@ package public
 import (
 	"bufio"
 	"bytes"
-	"context"
 	"fmt"
-	"io/ioutil"
-	"net/http"
-	"net/url"
 	"testing"
 
 	"github.com/golang/protobuf/proto"
-	publicPb "github.com/linkerd/linkerd2/controller/gen/public"
 	"github.com/linkerd/linkerd2/pkg/protohttp"
 	pb "github.com/linkerd/linkerd2/viz/metrics-api/gen/viz"
 )
 
-type mockTransport struct {
-	responseToReturn *http.Response
-	requestSent      *http.Request
-	errorToReturn    error
-}
-
-func (m *mockTransport) RoundTrip(req *http.Request) (*http.Response, error) {
-	m.requestSent = req
-	return m.responseToReturn, m.errorToReturn
-}
-
-func TestNewInternalClient(t *testing.T) {
-	t.Run("Makes a well-formed request over the Kubernetes public API", func(t *testing.T) {
-		mockTransport := &mockTransport{}
-		mockTransport.responseToReturn = &http.Response{
-			StatusCode: 200,
-			Body:       ioutil.NopCloser(bufferedReader(t, &pb.Empty{})),
-		}
-		mockHTTPClient := &http.Client{
-			Transport: mockTransport,
-		}
-
-		apiURL := &url.URL{
-			Scheme: "http",
-			Host:   "some-hostname",
-			Path:   "/",
-		}
-		client, err := newClient(apiURL, mockHTTPClient, "linkerd")
-		if err != nil {
-			t.Fatalf("Unexpected error: %v", err)
-		}
-
-		_, err = client.Version(context.Background(), &publicPb.Empty{})
-		if err != nil {
-			t.Fatalf("Unexpected error: %v", err)
-		}
-
-		expectedURLRequested := "http://some-hostname/api/v1/Version"
-		actualURLRequested := mockTransport.requestSent.URL.String()
-		if actualURLRequested != expectedURLRequested {
-			t.Fatalf("Expected request to URL [%v], but got [%v]", expectedURLRequested, actualURLRequested)
-		}
-	})
-}
-
 func TestFromByteStreamToProtocolBuffers(t *testing.T) {
-	t.Run("Correctly marshalls an valid object", func(t *testing.T) {
-		versionInfo := publicPb.VersionInfo{
-			GoVersion:      "1.9.1",
-			BuildDate:      "2017.11.17",
-			ReleaseVersion: "1.2.3",
-		}
-
-		var protobufMessageToBeFilledWithData publicPb.VersionInfo
-		reader := bufferedReader(t, &versionInfo)
-
-		err := protohttp.FromByteStreamToProtocolBuffers(reader, &protobufMessageToBeFilledWithData)
-		if err != nil {
-			t.Fatalf("Unexpected error: %v", err)
-		}
-
-		if !proto.Equal(&protobufMessageToBeFilledWithData, &versionInfo) {
-			t.Fatalf("mismatch, %s != %s", protobufMessageToBeFilledWithData.String(), versionInfo.String())
-		}
-	})
-
 	t.Run("Correctly marshalls a large byte array", func(t *testing.T) {
 		rows := make([]*pb.StatTable_PodGroup_Row, 0)
 
@@ -137,22 +67,6 @@ func TestFromByteStreamToProtocolBuffers(t *testing.T) {
 			t.Fatalf("Expected object to contain message [%s], but got [%s]", expectedErrorMessage, actualErrorMessage)
 		}
 	})
-
-	t.Run("Returns error if byte stream contains wrong object", func(t *testing.T) {
-		versionInfo := &publicPb.VersionInfo{
-			GoVersion:      "1.9.1",
-			BuildDate:      "2017.11.17",
-			ReleaseVersion: "1.2.3",
-		}
-
-		reader := bufferedReader(t, versionInfo)
-
-		protobufMessageToBeFilledWithData := &pb.StatSummaryResponse{}
-		err := protohttp.FromByteStreamToProtocolBuffers(reader, protobufMessageToBeFilledWithData)
-		if err == nil {
-			t.Fatal("Expecting error, got nothing")
-		}
-	})
 }
 
 func bufferedReader(t *testing.T, msg proto.Message) *bufio.Reader {

controller/api/public/grpc_server.go

@@ -1,21 +1,15 @@
 package public
 
 import (
-	"context"
 	"errors"
-	"runtime"
 
 	destinationPb "github.com/linkerd/linkerd2-proxy-api/go/destination"
-	pb "github.com/linkerd/linkerd2/controller/gen/public"
 	"github.com/linkerd/linkerd2/controller/k8s"
-	"github.com/linkerd/linkerd2/pkg/prometheus"
-	"github.com/linkerd/linkerd2/pkg/version"
 	log "github.com/sirupsen/logrus"
 )
 
 // Server specifies the interface the Public API server should implement
 type Server interface {
-	pb.ApiServer
 	destinationPb.DestinationServer
 }
 
@@ -40,15 +34,9 @@ func newGrpcServer(
 		clusterDomain:       clusterDomain,
 	}
 
-	pb.RegisterApiServer(prometheus.NewGrpcServer(), grpcServer)
-
 	return grpcServer
 }
 
-func (*grpcServer) Version(ctx context.Context, req *pb.Empty) (*pb.VersionInfo, error) {
-	return &pb.VersionInfo{GoVersion: runtime.Version(), ReleaseVersion: version.Version, BuildDate: "1970-01-01T00:00:00Z"}, nil
-}
-
 // Pass through to Destination service
 func (s *grpcServer) Get(req *destinationPb.GetDestination, stream destinationPb.Destination_GetServer) error {
 	destinationStream := stream.(destinationServer)