controller: refactor progress api

Refactor the progress printer creation to the caller-side of the
controller api. Then, instead of passing around status channels (and
progressMode strings), we can simply pass around the higher level
interface progress.Writer.

This has a couple of benefits:
- A simplified interface to the controller
- Allows us to correctly extract warnings out of the controller, so that
  they can be displayed correctly from the client side.

Some extra work is required to make sure that we can pass a
progress.Printer into the debug monitor. If we want to keep it
persistent, then we need a way to temporarily suspend output from it,
otherwise it will continue printing as the monitor is prompting for
input from the user, and forwarding output from debug containers.

To handle this, we add two methods to the printer, `Pause` and
`Unpause`. `Pause` acts similarly to `Wait`, closing the printer, and
cleanly shutting down the display - however, the printer does not
terminate, and can later be resumed by a call to `Unpause`. This
provides a neater interface to the caller, instead of needing to
continually reconstruct printers for every single time we want to
produce progress output.

Signed-off-by: Justin Chadwell <me@jedevc.com>

controller/build/build.go

@@ -1,12 +1,10 @@
 package build
 
 import (
-	"bytes"
 	"context"
 	"encoding/base64"
 	"encoding/csv"
 	"encoding/json"
-	"fmt"
 	"io"
 	"os"
 	"path/filepath"
@@ -30,12 +28,8 @@ import (
 	"github.com/docker/go-units"
 	"github.com/moby/buildkit/client"
 	"github.com/moby/buildkit/session/auth/authprovider"
-	"github.com/moby/buildkit/solver/errdefs"
 	"github.com/moby/buildkit/util/grpcerrors"
-	"github.com/moby/buildkit/util/progress/progressui"
-	"github.com/morikuni/aec"
 	"github.com/pkg/errors"
-	"github.com/sirupsen/logrus"
 	"google.golang.org/grpc/codes"
 )
 
@@ -46,7 +40,7 @@ const defaultTargetName = "default"
 // NOTE: When an error happens during the build and this function acquires the debuggable *build.ResultContext,
 // this function returns it in addition to the error (i.e. it does "return nil, res, err"). The caller can
 // inspect the result and debug the cause of that error.
-func RunBuild(ctx context.Context, dockerCli command.Cli, in controllerapi.BuildOptions, inStream io.Reader, progressMode string, statusChan chan *client.SolveStatus, generateResult bool) (*client.SolveResponse, *build.ResultContext, error) {
+func RunBuild(ctx context.Context, dockerCli command.Cli, in controllerapi.BuildOptions, inStream io.Reader, progress progress.Writer, generateResult bool) (*client.SolveResponse, *build.ResultContext, error) {
 	if in.NoCache && len(in.NoCacheFilter) > 0 {
 		return nil, nil, errors.Errorf("--no-cache and --no-cache-filter cannot currently be used together")
 	}
@@ -164,6 +158,7 @@ func RunBuild(ctx context.Context, dockerCli command.Cli, in controllerapi.Build
 		contextPathHash = in.ContextPath
 	}
 
+	// TODO: this should not be loaded this side of the controller api
 	b, err := builder.New(dockerCli,
 		builder.WithName(in.Builder),
 		builder.WithContextPathHash(contextPathHash),
@@ -179,7 +174,7 @@ func RunBuild(ctx context.Context, dockerCli command.Cli, in controllerapi.Build
 		return nil, nil, err
 	}
 
-	resp, res, err := buildTargets(ctx, dockerCli, b.NodeGroup, nodes, map[string]build.Options{defaultTargetName: opts}, progressMode, in.MetadataFile, statusChan, generateResult)
+	resp, res, err := buildTargets(ctx, dockerCli, b.NodeGroup, nodes, map[string]build.Options{defaultTargetName: opts}, progress, in.MetadataFile, generateResult)
 	err = wrapBuildError(err, false)
 	if err != nil {
 		// NOTE: buildTargets can return *build.ResultContext even on error.
@@ -193,24 +188,14 @@ func RunBuild(ctx context.Context, dockerCli command.Cli, in controllerapi.Build
 // NOTE: When an error happens during the build and this function acquires the debuggable *build.ResultContext,
 // this function returns it in addition to the error (i.e. it does "return nil, res, err"). The caller can
 // inspect the result and debug the cause of that error.
-func buildTargets(ctx context.Context, dockerCli command.Cli, ng *store.NodeGroup, nodes []builder.Node, opts map[string]build.Options, progressMode string, metadataFile string, statusChan chan *client.SolveStatus, generateResult bool) (*client.SolveResponse, *build.ResultContext, error) {
-	ctx2, cancel := context.WithCancel(context.TODO())
-	defer cancel()
-
-	printer, err := progress.NewPrinter(ctx2, os.Stderr, os.Stderr, progressMode, progressui.WithDesc(
-		fmt.Sprintf("building with %q instance using %s driver", ng.Name, ng.Driver),
-		fmt.Sprintf("%s:%s", ng.Driver, ng.Name),
-	))
-	if err != nil {
-		return nil, nil, err
-	}
-
+func buildTargets(ctx context.Context, dockerCli command.Cli, ng *store.NodeGroup, nodes []builder.Node, opts map[string]build.Options, progress progress.Writer, metadataFile string, generateResult bool) (*client.SolveResponse, *build.ResultContext, error) {
 	var res *build.ResultContext
 	var resp map[string]*client.SolveResponse
+	var err error
 	if generateResult {
 		var mu sync.Mutex
 		var idx int
-		resp, err = build.BuildWithResultHandler(ctx, nodes, opts, dockerutil.NewClient(dockerCli), confutil.ConfigDir(dockerCli), progress.Tee(printer, statusChan), func(driverIndex int, gotRes *build.ResultContext) {
+		resp, err = build.BuildWithResultHandler(ctx, nodes, opts, dockerutil.NewClient(dockerCli), confutil.ConfigDir(dockerCli), progress, func(driverIndex int, gotRes *build.ResultContext) {
 			mu.Lock()
 			defer mu.Unlock()
 			if res == nil || driverIndex < idx {
@@ -218,11 +203,7 @@ func buildTargets(ctx context.Context, dockerCli command.Cli, ng *store.NodeGrou
 			}
 		})
 	} else {
-		resp, err = build.Build(ctx, nodes, opts, dockerutil.NewClient(dockerCli), confutil.ConfigDir(dockerCli), progress.Tee(printer, statusChan))
-	}
-	err1 := printer.Wait()
-	if err == nil {
-		err = err1
+		resp, err = build.Build(ctx, nodes, opts, dockerutil.NewClient(dockerCli), confutil.ConfigDir(dockerCli), progress)
 	}
 	if err != nil {
 		return nil, res, err
@@ -234,8 +215,6 @@ func buildTargets(ctx context.Context, dockerCli command.Cli, ng *store.NodeGrou
 		}
 	}
 
-	printWarnings(os.Stderr, printer.Warnings(), progressMode)
-
 	for k := range resp {
 		if opts[k].PrintFunc != nil {
 			if err := printResult(opts[k].PrintFunc, resp[k].ExporterResponse); err != nil {
@@ -247,46 +226,6 @@ func buildTargets(ctx context.Context, dockerCli command.Cli, ng *store.NodeGrou
 	return resp[defaultTargetName], res, err
 }
 
-func printWarnings(w io.Writer, warnings []client.VertexWarning, mode string) {
-	if len(warnings) == 0 || mode == progress.PrinterModeQuiet {
-		return
-	}
-	fmt.Fprintf(w, "\n ")
-	sb := &bytes.Buffer{}
-	if len(warnings) == 1 {
-		fmt.Fprintf(sb, "1 warning found")
-	} else {
-		fmt.Fprintf(sb, "%d warnings found", len(warnings))
-	}
-	if logrus.GetLevel() < logrus.DebugLevel {
-		fmt.Fprintf(sb, " (use --debug to expand)")
-	}
-	fmt.Fprintf(sb, ":\n")
-	fmt.Fprint(w, aec.Apply(sb.String(), aec.YellowF))
-
-	for _, warn := range warnings {
-		fmt.Fprintf(w, " - %s\n", warn.Short)
-		if logrus.GetLevel() < logrus.DebugLevel {
-			continue
-		}
-		for _, d := range warn.Detail {
-			fmt.Fprintf(w, "%s\n", d)
-		}
-		if warn.URL != "" {
-			fmt.Fprintf(w, "More info: %s\n", warn.URL)
-		}
-		if warn.SourceInfo != nil && warn.Range != nil {
-			src := errdefs.Source{
-				Info:   warn.SourceInfo,
-				Ranges: warn.Range,
-			}
-			src.Print(w)
-		}
-		fmt.Fprintf(w, "\n")
-
-	}
-}
-
 func parsePrintFunc(str string) (*build.PrintFunc, error) {
 	if str == "" {
 		return nil, nil