Connect to the buildkitd embeded in dockerd

go.mod

module q

go 1.18

replace github.com/docker/docker => github.com/docker/docker v20.10.3-0.20220224222438-c78f6963a1c0+incompatible

require (
	github.com/containerd/console v1.0.3
	github.com/docker/docker v20.10.7+incompatible
	github.com/moby/buildkit v0.10.3
)

require (
	github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 // indirect
	github.com/Microsoft/go-winio v0.5.1 // indirect
	github.com/containerd/containerd v1.6.3-0.20220401172941-5ff8fce1fcc6 // indirect
	github.com/containerd/continuity v0.2.3-0.20220330195504-d132b287edc8 // indirect
	github.com/containerd/typeurl v1.0.2 // indirect
	github.com/docker/cli v20.10.13+incompatible // indirect
	github.com/docker/distribution v2.8.0+incompatible // indirect
	github.com/docker/go-connections v0.4.0 // indirect
	github.com/docker/go-units v0.4.0 // indirect
	github.com/go-logr/logr v1.2.2 // indirect
	github.com/go-logr/stdr v1.2.2 // indirect
	github.com/gofrs/flock v0.7.3 // indirect
	github.com/gogo/googleapis v1.4.1 // indirect
	github.com/gogo/protobuf v1.3.2 // indirect
	github.com/golang/protobuf v1.5.2 // indirect
	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
	github.com/gorilla/mux v1.8.0 // indirect
	github.com/grpc-ecosystem/go-grpc-middleware v1.3.0 // indirect
	github.com/grpc-ecosystem/grpc-gateway v1.16.0 // indirect
	github.com/moby/sys/signal v0.6.0 // indirect
	github.com/morikuni/aec v1.0.0 // indirect
	github.com/opencontainers/go-digest v1.0.0 // indirect
	github.com/opencontainers/image-spec v1.0.3-0.20211202183452-c5a74bcca799 // indirect
	github.com/pkg/errors v0.9.1 // indirect
	github.com/sirupsen/logrus v1.8.1 // indirect
	github.com/tonistiigi/fsutil v0.0.0-20220115021204-b19f7f9cb274 // indirect
	github.com/tonistiigi/units v0.0.0-20180711220420-6950e57a87ea // indirect
	github.com/tonistiigi/vt100 v0.0.0-20210615222946-8066bb97264f // indirect
	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.29.0 // indirect
	go.opentelemetry.io/otel v1.4.1 // indirect
	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.4.1 // indirect
	go.opentelemetry.io/otel/sdk v1.4.1 // indirect
	go.opentelemetry.io/otel/trace v1.4.1 // indirect
	go.opentelemetry.io/proto/otlp v0.12.0 // indirect
	golang.org/x/crypto v0.0.0-20211202192323-5770296d904e // indirect
	golang.org/x/net v0.0.0-20211216030914-fe4d6282115f // indirect
	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
	golang.org/x/sys v0.0.0-20220114195835-da31bd327af9 // indirect
	golang.org/x/text v0.3.7 // indirect
	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac // indirect
	google.golang.org/genproto v0.0.0-20211208223120-3a66f561d7aa // indirect
	google.golang.org/grpc v1.45.0 // indirect
	google.golang.org/protobuf v1.27.1 // indirect
)

main.go

package main

import (
	"context"
	"fmt"
	"net"
	"os"

	"github.com/containerd/console"
	dockerclient "github.com/docker/docker/client"
	"github.com/moby/buildkit/client"
	"github.com/moby/buildkit/client/llb"
	"github.com/moby/buildkit/util/progress/progresswriter"
)

func build() error {
	ctx := context.Background()
	dockerCli, err := dockerclient.NewClientWithOpts(dockerclient.FromEnv, dockerclient.WithAPIVersionNegotiation())
	if err != nil {
		return fmt.Errorf("create docker client: %w", err)
	}
	_ = dockerCli
	bkcli, err := client.New(ctx, "",
		client.WithFailFast(),
		// See also https://github.com/docker/buildx/blob/69824a5d2725205aca8155a8e38b5a10854dcf2b/driver/docker/driver.go#L48
		client.WithContextDialer(func(context.Context, string) (net.Conn, error) {
			return dockerCli.DialHijack(ctx, "/grpc", "h2c", nil)
		}), client.WithSessionDialer(func(ctx context.Context, proto string, meta map[string][]string) (net.Conn, error) {
			return dockerCli.DialHijack(ctx, "/session", proto, meta)
		}),
	)
	if err != nil {
		return fmt.Errorf("create buildkit client: %w", err)
	}
	state := llb.Image("alpine:edge").Run(llb.Shlex(`sh -c "echo 1 > /1.txt"`)).Root()
	def, err := state.Marshal(ctx, llb.LinuxAmd64)
	if err != nil {
		return fmt.Errorf("marshal state: %w", err)
	}
	c, err := console.ConsoleFromFile(os.Stdout)
	if err != nil {
		return fmt.Errorf("create console: %w", err)
	}
	printer, err := progresswriter.NewPrinter(ctx, c, "auto")
	if err != nil {
		return fmt.Errorf("create progress writer: %w", err)
	}
	_, err = bkcli.Solve(ctx, def, client.SolveOpt{
		Exports: []client.ExportEntry{
			{
				Type: "moby",
				Attrs: map[string]string{
					"name": "test:dev",
				},
			},
		},
		LocalDirs: map[string]string{
			"context-dir": ".",
		},
	}, printer.Status())
	if err != nil {
		return fmt.Errorf("solve: %w", err)
	}
	<-printer.Done()
	return printer.Err()
}

func main() {
	err := build()
	if err != nil {
		panic(err)
	}
}

		// See also https://github.com/docker/buildx/blob/69824a5d2725205aca8155a8e38b5a10854dcf2b/driver/docker/driver.go#L48
		client.WithContextDialer(func(context.Context, string) (net.Conn, error) {
			return dockerCli.DialHijack(ctx, "/grpc", "h2c", nil)
		}), client.WithSessionDialer(func(ctx context.Context, proto string, meta map[string][]string) (net.Conn, error) {
			return dockerCli.DialHijack(ctx, "/session", proto, meta)
		}),

Is it necessary for built-in load?

I followed the code here and got this error:

exporter "moby" could not be found

Not sure if it is related to the version.

Is it necessary for built-in load?

It is necessary, but for connecting to the buildkitd bundled in dockerd. There is no extra image loading if we switch to the docker driver.

exporter "moby" could not be found

That's a bit weird.. What's the output of docker version?

I resolved it. Thanks for the reply.