examples: demonstrate client-side Build() interface.

This is a clone-and-hack of `examples/build-using-dockerfile` which uses the
new `Build()` client method and thus runs as a clientside-frontend.

Signed-off-by: Ian Campbell <ijc@docker.com>

examples/build-using-dockerfile/main.go

@@ -11,6 +11,7 @@ import (
 
  "github.com/containerd/console"
  "github.com/moby/buildkit/client"
+ dockerfile "github.com/moby/buildkit/frontend/dockerfile/builder"
  "github.com/moby/buildkit/util/appcontext"
  "github.com/moby/buildkit/util/appdefaults"
  "github.com/moby/buildkit/util/progress/progressui"
@@ -39,6 +40,11 @@ By default, the built image is loaded to Docker.
  EnvVar: "BUILDKIT_HOST",
  Value: appdefaults.Address,
  },
+ cli.BoolFlag{
+ Name: "clientside-frontend",
+ Usage: "run dockerfile frontend client side, rather than builtin to buildkitd",
+ EnvVar: "CLIENTSIDE_FRONTEND",
+ },
  }
  app.Flags = append([]cli.Flag{
  cli.StringSliceFlag{
@@ -83,7 +89,12 @@ func action(clicontext *cli.Context) error {
  ch := make(chan *client.SolveStatus)
  eg, ctx := errgroup.WithContext(ctx)
  eg.Go(func() error {
- _, err := c.Solve(ctx, nil, *solveOpt, ch)
+ var err error
+ if clicontext.Bool("clientside-frontend") {
+ _, err = c.Build(ctx, *solveOpt, "", dockerfile.Build, ch)
+ } else {
+ _, err = c.Solve(ctx, nil, *solveOpt, ch)
+ }
  return err
  })
  eg.Go(func() error {
@@ -124,6 +135,10 @@ func newSolveOpt(clicontext *cli.Context, w io.WriteCloser) (*client.SolveOpt, e
  "dockerfile": filepath.Dir(file),
  }
 
+ frontend := "dockerfile.v0" // TODO: use gateway
+ if clicontext.Bool("clientside-frontend") {
+ frontend = ""
+ }
  frontendAttrs := map[string]string{
  "filename": filepath.Base(file),
  }
@@ -145,7 +160,7 @@ func newSolveOpt(clicontext *cli.Context, w io.WriteCloser) (*client.SolveOpt, e
  },
  ExporterOutput: w,
  LocalDirs: localDirs,
- Frontend: "dockerfile.v0", // TODO: use gateway
+ Frontend: frontend,
  FrontendAttrs: frontendAttrs,
  }, nil
 }