implemented "write-file" and "mkdir" ops

Signed-off-by: Sam Alba <sam.alba@gmail.com>

dagger/compiler/value.go

@@ -92,6 +92,11 @@ func (v *Value) String() (string, error) {
 	return v.val.String()
 }
 
+// Proxy function to the underlying cue.Value
+func (v *Value) Int64() (int64, error) {
+	return v.val.Int64()
+}
+
 func (v *Value) SourceUnsafe() string {
 	s, _ := v.SourceString()
 	return s

dagger/pipeline.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io/fs"
 	"strings"
 
 	"github.com/docker/distribution/reference"
@@ -167,6 +168,10 @@ func (p *Pipeline) doOp(ctx context.Context, op *compiler.Value) error {
 		return p.Subdir(ctx, op)
 	case "docker-build":
 		return p.DockerBuild(ctx, op)
+	case "write-file":
+		return p.WriteFile(ctx, op)
+	case "mkdir":
+		return p.Mkdir(ctx, op)
 	default:
 		return fmt.Errorf("invalid operation: %s", op.JSON())
 	}
@@ -679,3 +684,55 @@ func (p *Pipeline) DockerBuild(ctx context.Context, op *compiler.Value) error {
 
 	return nil
 }
+
+func (p *Pipeline) WriteFile(ctx context.Context, op *compiler.Value) error {
+	content, err := op.Get("content").String()
+	if err != nil {
+		return err
+	}
+
+	dest, err := op.Get("dest").String()
+	if err != nil {
+		return err
+	}
+
+	mode, err := op.Get("mode").Int64()
+	if err != nil {
+		return err
+	}
+
+	p.fs = p.fs.Change(func(st llb.State) llb.State {
+		return st.File(
+			llb.Mkfile(dest, fs.FileMode(mode), []byte(content)),
+			llb.WithCustomName(p.vertexNamef("WriteFile %s", dest)),
+		)
+	})
+
+	return nil
+}
+
+func (p *Pipeline) Mkdir(ctx context.Context, op *compiler.Value) error {
+	path, err := op.Get("path").String()
+	if err != nil {
+		return err
+	}
+
+	dir, err := op.Get("dir").String()
+	if err != nil {
+		return err
+	}
+
+	mode, err := op.Get("mode").Int64()
+	if err != nil {
+		return err
+	}
+
+	p.fs = p.fs.Change(func(st llb.State) llb.State {
+		return st.Dir(dir).File(
+			llb.Mkdir(path, fs.FileMode(mode)),
+			llb.WithCustomName(p.vertexNamef("Mkdir %s", path)),
+		)
+	})
+
+	return nil
+}

stdlib/dagger/dagger.cue

@@ -71,3 +71,17 @@ package dagger
 	buildArg?: [string]: string
 	label?: [string]:    string
 }
+
+#WriteFile: {
+	do:      "write-file"
+	content: string
+	dest:    string
+	mode:    int | *0o644
+}
+
+#Mkdir: {
+	do:      "mkdir"
+	dir:     *"/" | string
+	path:    string
+	mode:    int | *0o755
+}