Add chroot builder framework

builder/azure/chroot/builder.go

@@ -0,0 +1,75 @@
+package chroot
+
+import (
+	"context"
+	"errors"
+	"runtime"
+
+	azcommon "github.com/hashicorp/packer/builder/azure/common"
+	"github.com/hashicorp/packer/common"
+	"github.com/hashicorp/packer/helper/config"
+	"github.com/hashicorp/packer/helper/multistep"
+	"github.com/hashicorp/packer/packer"
+	"github.com/hashicorp/packer/template/interpolate"
+)
+
+type Config struct {
+	common.PackerConfig `mapstructure:",squash"`
+
+	ctx interpolate.Context
+}
+
+type Builder struct {
+	config Config
+	runner multistep.Runner
+}
+
+func (b *Builder) Prepare(raws ...interface{}) ([]string, error) {
+	b.config.ctx.Funcs = azcommon.TemplateFuncs
+	err := config.Decode(&b.config, &config.DecodeOpts{
+		Interpolate:        true,
+		InterpolateContext: &b.config.ctx,
+		InterpolateFilter: &interpolate.RenderFilter{
+			Exclude: []string{
+				// fields to exclude from interpolation
+			},
+		},
+	}, raws...)
+
+	// checks, accumulate any errors or warnings
+	var errs *packer.MultiError
+	var warns []string
+
+	if err != nil {
+		return nil, err
+	}
+	return warns, errs
+}
+
+func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (packer.Artifact, error) {
+	if runtime.GOOS != "linux" {
+		return nil, errors.New("The azure-chroot builder only works on Linux environments.")
+	}
+
+	// Setup the state bag and initial state for the steps
+	state := new(multistep.BasicStateBag)
+	state.Put("config", &b.config)
+	state.Put("hook", hook)
+	state.Put("ui", ui)
+
+	// Build the steps
+	var steps []multistep.Step
+
+	// Run!
+	b.runner = common.NewRunner(steps, b.config.PackerConfig, ui)
+	b.runner.Run(ctx, state)
+
+	// If there was an error, return that
+	if rawErr, ok := state.GetOk("error"); ok {
+		return nil, rawErr.(error)
+	}
+
+	return nil, nil
+}
+
+var _ packer.Builder = &Builder{}