Implement the mu apply command

This change implements `mu apply`, by driving compilation, evaluation,
planning, and then walking the plan and evaluating it.  This is the bulk
of marapongo/mu#21, except that there's a ton of testing/hardening to
perform, in addition to things like progress reporting.

cmd/apply.go

@@ -4,9 +4,12 @@ package cmd
 
 import (
 	"github.com/spf13/cobra"
+
+	"github.com/marapongo/mu/pkg/compiler/errors"
 )
 
 func newApplyCmd() *cobra.Command {
+	var delete bool
 	var cmd = &cobra.Command{
 		Use:   "apply [blueprint] [-- [args]]",
 		Short: "Apply a deployment plan from a Mu blueprint",
@@ -23,10 +26,21 @@ func newApplyCmd() *cobra.Command {
 			"By default, a blueprint package is loaded from the current directory.  Optionally,\n" +
 			"a path to a blueprint elsewhere can be provided as the [blueprint] argument.",
 		Run: func(cmd *cobra.Command, args []string) {
+			if comp, plan := plan(cmd, args, delete); plan != nil {
+				if _, err, _ := plan.Apply(); err != nil {
+					// TODO: we want richer diagnostics in the event that a plan apply fails.  For instance, we want to
+					//     know precisely what step failed, we want to know whether it was catastrophic, etc.  We also
+					//     probably want to plumb diag.Sink through apply so it can issue its own rich diagnostics.
+					comp.Diag().Errorf(errors.ErrorPlanApplyFailed, err)
+				}
+			}
 		},
 	}
 
 	// TODO: options; most importantly, what to compare the blueprint against.
+	cmd.PersistentFlags().BoolVar(
+		&delete, "delete", false,
+		"Delete the entirety of the blueprint's resources")
 
 	return cmd
 }

cmd/compile_shared.go

@@ -9,14 +9,16 @@ import (
 
 	"github.com/marapongo/mu/pkg/compiler"
 	"github.com/marapongo/mu/pkg/compiler/core"
+	"github.com/marapongo/mu/pkg/compiler/errors"
+	"github.com/marapongo/mu/pkg/diag"
 	"github.com/marapongo/mu/pkg/graph"
+	"github.com/marapongo/mu/pkg/resource"
 	"github.com/marapongo/mu/pkg/util/cmdutil"
-	"github.com/marapongo/mu/pkg/util/contract"
 )
 
 // compile just uses the standard logic to parse arguments, options, and to locate/compile a package.  It returns the
 // MuGL graph that is produced, or nil if an error occurred (in which case, we would expect non-0 errors).
-func compile(cmd *cobra.Command, args []string) graph.Graph {
+func compile(cmd *cobra.Command, args []string) (compiler.Compiler, graph.Graph) {
 	// If there's a --, we need to separate out the command args from the stack args.
 	flags := cmd.Flags()
 	dashdash := flags.ArgsLenAtDash()
@@ -26,23 +28,29 @@ func compile(cmd *cobra.Command, args []string) graph.Graph {
 		args = args[0:dashdash]
 	}
 
+	// A func to lazily allocate a sink to be used if we can't create a compiler.
+	d := func() diag.Sink { return core.DefaultSink("") }
+
 	// Create a compiler options object and map any flags and arguments to settings on it.
 	opts := core.DefaultOptions()
 	opts.Args = dashdashArgsToMap(packArgs)
 
 	// In the case of an argument, load that specific package and new up a compiler based on its base path.
 	// Otherwise, use the default workspace and package logic (which consults the current working directory).
+	var comp compiler.Compiler
 	var mugl graph.Graph
 	if len(args) == 0 {
-		comp, err := compiler.Newwd(opts)
+		var err error
+		comp, err = compiler.Newwd(opts)
 		if err != nil {
-			contract.Failf("fatal: %v", err)
+			// Create a temporary diagnostics sink so that we can issue an error and bail out.
+			d().Errorf(errors.ErrorCantCreateCompiler, err)
+			return nil, nil
 		}
 		mugl = comp.Compile()
 	} else {
 		fn := args[0]
 		if pkg := cmdutil.ReadPackageFromArg(fn); pkg != nil {
-			var comp compiler.Compiler
 			var err error
 			if fn == "-" {
 				comp, err = compiler.Newwd(opts)
@@ -50,10 +58,41 @@ func compile(cmd *cobra.Command, args []string) graph.Graph {
 				comp, err = compiler.New(filepath.Dir(fn), opts)
 			}
 			if err != nil {
-				contract.Failf("fatal: %v", err)
+				d().Errorf(errors.ErrorCantReadPackage, fn, err)
+				return nil, nil
 			}
 			mugl = comp.CompilePackage(pkg)
 		}
 	}
-	return mugl
+	return comp, mugl
+}
+
+// plan just uses the standard logic to parse arguments, options, and to create a plan for a package.
+func plan(cmd *cobra.Command, args []string, delete bool) (compiler.Compiler, resource.Plan) {
+	// Perform the compilation and, if non-nil is returned, create a plan and print it.
+	comp, mugl := compile(cmd, args)
+	if mugl != nil {
+		// TODO: fetch the old plan for purposes of diffing.
+		rs, err := resource.NewSnapshot(mugl) // create a resource snapshot from the object graph.
+		if err != nil {
+			comp.Diag().Errorf(errors.ErrorCantCreateSnapshot, err)
+			return comp, nil
+		}
+
+		// Create a new context for the plan operations.
+		ctx := resource.NewContext()
+
+		var plan resource.Plan
+		if delete {
+			// Generate a plan for deleting the entire snapshot.
+			plan = resource.NewDeletePlan(ctx, rs)
+		} else {
+			// Generate a plan for creating the resources from scratch.
+			plan = resource.NewCreatePlan(ctx, rs)
+		}
+
+		return comp, plan
+	}
+
+	return comp, nil
 }

cmd/eval.go

@@ -31,7 +31,7 @@ func newEvalCmd() *cobra.Command {
 			"a path to a blueprint elsewhere can be provided as the [blueprint] argument.",
 		Run: func(cmd *cobra.Command, args []string) {
 			// Perform the compilation and, if non-nil is returned, output the graph.
-			if mugl := compile(cmd, args); mugl != nil {
+			if _, mugl := compile(cmd, args); mugl != nil {
 				// Serialize that MuGL graph so that it's suitable for printing/serializing.
 				if dotOutput {
 					// Convert the output to a DOT file.

cmd/plan.go

@@ -5,7 +5,6 @@ package cmd
 import (
 	"bytes"
 	"fmt"
-	"os"
 	"strconv"
 
 	"github.com/spf13/cobra"
@@ -33,28 +32,7 @@ func newPlanCmd() *cobra.Command {
 			"By default, a blueprint package is loaded from the current directory.  Optionally,\n" +
 			"a path to a blueprint elsewhere can be provided as the [blueprint] argument.",
 		Run: func(cmd *cobra.Command, args []string) {
-			// Perform the compilation and, if non-nil is returned, create a plan and print it.
-			if mugl := compile(cmd, args); mugl != nil {
-				// TODO: fetch the old plan for purposes of diffing.
-				rs, err := resource.NewSnapshot(mugl) // create a resource snapshot from the object graph.
-				if err != nil {
-					fmt.Fprintf(os.Stderr, "fatal: %v\n", err)
-					os.Exit(-1)
-				}
-
-				// Create a new context for the plan operations.
-				ctx := resource.NewContext()
-
-				var plan resource.Plan
-				if delete {
-					// Generate a plan for deleting the entire snapshot.
-					plan = resource.NewDeletePlan(ctx, rs)
-				} else {
-					// Generate a plan for creating the resources from scratch.
-					plan = resource.NewCreatePlan(ctx, rs)
-				}
-
-				// Finally just pretty-print out the plan.
+			if _, plan := plan(cmd, args, delete); plan != nil {
 				printPlan(plan)
 			}
 		},

pkg/compiler/compiler.go

@@ -59,10 +59,7 @@ func New(path string, opts *core.Options) (Compiler, error) {
 	}
 	d := opts.Diag
 	if d == nil {
-		d = diag.DefaultSink(diag.FormatOptions{
-			Pwd:    path, // ensure output paths are relative to the current path.
-			Colors: true, // turn on colorization of warnings/errors.
-		})
+		d = core.DefaultSink(path)
 	}
 
 	// Now create a new context to share amongst the compiler and workspace.

pkg/compiler/core/opts.go

@@ -20,3 +20,11 @@ type Options struct {
 func DefaultOptions() *Options {
 	return &Options{}
 }
+
+// DefaultOptionsSink returns the default preconfigured diagnostics sink.
+func DefaultSink(path string) diag.Sink {
+	return diag.DefaultSink(diag.FormatOptions{
+		Pwd:    path, // ensure output paths are relative to the current path.
+		Colors: true, // turn on colorization of warnings/errors.
+	})
+}

pkg/compiler/errors/planapply.go

@@ -0,0 +1,11 @@
+// Copyright 2016 Marapongo, Inc. All rights reserved.
+
+package errors
+
+// Plan and apply errors are in the [2000,3000) range.
+var (
+	ErrorCantCreateCompiler = newError(2000, "An error occurred during compiler construction: %v")
+	ErrorCantReadPackage    = newError(2001, "An error occurred while reading the package '%v': %v")
+	ErrorCantCreateSnapshot = newError(2002, "Illegal MuGL structure detected; cannot create a snapshot: %v")
+	ErrorPlanApplyFailed    = newError(2003, "Plan apply failed: %v")
+)