pulumi/pkg/resource/deploy/source_eval.go

// Copyright 2016-2017, Pulumi Corporation.  All rights reserved.

package deploy

import (
	"fmt"

	"github.com/golang/glog"
	"github.com/pkg/errors"
	"golang.org/x/net/context"
	"google.golang.org/grpc"

	"github.com/pulumi/pulumi/pkg/pack"
	"github.com/pulumi/pulumi/pkg/resource"
	"github.com/pulumi/pulumi/pkg/resource/plugin"
	"github.com/pulumi/pulumi/pkg/tokens"
	"github.com/pulumi/pulumi/pkg/util/contract"
	"github.com/pulumi/pulumi/pkg/util/rpcutil"
	lumirpc "github.com/pulumi/pulumi/sdk/proto/go"
)

// EvalRunInfo provides information required to execute and deploy resources within a package.
type EvalRunInfo struct {
	Pkg     *pack.Package `json:"pkg" yaml:"pkg"`                           // the package metadata.
	Pwd     string        `json:"pwd" yaml:"pwd"`                           // the package's working directory.
	Program string        `json:"program" yaml:"program"`                   // the path to the program we are executing.
	Args    []string      `json:"args,omitempty" yaml:"args,omitempty"`     // any arguments to pass to the package.
	Target  *Target       `json:"target,omitempty" yaml:"target,omitempty"` // the target being deployed into.
}

// NewEvalSource returns a planning source that fetches resources by evaluating a package with a set of args and
// a confgiuration map.  This evaluation is performed using the given plugin context and may optionally use the
// given plugin host (or the default, if this is nil).  Note that closing the eval source also closes the host.
//
// If destroy is true, then all of the usual initialization will take place, but the state will be presented to the
// planning engine as if no new resources exist.  This will cause it to forcibly remove them.
func NewEvalSource(plugctx *plugin.Context, runinfo *EvalRunInfo, destroy bool, dryRun bool) Source {
	return &evalSource{
		plugctx: plugctx,
		runinfo: runinfo,
		destroy: destroy,
		dryRun:  dryRun,
	}
}

type evalSource struct {
	plugctx *plugin.Context // the plugin context.
	runinfo *EvalRunInfo    // the directives to use when running the program.
	destroy bool            // true if this source will trigger total destruction.
	dryRun  bool            // true if this is a dry-run operation only.
}

func (src *evalSource) Close() error {
	return nil
}

func (src *evalSource) Pkg() tokens.PackageName {
	return src.runinfo.Pkg.Name
}

func (src *evalSource) Info() interface{} {
	return src.runinfo
}

// Iterate will spawn an evaluator coroutine and prepare to interact with it on subsequent calls to Next.
func (src *evalSource) Iterate(opts Options) (SourceIterator, error) {
	// First, fire up a resource monitor that will watch for and record resource creation.
	regChan := make(chan *evalBeginReg)
	compChan := make(chan *evalEndReg)
	mon, err := newResourceMonitor(src, regChan, compChan)
	if err != nil {
		return nil, errors.Wrap(err, "failed to start resource monitor")
	}

	// Create a new iterator with appropriate channels, and gear up to go!
	iter := &evalSourceIterator{
		mon:      mon,
		src:      src,
		regChan:  regChan,
		compChan: compChan,
		finChan:  make(chan error),
	}

	// Now invoke Run in a goroutine.  All subsequent resource creation events will come in over the gRPC channel,
	// and we will pump them through the channel.  If the Run call ultimately fails, we need to propagate the error.
	iter.forkRun(opts)

	// Finally, return the fresh iterator that the caller can use to take things from here.
	return iter, nil
}

type evalSourceIterator struct {
	mon      *resmon            // the resource monitor, per iterator.
	src      *evalSource        // the owning eval source object.
	regChan  chan *evalBeginReg // the channel that contains resource registrations.
	compChan chan *evalEndReg   // the channel that contains resource completions.
	finChan  chan error         // the channel that communicates completion.
	done     bool               // set to true when the evaluation is done.
}

func (iter *evalSourceIterator) Close() error {
	// Cancel the monitor and reclaim any associated resources.
	return iter.mon.Cancel()
}

func (iter *evalSourceIterator) Next() (SourceEvent, error) {
	// If we are done, quit.
	if iter.done {
		return nil, nil
	}

	// If we are destroying, we simply return nothing.
	if iter.src.destroy {
		return nil, nil
	}

	// Await the program to compute some more state and then inspect what it has to say.
	select {
	case reg := <-iter.regChan:
		contract.Assert(reg != nil)
		goal := reg.Goal()
		glog.V(5).Infof("EvalSourceIterator produced a registration: t=%v,name=%v,#props=%v",
			goal.Type, goal.Name, len(goal.Properties))
		return reg, nil
	case comp := <-iter.compChan:
		contract.Assert(comp != nil)
		glog.V(5).Infof("EvalSourceIterator produced a completion: urn=%v,#extras=%v",
			comp.URN(), len(comp.Extras()))
		return comp, nil
	case err := <-iter.finChan:
		// If we are finished, we can safely exit.  The contract with the language provider is that this implies
		// that the language runtime has exited and so calling Close on the plugin is fine.
		iter.done = true
		if err != nil {
			glog.V(5).Infof("EvalSourceIterator ended with an error: %v", err)
		}
		return nil, err
	}
}

// forkRun performs the evaluation from a distinct goroutine.  This function blocks until it's our turn to go.
func (iter *evalSourceIterator) forkRun(opts Options) {
	// If we are destroying, no need to perform any evaluation beyond the config initialization.
	if !iter.src.destroy {
		// Fire up the goroutine to make the RPC invocation against the language runtime.  As this executes, calls
		// to queue things up in the resource channel will occur, and we will serve them concurrently.
		// FIXME: we need to ensure that out of order calls won't deadlock us.  In particular, we need to ensure: 1)
		//    gRPC won't block the dispatching of calls, and 2) that the channel's fixed size won't cause troubles.
		go func() {
			// Next, launch the language plugin.
			// IDEA: cache these so we reuse the same language plugin instance; if we do this, monitors must be per-run.
			rt := iter.src.runinfo.Pkg.Runtime
			langhost, err := iter.src.plugctx.Host.LanguageRuntime(rt, iter.mon.Address())
			if err != nil {
				err = errors.Wrapf(err, "failed to launch language host for '%v'", rt)
			} else if langhost == nil {
				err = errors.Errorf("could not load language plugin for '%v' from $PATH", rt)
			} else {
				// Make sure to clean up before exiting.
				defer contract.IgnoreClose(langhost)

				// Now run the actual program.
				var progerr string
				progerr, err = langhost.Run(plugin.RunInfo{
					Stack:    string(iter.src.runinfo.Target.Name),
					Project:  string(iter.src.runinfo.Pkg.Name),
					Pwd:      iter.src.runinfo.Pwd,
					Program:  iter.src.runinfo.Program,
					Args:     iter.src.runinfo.Args,
					Config:   iter.src.runinfo.Target.Config,
					DryRun:   iter.src.dryRun,
					Parallel: opts.Parallel,
				})
				if err == nil && progerr != "" {
					// If the program had an unhandled error; propagate it to the caller.
					err = errors.Errorf("an unhandled error occurred: %v", progerr)
				}
			}

			// Communicate the error, if it exists, or nil if the program exited cleanly.
			iter.finChan <- err
		}()
	}
}

// resmon implements the lumirpc.ResourceMonitor interface and acts as the gateway between a language runtime's
// evaluation of a program and the internal resource planning and deployment logic.
type resmon struct {
	src      *evalSource        // the evaluation source.
	resChan  chan *evalBeginReg // the channel to send resource registrations to.
	compChan chan *evalEndReg   // the channel to send resource completions to.
	addr     string             // the address the host is listening on.
	cancel   chan bool          // a channel that can cancel the server.
	done     chan error         // a channel that resolves when the server completes.
}

// newResourceMonitor creates a new resource monitor RPC server.
func newResourceMonitor(src *evalSource, resChan chan *evalBeginReg, compChan chan *evalEndReg) (*resmon, error) {
	// New up an engine RPC server.
	resmon := &resmon{
		src:      src,
		resChan:  resChan,
		compChan: compChan,
		cancel:   make(chan bool),
	}

	// Fire up a gRPC server and start listening for incomings.
	port, done, err := rpcutil.Serve(0, resmon.cancel, []func(*grpc.Server) error{
		func(srv *grpc.Server) error {
			lumirpc.RegisterResourceMonitorServer(srv, resmon)
			return nil
		},
	})
	if err != nil {
		return nil, err
	}

	resmon.addr = fmt.Sprintf("127.0.0.1:%d", port)
	resmon.done = done

	return resmon, nil
}

// Address returns the address at which the monitor's RPC server may be reached.
func (rm *resmon) Address() string {
	return rm.addr
}

// Cancel signals that the engine should be terminated, awaits its termination, and returns any errors that result.
func (rm *resmon) Cancel() error {
	rm.cancel <- true
	return <-rm.done
}

// Invoke performs an invocation of a member located in a resource provider.
func (rm *resmon) Invoke(ctx context.Context, req *lumirpc.InvokeRequest) (*lumirpc.InvokeResponse, error) {
	// Fetch the token and load up the resource provider.
	tok := tokens.ModuleMember(req.GetTok())
	prov, err := rm.src.plugctx.Host.Provider(tok.Package())
	if err != nil {
		return nil, err
	} else if prov == nil {
		return nil, errors.Errorf("could not load resource provider for package '%v' from $PATH", tok.Package())
	}

	// Now unpack all of the arguments and prepare to perform the invocation.
	args, err := plugin.UnmarshalProperties(
		req.GetArgs(), plugin.MarshalOptions{KeepUnknowns: true})
	if err != nil {
		return nil, errors.Wrapf(err, "failed to unmarshal %v args", tok)
	}

	// Do the invoke and then return the arguments.
	glog.V(5).Infof("ResourceMonitor.Invoke received: tok=%v #args=%v", tok, len(args))
	ret, failures, err := prov.Invoke(tok, args)
	if err != nil {
		return nil, errors.Wrapf(err, "invocation of %v returned an error", tok)
	}
	mret, err := plugin.MarshalProperties(ret, plugin.MarshalOptions{KeepUnknowns: true})
	if err != nil {
		return nil, errors.Wrapf(err, "failed to marshal %v return", tok)
	}
	var chkfails []*lumirpc.CheckFailure
	for _, failure := range failures {
		chkfails = append(chkfails, &lumirpc.CheckFailure{
			Property: string(failure.Property),
			Reason:   failure.Reason,
		})
	}
	return &lumirpc.InvokeResponse{Return: mret, Failures: chkfails}, nil
}

// BeginRegisterResource is invoked by a language process when a new resource has been allocated.
func (rm *resmon) BeginRegisterResource(ctx context.Context,
	req *lumirpc.BeginRegisterResourceRequest) (*lumirpc.BeginRegisterResourceResponse, error) {

	// Communicate the type, name, and object information to the iterator that is awaiting us.
	props, err := plugin.UnmarshalProperties(
		req.GetObject(), plugin.MarshalOptions{KeepUnknowns: true, ComputeAssetHashes: true})
	if err != nil {
		return nil, err
	}

	t := tokens.Type(req.GetType())
	name := tokens.QName(req.GetName())
	custom := req.GetCustom()
	parent := resource.URN(req.GetParent())
	glog.V(5).Infof("ResourceMonitor.BeginRegisterResource received: t=%v, name=%v, custom=%v, #props=%v, parent=%v",
		t, name, custom, len(props), parent)

	// Send the goal state to the engine.
	step := &evalBeginReg{
		goal: resource.NewGoal(t, name, custom, props, parent),
		done: make(chan resource.URN),
	}
	rm.resChan <- step

	// Now block waiting for the operation to finish.
	// IDEA: we probably need some way to cancel this in case of catastrophe.
	urn := string(<-step.done)
	glog.V(5).Infof(
		"ResourceMonitor.BeginRegisterResource operation finished: t=%v, name=%v, urn=%v", t, name, urn)
	return &lumirpc.BeginRegisterResourceResponse{Urn: urn}, nil
}

// EndRegisterResource records some new output properties for a resource that have arrived after its initial
// provisioning.  These will make their way into the eventual checkpoint state file for that resource.
func (rm *resmon) EndRegisterResource(ctx context.Context,
	req *lumirpc.EndRegisterResourceRequest) (*lumirpc.EndRegisterResourceResponse, error) {

	// Obtain and validate the message's inputs (a URN plus the output property map).
	urn := resource.URN(req.GetUrn())
	if urn == "" {
		return nil, errors.New("missing required URN")
	}
	extras, err := plugin.UnmarshalProperties(
		req.GetExtras(), plugin.MarshalOptions{KeepUnknowns: true, ComputeAssetHashes: true})
	if err != nil {
		return nil, errors.Wrapf(err, "cannot unmarshal output properties")
	}
	glog.V(5).Infof("ResourceMonitor.EndRegisterResource received: urn=%v, #extras=%v", urn, len(extras))

	// Now send the step over to the engine to perform.
	step := &evalEndReg{
		urn:    urn,
		extras: extras,
		done:   make(chan *FinalState),
	}
	rm.compChan <- step

	// Now block waiting for the operation to finish.
	// IDEA: we probably need some way to cancel this in case of catastrophe.
	result := <-step.done
	state := result.State
	outprops := state.Synthesized()
	stable := result.Stable
	var stables []string
	for _, sta := range result.Stables {
		stables = append(stables, string(sta))
	}
	glog.V(5).Infof(
		"ResourceMonitor.EndRegisterResource operation finished: t=%v, urn=%v, name=%v, stable=%v, #stables=%v #outs=%v",
		state.Type, state.URN, stable, len(stables), len(outprops))

	// Finally, unpack the response into properties that we can return to the language runtime.  This mostly includes
	// an ID, URN, and defaults and output properties that will all be blitted back onto the runtime object.
	outs, err := plugin.MarshalProperties(outprops, plugin.MarshalOptions{KeepUnknowns: true})
	if err != nil {
		return nil, err
	}
	return &lumirpc.EndRegisterResourceResponse{
		Id:      string(state.ID),
		Object:  outs,
		Stable:  stable,
		Stables: stables,
	}, nil
}

type evalBeginReg struct {
	goal *resource.Goal    // the resource goal state produced by the iterator.
	done chan resource.URN // the channel to communicate with after the resource state is available.
}

var _ BeginRegisterResourceEvent = (*evalBeginReg)(nil)

func (g *evalBeginReg) event() {}

func (g *evalBeginReg) Goal() *resource.Goal {
	return g.goal
}

func (g *evalBeginReg) Done(urn resource.URN) {
	// Communicate the resulting state back to the RPC thread, which is parked awaiting our reply.
	g.done <- urn
}

type evalEndReg struct {
	urn    resource.URN         // the URN to which this completion applies.
	extras resource.PropertyMap // an optional property bag for "extra" output properties.
	done   chan *FinalState     // the channel to communicate with after the resource state is available.
}

var _ EndRegisterResourceEvent = (*evalEndReg)(nil)

func (g *evalEndReg) event() {}

func (g *evalEndReg) URN() resource.URN {
	return g.urn
}

func (g *evalEndReg) Extras() resource.PropertyMap {
	return g.extras
}

func (g *evalEndReg) Done(res *FinalState) {
	// Communicate the resulting state back to the RPC thread, which is parked awaiting our reply.
	g.done <- res
}