Code cleanup, providing better commentary to decisions

environment/docker/container.go

@@ -38,13 +38,13 @@ func (nw noopWriter) Write(b []byte) (int, error) {
 }
 
 // Attach attaches to the docker container itself and ensures that we can pipe
-// data in and out of the process stream. This should not be used for reading
-// console data as you *will* miss important output at the beginning because of
-// the time delay with attaching to the output.
+// data in and out of the process stream. This should always be called before
+// you have started the container, but after you've ensured it exists.
 //
 // Calling this function will poll resources for the container in the background
-// until the provided context is canceled by the caller. Failure to cancel said
-// context will cause background memory leaks as the goroutine will not exit.
+// until the container is stopped. The context provided to this function is used
+// for the purposes of attaching to the container, a seecond context is created
+// within the function for managing polling.
 func (e *Environment) Attach(ctx context.Context) error {
 	if e.IsAttached() {
 		return nil

environment/docker/environment.go

@@ -27,7 +27,6 @@ var _ environment.ProcessEnvironment = (*Environment)(nil)
 
 type Environment struct {
 	mu      sync.RWMutex
-	eventMu sync.Once
 
 	// The public identifier for this environment. In this case it is the Docker container
 	// name that will be used for all instances created under it.
@@ -73,6 +72,7 @@ func New(id string, m *Metadata, c *environment.Configuration) (*Environment, er
 		meta:          m,
 		client:        cli,
 		st:            system.NewAtomicString(environment.ProcessOfflineState),
+		emitter:       events.NewBus(),
 	}
 
 	return e, nil
@@ -86,34 +86,33 @@ func (e *Environment) Type() string {
 	return "docker"
 }
 
-// Set if this process is currently attached to the process.
+// SetStream sets the current stream value from the Docker client. If a nil
+// value is provided we assume that the stream is no longer operational and the
+// instance is effectively offline.
 func (e *Environment) SetStream(s *types.HijackedResponse) {
 	e.mu.Lock()
-	defer e.mu.Unlock()
-
 	e.stream = s
+	e.mu.Unlock()
 }
 
-// Determine if the this process is currently attached to the container.
+// IsAttached determine if the this process is currently attached to the
+// container instance by checking if the stream is nil or not.
 func (e *Environment) IsAttached() bool {
 	e.mu.RLock()
 	defer e.mu.RUnlock()
-
 	return e.stream != nil
 }
 
+// Events returns an event bus for the environment.
 func (e *Environment) Events() *events.Bus {
-	e.eventMu.Do(func() {
-		e.emitter = events.NewBus()
-	})
-
 	return e.emitter
 }
 
-// Determines if the container exists in this environment. The ID passed through should be the
-// server UUID since containers are created utilizing the server UUID as the name and docker
-// will work fine when using the container name as the lookup parameter in addition to the longer
-// ID auto-assigned when the container is created.
+// Exists determines if the container exists in this environment. The ID passed
+// through should be the server UUID since containers are created utilizing the
+// server UUID as the name and docker will work fine when using the container
+// name as the lookup parameter in addition to the longer ID auto-assigned when
+// the container is created.
 func (e *Environment) Exists() (bool, error) {
 	_, err := e.ContainerInspect(context.Background())
 	if err != nil {
@@ -122,10 +121,8 @@ func (e *Environment) Exists() (bool, error) {
 		if client.IsErrNotFound(err) {
 			return false, nil
 		}
-
 		return false, err
 	}
-
 	return true, nil
 }
 
@@ -146,7 +143,7 @@ func (e *Environment) IsRunning(ctx context.Context) (bool, error) {
 	return c.State.Running, nil
 }
 
-// Determine the container exit state and return the exit code and whether or not
+// ExitState returns the container exit state, the exit code and whether or not
 // the container was killed by the OOM killer.
 func (e *Environment) ExitState() (uint32, bool, error) {
 	c, err := e.ContainerInspect(context.Background())
@@ -163,15 +160,13 @@ func (e *Environment) ExitState() (uint32, bool, error) {
 		if client.IsErrNotFound(err) {
 			return 1, false, nil
 		}
-
 		return 0, false, err
 	}
-
 	return uint32(c.State.ExitCode), c.State.OOMKilled, nil
 }
 
-// Returns the environment configuration allowing a process to make modifications of the
-// environment on the fly.
+// Config returns the environment configuration allowing a process to make
+// modifications of the environment on the fly.
 func (e *Environment) Config() *environment.Configuration {
 	e.mu.RLock()
 	defer e.mu.RUnlock()
@@ -179,12 +174,11 @@ func (e *Environment) Config() *environment.Configuration {
 	return e.Configuration
 }
 
-// Sets the stop configuration for the environment.
+// SetStopConfiguration sets the stop configuration for the environment.
 func (e *Environment) SetStopConfiguration(c remote.ProcessStopConfiguration) {
 	e.mu.Lock()
-	defer e.mu.Unlock()
-
 	e.meta.Stop = c
+	e.mu.Unlock()
 }
 
 func (e *Environment) SetImage(i string) {

environment/docker/power.go

@@ -111,6 +111,13 @@ func (e *Environment) Start(ctx context.Context) error {
 	actx, cancel := context.WithTimeout(ctx, time.Second*30)
 	defer cancel()
 
+	// You must attach to the instance _before_ you start the container. If you do this
+	// in the opposite order you'll enter a deadlock condition where we're attached to
+	// the instance successfully, but the container has already stopped and you'll get
+	// the entire program into a very confusing state.
+	//
+	// By explicitly attaching to the instance before we start it, we can immediately
+	// react to errors/output stopping/etc. when starting.
 	if err := e.Attach(actx); err != nil {
 		return err
 	}

server/server.go

@@ -239,14 +239,6 @@ func (s *Server) ReadLogfile(len int) ([]string, error) {
 	return s.Environment.Readlog(len)
 }
 
-// Determine if the server is bootable in it's current state or not. This will not
-// indicate why a server is not bootable, only if it is.
-func (s *Server) IsBootable() bool {
-	exists, _ := s.Environment.Exists()
-
-	return exists
-}
-
 // Initializes a server instance. This will run through and ensure that the environment
 // for the server is setup, and that all of the necessary files are created.
 func (s *Server) CreateEnvironment() error {