Significant improvements to attaching/console handling

server/console.go

@@ -0,0 +1,21 @@
+package server
+
+import "io"
+
+type Console struct {
+	Server *Server
+	HandlerFunc *func(string)
+}
+
+var _ io.Writer = Console{}
+
+func (c Console) Write(b []byte) (int, error) {
+	if c.HandlerFunc != nil {
+		l := make([]byte, len(b))
+		copy(l, b)
+
+		(*c.HandlerFunc)(string(l))
+	}
+
+	return len(b), nil
+}

server/environment.go

@@ -1,7 +1,6 @@
 package server
 
 import (
-	"io"
 	"os"
 )
 
@@ -11,6 +10,10 @@ type Environment interface {
 	// Returns the name of the environment.
 	Type() string
 
+	// Determines if the environment is currently active and running a server process
+	// for this specific server instance.
+	IsRunning() (bool, error)
+
 	// Starts a server instance. If the server instance is not in a state where it
 	// can be started an error should be returned.
 	Start() error
@@ -22,7 +25,7 @@ type Environment interface {
 	// Determines if the server instance exists. For example, in a docker environment
 	// this should confirm that the container is created and in a bootable state. In
 	// a basic CLI environment this can probably just return true right away.
-	Exists() bool
+	Exists() (bool, error)
 
 	// Terminates a running server instance using the provided signal. If the server
 	// is not running no error should be returned.
@@ -34,8 +37,16 @@ type Environment interface {
 	Create() error
 
 	// Attaches to the server console environment and allows piping the output to a
-	// websocket or other internal tool to monitor output.
-	Attach() (io.ReadCloser, error)
+	// websocket or other internal tool to monitor output. Also allows you to later
+	// send data into the environment's stdin.
+	Attach() error
+
+	// Follows the output from the server console and will begin piping the output to
+	// the server's emitter.
+	FollowConsoleOutput() error
+
+	// Sends the provided command to the running server instance.
+	SendCommand(string) error
 
 	// Reads the log file for the process from the end backwards until the provided
 	// number of bytes is met.

server/environment_docker.go

@@ -12,6 +12,7 @@ import (
 	"github.com/docker/docker/daemon/logger/jsonfilelog"
 	"github.com/docker/go-connections/nat"
 	"github.com/pkg/errors"
+	"go.uber.org/zap"
 	"golang.org/x/net/context"
 	"io"
 	"os"
@@ -33,6 +34,15 @@ type DockerEnvironment struct {
 
 	// The Docker client being used for this instance.
 	Client *client.Client
+
+	// Tracks if we are currently attached to the server container. This allows us to attach
+	// once and then just use that attachment to stream logs out of the server and also stream
+	// commands back into it without constantly attaching and detaching.
+	attached bool
+
+	// Controls the hijacked response stream which exists only when we're attached to
+	// the running container instance.
+	stream types.HijackedResponse
 }
 
 // Creates a new base Docker environment. A server must still be attached to it.
@@ -64,10 +74,39 @@ func (d *DockerEnvironment) Type() string {
 }
 
 // Determines if the container exists in this environment.
-func (d *DockerEnvironment) Exists() bool {
+func (d *DockerEnvironment) Exists() (bool, error) {
 	_, err := d.Client.ContainerInspect(context.Background(), d.Server.Uuid)
 
-	return err == nil
+	if err != nil {
+		// If this error is because the container instance wasn't found via Docker we
+		// can safely ignore the error and just return false.
+		if client.IsErrNotFound(err) {
+			return false, nil
+		}
+
+		return false, err
+	}
+
+	return true, nil
+}
+
+// Determines if the server's docker container is currently running. If there is no container
+// present, an error will be raised (since this shouldn't be a case that ever happens under
+// correctly developed circumstances).
+//
+// You can confirm if the instance wasn't found by using client.IsErrNotFound from the Docker
+// API.
+//
+// @see docker/client/errors.go
+func (d *DockerEnvironment) IsRunning() (bool, error) {
+	ctx := context.Background()
+
+	c, err := d.Client.ContainerInspect(ctx, d.Server.Uuid)
+	if err != nil {
+		return false, err
+	}
+
+	return c.State.Running, nil
 }
 
 // Checks if there is a container that already exists for the server. If so that
@@ -81,12 +120,21 @@ func (d *DockerEnvironment) Start() error {
 
 	// No reason to try starting a container that is already running.
 	if c.State.Running {
+		if !d.attached {
+			return d.Attach()
+		}
+
 		return nil
 	}
 
 	opts := types.ContainerStartOptions{}
 
-	return d.Client.ContainerStart(context.Background(), d.Server.Uuid, opts)
+	if err := d.Client.ContainerStart(context.Background(), d.Server.Uuid, opts); err != nil {
+		return err
+	}
+
+	d.FollowConsoleOutput()
+	return d.Attach()
 }
 
 // Stops the container that the server is running in. This will allow up to 10
@@ -113,17 +161,57 @@ func (d *DockerEnvironment) Terminate(signal os.Signal) error {
 	return d.Client.ContainerKill(ctx, d.Server.Uuid, signal.String())
 }
 
-// Contrary to the name, this doesn't actually attach to the Docker container itself,
-// but rather attaches to the log for the container and then pipes that output to
-// a websocket.
-//
-// This avoids us missing cruicial output that happens in the split seconds before the
-// code moves from 'Starting' to 'Attaching' on the process.
-//
-// @todo add throttle code
-func (d *DockerEnvironment) Attach() (io.ReadCloser, error) {
-	if !d.Exists() {
-		return nil, errors.New(fmt.Sprintf("no such container: %s", d.Server.Uuid))
+// 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.
+func (d *DockerEnvironment) Attach() error {
+	if d.attached {
+		return nil
+	}
+
+	ctx := context.Background()
+
+	var err error
+	d.stream, err = d.Client.ContainerAttach(ctx, d.Server.Uuid, types.ContainerAttachOptions{
+		Stdin: true,
+		Stdout: true,
+		Stderr: true,
+		Stream: true,
+	})
+
+	if err != nil {
+		return err
+	}
+
+	console := Console{
+		Server: d.Server,
+	}
+
+	d.attached = true
+
+	go func() {
+		defer d.stream.Close()
+		defer func() {
+			d.attached = false
+		}()
+
+		io.Copy(console, d.stream.Reader)
+	}()
+
+	return nil
+}
+
+// Attaches to the log for the container. This avoids us missing cruicial output that
+// happens in the split seconds before the code moves from 'Starting' to 'Attaching'
+// on the process.
+func (d *DockerEnvironment) FollowConsoleOutput() error {
+	if exists, err := d.Exists(); !exists {
+		if err != nil {
+			return err
+		}
+
+		return errors.New(fmt.Sprintf("no such container: %s", d.Server.Uuid))
 	}
 
 	ctx := context.Background()
@@ -133,9 +221,22 @@ func (d *DockerEnvironment) Attach() (io.ReadCloser, error) {
 		Follow:     true,
 	}
 
-	r, err := d.Client.ContainerLogs(ctx, d.Server.Uuid, opts)
+	reader, err := d.Client.ContainerLogs(ctx, d.Server.Uuid, opts)
 
-	return r, err
+	go func(r io.ReadCloser) {
+		defer r.Close()
+
+		s := bufio.NewScanner(r)
+		for s.Scan() {
+			fmt.Println(s.Text())
+		}
+
+		if err := s.Err(); err != nil {
+			zap.S().Errorw("error in scanner", zap.Error(err))
+		}
+	}(reader)
+
+	return err
 }
 
 // Creates a new container for the server using all of the data that is currently
@@ -154,6 +255,8 @@ func (d *DockerEnvironment) Create() error {
 	// container anyways.
 	if _, err := cli.ContainerInspect(ctx, d.Server.Uuid); err == nil {
 		return nil
+	} else if !client.IsErrNotFound(err) {
+		return err
 	}
 
 	conf := &container.Config{
@@ -250,6 +353,18 @@ func (d *DockerEnvironment) Create() error {
 	return nil
 }
 
+// Sends the specified command to the stdin of the running container instance. There is no
+// confirmation that this data is sent successfully, only that it gets pushed into the stdin.
+func (d *DockerEnvironment) SendCommand(c string) error {
+	if !d.attached {
+		return errors.New("attempting to send command to non-attached instance")
+	}
+
+	_, err := d.stream.Conn.Write([]byte(c + "\n"))
+
+	return err
+}
+
 // Reads the log file for the server. This does not care if the server is running or not, it will
 // simply try to read the last X bytes of the file and return them.
 func (d *DockerEnvironment) Readlog(len int64) ([]string, error) {

server/server.go

@@ -252,7 +252,9 @@ func (s *Server) SetState(state ProcessState) error {
 // 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 {
-	return s.environment.Exists()
+	exists, _ := s.environment.Exists()
+
+	return exists
 }
 
 // Initalizes a server instance. This will run through and ensure that the environment

websocket.go

@@ -110,7 +110,7 @@ func (wsm *WebsocketMessage) HandleInbound(c *websocket.Conn) error {
 		}
 	case "send command":
 		{
-			return nil
+			return wsm.server.Environment().SendCommand(strings.Join(wsm.Args, ""))
 		}
 	}
 

wings.go

@@ -67,6 +67,15 @@ func main() {
 		if err := s.CreateEnvironment(); err != nil {
 			zap.S().Errorw("failed to create an environment for server", zap.String("server", s.Uuid), zap.Error(err))
 		}
+
+		if r, err := s.Environment().IsRunning(); err != nil {
+			zap.S().Errorw("error checking server environment status", zap.String("server", s.Uuid), zap.Error(err))
+		} else if r {
+			zap.S().Infow("detected server is running, re-attaching to process", zap.String("server", s.Uuid))
+			if err := s.Environment().Attach(); err != nil {
+				zap.S().Errorw("error attaching to server environment", zap.String("server", s.Uuid), zap.Error(err))
+			}
+		}
 	}
 
 	r := &Router{