Merge pull request #4 from alexellis/ulimit_experimental

Experimental ulimit implementation and README.md

.gitignore

@@ -0,0 +1,2 @@
+play-with-docker
+

README.md

@@ -1 +1,29 @@
-# play-with-docker
+# play-with-docker
+
+Play With Docker gives you the experience of having a free Alpine Linux Virtual Machine in the cloud
+where you can build and run Docker containers and even create clusters with Docker features like Swarm Mode.
+
+Under the hood DIND or Docker-in-Docker is used to give the effect of multiple VMs/PCs.
+
+A live version is available at: http://play-with-docker.com/
+
+## Installation
+
+Start the Docker daemon on your machine and run `docker pull docker:1.12.2-rc2-dind`. 
+
+1) Install go 1.7.1 with `brew` on Mac or through a package manager.
+
+2) `go get`
+
+3) `go build`
+
+4) Run the binary produced as `play-with-docker`
+
+5) Point to http://localhost:3000/ and click "New Instance"
+
+Notes:
+
+* There is a hard-coded limit to 5 Docker playgrounds per session. After 1 hour sessions are deleted.
+* If you want to override the DIND version or image then set the environmental variable i.e.
+  `DIND_IMAGE=docker:dind`
+

services/docker.go

@@ -29,10 +29,14 @@ func GetContainerInfo(id string) (types.ContainerJSON, error) {
 }
 
 func CreateNetwork(name string) error {
+	// TODO: This line appears to give an error when running on localhost:3000
+	// when driver is specified a name must be given.
 	opts := types.NetworkCreate{Attachable: true, Driver: "overlay"}
 	_, err := c.NetworkCreate(context.Background(), name, opts)
 
 	if err != nil {
+		log.Printf("Starting session err [%s]\n", err)
+
 		return err
 	}
 
@@ -70,10 +74,14 @@ func AttachExecConnection(execId string, ctx context.Context) (*types.HijackedRe
 	return &conn, nil
 }
 
-func CreateInstance(net string) (*ptypes.Instance, error) {
+func CreateInstance(net string, dindImage string) (*ptypes.Instance, error) {
 
+	var maximumPidLimit int64
+	maximumPidLimit = 150 // Set a ulimit value to prevent misuse
 	h := &container.HostConfig{NetworkMode: container.NetworkMode(net), Privileged: true}
-	conf := &container.Config{Image: "docker:dind"}
+	h.Resources.PidsLimit = maximumPidLimit
+
+	conf := &container.Config{Image: dindImage}
 	container, err := c.ContainerCreate(context.Background(), conf, h, nil, "")
 
 	if err != nil {

services/instance.go

@@ -1,19 +1,37 @@
 package services
 
-import "github.com/franela/play-with-docker/types"
+import (
+	"log"
+	"os"
+
+	"github.com/franela/play-with-docker/types"
+)
 
 var instances map[string]map[string]*types.Instance
 
+var dindImage string
+var defaultDindImageName string
+
 func init() {
 	instances = make(map[string]map[string]*types.Instance)
+        dindImage = getDindImageName()
+}
+
+func getDindImageName() string {
+	dindImage := os.Getenv("DIND_IMAGE")
+        defaultDindImageName = "docker:1.12.2-rc2-dind"
+        if len(dindImage) == 0 {
+		dindImage = defaultDindImageName
+	}
+	return dindImage
 }
 
 func NewInstance(session *types.Session) (*types.Instance, error) {
-	//TODO: Validate that a session can only have 10 instances
 
+	//TODO: Validate that a session can only have 5 instances
 	//TODO: Create in redis
-
-	instance, err := CreateInstance(session.Id)
+	log.Printf("NewInstance - using image: [%s]\n", dindImage)
+	instance, err := CreateInstance(session.Id, dindImage)
 
 	if err != nil {
 		return nil, err

services/session.go

@@ -18,6 +18,7 @@ func NewSession() (*types.Session, error) {
 	s := &types.Session{}
 	s.Id = uuid.NewV4().String()
 	s.Instances = map[string]*types.Instance{}
+	log.Printf("NewSession id=[%s]\n", s.Id)
 
 	//TODO: Store in something like redis
 	sessions[s.Id] = s