add -experimental to enable rescheduling

Signed-off-by: Victor Vieux <vieux@docker.com>

cli/cli.go

@@ -7,6 +7,7 @@ import (
 
 	log "github.com/Sirupsen/logrus"
 	"github.com/codegangsta/cli"
+	"github.com/docker/swarm/experimental"
 	"github.com/docker/swarm/version"
 )
 
@@ -32,6 +33,11 @@ func Run() {
 			Value: "info",
 			Usage: fmt.Sprintf("Log level (options: debug, info, warn, error, fatal, panic)"),
 		},
+
+		cli.BoolFlag{
+			Name:  "experimental",
+			Usage: "enable experimental features",
+		},
 	}
 
 	// logs
@@ -49,6 +55,8 @@ func Run() {
 			log.SetLevel(log.DebugLevel)
 		}
 
+		experimental.ENABLED = c.Bool("experimental")
+
 		return nil
 	}
 

cli/manage.go

@@ -17,6 +17,7 @@ import (
 	"github.com/docker/swarm/cluster"
 	"github.com/docker/swarm/cluster/mesos"
 	"github.com/docker/swarm/cluster/swarm"
+	"github.com/docker/swarm/experimental"
 	"github.com/docker/swarm/leadership"
 	"github.com/docker/swarm/scheduler"
 	"github.com/docker/swarm/scheduler/filter"
@@ -324,6 +325,9 @@ func manage(c *cli.Context) {
 		server.SetHandler(api.NewPrimary(cl, tlsConfig, &statusHandler{cl, nil, nil}, c.GlobalBool("debug"), c.Bool("cors")))
 	}
 
-	cluster.NewWatchdog(cl)
+	if experimental.ENABLED {
+		log.Warn("WARNING: rescheduling is currently experimental, use at your own risks")
+		cluster.NewWatchdog(cl)
+	}
 	log.Fatal(server.ListenAndServe())
 }

cluster/config.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/docker/swarm/experimental"
 	"github.com/samalba/dockerclient"
 )
 
@@ -86,25 +87,26 @@ func BuildContainerConfig(c dockerclient.ContainerConfig) *ContainerConfig {
 		json.Unmarshal([]byte(labels), &constraints)
 	}
 
-	// parse reschedule policy from labels (ex. docker run --label 'com.docker.swarm.reschedule-policies=on-node-failure')
-	if labels, ok := c.Labels[SwarmLabelNamespace+".reschedule-policies"]; ok {
-		json.Unmarshal([]byte(labels), &reschedulePolicies)
+	if experimental.ENABLED {
+		// parse reschedule policy from labels (ex. docker run --label 'com.docker.swarm.reschedule-policies=on-node-failure')
+		if labels, ok := c.Labels[SwarmLabelNamespace+".reschedule-policies"]; ok {
+			json.Unmarshal([]byte(labels), &reschedulePolicies)
+		}
 	}
-
 	// parse affinities/constraints/reschedule policies from env (ex. docker run -e affinity:container==redis -e affinity:image==nginx -e constraint:region==us-east -e constraint:storage==ssd -e reschedule:off)
 	for _, e := range c.Env {
 		if ok, key, value := parseEnv(e); ok && key == "affinity" {
 			affinities = append(affinities, value)
 		} else if ok && key == "constraint" {
 			constraints = append(constraints, value)
-		} else if ok && key == "reschedule" {
+		} else if experimental.ENABLED && ok && key == "reschedule" {
 			reschedulePolicies = append(reschedulePolicies, value)
 		} else {
 			env = append(env, e)
 		}
 	}
 
-	// remove affinities/constraints from env
+	// remove affinities/constraints/reschedule policies from env
 	c.Env = env
 
 	// store affinities in labels
@@ -121,10 +123,12 @@ func BuildContainerConfig(c dockerclient.ContainerConfig) *ContainerConfig {
 		}
 	}
 
-	// store reschedule policies in labels
-	if len(reschedulePolicies) > 0 {
-		if labels, err := json.Marshal(reschedulePolicies); err == nil {
-			c.Labels[SwarmLabelNamespace+".reschedule-policies"] = string(labels)
+	if experimental.ENABLED {
+		// store reschedule policies in labels
+		if len(reschedulePolicies) > 0 {
+			if labels, err := json.Marshal(reschedulePolicies); err == nil {
+				c.Labels[SwarmLabelNamespace+".reschedule-policies"] = string(labels)
+			}
 		}
 	}
 
@@ -217,19 +221,23 @@ func (c *ContainerConfig) HasReschedulePolicy(p string) bool {
 // Validate returns an error if the config isn't valid
 func (c *ContainerConfig) Validate() error {
 	//TODO: add validation for affinities and constraints
-	reschedulePolicies := c.extractExprs("reschedule-policies")
-	if len(reschedulePolicies) > 1 {
-		return errors.New("too many reschedule policies")
-	} else if len(reschedulePolicies) == 1 {
-		valid := false
-		for _, validReschedulePolicy := range []string{"off", "on-node-failure"} {
-			if reschedulePolicies[0] == validReschedulePolicy {
-				valid = true
+
+	if experimental.ENABLED {
+		reschedulePolicies := c.extractExprs("reschedule-policies")
+		if len(reschedulePolicies) > 1 {
+			return errors.New("too many reschedule policies")
+		} else if len(reschedulePolicies) == 1 {
+			valid := false
+			for _, validReschedulePolicy := range []string{"off", "on-node-failure"} {
+				if reschedulePolicies[0] == validReschedulePolicy {
+					valid = true
+				}
+			}
+			if !valid {
+				return fmt.Errorf("invalid reschedule policy: %s", reschedulePolicies[0])
 			}
 		}
-		if !valid {
-			return fmt.Errorf("invalid reschedule policy: %s", reschedulePolicies[0])
-		}
 	}
+
 	return nil
 }

experimental/README.md

@@ -8,7 +8,15 @@ The information below describes each feature and the GitHub pull requests and
 issues associated with it. If necessary, links are provided to additional
 documentation on an issue.  As an active Docker user and community member,
 please feel free to provide any feedback on these features you wish.
+## Enable experimental features
 
+To enable experimental feature, use the flag `-experimental` on swarm, for example:
+
+```
+$ swarm -experimental manage ...
+# or
+$ swarm -experimental join ...
+```
 
 ## Current experimental features
 

experimental/experimental.go

@@ -0,0 +1,4 @@
+package experimental
+
+// ENABLED is set to true when the -experimental flag is set.
+var ENABLED = false

test/integration/helpers.bash

@@ -117,7 +117,7 @@ function swarm_manage_no_wait() {
 	local port=$(($SWARM_BASE_PORT + $i))
 	local host=127.0.0.1:$port
 
-	"$SWARM_BINARY" -l debug manage -H "$host" --heartbeat=1s $discovery &
+	"$SWARM_BINARY" -l debug -experimental manage -H "$host" --heartbeat=1s $discovery &
 	SWARM_MANAGE_PID[$i]=$!
 	SWARM_HOSTS[$i]=$host