From 4c01af4e1d1e18ec06596fe7c68f2bf8f7320265 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Fri, 12 Jun 2015 16:51:33 +0100
Subject: [PATCH] Check if container is still running right after allocating

---
 ipam/http.go        | 13 ++++++++++++-
 ipam/http_test.go   |  2 +-
 prog/weaver/main.go | 26 +++++++++++++-------------
 3 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/ipam/http.go b/ipam/http.go
index a9de0988..8164d8c8 100644
--- a/ipam/http.go
+++ b/ipam/http.go
@@ -7,6 +7,7 @@ import (
 	"github.com/gorilla/mux"
 
 	"github.com/weaveworks/weave/common"
+	"github.com/weaveworks/weave/common/docker"
 	"github.com/weaveworks/weave/ipam/address"
 )
 
@@ -16,7 +17,7 @@ func badRequest(w http.ResponseWriter, err error) {
 }
 
 // HandleHTTP wires up ipams HTTP endpoints to the provided mux.
-func (alloc *Allocator) HandleHTTP(router *mux.Router, defaultSubnet address.CIDR) {
+func (alloc *Allocator) HandleHTTP(router *mux.Router, defaultSubnet address.CIDR, dockerCli *docker.Client) {
 	router.Methods("PUT").Path("/ip/{id}/{ip}").HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		closedChan := w.(http.CloseNotifier).CloseNotify()
 		vars := mux.Vars(r)
@@ -77,6 +78,11 @@ func (alloc *Allocator) HandleHTTP(router *mux.Router, defaultSubnet address.CID
 			badRequest(w, fmt.Errorf("Unable to allocate: %s", err))
 			return
 		}
+		if dockerCli != nil && dockerCli.IsContainerNotRunning(ident) {
+			common.Info.Printf("[allocator] '%s' is not running: freeing %s", ident, addr)
+			alloc.Free(ident, addr)
+			return
+		}
 
 		fmt.Fprintf(w, "%s/%d", addr, cidr.PrefixLen)
 	})
@@ -89,6 +95,11 @@ func (alloc *Allocator) HandleHTTP(router *mux.Router, defaultSubnet address.CID
 			badRequest(w, err)
 			return
 		}
+		if dockerCli != nil && dockerCli.IsContainerNotRunning(ident) {
+			common.Info.Printf("[allocator] '%s' is not running: freeing %s", ident, newAddr)
+			alloc.Free(ident, newAddr)
+			return
+		}
 
 		fmt.Fprintf(w, "%s/%d", newAddr, defaultSubnet.PrefixLen)
 	})
diff --git a/ipam/http_test.go b/ipam/http_test.go
index b93360c6..10b1581c 100644
--- a/ipam/http_test.go
+++ b/ipam/http_test.go
@@ -44,7 +44,7 @@ func listenHTTP(alloc *Allocator, subnet address.CIDR) int {
 	router.HandleFunc("/status", func(w http.ResponseWriter, r *http.Request) {
 		io.WriteString(w, fmt.Sprintln(alloc))
 	})
-	alloc.HandleHTTP(router, subnet)
+	alloc.HandleHTTP(router, subnet, nil)
 
 	httpListener, err := net.Listen("tcp", ":0")
 	if err != nil {
diff --git a/prog/weaver/main.go b/prog/weaver/main.go
index 1c4de362..25fdad75 100644
--- a/prog/weaver/main.go
+++ b/prog/weaver/main.go
@@ -141,8 +141,16 @@ func main() {
 
 	var allocator *ipam.Allocator
 	var defaultSubnet address.CIDR
+	var dockerCli *docker.Client
 	if iprangeCIDR != "" {
-		allocator, defaultSubnet = createAllocator(router, apiPath, iprangeCIDR, ipsubnetCIDR, determineQuorum(peerCount, peers))
+		allocator, defaultSubnet = createAllocator(router, iprangeCIDR, ipsubnetCIDR, determineQuorum(peerCount, peers))
+		dockerCli, err = docker.NewClient(apiPath)
+		if err != nil {
+			Error.Fatal("Unable to start docker client: ", err)
+		}
+		if err = dockerCli.AddObserver(allocator); err != nil {
+			Error.Fatal("Unable to start watcher", err)
+		}
 	} else if peerCount > 0 {
 		log.Fatal("-initpeercount flag specified without -iprange")
 	} else {
@@ -158,7 +166,7 @@ func main() {
 	// so there is no point in doing "weave launch -httpaddr ''".
 	// This is here to support stand-alone use of weaver.
 	if httpAddr != "" {
-		go handleHTTP(router, httpAddr, allocator, defaultSubnet)
+		go handleHTTP(router, httpAddr, allocator, defaultSubnet, dockerCli)
 	}
 
 	SignalHandlerLoop(router)
@@ -209,7 +217,7 @@ func parseAndCheckCIDR(cidrStr string) address.CIDR {
 	return cidr
 }
 
-func createAllocator(router *weave.Router, apiPath string, ipRangeStr string, defaultSubnetStr string, quorum uint) (*ipam.Allocator, address.CIDR) {
+func createAllocator(router *weave.Router, ipRangeStr string, defaultSubnetStr string, quorum uint) (*ipam.Allocator, address.CIDR) {
 	ipRange := parseAndCheckCIDR(ipRangeStr)
 	defaultSubnet := ipRange
 	if defaultSubnetStr != "" {
@@ -223,14 +231,6 @@ func createAllocator(router *weave.Router, apiPath string, ipRangeStr string, de
 	allocator.SetInterfaces(router.NewGossip("IPallocation", allocator))
 	allocator.Start()
 
-	dockerCli, err := docker.NewClient(apiPath)
-	if err != nil {
-		Error.Fatal("Unable to start docker client: ", err)
-	}
-	if err = dockerCli.AddObserver(allocator); err != nil {
-		Error.Fatal("Unable to start watcher", err)
-	}
-
 	return allocator, defaultSubnet
 }
 
@@ -254,11 +254,11 @@ func determineQuorum(initPeerCountFlag int, peers []string) uint {
 	return quorum
 }
 
-func handleHTTP(router *weave.Router, httpAddr string, allocator *ipam.Allocator, defaultSubnet address.CIDR) {
+func handleHTTP(router *weave.Router, httpAddr string, allocator *ipam.Allocator, defaultSubnet address.CIDR, docker *docker.Client) {
 	muxRouter := mux.NewRouter()
 
 	if allocator != nil {
-		allocator.HandleHTTP(muxRouter, defaultSubnet)
+		allocator.HandleHTTP(muxRouter, defaultSubnet, docker)
 	}
 
 	muxRouter.Methods("GET").Path("/status").HandlerFunc(func(w http.ResponseWriter, r *http.Request) {