add support for docker ps -l / -n

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

api/api.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"runtime"
 	"sort"
+	"strconv"
 	"strings"
 
 	log "github.com/Sirupsen/logrus"
@@ -117,12 +118,13 @@ func getContainersJSON(c *context, w http.ResponseWriter, r *http.Request) {
 	}
 
 	all := r.Form.Get("all") == "1"
+	limit, _ := strconv.Atoi(r.Form.Get("limit"))
 
 	out := []*dockerclient.Container{}
 	for _, container := range c.cluster.Containers() {
 		tmp := (*container).Container
 		// Skip stopped containers unless -a was specified.
-		if !strings.Contains(tmp.Status, "Up") && !all {
+		if !strings.Contains(tmp.Status, "Up") && !all && limit <= 0 {
 			continue
 		}
 		// Skip swarm containers unless -a was specified.
@@ -151,7 +153,11 @@ func getContainersJSON(c *context, w http.ResponseWriter, r *http.Request) {
 	sort.Sort(sort.Reverse(ContainerSorter(out)))
 
 	w.Header().Set("Content-Type", "application/json")
-	json.NewEncoder(w).Encode(out)
+	if limit > 0 && limit < len(out) {
+		json.NewEncoder(w).Encode(out[:limit])
+	} else {
+		json.NewEncoder(w).Encode(out)
+	}
 }
 
 // GET /containers/{name:.*}/json

test/integration/api.bats

@@ -14,3 +14,26 @@ function teardown() {
 	[ "$status" -eq 0 ]
 	[[ "${lines[1]}" == *"Nodes: 3" ]]
 }
+
+@test "docker ps -n 3 should return the 3 last containers, including non running one" {
+skip
+       start_docker 1
+       start_manager
+       run docker_swarm run -d busybox sleep 42
+       run docker_swarm run -d busybox false
+       run docker_swarm run -d busybox true
+       run docker_swarm ps -a -n 3
+       [ "${#lines[@]}" -eq  3 ]
+}
+
+@test "docker ps -l should return the last container, including non running one" {
+skip
+       start_docker 1
+       start_manager
+       run docker_swarm run -d busybox sleep 42
+       run docker_swarm run -d busybox false
+       run docker_swarm run -d busybox true
+       run docker_swarm ps -l
+       [ "${#lines[@]}" -eq  2 ]
+       [[ "${lines[1]}" == *"true"* ]]
+}

test/integration/helpers.bash

@@ -28,10 +28,12 @@ function swarm() {
 # Waits until the given docker engine API becomes reachable.
 function wait_until_reachable() {
 	local attempts=0
-	until docker -H $1 info &> /dev/null || [ $attempts -ge 10 ]; do
+	local max_attempts=5
+	until docker -H $1 info || [ $attempts -ge $max_attempts ]; do
 		echo "Attempt to connect to ${HOSTS[$i]} failed for the $((++attempts)) time" >&2
 		sleep 0.5
 	done
+	[[ $attempts -lt $max_attempts ]] 
 }
 
 # Start the swarm manager in background.