From 5d08dcf8377e76f2ce303dc79404f511ebef82e3 Mon Sep 17 00:00:00 2001
From: Janet Kuo <chiachenk@google.com>
Date: Tue, 29 Sep 2015 17:02:28 -0700
Subject: [PATCH] Use random ports when doing kubectl proxy in testing

---
 hack/lib/util.sh | 26 ++++++++++++++++++++++++++
 hack/test-cmd.sh | 17 +++++++++++++----
 2 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/hack/lib/util.sh b/hack/lib/util.sh
index 7154e1e0082..22a81315a2c 100755
--- a/hack/lib/util.sh
+++ b/hack/lib/util.sh
@@ -48,6 +48,32 @@ kube::util::wait_for_url() {
   return 1
 }
 
+# returns a random port
+kube::util::get_random_port() {
+  awk -v min=1 -v max=65535 'BEGIN{srand(); print int(min+rand()*(max-min+1))}'
+}
+
+# use netcat to check if the host($1):port($2) is free (return 0 means free, 1 means used)
+kube::util::test_host_port_free() {
+  local host=$1
+  local port=$2
+  local success=0
+  local fail=1
+
+  which nc >/dev/null || {
+    kube::log::usage "netcat isn't installed, can't verify if ${host}:${port} is free, skipping the check..."
+    return ${success}
+  }
+
+  if [ ! $(nc -vz "${host} ${port}") ]; then
+    kube::log::status "${host}:${port} is free, proceeding..."
+    return ${success}
+  else
+    kube::log::status "${host}:${port} is already used"
+    return ${fail}
+  fi
+}
+
 # Example:  kube::util::trap_add 'echo "in trap DEBUG"' DEBUG
 # See: http://stackoverflow.com/questions/3338030/multiple-bash-traps-for-the-same-signal
 kube::util::trap_add() {
diff --git a/hack/test-cmd.sh b/hack/test-cmd.sh
index 040a3f44efa..add0823ae5f 100755
--- a/hack/test-cmd.sh
+++ b/hack/test-cmd.sh
@@ -30,6 +30,7 @@ function stop-proxy()
 {
   [[ -n "${PROXY_PID-}" ]] && kill "${PROXY_PID}" 1>&2 2>/dev/null
   PROXY_PID=
+  PROXY_PORT=
 }
 
 # Starts "kubect proxy" to test the client proxy. You may pass options, e.g.
@@ -39,9 +40,18 @@ function start-proxy()
   stop-proxy
 
   kube::log::status "Starting kubectl proxy"
-  # the --www and --www-prefix are just to make something definitely show up for
-  # wait_for_url to see.
-  kubectl proxy -p ${PROXY_PORT} --www=. --www-prefix=/healthz "$@" 1>&2 &
+
+  for retry in $(seq 1 3); do
+    PROXY_PORT=$(kube::util::get_random_port)
+    kube::log::status "On try ${retry}, use proxy port ${PROXY_PORT} if it's free"
+    if kube::util::test_host_port_free "127.0.0.1" "${PROXY_PORT}"; then
+      # the --www and --www-prefix are just to make something definitely show up for
+      # wait_for_url to see.
+      kubectl proxy -p ${PROXY_PORT} --www=. --www-prefix=/healthz "$@" 1>&2 & break
+    fi
+    sleep 1;
+  done
+
   PROXY_PID=$!
   kube::util::wait_for_url "http://127.0.0.1:${PROXY_PORT}/healthz" "kubectl proxy $@"
 }
@@ -86,7 +96,6 @@ API_HOST=${API_HOST:-127.0.0.1}
 KUBELET_PORT=${KUBELET_PORT:-10250}
 KUBELET_HEALTHZ_PORT=${KUBELET_HEALTHZ_PORT:-10248}
 CTLRMGR_PORT=${CTLRMGR_PORT:-10252}
-PROXY_PORT=${PROXY_PORT:-8001}
 PROXY_HOST=127.0.0.1 # kubectl only serves on localhost.
 
 # ensure ~/.kube/config isn't loaded by tests