added watch_containers.sh

watch_containers.sh

@@ -0,0 +1,90 @@
+#!/bin/bash
+
+# name:		watch_containers.sh
+# author:	david@socialnerds.org
+# version:	0.1
+# license:	GPLv3
+# description:	Checks if the running container count
+#		matches a number provided as $1 and optionally
+#		reports results to a healthchecks endpoint.
+
+# usage: ./watch_containers.sh <number> <optional-healthchecks-url>
+
+# **** function definitions ****
+function usage {
+  echo "usage: ./watch_containers.sh <number> <optional-healthchecks-url>"
+}
+
+function get_container_count {
+  local CNT=$(docker ps -q | wc -l)
+  if is_int "$CNT"; then
+    echo $CNT
+  fi
+}
+
+function is_int {
+  local INT_EXPR='^[0-9]+$'
+  if [[ $1 =~ $INT_EXPR ]]; then
+    return 0
+  else
+    return 1
+  fi
+}
+
+function is_url {
+  local URL_EXPR='^https?://.+$'
+  if [[ $1 =~ $URL_EXPR ]]; then
+    return 0
+  else
+    return 1
+  fi
+}
+
+# **** start ****
+
+#exit if no options
+if [ -z "$1" ]; then
+  usage
+  exit 1
+fi
+
+#exit if $1 is no intager
+if ! is_int "$1"; then
+  usage
+  exit 1
+fi
+
+#set expected running containers
+NUM=$1
+
+#get running container count
+CNT=$(get_container_count)
+
+#set healthchecks url if not empty
+URL=""
+if [ -n "$2" ]; then
+ #exit if $2 is no valid url
+  if ! is_url "$2"; then
+    usage
+    exit 1
+  fi
+  URL="$2"
+fi
+
+MSG="Running containers: $CNT
+Expected containers: $NUM"
+
+echo "$MSG"
+
+#report to healthchecks
+if [ -n "$URL" ]; then
+  if [ $NUM -eq $CNT ]; then
+    curl -m 10 --retry 5 --data-raw "$MSG" "$URL"
+  else
+    curl -m 10 --retry 5 --data-raw "$MSG" "$URL/fail"
+  fi
+fi
+
+# **** end ****
+exit 0
+