Merge pull request #2 from fcrisciani/tweaks

Simplified the script output

README.md

@@ -23,11 +23,11 @@ The script flags several potential conditions for each overlay:
 
 Building the Container
 ======================
-docker image build -t ctelfer/ip-util-check . 
+docker image build -t docker/ip-util-check .
 
 
 Running the Container
 =====================
 
     docker run -it --rm -v /var/run/docker.sock:/var/run/docker.sock \
-            ctelfer/ip-util-check
+            docker/ip-util-check

ip-util-check

@@ -8,11 +8,12 @@ set -e
 
 # Per-network state keyed on network ID
 #
-declare -A NET2SUB	# list of subnets for each overlay network
-declare -A NET2CAP	# network capacity of each overlay network
-declare -A NET2NAME	# network name of each overlay network
-declare -A NET2NCIP	# number of container IP addresses for each overlay network
-declare -A NET2NVIP	# number of virtuail IP addresses for each overlay network
+declare -A NET2SUB	  # list of subnets for each overlay network
+declare -A NET2CAP	  # network capacity of each overlay network
+declare -A NET2NAME	  # network name of each overlay network
+declare -A NET2NCIP	  # number of container IP addresses for each overlay network
+declare -A NET2NVIP	  # number of virtual IP addresses for each overlay network
+declare -A NET2NNODES # number of nodes where the overlay is currently used
 
 
 # Report the general IP utilization status of an overlay network
@@ -24,20 +25,18 @@ report() {
 		echo "Network ${NET2NAME[$1]}/$1 has no assigned IP addresses"
 		echo "	Network OK"
 	else
-		USE=$(( ${NET2NCIP[$1]} + ${NET2NVIP[$1]} ))
-		SAFECAP=$(( (${NET2CAP[$1]} - ${NET2NVIP[$1]}) / 2 ))
-		echo "Network ${NET2NAME[$1]}/$1 has an IP address capacity of ${NET2CAP[$1]} and uses $USE addresses"
-
-		if [ $(( $USE + $NNODES )) -ge ${NET2CAP[$1]} ] ; then
-			echo "	ERROR: network will be over capacity if upgrading Docker Enterprise engine version 18.09"
-			echo "	       or later."
-		elif [ $(( ${NET2NCIP[$1]} * 2 )) -ge $SAFECAP ] ; then
-			HDRM=$(( ${NET2CAP[$1]} - ${NET2NCIP[$1]} - ${NET2NVIP[$1]} ))
-			echo "	WARNING: network could exhaust IP addresses if the cluster scales to $HDRM or more nodes"
-		elif [ ${NET2NCIP[$1]} -ge $(( $SAFECAP * 8 / 10 )) ] ; then
-			echo "	WARNING: network using more than 80% of safe IP capacity ($SAFECAP)"
+		USE=$(( ${NET2NCIP[$1]} + ${NET2NVIP[$1]} ))            # how many IPs are currently in use
+		SAFECAP=$(( ${NET2CAP[$1]} * 75 / 100 ))                # safe capacity is the 75% of the whole address space
+    HDRM=$(( ${NET2CAP[$1]} - $USE - ${NET2NNODES[$1]}))    # how many IPs are currently free in the network
+		echo "Network ${NET2NAME[$1]}/$1 has an IP address capacity of ${NET2CAP[$1]} and uses $USE addresses spanning over ${NET2NNODES[$1]} nodes"
+
+		if [ $(( $USE + ${NET2NNODES[$1]} )) -ge ${NET2CAP[$1]} ] ; then
+			echo "	ERROR: network will be over capacity if upgrading Docker Enterprise engine version 18.09 or later"
+		elif [ $(( $USE + ${NET2NNODES[$1]} )) -ge $SAFECAP ] ; then
+			echo -n "	WARNING: network is using more than the 75% of the total space. "
+      echo "Remaining only $HDRM IPs after upgrade"
 		else
-			echo "	Network OK: network support up to $(( $SAFECAP - ${NET2NCIP[$1]} )) additional tasks safely"
+      echo "	Network OK: network will have $(( $SAFECAP - $USE - ${NET2NNODES[$1]} )) available IPs before passing the 75% subnet use"
 		fi
 	fi
 }
@@ -53,16 +52,18 @@ SVCIDS=$(docker service ls -q)
 
 echo "Gathering overlay network information"
 for net in $NETS ; do
-        NET2NAME[$net]=$(docker network inspect $net | jq -r '.[].Name')
+  networkInspect=$( docker network inspect $net )
+        NET2NAME[$net]=$(echo $networkInspect | jq -r '.[].Name')
 	set +e
-        NET2SUB[$net]=$(docker network inspect $net | jq -r '.[].IPAM.Config[].Subnet' 2>/dev/null)
+        NET2SUB[$net]=$(echo $networkInspect | jq -r '.[].IPAM.Config[].Subnet' 2>/dev/null)
 	if [ -z "${NET2SUB[$net]}" ] ; then
 		NET2SUB[$net]=$(docker network inspect ${NET2NAME[$net]} | jq -r '.[].IPAM.Config[].Subnet' 2>/dev/null)
 	fi
 	set -e
         NET2CAP[$net]=0
         NET2NCIP[$net]=0
         NET2NVIP[$net]=0
+        NET2NNODES[$net]=$( echo $networkInspect | jq -r '.[].Peers | length' )
         for sub in ${NET2SUB[$net]} ; do
                 pfxlen=$(echo $sub | awk -F / '{print $2}')
                 subcap=$(( (1 << (32 - $pfxlen)) - 3 ))