Update build.sh

Following review comments

.github/build-and-upload.sh

@@ -1,20 +1,12 @@
 #!/bin/bash
 
-echo "Cloning graphhopper"
-git clone https://github.com/graphhopper/graphhopper.git
-echo "Building docker image"
-docker build . -t israelhikingmap/graphhopper:latest
-docker login --username $DOCKERHUB_USER --password $DOCKERHUB_TOKEN
-echo "Publishing docker image"
-docker push israelhikingmap/graphhopper:latest
+echo "Buidling and pushing israelhikingmap/graphhopper:latest"
+./build.sh --push
 
-TAG=`cd graphhopper; git for-each-ref --sort=committerdate refs/tags | tail -n 1 | cut -d "/" -f3`
-if docker manifest inspect israelhikingmap/graphhopper:$TAG >/dev/null; then 
-    echo "No need to publish existing version: $TAG";
+TAG=`cd graphhopper; git for-each-ref --sort=committerdate refs/tags | sed -n '$s/.*\///p'`
+if docker manifest inspect "israelhikingmap/graphhopper:${TAG}" >/dev/null; then 
+    echo "No need to push existing version: ${TAG}";
 else
-    (cd graphhopper ; git checkout tags/$TAG)
-    echo "Building docker image for tag: $TAG"
-    docker build . -t israelhikingmap/graphhopper:$TAG
-    echo "Publishing docker image for tag: $TAG"
-    docker push israelhikingmap/graphhopper:$TAG
+    echo "Buidling and pushing israelhikingmap/graphhopper:${TAG}"
+    ./build.sh --push "${TAG}"
 fi

build.sh

@@ -2,19 +2,32 @@
 
 usage() (
 cat <<USAGE
-Build a docker image
+Build a docker image for GraphHopper and optionally push it to Docker Hub
 
 Usage:
-  ./build.sh [<tag> | --help]
+  ./build.sh [[--push] <tag>]
+  ./build.sh --help
 
 Argument:
-  <tag>   Build an image for the given graphhopper repository tag [default: master]
+  <tag>         Build an image for the given graphhopper repository tag [default: master]
 
 Option:
-  --help  Print this message
+  --push        Push the image to Docker Hub
+  --help        Print this message
+  
+Docker Hub credentials are needed for pushing the image. If they are not provided using the
+DOCKERHUB_USER and DOCKERHUB_TOKEN environment variables, then they will be asked interactively.
 USAGE
 )
 
+if [ "$1" == "--push" ]; then
+  push="true"
+  docker login --username "${DOCKERHUB_USER}" --password "${DOCKERHUB_TOKEN}" || exit $?
+  shift
+else
+  push="false"
+fi
+
 if [ $# -gt 1 ] || [ "$1" == "--help" ]; then
   usage
   exit
@@ -23,6 +36,9 @@ fi
 if [ ! -d graphhopper ]; then
   echo "Cloning graphhopper"
   git clone https://github.com/graphhopper/graphhopper.git
+else
+  echo "Pulling graphhopper"
+  (cd graphhopper; git checkout master; git pull)
 fi
 
 imagename="israelhikingmap/graphhopper:${1:-latest}"
@@ -32,8 +48,10 @@ if [ "$1" ]; then
 fi
 
 echo "Building docker image ${imagename}"
-docker build . -t ${imagename}
+docker build . -t "${imagename}"
 
-if [ $# -eq 1 ]; then
+if [ "${push}" == "false" ]; then
   echo "Use \"docker push ${imagename}\" to publish the image on Docker Hub"
+else
+  docker push "${imagename}"
 fi