diff --git a/Dockerfile-alpine b/Dockerfile-alpine
index 5ed0c21..81bb6f6 100644
--- a/Dockerfile-alpine
+++ b/Dockerfile-alpine
@@ -1,5 +1,4 @@
-# DO NOT UPGRADE alpine until https://github.com/jenkinsci/docker/issues/508 is fixed
-FROM openjdk:8u121-jdk-alpine
+FROM openjdk:8-jdk-alpine
 
 RUN apk add --no-cache git openssh-client curl unzip bash ttf-dejavu coreutils tini
 
@@ -14,17 +13,17 @@ ENV JENKINS_HOME /var/jenkins_home
 ENV JENKINS_SLAVE_AGENT_PORT ${agent_port}
 
 # Jenkins is run with user `jenkins`, uid = 1000
-# If you bind mount a volume from the host or a data container, 
+# If you bind mount a volume from the host or a data container,
 # ensure you use the same uid
 RUN addgroup -g ${gid} ${group} \
     && adduser -h "$JENKINS_HOME" -u ${uid} -G ${group} -s /bin/bash -D ${user}
 
-# Jenkins home directory is a volume, so configuration and build history 
+# Jenkins home directory is a volume, so configuration and build history
 # can be persisted and survive image upgrades
 VOLUME /var/jenkins_home
 
-# `/usr/share/jenkins/ref/` contains all reference configuration we want 
-# to set on a fresh new installation. Use it to bundle additional plugins 
+# `/usr/share/jenkins/ref/` contains all reference configuration we want
+# to set on a fresh new installation. Use it to bundle additional plugins
 # or config file with your custom jenkins Docker image.
 RUN mkdir -p /usr/share/jenkins/ref/init.groovy.d
 
@@ -40,7 +39,7 @@ ARG JENKINS_SHA=2d71b8f87c8417f9303a73d52901a59678ee6c0eefcf7325efed6035ff39372a
 # Can be used to customize where jenkins.war get downloaded from
 ARG JENKINS_URL=https://repo.jenkins-ci.org/public/org/jenkins-ci/main/jenkins-war/${JENKINS_VERSION}/jenkins-war-${JENKINS_VERSION}.war
 
-# could use ADD but this one does not check Last-Modified header neither does it allow to control checksum 
+# could use ADD but this one does not check Last-Modified header neither does it allow to control checksum
 # see https://github.com/docker/docker/issues/8331
 RUN curl -fsSL ${JENKINS_URL} -o /usr/share/jenkins/jenkins.war \
   && echo "${JENKINS_SHA}  /usr/share/jenkins/jenkins.war" | sha256sum -c -
diff --git a/Jenkinsfile b/Jenkinsfile
index f42d95e..f2620fc 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -1,8 +1,8 @@
 #!/usr/bin/env groovy
 
 properties([
-    buildDiscarder(logRotator(numToKeepStr: '5', artifactNumToKeepStr: '5')),
-    pipelineTriggers([cron('@daily')]),
+    buildDiscarder(logRotator(numToKeepStr: '50', artifactNumToKeepStr: '5')),
+    pipelineTriggers([cron('H H/6 * * *')]),
 ])
 
 node('docker') {
diff --git a/README.md b/README.md
index f40e375..ec24157 100644
--- a/README.md
+++ b/README.md
@@ -151,7 +151,7 @@ COPY custom.groovy /usr/share/jenkins/ref/init.groovy.d/custom.groovy
 ## Preinstalling plugins
 
 You can rely on the `install-plugins.sh` script to pass a set of plugins to download with their dependencies.
-This script will perform downloads from update centers, an internet access is required for the default update centers.
+This script will perform downloads from update centers, and internet access is required for the default update centers.
 
 ### Setting update centers
 
diff --git a/install-plugins.sh b/install-plugins.sh
index 10031b4..34b2c23 100755
--- a/install-plugins.sh
+++ b/install-plugins.sh
@@ -111,7 +111,7 @@ resolveDependencies() {
             echo "Skipping optional dependency $plugin"
         else
             local pluginInstalled
-            if pluginInstalled="$(echo "${bundledPlugins}" | grep "^${plugin}:")"; then
+            if pluginInstalled="$(echo -e "${bundledPlugins}\n${installedPlugins}" | grep "^${plugin}:")"; then
                 pluginInstalled="${pluginInstalled//[$'\r']}"
                 local versionInstalled; versionInstalled=$(versionFromPlugin "${pluginInstalled}")
                 local minVersion; minVersion=$(versionFromPlugin "${d}")
@@ -119,7 +119,7 @@ resolveDependencies() {
                     echo "Upgrading bundled dependency $d ($minVersion > $versionInstalled)"
                     download "$plugin" &
                 else
-                    echo "Skipping already bundled dependency $d ($minVersion <= $versionInstalled)"
+                    echo "Skipping already installed dependency $d ($minVersion <= $versionInstalled)"
                 fi
             else
                 download "$plugin" &
@@ -190,8 +190,14 @@ main() {
 
     # Read plugins from stdin or from the command line arguments
     if [[ ($# -eq 0) ]]; then
-        while read -r line; do
-            plugins+=("${line}")
+        while read -r line || [ "$line" != "" ]; do
+            # Remove leading/trailing spaces, comments, and empty lines
+            plugin=$(echo "${line}" | sed -e 's/^[ \t]*//g' -e 's/[ \t]*$//g' -e 's/[ \t]*#.*$//g' -e '/^[ \t]*$/d')
+
+            # Avoid adding empty plugin into array
+            if [ ${#plugin} -ne 0 ]; then
+                plugins+=("${plugin}")
+            fi
         done
     else
         plugins=("$@")
@@ -206,6 +212,9 @@ main() {
     echo "Analyzing war..."
     bundledPlugins="$(bundledPlugins)"
 
+    echo "Registering preinstalled plugins..."
+    installedPlugins="$(installedPlugins)"
+
     # Check if there's a version-specific update center, which is the case for LTS versions
     jenkinsVersion="$(jenkinsMajorMinorVersion)"
     if curl -fsL -o /dev/null "$JENKINS_UC/$jenkinsVersion"; then
diff --git a/publish.sh b/publish.sh
index f1c5945..5ae5ebb 100755
--- a/publish.sh
+++ b/publish.sh
@@ -85,12 +85,7 @@ publish() {
         build_opts=()
     fi
 
-    local dir=war
-    # lts is in a different dir
-    if [[ "$version" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
-        dir=war-stable
-    fi
-    sha=$(curl -q -fsSL "http://mirrors.jenkins.io/${dir}/${version}/jenkins.war.sha256" | cut -d' ' -f 1)
+    sha=$(curl -q -fsSL "https://repo.jenkins-ci.org/releases/org/jenkins-ci/main/jenkins-war/${version}/jenkins-war-${version}.war.sha256" )
 
     docker build --file "Dockerfile$variant" \
                  --build-arg "JENKINS_VERSION=$version" \
diff --git a/tests/install-plugins.bats b/tests/install-plugins.bats
index 3cf7093..9982c57 100644
--- a/tests/install-plugins.bats
+++ b/tests/install-plugins.bats
@@ -26,7 +26,7 @@ SUT_IMAGE=$(sut_image)
 @test "plugins are installed with install-plugins.sh" {
   run docker_build_child $SUT_IMAGE-install-plugins $BATS_TEST_DIRNAME/install-plugins
   assert_success
-  refute_line --partial 'Skipping already bundled dependency'
+  refute_line --partial 'Skipping already installed dependency'
   # replace DOS line endings \r\n
   run bash -c "docker run --rm $SUT_IMAGE-install-plugins ls --color=never -1 /var/jenkins_home/plugins | tr -d '\r'"
   assert_success
@@ -55,7 +55,7 @@ SUT_IMAGE=$(sut_image)
 @test "plugins are installed with install-plugins.sh from a plugins file" {
   run docker_build_child $SUT_IMAGE-install-plugins-pluginsfile $BATS_TEST_DIRNAME/install-plugins/pluginsfile
   assert_success
-  refute_line --partial 'Skipping already bundled dependency'
+  refute_line --partial 'Skipping already installed dependency'
   # replace DOS line endings \r\n
   run bash -c "docker run --rm $SUT_IMAGE-install-plugins ls --color=never -1 /var/jenkins_home/plugins | tr -d '\r'"
   assert_success
@@ -84,8 +84,8 @@ SUT_IMAGE=$(sut_image)
 @test "plugins are installed with install-plugins.sh even when already exist" {
   run docker_build_child $SUT_IMAGE-install-plugins-update $BATS_TEST_DIRNAME/install-plugins/update --no-cache
   assert_success
+  assert_line --partial 'Skipping already installed dependency javadoc'
   assert_line "Using provided plugin: ant"
-  refute_line --partial 'Skipping already bundled dependency'
   # replace DOS line endings \r\n
   run bash -c "docker run --rm $SUT_IMAGE-install-plugins-update unzip -p /var/jenkins_home/plugins/maven-plugin.jpi META-INF/MANIFEST.MF | tr -d '\r'"
   assert_success
diff --git a/tests/install-plugins/pluginsfile/plugins.txt b/tests/install-plugins/pluginsfile/plugins.txt
index ed6cf8d..090a044 100644
--- a/tests/install-plugins/pluginsfile/plugins.txt
+++ b/tests/install-plugins/pluginsfile/plugins.txt
@@ -1,5 +1,21 @@
+# comment line should be skipped
+
+# simple case
 ant:1.3
-maven-plugin:2.7.1
-mesos:0.13.0
-git:latest
-filesystem_scm:experimental
+
+# trailing spaces
+maven-plugin:2.7.1   
+
+# leading spaces
+  mesos:0.13.0
+
+# leading spaces, and trailing spaces
+  git:latest  
+
+# with comments at the end
+filesystem_scm:experimental  # comment at the end
+
+# empty line
+ 
+    #  
+     # empty line