diff --git a/common.sh b/common.sh
new file mode 100644
index 0000000..224380f
--- /dev/null
+++ b/common.sh
@@ -0,0 +1,57 @@
+# TODO generalise this for the non adoptium build farm case
+function checkArgs() {
+  if [ "$1" -lt 1 ]; then
+     echo Usage: "$0" '[jdk8u|jdk11u|jdk17u|jdk19u|...]'
+     echo "Skara Repo supplied should match a repository in https://github.com/openjdk/"
+     echo "For example, to mirror https://github.com/openjdk/jdk17u"
+     echo "e.g. $0 jdk17u"
+     exit 1
+  fi
+}
+
+function cloneGitHubRepo() {
+  cd "$WORKSPACE" || exit 1
+  GITHUB_REPO=$1 # https://github.com/adoptium/adoptium/jdk17u.git
+  if [ ! -d "$JDKVERSION" ] ; then
+    echo "First time clone repo $GITHUB_REPO"
+    git clone -q "$GITHUB_REPO" || exit 1
+  else
+    cd "$JDKVERSION" && git clean -fd && git fetch --all --tags
+  fi
+}
+
+function readExpectedGATag() {
+    source ${SCRIPT_DIR}/releasePlan.cfg
+    jdkVersion=$1  # e.g jdk17u
+    gaTagVariable="${jdkVersion}GA" # set gaTagVariable=jdk17uGA match releasePlan.cfg
+    expectedTag=${!gaTagVariable} # get value, e.g: expectedTag=jdk-17.0.6
+    echo ${expectedTag}
+}
+
+# this function is not in use, due to agent does not have "jq" to parse json payload
+function queryGHAPI(){
+  repo=$1 # adoptium/jdk8u, openjdk/jdk8u
+  tag=$2 # jdk8u362-b05_adopt, jdk8u362-ga
+  exist="$(curl -s -o /dev/null -w "%{http_code}" "https://api.github.com/repos/${repo}/git/refs/tags/${tag}")"
+  if [ $exist == "200" ]; then
+    echo "Found tag: ${tag} in ${repo}"
+  else
+    echo "Cannot find tag: ${tag} in ${repo}"
+  fi
+  echo ${exist}
+}
+
+# to check if the same _adopt scmReference tag has been used to trigger a release pipeline in the past
+# if yes, wont trigger; if not, do the first time trigger
+function checkPrevious() {
+  if [ -f ${WORKSPACE}/tracking ]; then # already have tracking from previous
+    local scmRef=$1 # _adopt scmReference tag we have found
+    local trackerTag="$(cut -d '=' -f 2 ${WORKSPACE}/tracking)" # previousSCM=jdk-17.0.5+8_adopt
+
+    if [[ "${scmRef}" == "${trackerTag}" ]]; then
+        echo "Release tag ${trackerTag} has triggered a release pipeline build already in the current release"
+        echo "Will not continue job"
+        exit 0
+    fi
+  fi  
+}