add: check.sh

check.sh

@@ -0,0 +1,53 @@
+#! /usr/bin/env bash
+
+set -e
+
+if [ -z "${BASE}" ]; then
+  echo "the environment variable BASE is not set"
+  exit 1
+fi
+
+if [ -z "${TARGET}" ]; then
+  echo "the environment variable TARGET is not set"
+  exit 1
+fi
+
+
+# add "library/" if its a "official" docker image (it has no username)
+echo "${BASE}" | grep -q "/" || BASE="library/${BASE}"
+echo "${TARGET}" | grep -q "/" || TARGET="library/${TARGET}" 
+
+
+# move tha tag to its own var and remove it from the repo name
+BASE_TAG=$(sed 's/[^:]*://' <<< $BASE)
+TARGET_TAG=$(sed 's/[^:]*://' <<< $TARGET)
+
+BASE_REPO=$(sed 's/:.*//' <<< $BASE)
+TARGET_REPO=$(sed 's/:.*//' <<< $TARGET) 
+
+BASE_URL="https://hub.docker.com/v2/repositories/${BASE_REPO}/tags/${BASE_TAG}"
+TARGET_URL="https://hub.docker.com/v2/repositories/${TARGET_REPO}/tags/${TARGET_TAG}"
+
+
+# login if credentias are passed
+HEADER=""
+if [[ ! -z "${DOCKER_USERNAME}" && ! -z "${DOCKER_PASSWORD}" ]]; then
+  TOKEN=$(curl -s -H "Content-Type: application/json" -X POST -d '{"username": "'${DOCKER_USERNAME}'", "password": "'${DOCKER_PASSWORD}'"}' https://hub.docker.com/v2/users/login/ | jq -r .token) 
+  HEADER="Authorization: JWT ${TOKEN}"
+fi
+
+
+# compare the update time of the BASE and TARGET images
+BASE_DATE=$(curl -s -H "${HEADER}" "${BASE_URL}" | jq -r .last_updated ) 
+TARGET_DATE=$(curl -s -H "${HEADER}" "${TARGET_URL}" | jq -r .last_updated)
+
+BASE_TIMESTAMP=$(date -d "${BASE_DATE}" +%s)
+TARGET_TIMESTAMP=$(date -d "${TARGET_DATE}" +%s)
+
+if [ $BASE_TIMESTAMP -le $TARGET_TIMESTAMP ]; then
+  echo "no update needed"
+  exit 1
+fi
+
+echo "$TARGET needs updating"
+exit 0