add Travis ctrl file for checking if changes happened (#11383)

* #10298 add Travis ctrl file for checking if changes happened since last nightly

* missing comment subject

* #10298 repair shellcheck warning - useless cat

3 files changed, 21 insertions, 2 deletions

diff --git a/.travis/create_artifacts.sh b/.travis/create_artifacts.sh
index a5349cca34..287f45c1c2 100755
--- a/.travis/create_artifacts.sh
+++ b/.travis/create_artifacts.sh
@@ -26,6 +26,21 @@ if [ ! "${TRAVIS_REPO_SLUG}" == "netdata/netdata" ]; then
   exit 0
 fi
 
+# if nightlies.sh has not written this TRAVIS_BUILD_NUMBER, there's no 
+# changes from last nigthly
+if [ -f .travis/current_build_status ]; then
+  FILE_TRAVIS_BUILD_NUMBER=$(cut -d'#' -f2 < .travis/current_build_status)
+  FILE_TRAVIS_BUILD_STATUS=$(cut -d- -f1 < .travis/current_build_status)
+  if [[ ${FILE_TRAVIS_BUILD_NUMBER} -eq ${TRAVIS_BUILD_NUMBER} ]] && [[ ${FILE_TRAVIS_BUILD_STATUS} == "changes" ]]; then
+  	echo "Changes happen since last nightly release, let's continue"
+  else
+    echo "No changes since last nightly release, nothing else to do"
+	  exit 0
+  fi
+else
+  echo "File .travis/current_build_status doesn't exist, probably this is the very first build, let's continue"
+fi
+
 echo "--- Initialize git configuration ---"
 git checkout "${1-master}"
 git pull
diff --git a/.travis/generate_changelog_for_nightlies.sh b/.travis/generate_changelog_for_nightlies.sh
index 59173af3f6..0cfc3e1557 100755
--- a/.travis/generate_changelog_for_nightlies.sh
+++ b/.travis/generate_changelog_for_nightlies.sh
@@ -37,8 +37,9 @@ echo "Changelog created! Adding packaging/version(${NEW_VERSION}) and CHANGELOG.
 echo "${NEW_VERSION}" > packaging/version
 git add packaging/version && echo "1) Added packaging/version to repository" || FAIL=1
 git add CHANGELOG.md && echo "2) Added changelog file to repository" || FAIL=1
-git commit -m '[ci skip] create nightly packages and update changelog' --author "${GIT_USER} <${GIT_MAIL}>" && echo "3) Committed changes to repository" || FAIL=1
-git push "https://${GITHUB_TOKEN}:@${PUSH_URL}" && echo "4) Pushed changes to remote ${PUSH_URL}" || FAIL=1
+git add .travis/current_build_status && echo "3) Added travis current build status file to repository" || FAIL=1
+git commit -m '[ci skip] create nightly packages and update changelog' --author "${GIT_USER} <${GIT_MAIL}>" && echo "4) Committed changes to repository" || FAIL=1
+git push "https://${GITHUB_TOKEN}:@${PUSH_URL}" && echo "5) Pushed changes to remote ${PUSH_URL}" || FAIL=1
 
 # In case of a failure, wrap it up and bail out cleanly
 if [ $FAIL -eq 1 ]; then
diff --git a/.travis/nightlies.sh b/.travis/nightlies.sh
index 7240a784d6..1679afb237 100755
--- a/.travis/nightlies.sh
+++ b/.travis/nightlies.sh
@@ -31,6 +31,9 @@ PREVIOUS_NIGHTLY_COUNT="$(rev <packaging/version | cut -d- -f 2 | rev)"
 if [ "${COMMITS_SINCE_RELEASE}" == "${PREVIOUS_NIGHTLY_COUNT}" ]; then
 	echo "No changes since last nightly release, nothing else to do"
 	exit 0
+else
+	echo "Changes happen since last nightly release"
+	echo "changes-#${TRAVIS_BUILD_NUMBER}" > .travis/current_build_status
 fi
 
 if [ ! "${TRAVIS_REPO_SLUG}" == "netdata/netdata" ]; then