update:CI: skip the build steps if the change is only for documentation (#941)

* update:CI: skip the build steps if the change is only for documentation

* Use spaces not comma to separate array elements (codefactor)

* unrelated: fix missing checkstyle result storage

* Testing if the circleci command works in our custom images

* Make sure git is installed on certain steps

* local -n is not supported everywhere

* git package on the old image for wince is called git-core

* Just do an exit 1 when we are on a tag

* Revert the testing part. Now ready for merge

* Fix some variables names forgotten in the refactoring

* Revert the testing part. Now ready for merge

1 files changed, 35 insertions, 0 deletions

diff --git a/scripts/check_need_build.sh b/scripts/check_need_build.sh
new file mode 100755
index 000000000..124722e9a
--- /dev/null
+++ b/scripts/check_need_build.sh
@@ -0,0 +1,35 @@
+#!/bin/bash -e
+# ################################################################################################################### #
+# This file exits 1 if there are files of interest that should trigger a build and exits normally otherwise.          #
+# The idea is also to build if the exit code is different from 0 as it means we cannot get a filtered list properly.  #
+# ################################################################################################################### #
+
+# If we are on a tag, just exit 1 as we want to go on with the build
+git describe --exact-match --tags HEAD 2>&1 2>/dev/null && exit 1 || echo "Not on a tag, checking files diff"
+
+# This block constructs the list of files that differ from the trunk branch.
+# Note that if you are on the trunk or master branch it will return the files modified by the last commit.
+declare -a file_list=$(git diff --name-only refs/remotes/origin/trunk)
+# If there is no diff that might just mean that you are on the trunk or master branch
+# so you just want to check the last commit. This way we still have that check more
+# or less working when pushing directly to trunk or when merging in master.
+if [[ -z "$file_list" ]]; then
+    file_list=$(git diff --name-only HEAD^)
+fi
+
+# This block filters out those don't match the pattern we use to exclude files that should not trigger a build.
+declare -a filters=('^docs/.*' '.*\.md$' '.*\.rst$')
+for f in ${file_list[@]}; do
+    for filter in "${filters[@]}" ; do
+        echo "checking $f with filter $filter"
+        if [[ "$f" =~ $filter ]]; then
+            # This removes the element from the element matching the filter
+            file_list=(${file_list[@]/$f})
+            echo "filtering out $f"
+            break
+        fi
+    done
+done
+
+# exits with a 0 if the list is empty
+[[ -z "${file_list}" ]]