travis-ci: skip a branch build if equal tag is present

If we push a branch and a tag pointing to the HEAD of this branch, then Travis CI would run the build twice. This wastes resources and slows the testing. Add a function to detect this situation and skip the build the branch if appropriate. Invoke this function on every build. Helped-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Lars Schneider <larsxschneider@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Lars Schneider committed Sep 10, 2017 at 16:44 UTC 09f5e9746ce8be640683f9f5f1ffb54a34d4dc90
1 file changed +23
ci/lib-travisci.sh
+23
@@ -1,5 +1,28 @@
1 # Library of functions shared by all CI scripts
2
3 +skip_branch_tip_with_tag () {
4 + # Sometimes, a branch is pushed at the same time the tag that points
5 + # at the same commit as the tip of the branch is pushed, and building
6 + # both at the same time is a waste.
7 + #
8 + # Travis gives a tagname e.g. v2.14.0 in $TRAVIS_BRANCH when
9 + # the build is triggered by a push to a tag. Let's see if
10 + # $TRAVIS_BRANCH is exactly at a tag, and if so, if it is
11 + # different from $TRAVIS_BRANCH. That way, we can tell if
12 + # we are building the tip of a branch that is tagged and
13 + # we can skip the build because we won't be skipping a build
14 + # of a tag.
15 +
16 + if TAG=$(git describe --exact-match "$TRAVIS_BRANCH" 2>/dev/null) &&
17 + $TAG != $TRAVIS_BRANCH
18 + then
19 + echo "Tip of $TRAVIS_BRANCH is exactly at $TAG"
20 + exit 0
21 + fi
22 +}
23 +
24 # Set 'exit on error' for all CI scripts to let the caller know that
25 # something went wrong
26 set -e
27 +
28 +skip_branch_tip_with_tag