ci: add check:merge:conflict job (#153)

* ci: add check:merge:conflict job

* split caches between test and release job

polkadot/scripts/gitlab/check_merge_conflict.sh

@@ -0,0 +1,110 @@
+#!/bin/sh
+#
+# check if there is a merge conflict with this pull request only about wasm 
+# binary blobs. if so trigger a rebuild of it and push it on the feature 
+# branch if owned by paritytech
+#
+
+set -e # fail on any error
+
+NODE_RUNTIME_COMPACT="runtime/wasm/target/wasm32-unknown-unknown/release/polkadot_runtime.compact.wasm"
+NODE_RUNTIME="runtime/wasm/target/wasm32-unknown-unknown/release/polkadot_runtime.wasm"
+
+
+
+jsonfile="$(mktemp)"
+
+attemptno="1"
+while ( ! test -s ${jsonfile} ) \
+	|| ( [ "$(jq -r .mergeable ${jsonfile})" = "null" ] \
+	     && [ "${attemptno}" -lt 5 ] )
+do
+	echo "|  checking pull request status (attempt no ${attemptno})"
+	curl -sS -o ${jsonfile} -H "Accept: application/vnd.github.v3+json" \
+	  "${GITHUB_API}/repos/paritytech/polkadot/pulls/${CI_COMMIT_REF_NAME}"
+	sleep 3
+	attemptno="$(( ${attemptno} + 1 ))"
+done
+
+
+
+baseref="$(jq -r .head.ref ${jsonfile})"
+baserepo="$(jq -r .head.repo.full_name ${jsonfile})"
+mergeable="$(jq -r .mergeable ${jsonfile})"
+
+rm -f ${jsonfile}
+
+
+cat <<-EOT
+|
+|  pr is of feature branch ${baseref} on ${baserepo}
+|
+|  tell me github is this branch mergeable into the master branch?
+|
+EOT
+
+test "${mergeable}" = "true" && echo "|  yes, it is." && exit 0
+
+if [ "${baseref}" = "null" -a "${baserepo}" = "null" ]
+then
+	echo "| either connectivity issues with github or pull request not existant"
+	exit 3
+fi
+
+cat <<-EOT
+|  not mergeable
+|
+|  github sees a conflict - check if it's only about the following wasm blobs
+|
+|	- ${NODE_RUNTIME_COMPACT}
+|	- ${NODE_RUNTIME}
+|
+EOT
+
+git fetch origin master
+git config --global user.email "devops-team+polkadot-ci-merge-conflict@parity.io"
+git config --global user.name "I shall never commit to anything"
+
+cat <<-EOT
+|
+|  trying to merge with the master branch to see if there is a conflict about
+|  the wasm files only
+|
+EOT
+
+if git merge --no-commit --no-ff origin/master | grep '^CONFLICT ' \
+	| grep -v -e ${NODE_RUNTIME_COMPACT} -e ${NODE_RUNTIME}
+then
+  git merge --abort
+	echo "|  there are more conflicting files than the wasm blobs"
+	exit 1
+fi
+git merge --abort
+
+
+cat <<-EOT
+|
+|  only wasm blobs block the merge.
+|
+|  triggering rebuild of wasm blobs which will be pushed onto the feature 
+|  branch of this pull request upon success.
+| 
+|  see:
+|
+EOT
+
+
+
+curl -sS -X POST \
+	-F "token=${CI_JOB_TOKEN}" \
+	-F "ref=master" \
+	-F "variables[REBUILD_WASM]=\"${baserepo}:${baseref}\"" \
+	${GITLAB_API}/projects/${GITHUB_API_PROJECT}/trigger/pipeline \
+	| jq -r .web_url
+
+# fail as there will be another commit on top of that feature branch that will
+# be tested anyway.
+exit 1
+
+
+# vim: noexpandtab