Add option to create release candidates (#4706)

[netdata patch release]

3 files changed, 64 insertions, 30 deletions

diff --git a/.travis/README.md b/.travis/README.md
index 5a51b2a7c6..e37e9feffb 100644
--- a/.travis/README.md
+++ b/.travis/README.md
@@ -29,40 +29,43 @@ installations of netdata. Jobs are run on following operating systems:
   - CentOS 7 (containerized)
   - alpine (containerized)
 
-### Release
+### Packaging
 
 This stage is executed only on "master" brach and allows us to create a new tag just looking at git commit message.
-It also has an option to automatically generate changelog based on GitHub labels and sync it with GitHub release.
-For the sake of simplicity and to use travis features this stage cannot be integrated with next stage.
-
-Releases are generated by searching for a keyword in last commit message. Keywords are:
- - [patch] or [fix] to bump patch number
- - [minor], [feature] or [feat] to bump minor number
- - [major] or [breaking change] to bump major number
-All keywords MUST be surrounded with square braces.
-Alternative is to push a tag to master branch.
-
-### Packaging
+It executes one script called `releaser.sh` which is responsible for creating a release on GitHub by using
+[hub](https://github.com/github/hub). This script is also executing other scripts which can also be used in other
+CI jobs:
+  - `tagger.sh`
+  - `generate_changelog.sh`
+  - `build.sh`
+  - `create_artifacts.sh`
 
-This stage is executed only on "master" branch and it is separated into 3 jobs:
-  - Update Changelog/Create release
-  - Nightly tarball and self-extractor build
-  - Nightly docker images
+Alternatively new release can be also created by pushing new tag to master branch.
 
-##### Update Changelog/Create release
+##### tagger.sh
 
-This job is running one script called `releaser.sh`, which is responsible for a couple of things. First of all it 
-automatically updates our CHANGELOG.md file based on GitHub features (mostly labels and pull requests). Apart from 
-that it can also create a new git tag and a github draft release connected to that tag.
-Releases are generated by searching for a keyword in last commit message. Keywords are:
+Script responsible to find out what will be the next tag based on a keyword in last commit message. Keywords are:
  - `[netdata patch release]` to bump patch number
  - `[netdata minor release]` to bump minor number
  - `[netdata major release]` to bump major number
+ - `[netdata release candidate]` to create a new release candidate (appends or modifies suffix `-rcX` of previous tag)
 All keywords MUST be surrounded with square brackets.
+Tag is then stored in `GIT_TAG` variable.
 
-Alternatively new release can be also created by pushing new tag to master branch.
+##### generate_changelog.sh
 
-##### Nightly tarball and self-extractor build AND Nightly docker images
+Automatic changelog generator which updates our CHANGELOG.md file based on GitHub features (mostly labels and pull
+requests). Internally it uses
+[github-changelog-generator](https://github.com/github-changelog-generator/github-changelog-generator) and more
+information can be found on that project site.
+
+##### build.sh and create_artifacts.sh
+
+Scripts used to build new container images and provide release artifacts (tar.gz and makeself archives)
+
+### Nightlies
+
+##### Tarball and self-extractor build AND Nightly docker images
 
 As names might suggest those two jobs are responsible for nightly netdata package creation and are run every day (in
 cron). Combined they produce:
@@ -70,11 +73,16 @@ cron). Combined they produce:
   - tar.gz archive (soon to be removed)
   - self-extracting package
 
-Currently "Nightly tarball and self-extractor build" is using old firehol script and it is planed to be replaced with
-new design.
+This is achieved by running 2 scripts described earlier:
+  - `create_artifacts.sh`
+  - `build.sh`
 
-##### Nightly changelog generation
+##### Changelog generation
 
 This job is responsible for regenerating changelog every day by executing `generate_changelog.sh` script. This is done
 only once a day due to github rate limiter.
 
+##### Labeler
+
+Once a day we are doing automatic label assignment by executing `labeler.sh`. This script is a temporary workaround until
+we start using GitHub Actions. For more information what it is currently doing go to its code.
diff --git a/.travis/releaser.sh b/.travis/releaser.sh
index e12d5da5bf..e74741ad2c 100755
--- a/.travis/releaser.sh
+++ b/.travis/releaser.sh
@@ -21,7 +21,6 @@
 # Requirements:
 #   - GITHUB_TOKEN variable set with GitHub token. Access level: repo.public_repo
 #   - docker
-#   - git-semver python package (pip install git-semver)
 
 set -e
 
@@ -37,7 +36,9 @@ git config user.email "${GIT_MAIL}"
 git config user.name "${GIT_USER}"
 
 echo "---- FIGURING OUT TAGS ----"
-./.travis/tagger.sh || exit 0
+# tagger.sh is sourced since we need environment variables it sets
+#shellcheck source=/dev/null
+source .travis/tagger.sh || exit 0
 
 echo "---- GENERATING CHANGELOG -----"
 ./.travis/generate_changelog.sh
@@ -57,4 +58,12 @@ tar -C /tmp -xvf "/tmp/hub-linux-amd64-${HUB_VERSION}.tgz"
 export PATH=$PATH:"/tmp/hub-linux-amd64-${HUB_VERSION}/bin"
 
 # Create a release draft
-hub release create --draft -a "netdata-${GIT_TAG}.tar.gz" -a "netdata-${GIT_TAG}.gz.run" -a "sha256sums.txt" -m "${GIT_TAG}" "${GIT_TAG}"
+if [ -z ${GIT_TAG+x} ]; then
+	echo "Variable GIT_TAG is not set. Something went terribly wrong! Exiting."
+	exit 1
+fi
+if [ -z ${RC+x} ]; then
+	hub release create --prerelease --draft -a "netdata-${GIT_TAG}.tar.gz" -a "netdata-${GIT_TAG}.gz.run" -a "sha256sums.txt" -m "${GIT_TAG}" "${GIT_TAG}"
+else
+	hub release create --draft -a "netdata-${GIT_TAG}.tar.gz" -a "netdata-${GIT_TAG}.gz.run" -a "sha256sums.txt" -m "${GIT_TAG}" "${GIT_TAG}"
+fi
diff --git a/.travis/tagger.sh b/.travis/tagger.sh
index 3b71277420..e4d4e0af57 100755
--- a/.travis/tagger.sh
+++ b/.travis/tagger.sh
@@ -35,6 +35,22 @@ function embed_version {
 	git add configure.ac
 }
 
+# Figure out what will be new release candidate tag based only on previous ones.
+# This assumes that RELEASES are in format of "v0.1.2" and prereleases (RCs) are using "v0.1.2-rc0"
+function release_candidate {
+	LAST_TAG=$(git semver)
+	if [[ $LAST_TAG =~ -rc* ]]; then
+		LAST_RELEASE=$(echo "$LAST_TAG" | cut -d'-' -f 1)
+		LAST_RC=$(echo "$LAST_TAG" | cut -d'c' -f 2)
+		RC=$((LAST_RC + 1))
+	else
+		LAST_RELEASE=$LAST_TAG
+		RC=0
+	fi
+	GIT_TAG="v$LAST_RELEASE-rc$RC"
+	export GIT_TAG
+}
+
 # Check if current commit is tagged or not
 GIT_TAG=$(git tag --points-at)
 if [ -z "${GIT_TAG}" ]; then
@@ -45,9 +61,9 @@ if [ -z "${GIT_TAG}" ]; then
 	*"[netdata patch release]"*) GIT_TAG="v$(git semver --next-patch)" ;;
 	*"[netdata minor release]"*) GIT_TAG="v$(git semver --next-minor)" ;;
 	*"[netdata major release]"*) GIT_TAG="v$(git semver --next-major)" ;;
+	*"[netdata release candidate]"*) release_candidate ;;
 	*) echo "Keyword not detected. Exiting..."; exit 1;;
 	esac
-
 	# Tag it!
 	if [ "$GIT_TAG" != "HEAD" ]; then
 		echo "Assigning a new tag: $GIT_TAG"
@@ -62,3 +78,4 @@ else
 	git commit -m "[ci skip] release $GIT_TAG"
 	git push "https://${GITHUB_TOKEN}:@$(git config --get remote.origin.url | sed -e 's/^https:\/\///')"
 fi
+export GIT_TAG