jctong/automate release (#45)

* ci(travis): github release via pushing git tag

* linting issue

* simplify

* simplify some more

* remove whitespace

.travis.yml

@@ -4,6 +4,7 @@ os: linux
 stages:
   - 'Lint markdown files'
   - 'Test'
+  - 'Publish'
 
 jobs:
   include:
@@ -30,9 +31,25 @@ jobs:
     - stage: 'Test'
       os: linux
       language: node_js
-      node_js:
-        - 10
+      node_js: 10
       install: yarn
       script: yarn test
       addons:
         srcclr: true
+
+    - stage: 'Publish'
+      if: type = push AND tag IS present AND tag =~ /^[0-9]+\.[0-9]+\.[0-9]+/
+      name: publish to github release
+      os: linux
+      language: minimal
+      install:
+        # installs hub to /tmp/bin
+        - URL=$(curl https://api.github.com/repos/github/hub/releases/latest 2>/dev/null |  jq -r '.assets[] | select(.browser_download_url | contains("linux-amd64")) | .browser_download_url')
+        - curl -fsSL "$URL" | tar xz -C /tmp --strip-components=1 --wildcards '*/bin/hub'
+        - export PATH=/tmp/bin:$PATH
+        - hub version
+      script:
+        - NEW_VERSION=$(grep -P '^## \[\d+\.\d+\.\d+.*\]' CHANGELOG.md | awk 'NR==1' |  sed -e 's/\[/\\\[/' | sed -e 's/\]/\\\]/')
+        - LAST_VERSION=$(grep -P '^## \[\d+\.\d+\.\d+.*\]' CHANGELOG.md | awk 'NR==2' |  sed -e 's/\[/\\\[/' | sed -e 's/\]/\\\]/')
+        - DESCRIPTION=$(awk "/^${NEW_VERSION}$/,/^${LAST_VERSION:-nothingmatched}$/" CHANGELOG.md | grep -v "^${LAST_VERSION:-nothingmatched}$")
+        - hub release create -m "Release ${TRAVIS_TAG}" -m "${DESCRIPTION}" "${TRAVIS_TAG}"