Check a version hasn't been pushed/released already during Wercker build (#194)

Fixes #154

Author: simonlord

wercker.yml

@@ -59,6 +59,14 @@ push:
           export VERSION=$(cat VERSION.txt)
           echo "${VERSION}"
 
+    - script:
+        name: Ensure version is unique
+        code: |
+          if curl -s https://api.github.com/repos/oracle/oci-cloud-controller-manager/git/refs/tags | grep "tags/$VERSION"; then
+            echo "Tag $VERSION already exists. Doing nothing."
+            exit 1
+          fi
+
     - script:
         name: prepare
         code: |
@@ -81,6 +89,14 @@ release:
           export VERSION=$(cat VERSION.txt)
           echo "${VERSION}"
 
+    - script:
+        name: Ensure version is unique
+        code: |
+          if curl -s https://api.github.com/repos/oracle/oci-cloud-controller-manager/git/refs/tags | grep "tags/$VERSION"; then
+            echo "Tag $VERSION already exists. Doing nothing."
+            exit 1
+          fi
+
     - github-create-release:
       token: $GITHUB_TOKEN
       tag: $VERSION