Merge pull request #48 from phish108/master

Adding DRY_RUN feature that fixes #47

README.md

@@ -44,6 +44,7 @@ _NOTE: set the fetch-depth for `actions/checkout@master` to be sure you retrieve
 * **RELEASE_BRANCHES** *(optional)* - Comma separated list of branches (bash reg exp accepted) that will generate the release tags. Other branches and pull-requests generate versions postfixed with the commit hash and do not generate any tag. Examples: `master` or `.*` or `release.*,hotfix.*,master` ...
 * **CUSTOM_TAG** *(optional)* - Set a custom tag, useful when generating tag based on f.ex FROM image in a docker image. **Setting this tag will invalidate any other settings set!**
 * **SOURCE** *(optional)* - Operate on a relative path under $GITHUB_WORKSPACE.
+* **DRY_RUN** *(optional)* - Determine the next version without tagging the branch. The workflow can use the outputs `new_tag` and `tag` in subsequent steps. Possible values are ```true``` and ```false``` (default). 
 
 #### Outputs
 

entrypoint.sh

@@ -6,6 +6,7 @@ with_v=${WITH_V:-false}
 release_branches=${RELEASE_BRANCHES:-master}
 custom_tag=${CUSTOM_TAG}
 source=${SOURCE:-.}
+dryrun=${DRY_RUN:-false}
 
 cd ${GITHUB_WORKSPACE}/${source}
 
@@ -80,8 +81,17 @@ echo $new
 
 # set outputs
 echo ::set-output name=new_tag::$new
+
+# use dry run to determine the next tag
+if $dryrun
+then
+    echo ::set-output name=tag::$tag
+    exit 0
+fi 
+
 echo ::set-output name=tag::$new
 
+
 if $pre_release
 then
     echo "This branch is not a release branch. Skipping the tag creation."