Pass env substitutions

Author: ogheorghies

cloudbuild.yaml

@@ -1,8 +1,12 @@
 steps:
 - name: 'blang/latex:ctanfull'
   args: ['bash', '-c', 'rm -rf /usr/local/texlive/2017/texmf-dist/metapost/metauml; ln -svf $(pwd)/src /usr/local/texlive/2017/texmf-dist/metapost/metauml; make release; make release-tgz']
+  env:
+  - 'BRANCH_NAME=$BRANCH_NAME'
+  - 'TAG_NAME=$TAG_NAME'
+  - 'REVISION_ID=$REVISION_ID'
 
 artifacts:
   objects:
     location: 'gs://metauml'
-    paths: ['metauml-$TAG_NAME-$REVISION_ID.tgz']
+    paths: ['dist/archive/metauml-$TAG_NAME-$REVISION_ID.tgz']