git-version: Add git-version commit/tag detection script

docker-build

@@ -1,7 +1,7 @@
 #!/bin/bash -e
 
 REPO=coreos/bootcfg
-GIT_SHA=$(git rev-parse HEAD)
+GIT_SHA=$(./git-version)
 
 docker build -q --rm=true -t $REPO:$GIT_SHA .
 docker tag -f $REPO:$GIT_SHA $REPO:latest

docker-push

@@ -2,7 +2,7 @@
 
 REPO=coreos/bootcfg
 QUAY_REPO=quay.io/coreos/bootcfg
-GIT_SHA=$(git rev-parse HEAD)
+GIT_SHA=$(./git-version)
 
 # quay.io
 docker tag -f $REPO:$GIT_SHA $QUAY_REPO:latest

git-version

@@ -0,0 +1,21 @@
+#!/bin/bash -e
+
+# parse the current git commit hash
+COMMIT=`git rev-parse HEAD`
+
+# check if the current commit has a matching tag
+TAG=$(git describe --exact-match --abbrev=0 --tags ${COMMIT} 2> /dev/null || true)
+
+# use the matching tag as the version, if available
+if [ -z "$TAG" ]; then
+    VERSION=$COMMIT
+else
+    VERSION=$TAG
+fi
+
+# check for changed files (not untracked files)
+if [ -n "$(git diff --shortstat 2> /dev/null | tail -n1)" ]; then
+    VERSION="${VERSION}+dirty"
+fi
+
+echo $VERSION