Fix develop image deployment

The $TRAVIS_TAG variable is available for tagged branches only. Separate
tag deployments and branch deployments with their own docker tag
commands in scripts/deploy.sh.

.travis.yml

@@ -65,14 +65,12 @@ jobs:
         - make image/cluster-operator
       before_deploy:
         - docker login -u "$REGISTRY_USER" -p "$REGISTRY_PASS"
-        - docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "${IMAGE_NAME}:latest"
-        - docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "${IMAGE_NAME}:${TRAVIS_TAG}"
       deploy:
         - provider: script
-          script: docker push "${IMAGE_NAME}:latest" && docker push "${IMAGE_NAME}:${TRAVIS_TAG}"
+          script: bash scripts/deploy.sh tagged
           on:
             tags: true
         - provider: script
-          script: docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "${IMAGE_NAME}:develop" && docker push "${IMAGE_NAME}:develop"
+          script: bash scripts/deploy.sh develop
           on:
             branch: master

scripts/deploy.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+set -e
+
+# This script is used for publishing latest(release) and develop(canary)
+# container images of the operator. Script argument "tagged" must be passed to
+# publish a new release and "develop" must be passed to publish a canary image.
+
+if [ "$1" = "tagged" ]; then
+    docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "${IMAGE_NAME}:latest"
+    docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "${IMAGE_NAME}:${TRAVIS_TAG}"
+    docker push "${IMAGE_NAME}:latest" && docker push "${IMAGE_NAME}:${TRAVIS_TAG}"
+elif [ "$1" = "develop" ]; then
+    docker tag "${IMAGE_NAME}:${IMAGE_TAG}" "${IMAGE_NAME}:develop"
+    docker push "${IMAGE_NAME}:develop"
+fi