Initial version of release.sh helper in prow-tests image (knative#14)

This helper manages flag parsing and test skipping, leaving the real script in the repos with only the important stuff (i.e., building the release).

This will reduce boilerplate code and unify the release strategy and features across the repos.

images/prow-tests/Dockerfile

@@ -27,3 +27,4 @@ RUN go get github.com/golang/dep/cmd/dep
 # Add our scripts
 ADD scripts/library.sh .
 ADD scripts/presubmit-tests.sh .
+ADD scripts/release.sh .

images/prow-tests/scripts/release.sh

@@ -0,0 +1,132 @@
+#!/bin/bash
+
+# Copyright 2018 The Knative Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This is a helper script for Knative release scripts. To use it:
+# 1. Source this script.
+# 2. Call the parse_flags() function passing $@ (without quotes).
+# 3. Call the run_validation_tests() passing the script or executable that
+#    runs the release validation tests.
+# 4. Write logic for the release process. Use the following boolean (0 is
+#    false, 1 is true) environment variables for the logic:
+#    SKIP_TESTS: true if --skip-tests is passed. This is handled automatically
+#                by the run_validation_tests() function.
+#    TAG_RELEASE: true if --tag-release is passed. In this case, the
+#                 environment variable TAG will contain the release tag in the
+#                 form vYYYYMMDD-<commit_short_hash>.
+#    PUBLISH_RELEASE: true if --publish is passed. In this case, the environment
+#                     variable KO_FLAGS will be updated with the -L option.
+#    SKIP_TESTS, TAG_RELEASE and PUBLISH_RELEASE default to false for safety.
+#    All environment variables above, except KO_FLAGS, are marked read-only once
+#    parse_flags() is called.
+
+# Load github.com/knative/test-infra/images/prow-tests/scripts/library.sh
+[ -f /workspace/library.sh ] \
+  && source /workspace/library.sh \
+  || eval "$(docker run --entrypoint sh gcr.io/knative-tests/test-infra/prow-tests -c 'cat library.sh')"
+[ -v KNATIVE_TEST_INFRA ] || exit 1
+
+# Simple banner for logging purposes.
+function banner() {
+    local msg="@@@@ $* @@@@"
+    local border="${msg//[-0-9A-Za-z _.]/@}"
+    echo -e "${border}\n${msg^^}\n$border"
+}
+
+# Tag images in the yaml file with a tag. If not tag is passed, does nothing.
+# Parameters: $1 - yaml file to parse for images.
+#             $2 - registry where the images are stored.
+#             $3 - tag to apply (optional).
+function tag_images_in_yaml() {
+  [[ -z $3 ]] && return 0
+  echo "Tagging images with $3"
+  for image in $(grep -o "$2/[a-z\./-]\+@sha256:[0-9a-f]\+" $1); do
+    gcloud -q container images add-tag ${image} ${image%%@*}:$3
+  done
+}
+
+# Copy the given yaml file to a GCS bucket. Image is tagged :latest, and optionally :$2.
+# Parameters: $1 - yaml file to copy.
+#             $2 - destination bucket name.
+#             $3 - tag to apply (optional).
+function publish_yaml() {
+  gsutil cp $1 gs://$2/latest/
+  [[ -n $3 ]] && gsutil cp $1 gs://$2/previous/$3/
+}
+
+SKIP_TESTS=0
+TAG_RELEASE=0
+PUBLISH_RELEASE=0
+TAG=""
+KO_FLAGS="-L"
+
+# Parses flags and sets environment variables accordingly.
+function parse_flags() {
+  cd ${REPO_ROOT_DIR}
+  for parameter in $@; do
+    case $parameter in
+      --skip-tests)
+        SKIP_TESTS=1
+        shift
+        ;;
+      --tag-release)
+        TAG_RELEASE=1
+        shift
+        ;;
+      --notag-release)
+        TAG_RELEASE=0
+        shift
+        ;;
+      --publish)
+        PUBLISH_RELEASE=1
+        # Remove -L from ko flags
+        KO_FLAGS="${KO_FLAGS/-L}"
+        shift
+        ;;
+      --nopublish)
+        PUBLISH_RELEASE=0
+        KO_FLAGS="-L ${KO_FLAGS}"
+        shift
+        ;;
+      *)
+        echo "error: unknown option ${parameter}"
+        exit 1
+        ;;
+    esac
+  done
+
+  TAG=""
+  if (( TAG_RELEASE )); then
+    # Currently we're not considering the tags in refs/tags namespace.
+    commit=$(git describe --always --dirty)
+    # Like kubernetes, image tag is vYYYYMMDD-commit
+    TAG="v$(date +%Y%m%d)-${commit}"
+  fi
+
+  readonly SKIP_TESTS
+  readonly TAG_RELEASE
+  readonly PUBLISH_RELEASE
+  readonly TAG
+}
+
+# Run tests (unless --skip-tests was passed). Conveniently displays a banner indicating so.
+# Parameters: $1 - executable that runs the tests.
+function run_validation_tests() {
+  if (( ! SKIP_TESTS )); then
+    banner "Running release validation tests"
+    # Run tests.
+    $1
+  fi
+}