Add bash script to help fork a release branch

As mentioned in the comments, we could make this more automated in
future. For now it's mostly a set of instructions for the human.

The key part is to establish the procedure and the naming
conventions.

hack/cut-release.sh

@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+# Copyright The Enterprise Contract Contributors
+#
+# 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.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+set -o errexit
+set -o nounset
+set -o pipefail
+
+CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+if [[ $CURRENT_BRANCH != "main" ]]; then
+  echo "Expecting to be in main branch!"
+  exit 1
+fi
+
+RELEASE_NAME=${1:-""}
+if [[ $RELEASE_NAME == "" ]]; then
+  echo "Please provide a release name, e.g. v0.1-tech-preview, or v1.1"
+  exit 1
+fi
+
+# Use release name as-is for the branch name
+BRANCH_NAME="${RELEASE_NAME}"
+
+# RHTAP disallows . chars in names so remove those
+RHTAP_APPLICATION_SUFFIX="${RELEASE_NAME/./}"
+
+# Could be whatever, but let's adopt a consistent convention
+RHTAP_APPLICATION_NAME=ec-${RHTAP_APPLICATION_SUFFIX}
+RHTAP_CLI_COMPONENT_NAME=cli-${RHTAP_APPLICATION_SUFFIX}
+
+# Show some useful values
+echo Release name: $RELEASE_NAME
+echo Release branch name: $BRANCH_NAME
+echo RHTAP application name: $RHTAP_APPLICATION_NAME
+echo RHTAP cli component name: $RHTAP_CLI_COMPONENT_NAME
+
+RHTAP_APPS_URL=https://console.redhat.com/preview/application-pipeline/workspaces/rhtap-contract/applications
+
+# Explain what needs to be done next
+# (We could make this more automated this in future.)
+cat <<EOT
+
+Next steps:
+
+# Create the new release branch in the upstream repo
+git fetch upstream
+git push upstream refs/remotes/upstream/main:refs/heads/${BRANCH_NAME}
+
+# Make your local version of the release branch
+git checkout -b ${BRANCH_NAME} upstream/${BRANCH_NAME}
+
+# Create the new application in RHTAP
+Login at ${RHTAP_APPS_URL}
+Create a new application by importing code from https://github.com/enterprise-contract/ec-cli
+Set Git reference to ${BRANCH_NAME} and click "Import code"
+Set the application name to ${RHTAP_APPLICATION_NAME}
+Set the component name to ${RHTAP_CLI_COMPONENT_NAME}
+Set Dockerfile to Dockerfile.dist
+Unset the "Default build pipeline" toggle
+Click "Create application"
+
+# Wait for PR
+Wait for the PR to be created
+Go look at the PR in GitHub
+Wait for the PR to pass the ${RHTAP_CLI_COMPONENT_NAME}-on-pull-request check
+You can also watch the activity at ${RHTAP_APPS_URL}/${RHTAP_APPLICATION_NAME}/activity/pipelineruns
+When it's done you can merge. (Continue to next section while you're waiting...)
+
+# Modify EC policy config
+Go to the integration tests at ${RHTAP_APPS_URL}/${RHTAP_APPLICATION_NAME}/integrationtests
+Edit ${RHTAP_APPLICATION_NAME}-enterprise-contract and add a parameter as follows:
+  Name: POLICY_CONFIGURATION
+  Value: github.com/enterprise-contract/config//redhat-no-hermetic
+Save changes
+
+EOT
+
+# Todo: What about the RPA?