add readme for manual image push and sync beam environment

.github/gh-actions-self-hosted-runners/arc/environments/beam.env

@@ -23,16 +23,16 @@ zone = "us-west1-b"
 min_main_node_count = "1"
 max_main_node_count = "5"
 environment = "beam"
-ingress_domain = "runners.example.com" 
+ingress_domain = "action.beam.apache.org" 
 organization = "apache"
 repository = "beam"
 github_app_id_secret_name = "gh-app_id"
 github_app_install_id_secret_name = "gh-app_installation_id"
 github_private_key_secret_name = "gh-pem_key"
-deploy_webhook = "false"
-max_main_replicas = "40"
+deploy_webhook = "true"
+max_main_replicas = "50"
 min_main_replicas = "5"
-webhook_scaling = "false"
+webhook_scaling = "true"
 runner_group = "beam"
 machine_type = "e2-standard-16"
 #state_bucket_name = "beam-arc-state"

.github/gh-actions-self-hosted-runners/arc/images/README.md

@@ -0,0 +1,36 @@
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you 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.
+-->
+# Manual build and push
+
+First set a tag you want to use:
+```
+export RUNNER_IMAGE_TAG=some_tag
+```
+After which you run the build command:
+```
+docker build -t us-central1-docker.pkg.dev/apache-beam-testing/beam-github-actions/beam-arc-runner:$RUNNER_IMAGE_TAG -t us-central1-docker.pkg.dev/apache-beam-testing/beam-github-actions/beam-arc-runner:$(git rev-parse --short HEAD) .
+```
+This builds and tags the image with both the Git SHA and desired tag set.
+
+Authenticate to the docker repository in GCP with:
+```
+gcloud auth configure-docker us-central1-docker.pkg.dev
+```
+docker push us-central1-docker.pkg.dev/apache-beam-testing/beam-github-actions/beam-arc-runner:$RUNNER_IMAGE_TAG
+docker push us-central1-docker.pkg.dev/apache-beam-testing/beam-github-actions/beam-arc-runner:$(git rev-parse --short HEAD)
+```