[CICD-24] Improve performance by utilizing pre-built Docker Image. (#46)

* Split original dockerfile into a stable hosted base image + custom dockerfile

* Add documentation to manage the Dockerfile and image

* Add changeset

Author: sarahricker

.changeset/loud-penguins-flash.md

@@ -0,0 +1,5 @@
+---
+"@wpengine/github-action-wpe-site-deploy": patch
+---
+
+Improve performance by utilizing pre-built Docker Image.

DEVELOPMENT.md

@@ -27,3 +27,28 @@ We use [Changesets](https://github.com/changesets/changesets) to automate versio
 3. Approve, then "Squash and merge" the PR into `main`.
 
 Merging the versioning PR will run a workflow that creates or updates all necessary tags. It will also create a new release in GitHub.
+
+## Managing the Dockerfile & Docker Image
+
+The base of the `Dockerfile` is hosted as a Docker image on DockerHub. The image is originally built locally from `Dockerfiles/Dockerfile` and pushed up to DockerHub.
+
+The main `Dockerfile` at the project root imports the `wpengine/gha:base-stable` hosted image from DockerHub. Customizations to the image should be added below the base image for code that is updated more frequently, such as:
+- entrypoint.sh
+- exclude.txt
+
+All other customizations that are updated less frequently, or managed by 3rd parties, should be added to the `base-stable` image. Rebuild and push the image to DockerHub to update the image.
+
+## Updating the Docker Image
+The `base-stable` Docker Image will rarely need to be updated, however it may be necessary to update it manually* from time to time.
+
+- Build the docker image locally:
+`docker build --no-cache -t wpengine/gha:base-stable Dockerfiles`
+
+- Push the image to DockerHub:
+`docker push wpengine/gha:base-stable`
+
+Once the hosted Docker image is updated, it will need to be imported (or updated) on the main project `Dockerfile`. If the Dockerhub tag name (image version) has changed, update the existing line in the project root `Dockerfile` to match the new tag name.
+- Update the root Docker file for the project with the latest version of the Docker Image:tagname. i.e.:
+`FROM wpengine/gha:base-stable`
+
+_*TO DO: Process will be automated in the future._

Dockerfile

@@ -1,11 +1,9 @@
-FROM instrumentisto/rsync-ssh:alpine3.13-r4
-LABEL "com.github.actions.name"="GitHub Action for WP Engine Site Deploy"
-LABEL "com.github.actions.description"="An action to deploy your repository to WP Engine via the SSH Gateway"
-LABEL "com.github.actions.icon"="upload-cloud"
-LABEL "com.github.actions.color"="blue"
-LABEL "repository"="http://github.com/wpengine/github-action-wpe-site-deploy"
-LABEL "maintainer"="Alex Zuniga <[email protected]>"
-RUN apk add bash php
+# Pull the base image from DockerHub. 
+# If you need to make changes to the base image, rebuild it manually from `Dockerfiles/Dockerfile` and push to DockerHub.
+# TODO: Automate this process to track stable tags and custom branch tags(based on regex).
+FROM wpengine/gha:base-stable
+
+# Add any additional directives after the import FROM wpengine/gha:base-stable
 ADD entrypoint.sh /entrypoint.sh
 ADD exclude.txt /exclude.txt
 ENTRYPOINT ["/entrypoint.sh"]

Dockerfiles/Dockerfile

@@ -0,0 +1,12 @@
+# Build and push a new image to Docker Hub when changes are made to this file.
+# - Import the base Docker image hosted in DockerHub: https://hub.docker.com/repository/docker/wpengine/gha `FROM wpengine/gha:base-stable`
+# - Customizations to the image should be added for code that is updated more frequently below the base image in github-action-wpe-site-deploy/Dockerfile.
+
+FROM instrumentisto/rsync-ssh:alpine3.13-r4
+LABEL "com.github.actions.name"="GitHub Action for WP Engine Site Deploy"
+LABEL "com.github.actions.description"="An action to deploy your repository to WP Engine via the SSH Gateway"
+LABEL "com.github.actions.icon"="upload-cloud"
+LABEL "com.github.actions.color"="blue"
+LABEL "repository"="http://github.com/wpengine/github-action-wpe-site-deploy"
+LABEL "maintainer"="Alex Zuniga <[email protected]>"
+RUN apk add bash php