Enrich README

Author: wangkuiyi

README.md

@@ -1,7 +1,8 @@
 # Provision SQLFlow Desktop for Linux
 
-This is an experimental work to check deploying the whole SQLFlow
-service mesh on a Ubuntu 18.04 VM.
+This is an experimental work to check deploying the whole
+[SQLFlow](https://sqlflow.org/sqlflow) service mesh on Windows, Linux,
+or macOS desktop.
 
 The general architecture of SQLFlow is as the following:
 
@@ -13,3 +14,34 @@ and MySQL running in a container executing the
 running on the VM.  The deployment is shown in the folllowing figure:
 
 ![](figures/arch_vm.svg)
+
+I chose this deployment plan for reasons:
+
+1. We don't have a well-written local workflow engine, and at the
+   right moment, we need to focus on the Kubernetes-native engine.
+   So, we use minikube and install Argo on minikube.
+
+1. We can install minikube directly on users' desktop computers
+   running Windows, Linux, macOS.  However, writing a shell script to
+   do that requires us to consider many edge cases.  To have a clear
+   deployment environment, I introduced VM.
+
+1. To make the VM manageable in a programmatic way, I used Vagrant.
+   Please be aware that Vagrant is the only software users need to
+   install to use SQLFlow on their desktop computer.  And Vagrant
+   provides official support for Windows, Linux, and macOS.
+
+1. We can run the SQLFlow server container (`sqlflow/sqlflow:latest`)
+   on minikube as well.  But that would add challenge to export ports.
+   Running the container directly in the VM but out of minikube, we
+
+   1. expoe the in-container port by adding `EXPOSE` statement in the
+      Dockerfile, and
+   1. expose the docker port for accessing from outside of the VM by
+      adding the following code snippet to the Vagrantfile.
+
+      ```ruby
+      config.vm.network "forwarded_port", guest: 3306, host: 3306
+      config.vm.network "forwarded_port", guest: 50051, host: 50051
+      config.vm.network "forwarded_port", guest: 8888, host: 8888
+      ```