docs/design: windows installer (#2780)

* Add design doc for windows installer

docs/design/storage-node-windows-installer.md

@@ -0,0 +1,85 @@
+# Storage Node Installer for Windows
+
+## Abstract
+
+This design doc outlines how we setup Storage Node on Windows.
+
+## Background
+
+Currently we are using Docker to maintain Storage Nodes.
+Unfortunately Docker is not supported for Windows Home, which is popular OS among Storage Node Operators.
+Similarly, Docker ends up using more resources than running natively on Windows.
+
+Therefore, it would be nice to be able to run Storage Node without Docker.
+
+For an easy setup process we would need an installer that:
+1. Sets up Storage Node to run in background,
+2. sets up automatic updates and
+3. ensures we log everything properly.
+
+We need to take care that we:
+* avoid triggering UAC unnecessarily,
+* start storage node before logging in and
+* restart on crashes.
+
+## Design
+
+The high-level idea is to create an installer using WIX and make Storage Node a Windows service.
+
+### Installer
+
+For creating an installer we can use WIX Toolkit.
+There is [go-msi](https://github.com/mh-cbon/go-msi), which helps to get us setup the basic template.
+We also need to ensure that we supply all the Operator information during installation.
+
+To make the installer work we need to:
+
+* Install [go-msi](https://github.com/mh-cbon/go-msi) on the build server.
+* Create a wix.json file like [this one](https://github.com/mh-cbon/go-msi/blob/master/wix.json)
+* Add a guid with `go-msi set-guid` to uniquely identify the process.
+* Ensure that binaries are signed before or during building the installer.
+* The wix.json should contain steps for:
+  * adding Dashboard shortcut to the desktop
+  * setting [service recovery properties](https://wixtoolset.org/documentation/manual/v3/xsd/util/serviceconfig.html)
+  * configuring Storage Node Operator information:
+       * Wallet Address
+       * Email
+       * Address/ Port
+       * Bandwidth 
+       * Storge
+       * Identity directory
+       * Storge Directory
+  * install storagenode binary
+  * register storagenode as a service
+  * adding Storage Node binary to Windows UserPath (optional)  
+  * open Dashboard at the end of the installer.
+* Run `go-msi make --msi your_program.msi --version 0.0.2` to create the installer.
+* Ensure that installer is signed by the build server.
+
+### Service
+
+We need to Storage Node to implement Windows service API, as shown in:
+
+* Modify storage node/automatic updater startup code to implement [ServiceMain](https://docs.microsoft.com/en-us/windows/win32/api/winsvc/nc-winsvc-lpservice_main_functiona).
+   * See [golang/sys](https://github.com/golang/sys/blob/master/windows/svc/example/service.go)
+* Create inbound firewall rule using the following Powershell command: `New-NetFirewallRule -DisplayName "Storj v3" -Direction Inbound –Protocol TCP –LocalPort 28967 -Action allow`
+
+This means that Windows handles starting and restarting the binary in the background.
+
+## Implementation
+
+1) Modify the storage node startup to implement ServiceMain so that the binary is considered a Windows Service.
+2) Create script for registering binary as a Windows Background Service. (sc.exc command)
+3) Create wix.json file for building an MSI.
+4) Update the build process to include the creation of the MSI. 
+5) Ensure the windows installer is working properly
+  * Install Storage Node using msi.
+  * Ensure binaries run on Windows startup, and it runs as a background process when not logged in.
+  * Ensure UAC(s) is not triggered after installation.
+  * Ensure that storage node restarts automatically after a crash 
+
+## Open Issues/ Comments (if applicable)
+
+* Consider writing an uninstaller.
+* How do we prevent UAC from triggering?
+* Consider using wix without go-msi.