These are some of the most useful .htaccess rules you'd need.

Rules

Enabling RewriteEngine and setting RewriteBase

RewriteEngine On
RewriteBase /

Setting the RewriteBase is required due to rule inheritance with synthetic addon domains and subdomains. Learn more here

Enable caching

UnsetEnv no-cache

Prevents page not found on vanilla installs

DirectoryIndex disabled

Redirect HTTP to HTTPS

RequestHeader set X-Forwarded-Proto expr=%{REQUEST_SCHEME}
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [R,L]

Proxy websocket requests

RewriteCond %{HTTP:Upgrade} =websocket [NC]
RewriteCond %{HTTP:Connection} =upgrade [NC]
RewriteRule ^ ws://127.0.0.1:40001%{REQUEST_URI} [P,L]

Note that 40001 is the port your app is listening to locally.

Proxy generic HTTP requests

RewriteRule ^ http://127.0.0.1:40001%{REQUEST_URI} [P,L,QSA]

Note that 40001 is the port your app is listening to locally.

Using a match result in a RewriteRule

RewriteRule ^(.*)$ http://127.0.0.1:40001/api/$1 [P,L,QSA]

A request to /example will be proxied to http://127.0.0.1:40001/api/example.

Usage

Here's an example of a fully fledged .htaccess proxying HTTP and WebSocket requests to a service exposed locally on port 40001:

DirectoryIndex disabled
UnsetEnv no-cache

RewriteEngine On
RewriteBase /

# Redirect HTTP to HTTPS
RequestHeader set X-Forwarded-Proto expr=%{REQUEST_SCHEME}
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [R,L]

# Proxy websocket requests
RewriteCond %{HTTP:Upgrade} =websocket [NC]
RewriteCond %{HTTP:Connection} =upgrade [NC]
RewriteRule ^ ws://127.0.0.1:40001%{REQUEST_URI} [P,L]

# Proxy generic HTTP requests
RewriteRule ^ http://127.0.0.1:40001%{REQUEST_URI} [P,L,QSA]