webapp-clojure-2020

Rationale

I needed project setup to support following workflow:

• The application running in development mode behave like application running in production (as much as possible). So all development code is addictive and excluded from production build.
• The application state keep running and reloading automatically on changes.
• Developer can easily extend development environment with any required tools.

So in about 2 years I've gradually built this prototype for my own needs.

Features

Project

• Leiningen based project.
• Code style settings for IntelliJ IDEA with Cursive.

System

• Integrant for application and development systems.
• Parallel start of integrant components.
• Separate sources for application and development code.
• Hot reloading on source files changes.
• mount as integrant component for compiled dependencies in code.
• Configuration in JAVA properties files.
• Daemon interface to be run as service with jsvc.

HTTP Server

• Immutant web server with multiple webapps, single port, multiple hostnames.
• Routing: metosin/reitit.
• Page-rendering: hiccup.

Frontend

• ClojureScript with Shadow CLJS (lein integration).
• React JS + Rum + Server-side rendering (SSR) + Passing component data from server
• Tailwind CSS
• Reload pages without Shadow CLJS (adapted ring-refresh)

SQL Database

• next.jdbc JDBC wrapper.
• HugSQL “query builder”.
• HikariCP connection pool.
• Log database queries via p6spy.
• Database migrations with Liquibase.
• Separate read-write and read-only database connections.

Q&A

Why mount and integrant?

During migration of my setup from mount to integrant I found:

• that integrant is good for
  • managing “big” components like web server, database connection pool and so on, which don't require direct reference in the code,
  • managing multiple systems like application and development once.
• but passing integrant state around as map to access it from code is
  • annoying,
  • not so performant as mount,
  • harder to trace dependencies in code using IDE's navigation tools.

So I decided to take best from both worlds and use mount and integrant simultaneously.

Installation

1. OpenJDK 11 https://adoptopenjdk.net/
2. Leiningen https://leiningen.org/
3. Node.js https://nodejs.org/
4. npm modules: npm install --no-package-lock

Usage

Run for development:

lein run

Run to check build with release options:

lein clean
lein with-profile test-release run

Build release:

lein uberjar

Run built release:

java -Dconfig.file=dev/app/config/default.props -jar ./target/uberjar/website.jar

Configuration

Custom configuration properties can be placed in optional file (excluded from version control):

dev/app/config/user.props

Custom configuration for the development environment can be placed in the optional file (excluded from version control):

dev/dev/config/user.edn