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An external profile for Duct template that introduces Hydrogen code.


This template profile needs to be used in conjunction with +site and +cljs hints.

lein new duct <project name> +site +cljs +hydrogen/core

It creates an SPA app that's ready for you to run. Front to back. It comes packed with some of the features we use in most of our projects:

Additional profiles

Authentication and session management

Hydrogen also offers two profiles that provide session management using OpenID Connect ID Tokens. To use them simply add:

  • +hydrogen/session.cognito for AWS Cognito User Pools-based session management or
  • +hydrogen/session.keycloak to add Keycloak-based session management.

Keep in mind that those two profiles are mutually exclusive.

These authentication profiles expect you to configure some environment variables in order to work properly. Please see the specs in buddy-auth.jwt-oid.

Figwheel main


Until further notice, usage of +hydrogen/figwheel-main profile will require some manual fixes in project.clj:

  1. The are two conflicting dependencies: hydrogen/module.cljs and duct/module.cljs. Please remove the latter one.
  2. Because of a known figwheel-main issue, even though :resource-paths includes target/resources, the compiler will complain about target/resources/<project name> not being found on classpath. Please add that path too.

SQL persistence boundary

Hydrogen also offers a profile that provides a boundary (based on Clojure protocols and records) for data persistence using SQL databases. By default it uses Postgresql (by adding its JDBC driver as a dependency), but can be used with any JDBC compatible database as long as you add its driver as a dependency. To use it simply add:

  • +hydrogen/persistence.sql to the list of required profiles

Job Scheduling

Hydrogen also offers a profile that provides job scheduling using Twarc scheduling library, with persistent JobStore backed by a Postgresql database, through scheduling.twarc Duct library. This profile depends on +hydrogen/persistence.sql profile, so make sure you also specify it when adding the job scheduling profile. To use it simply add:

  • +hydrogen/persistence.sql +hydrogen/scheduling.twarc to the list of required profiles

Isomorphic / Server Side Rendering

If you want to use either of those, hydrogen leverages the blogpost of Techascent to deliver this feature. Note that this is still in its infancy and it will be improved in future.

Usage: +hydrogen/ssr (NOTE: combo with session.keycloak profile is not fully supported yet)


Current re-frame (1.2.0 in the time of writing this documentation) doesn't support reliably using app db state in a multithreaded environment without running into concurrency problems. However there is a fork by Techascent that patches that. Please see the handle-route function in ssr/root.clj file to read more.

What else can it do?

In order to be able to finally share our toolset with the community, we had to cut some corners and narrow down the scope of the template's content. However we'll be delighted to highlight some of our libs, gists and blog posts with our know-how:

  • OpenID Authentication

    • buddy-auth.jwt-oidc - Integrant keys and associated code implementing a :duct.middleware.buddy/authentication compatible JWT token validation function for OpenID Connect ID Tokens
  • Object storage

  • Integration with third party systems

  • Persistence

    • sql-utils - A library designed as a thin convenience wapper over
    • ragtime-wrapper - Duct module wrapping configuration for Ragtime migrations
    • stork - A Clojure/Datomic migrations library heavily inspired by rkneufeld/conformity
  • IoT

    • pubsub - MQTT and AMQP Publish Subscribe library
  • Scheduling

    • scheduling.twarc - Integrant keys for using Twarc scheduling library, with persistent JobStore backed by a Postgresql database
  • Crypto

  • Misc.

Running the application

Development Start the REPL.

lein repl

Then load the development environment.

user=> (dev)

Run go to prep and initiate the system.

dev=> (go)
:duct.server.http.jetty/starting-server {:port 3000}

By default this creates a web server at http://localhost:3000.

When you make changes to your source files, use reset to reload any modified files and reset the server.

dev=> (reset)
:reloading (...)

Future work

For the list of our features to come please take a look at this project's issues list.


Copyright (c) 2018, 2019, 2020, 2021 Magnet S Coop.

The source code for the library is subject to the terms of the Mozilla Public License, v. 2.0. If a copy of the MPL was not distributed with this file, You can obtain one at