chris-crone / dockerized-clojure

Containerized Clojure Development Environment

⚠️ Warning: ⚠️ I'm not a Clojure expert! I put this environment together as a PoC.

The goal of this repo is to show how to containerize a development environment so that one gets the benefits of a local environment, like hot reloading, with the benefits of containerization– a development environment defined in code.

Prerequisites

• macOS or Windows:
  • Docker Desktop
  • make
• Linux:
  • Docker
  • Docker Compose

Development

Get started by running make dev:

$ make dev
Once you see the message "Started server on port 3000", open your browser to http://localhost:3000
COMPOSE_DOCKER_CLI_BUILD=1 DEV_IMAGE=clojure-demo:latest docker-compose up --build
...
Starting clojure_demo_1 ... done
Attaching to clojure_demo_1
demo_1  | OpenJDK 64-Bit Server VM warning: Options -Xverify:none and -noverify were deprecated in JDK 13 and will likely be removed in a future release.
demo_1  | 2020-08-11 15:08:55.742:INFO::main: Logging initialized @16243ms
demo_1  | 2020-08-11 15:08:55.781:INFO:oejs.Server:main: jetty-9.2.10.v20150310
demo_1  | 2020-08-11 15:08:55.900:INFO:oejs.ServerConnector:main: Started ServerConnector@3741a170{HTTP/1.1}{0.0.0.0:3000}
demo_1  | 2020-08-11 15:08:55.900:INFO:oejs.Server:main: Started @16402ms
demo_1  | Started server on port 3000

Once you see the "Started server on port 3000", navigate to http://localhost:3000 in a Web browser.

Open my-webapp/src/my_webapp/views.clj in your favorite code editor and edit the home-page view. When you save the file, your browser will automatically reload the page.

You can learn more about how this works by looking at the docker-compose.yaml file.

Unit testing

To run the unit tests, simply run make unit-test or make test:

$ make test
docker build --target unit-test --progress=plain .
...
#14 [unit-test 2/2] RUN lein test
#14 0.277 OpenJDK 64-Bit Server VM warning: Options -Xverify:none and -noverify were deprecated in JDK 13 and will likely be removed in a future release.
#14 10.82
#14 10.82 lein test my-webapp.handler-test
#14 10.92
#14 10.92 Ran 1 tests containing 2 assertions.
#14 10.92 0 failures, 0 errors.
#14 DONE 11.3s
...
#15 DONE 0.3s

The unit test code can be found in my-webapp/test/my_webapp.

Building a production image

To build a "production" image containing a standalone jar of the application, you can run make build.

Running the production image

To run the production image, you can run make run. You will then find the application served at http://localhost:8080.

$ make run
...
docker run --rm -p 8080:8080 --name myapp ccrone/clojure-demo:latest
2020-08-12 16:14:57.159:INFO::main: Logging initialized @6261ms
2020-08-12 16:14:59.128:INFO:oejs.Server:main: jetty-9.2.z-SNAPSHOT
2020-08-12 16:14:59.353:INFO:oejs.ServerConnector:main: Started ServerConnector@3ed981e1{HTTP/1.1}{0.0.0.0:8080}
2020-08-12 16:14:59.354:INFO:oejs.Server:main: Started @8456ms

Learn more!

There are extensive comments in the following files:

• Makefile for aliasing commands
• Dockerfile for building images
• docker-compose.yaml for the developer flow

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