Capsule – Package and Deploy JVM Applications

http://www.capsule.io/

by slantedview • 11 years ago

71 30 11 years ago

capsule.io

rozap• 11 years ago

Caplets are classes that hook into the capsule and modify its behavior.

What problem does this solve? Because it sounds like it is going to create quite a few new ones.

pron11• 11 years ago

For example: launch a capsule in a container, run a capsule as a daemon/service, or turn a capsule to a native app. Other uses may include reading configurations from etcd/ZooKeeper or querying information about the host and using it to set better JVM flags.

See the list of available caplets: http://www.capsule.io/caplets/

yrro• 11 years ago

I wrote a Caplet to add extra directories on the host system to the classpath of the JVM that ran my application.

Randgalt• 11 years ago

I've just started using Capsule for an internal project. It's an excellent library. For our use case, we need to have a bash script that runs before the app starts. With capsule this is very easy. Also, because capsule doesn't do any shading, you don't run into the compatibility issues that shaders add. NOTE: I use the Capsule Maven plugin instead of Capsule directly https://github.com/chrischristo/capsule-maven-plugin

Frozenlock• 11 years ago

Distribute a Clojure application without embedding Clojure itself in the capsule, and have Clojure downloaded the first time the capsule is launched. The Clojure runtime will be cached and shared among all Clojure capsules so it will only be downloaded once.

How would that be useful?

pron11• 11 years ago

Your artifacts would be smaller (the Clojure runtime is ~4MB; the Scala runtime is ~5MB) and you could even have the runtime auto-update if you like. But the main point is just to show how flexible Capsule is, and how you can have the deployment adapt itself to the environment in many ways.

jwr• 11 years ago

I think "smaller" is not what we should be chasing. Given drive sizes and network speeds, I'd much rather have "simple and reliable" than "small". In other words, I prefer to save my time rather than my computer's time.

As for the project, I'm trying to understand what it provides over "lein uberjar" that I'm already using (and happy with it)?

mingodad• 11 years ago

There is also this alternative http://oss.readytalk.com/avian/

pron11• 11 years ago

They're not at all alike. Capsule is a deployment mechanism for any JVM app and a JVM container solution (a "Docker for Java"). Avaian is an alternative JVM that supports a subset of Java.

vbezhenar• 11 years ago

That's an interesting project! I always liked the simplicity of `java -jar` command. Instead of that simplicity, many project choose to roll huge startup bash+bat scripts or even worse, native launchers.

pron11• 11 years ago

Well, they have to to set java command line arguments. Capsule solves that.

_Codemonkeyism6• 11 years ago

About Java packaging:

My personal feeling is that the local install approach of gem/npm has won over the pull dependency approach of Maven/Ant - at least for development, but I think also with Docker approaches.

Java will address this with Jigsaw in Java 9 at last.

http://openjdk.java.net/projects/jigsaw/doc/quickstart.html

Capsule seems to be pulling dependencies if not packaged.

But we switched to JAR/Docker deployments for Scala some time ago with Jetty instead of WARs and so Capsule is welcome and we'll definetly try it. Hope it will switch to supporting Jigsaw with Java 9.

konradb• 11 years ago

My personal feeling is that the local install approach of gem/npm has won over the pull dependency approach of Maven/Ant - at least for development, but I think also with Docker approaches.

What distinction are you drawing here, with local install vs pull dependency?

Whenever I've run maven it's created a local repository and saved all the dependencies in that, but perhaps I'm misunderstanding the distinction you are drawing?

_Codemonkeyism6• 11 years ago

My (unreflected) thoughts, wording not the best, but for me:

1. Push deps to an app means: npm install X

This makes it easier to promote libraries as it's easier to try them out. Just write npm install X and you're done.

2. Pull deps means: declare dependencies in your app and a package manager will download them.

This makes it harder to try libs you find on Github for my taste. It also ties dep management to packaging, where e.g. with Docker I prefer to manage dependency in the Docker file instead.

(npm can do pull too)

pron11• 11 years ago

Capsule has a caplet called Shield[1] which is much better than Docker for JVM applications. It creates an unprivileged container, doesn't require building an image (still shipped as a JAR), and in a week or so it will also automatically handle piping logging and JMX monitoring out of the container.

[1] https://github.com/puniverse/capsule-shield

_Codemonkeyism6• 11 years ago

Will take a look, but have the impression this one is lost. I'd (before reading) use Docker for easier recruiting, use the same for other deployments as well (Postgres etc.), more knowledge/best practices available etc.

kodablah2• 11 years ago

I admittedly have not read the docs yet and I'm curious how this compares to Java packaging[1], SBT assembly[2],and SBT native packager[3]. I understand that containerization is a feature, but I am unsure how it improves over a simple Dockerfile using one of the aforementioned packaging solutions.

1. https://docs.oracle.com/javase/8/docs/technotes/guides/deplo... 2. https://github.com/sbt/sbt-assembly 3. https://github.com/sbt/sbt-native-packager

pron11• 11 years ago

See my other comments but the short answer is that fat-jars often fail, and Capsule offers more -- and more versatile -- deployment solutions than native packaging (which is mostly used only by desktop apps).

CJefferson• 11 years ago

Given many people's opinion of Java, and the mess of installing Java on windows (where the installer installs adware), I would prefer something which went as far as packaging a private JVM, so my users didn't even know (or have to care about the fact) I was using Java.

kodablah2• 11 years ago

This exists in the Java 8 JDK: https://docs.oracle.com/javase/8/docs/technotes/guides/deplo...

pron11• 11 years ago

But such solutions already exist. While Capsule does have a caplet that targets the desktop but intentionally doesn't install its own JRE so that security and other updates could be installed -- some prefer it that way -- it is mostly geared towards server-side uses, where bundling a JRE is usually not the best solution.

Capsule – Package and Deploy JVM Applications

Related Stories