Transmode/gradle-docker

A Gradle plugin to build Docker images from the build script.

Matthias Grüter

@mattgruter

Welcome to the gradle-docker gitter chat room! :smile:

Dave Syer

@dsyer

Hurrah!

Fredrik Vihlborg

@frvi

haha, was 100% positive that this was an april fools'

Matthias Grüter

@mattgruter

it was, but you just made it into something permanent by replying here after 1 april... :-P

Dave Syer

@dsyer

Hi Matthias

We're using the plugin in a new guide (not yet officially published, but here's a link: https://spring.io/guides/gs/spring-boot-docker/)

I wondered if maybe we could talk about some enhancements to make using a Dockerfile more declarative

Or else get you to comment on how we did it wrong so far

Matthias Grüter

@mattgruter

Great! we're working on a new dockerfile DSL. I'm about to merge the changes hopefully during the Easter holiday. The idea is to be able dockerfile instructions in the build.gradle more naturally. Something as follows:

dockerfile {
   ADD file /
   RUN ...
   CMD ["foo"]
   ...
}

Matthias Grüter

@mattgruter

I've been close to a new 1.3 release of the plugin for some time now but never got around to actually do the final finish. When are you officially publishing your guide? Version 1.3 will simplify a few things: nicer Dockerfile syntax (see above), availability of the plugin through the plugin protal and other changes.

Dave Syer

@dsyer

I think we prefer to use an external Dockerfile. is that a bad idea?

Matthias Grüter

@mattgruter

No, that works as well. We have some improvements on the dev branch (also scheduled for 1.3) that will help with external Dockerfiles above all a fix for Transmode/gradle-docker#29

Dave Syer

@dsyer

But the original Dockerfile might be in src/main/docker

Matthias Grüter

@mattgruter

I'll try to look through your guide during the weekend.

Dave Syer

@dsyer

It would have no built artifacts in its context at all in other words

You don't want Dockerfile in the root of your project, otherwise loads of rubbish could end up in the container

Matthias Grüter

@mattgruter

ok, then Transmode/gradle-docker#29 doesn't affect you

Dave Syer

@dsyer

It does, sort of

In the sense that we would like a better solution than we have

We are more or less forced to copy the build artifacts using imperative Groovy into the Dockerfile's context

I think the approach in the maven plugin is sound (the one from Spotify )

They let you declare in the plugin config which "resources" (or artifacts) to make available to the Dockerfile

Matthias Grüter

@mattgruter

Great, I'll look at how they solved it.

Dave Syer

@dsyer

We use it in the guide

Matthias Grüter

@mattgruter

The new dockerfile stuff would allow you to use an external dockerfile and the augment it in the build.gradle with ADD/COPY instructions there and the plugin will take care of the rest. Not sure if that would help you though.,

Dave Syer

@dsyer

That might be useful in general

Specifically for this guide we want to have the same Dockerfile work for Maven and Gradle (I know it's slightly artificial, but we always try and support both)

In the Maven plugin as soon as you use an external Dockerfile everything else is ignored

So maybe I prefer your approach slightly, but we still have to work around one or the other

Matthias Grüter

@mattgruter

Ok, I see. Looking at the guide right now.

So you're copying your jar file into the docker stageDir (build/docker) manually.

Dave Syer

@dsyer

Yes

And that also means we have to define a custom task

Matthias Grüter

@mattgruter

Wouldn't something like:

copy {
    from jar
    into stageDir
}

work?

Dave Syer

@dsyer

and that it has to be deferred with "<<"

I'm not a gradler. Happy to take edits.

Where does that go?

Inside the task definition?

Matthias Grüter

@mattgruter

Yes, instead of the new File(stageDir, jar.archiveName).bytes = jar.archivePath.bytes

Dave Syer

@dsyer

Trying it...

Dave Syer

@dsyer

I don't think that worked

the image it builds has the same ID as docker/java

Actually that's a problem with the "<<" (cc @gregturn)

Matthias Grüter

@mattgruter

Exactly. The dockerfile, applicationName and push properties have to be defined in the configuration phase of the build not the execution phase (with the "<<" you push everything into the execution phase)

Dave Syer

@dsyer

Yeah. I'm unhacking that now.

Then the copy{} works, thanks

Matthias Grüter

@mattgruter

This should work:

task buildDocker(type: Docker, dependsOn: jar) {
  push = false
  applicationName = jar.baseName
  dockerfile = file('src/main/docker/Dockerfile')
  doFirst {
    copy {
      from jar
      into stageDir
    }
  } 
}

Dave Syer

@dsyer

@gregturn thought he found a problem that meant he had to defer to execution

It works for me though

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