[Hawkular-dev] Docker image size does matter

[Matt Wringe]

----- Original Message -----
> From: "Heiko W.Rupp" <hrupp at redhat.com>
> To: "Discussions around Hawkular development" <hawkular-dev at lists.jboss.org>
> Sent: Wednesday, 1 February, 2017 7:19:34 AM
> Subject: Re: [Hawkular-dev] Docker image size does matter
> 
> On 1 Feb 2017, at 12:29, Jiri Kremser wrote:
> 
> > base image with JRE 8 and Alpine linux: 76.8 MB
> 
> Yes, alpine is only 3-4 MB that is great.

Please also take into consideration that minimal docker images do not contain common commands and can be a pain if you need to go into the container and run commands.

Trying to debug issues when you don't have access to basic commands can be a bit frustrating. Especially if you are not root and cannot just install binaries in the container.

> > I also removed
> > 9.2M  /opt/jboss/wildfly/docs
> 
> Makes sense.
> 
> 
> > What also helped was squashing all the image layers into 1. This makes
> > the
> > download faster and possibly the image smaller. When applying
> > docker-squash
> > [1] to the current h-services image it saves ~50megs
> 
> This is a bit of a false friend as docker pull only transfers layers it
> does not yet have.
> 
> E.g
> 
> $ docker pull pilhuhn/hawkular-services:0.30.0.Final
> 0.30.0.Final: Pulling from pilhuhn/hawkular-services
> 08d48e6f1cff: Already exists
> 664e6a3041e6: Already exists
> 2f8461e7022b: Already exists
> 9500f4548bd3: Already exists
> 69e2e5217a47: Already exists
> cf95509fd4ad: Downloading [======>
>       ] 10.75 MB/89.61 MB
> 
> So what you say is true for the first download, but afterwards all
> the base layers of wf + jdk + ... are present. With stripping
> into 1 layer there is no chance of caching.
> Situation of course changes when the base layer is updated
> 
> 
> > I am aware that this probably wont fly with some RH policy that we
> > should
> > base our SW on Fedora/RHEL base OS images, but I am gonna use them for
> > development and because I often run out of space because of Docker.
> 
> I like those alpine images and use them for private stuff,
> but for Hawkular upstream I think we should use something
> that is close for downstream so minimise the moving parts.
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