ihrwein/syslog-ng-docker.md

## syslog-ng-docker.md

      
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              syslog-ng-docker.md
            
          
    When we started to create our own Docker images we didn't have much experience in this area. I think our current solution solves many problems but leaves one problem open: it's too complex. It it good for
our first try, we learned many things from it and got a lot of useful preliminary work on our Docker images but I think we should move on.
Base images

What I expect as an user

When I try to use some software through Docker I visit Docker Hub and search for a name: syslog-ng. I don't care  what's the underlying operating system I'm only interested in the software.
If I want to use a specific version I expect to work the following commands:
# this downloads the latest released syslog-ng
docker pull balabit/syslog-ng:latest
# this downloads a specific syslog-ng release
docker pull balabit/syslog-ng:3.7
docker pull balabit/syslog-ng:3.6.4

I think latest should be an alias to 3.7 (as now).
Proposal

I propose the following simplifications for the base images (when the users want to run syslog-ng in a Docker container):

support only one image:
we should decide what should be the OS we depend on (Debian Jessie, latest Ubuntu LTS, etc.),
name it as balabit/syslog-ng,
use version tags on it,
provide the default configuration, but give some hints how to use it with custom configs, like this:

FROM balabit/syslog-ng:3.7
COPY syslog-ng.conf /etc/syslog-ng/syslog-ng.conf


build these images from the packages in our own OBS repo,
I expect these requirements for incubator, too:
one balabit/syslog-ng-incubator image with version tags, etc...

Developer images

What I expect as a developer

If I use a Docker image as a developer I just want an environment, where I can build the source code and do some testing. I prefer to store the git repository on my host system and mount it into the Docker container. So I assume the following conditions are met:

developers have git and some editor installed on their host machine,
they expect to build and test syslog-ng in the developer images,
the developer tools (make, gcc, git) work the same way on every popular Linux. The point is I don't care about the underlying OS as far as I can compile and test syslog-ng without touching the OS. Nevertheless, installing some packages on a popular Linux distribution isn't so hard and a required skill
for a developer. Though I know developers are touchy about their favorite Linux distribution (and text editor of course).

Proposal


create one development image, which contains all the developer tools to compile and test syslog-ng (git, make, gcc, etc.)
create some documentation about the usage of the images

Incubator:

it can be built atop the base image + needs the developer tools. We may set some environment variables to ease its usage (PKG_CONFIG_PATH, etc.)

Summary

I would like to see 4 images:

balabit/syslog-ng: syslog-ng installed
balabit/syslog-ng-incubator: syslog-ng + incubator are installed
balabit/syslog-ng-dev: dev environment with dev tools + dependencies
balabit/syslog-ng-incubator-dev: syslog-ng installed  + dev tools + dependencies for incubator modules