Transition to Docker

[fxi]

AccessMod has some challenging constraints :

• AccessMod has to be usable offline by any computer using any OS with low requirements,
• It has to be usable independently from common GIS (ArcGIS, QGis, Saga, GRASS, R ...),
• It needs custom built version of some heavy geospatial libraries that could be conflicting with the user's currently installed libraries : native implementation is not an option,
• It should easily be handled by users with no computer background : CLI or anything text based is not an option,
• It should be uninstalled very easily,
• Its maintenance cost should be very low.

The current solution was to build a web app and ship it inside a Linux-based virtual machine. The interface is visible in any web browser.

AccessMod updates are provided as patches and only diffs are transferred : it's very efficient, but sometime unstable without supervision.

The main issue with that approach is that updating the dependencies is not possible unless providing a new virtual machine.

The solution is to use a "container" system to "ship" AccessMod : dependencies update and AccessMod update will be shipped as precompiled "layers". The updates will be heavier to transfer via the network, but not as much as a full virtual machine (current optimized size : ~700MB).

This approach could provide a big improvement on the application performance and also a big improvement on the storage issue users are experiencing.

The issue is that docker is not well supported on all operating systems. To have a better view on what this implies, here is a flowchart on the different options :

Note: to be completed with alternatives such as Singularity, Vagrant boxes or any other system that could solve our issues.

[mmschmitz]

Good flow chart, and this is a useful way to conceptualise the problem. I have to ask:

• Is there one way that you're leaning towards, without knowing anything about your user base?

• Do you know the OS breakdown of the users of the programme?

• Do you know how often people are updating the programme?

• Do you know how many people are downloading AccessMod in a month?

[mmschmitz]

I'll preface this next comment by admitting that I've only heard of these terms in the abstract, and never have considered the full ramifications of using either. I'm only writing a clarification post to ensure that the terms are clearly defined.

Just to clarify/keep things simple, here's what I believe you're defining your terms as. Is this how you conceptualised it in the flowchart above?

• "Dockers" are an instance of containerization that isolates the app within its own software box, and basically ships all dependencies along with the software of interest.

• In contrast, VirtualBox implementation (i.e., virtualization)) creates a virtual machine (i.e., extra OS) that runs on top of the host OS.