Launch Docker Container Compositions via Tutum and – But What About Container Stashing?

Via a couple of tweets, it seems that 1-click launching of runnable docker container compositions to the cloud is almost possible with Tutum – deploy to Tutum button [h/t @borja_burgos] – with collections of ready–to-go compositions (or in Tutum parlance, stacks) available on [h/t @tutumcloud].

The deploy to Tutum button is very much like the binder setup, with URLs taking the form:

The repository – such as a github repository – will look for tutum.yml, docker-compose.yml and fig.yml files (in that order) and pre-configure a Tutum stack dialogue with the information described in the file.

The stack can then be deployed to a one or more already running nodes.

The site hosts a range of pre-defined configuration files that can be used with the deploy button, so in certain respects it acts much the same way as the panamax directory (Panamax marketplace?)

One of the other things I learned about Tutum is that they have a container defined that can cope with load balancing: if you launch multiple container instances of the same docker image, you can load balance across them (tutum: load balancing a web service). At least one of the configurations on (Load balancing a Web Service) seems to show how to script this.

One of the downsides of the load balancing, and indeed the deploy to Tutum recipe generally is that there doesn’t seem to be a way to ensure that server nodes on which to run the containers are available: presumably, you have to start these yourself?

What would be nice would be the ability to also specify an autoscaling rule that could be used to fire up at least one node on which to run a deployed stack? Autoscaling rules would also let you power up/power down server nodes depending on load, which could presumably keep the cost of running servers down to a minimum needed to actually service whatever load is being experienced. (I’m thinking of occasional, and relative low usage models, which are perhaps also slightly different from a normal web scaling model. For example, the ability to fire up a configuration of several instances of OpenRefine for a workshop, and have autoscaling cope with deploying additional containers (and if required, additional server nodes) depending on how many people turn up to the workshop or want to participate).)

There seems to be a discussion thread about autoscaling on the Tutum site, but I’m not sure there is actually a corresponding service offering? (Via @tutumcloud, there is a webhook triggered version: Tutum triggers.)

One final thing that niggles at me particularly in respect of personal application hosting is the ability to “stash” a copy of a container somewhere so that it can be reused later, rather than destroying containers after each use. ( appears to have this sorted…) A major reason for doing this would be to preserve user files. I guess one way round it is to use a linked data container and then keep the server node containing that linked data container alive, in between rounds of destroying and starting up new application containers (application containers that link to the data container to store user files). The downside of this is that you need to keep a server alive – and keep paying for it.

What would be really handy would be the ability to “stash” a container in some cheap storage somewhere, and then retrieve that container each time someone wanted to run their application (this could be a linked data container, or it could be the application container itself, with files preserved locally inside it?) (Related: some of my earlier notes on how to share docker data containers.)

I’m not sure whether there are any string’n’glue models that might support this? (If you know of any, particularly if they work in a Tutum context, please let me know via the comments…)

Author: Tony Hirst

I'm a Senior Lecturer at The Open University, with an interest in #opendata policy and practice, as well as general web tinkering...

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