Impose resource constraints on demos

[drmrd]

As a first step towards emphasizing that EVerest is built for embedded systems, we're adding maximum CPU usage and RAM constraints of 100% (1 core) and 1 GB, respectively, in each demo.

Note that EVerest can run under much more aggressive resource constraints in realistic conditions. See for example this discussion from the mailing list for more details. The manager containers in our demos require more CPU and memory resources at present due to the inclusion of unoptimized test and simulation modules in these containers. Follow-up work will include a demo where the test and simulation code is isolated into a separate image to provide greater realism.

[drmrd]

@shankari: I have another PR ready for you. 😃

While we're here, there was an interesting discussion at the Weekly Technical Sync on Tuesday that's relevant to improved versions of this demo. Someone had asked about the possibility of extracting EV simulations into their own containers/running them on separate boards, and @corneliusclaussen had an in-depth comprehensive response. The short of it is that

• This is possible but challenging to do right.
• Ultimately there is a desire to create an ev_manager process that can operate like the evse_manager but independently from an EVSE EVerest stack.
• There is a long-running branch in everest-core called ccc-ev that addresses a lot of this work. (IIRC the "CCC" is due to the branch being developed at a Chaos Computer Club meeting/hackathon.)
• @corneliusclaussen would like to see this branch incorporated into EVerest in the not-too-distant future but is holding off on approaching it again until after updates to the BSP interface are completed.

[shankari]

Since I merged the OCPP change first, the semver needs to be bumped up by 2.

[shankari]

Although I am not sure that the limits should be applied to the CSMS, since it will typically run in the cloud.

[drmrd]

I am going to merge this now, but this PR is missing a couple of docker compose files (automated-tests and ocpp16j). @drmrd, please submit them in a separate PR 😄

Doh! 😆 Thanks for catching this, @shankari. I've added constraints to the OCPP 1.6J demo in #13. I had intentionally not included constraints on the automated tests demo, since it didn't seem useful to impose constraints on a Pytest run. (If constraints are needed for testing, I'd assume we would impose them from within the Pytest test cases themselves.) The automated testing demo is also called out in the README as the sole exception to the rule on resource constraints.

That said, they're easy to add to the automated testing demo if you'd like them there.