GSoC: The ECE configuration system – midterm update

Hi,
the GSoC is nearing its midterm evaluation, so let’s have a look at the current state of the “Experimental Configuration Environment” (working title)!

I started the project with defining models for configuration data, configuration diffs (that are used to modify data and store modifications) and schemas. All of the design documents I wrote can be found at: https://gitlab.com/neoraider/ece/wikis/design

I tried hard not to re-invent things that already exist in a more or less standardized way:

  • My configuration model is just JSON (without support for floating-point numbers right now, as the libubox blobmsg format ubus uses to represent JSON doesn’t support them – I plan to fix this)
  • JSON Pointers (https://tools.ietf.org/html/rfc6901) are used to refer to elements of the configuration tree
  • The schema format uses a subset of JSON Schema (http://json-schema.org/)

Based on this design, I’ve started implementing the configuration management daemon eced. The page https://gitlab.com/neoraider/ece/wikis/implementation gives a good overview of the current features and usage of eced. Quite a lot is already working:

  • Multiple schemas can be loaded and merged
  • Default configuration is generated from the schemas
  • A ubus interface allows to query and modify the configuration
  • Config modifications can be loaded from and stored into a diff file

There’s still a lot missing, so here’s what I plan to do next:

  • Make something use ECE! UCI is well-integrated in OpenWrt/LEDE and can be used from C, Lua and shell scripts; all of these languages should also be supported by an ECE client library. An example schema to replace /etc/config/system does already exist and could be used to experiment with partially replacing UCI with ECE.
  • Support schema upgrades: When schemas are updated, this can partially invalidate config diffs. A way to deal with such inconsistencies must be defined.

Discussions and feedback have also led me to the decision to put a stronger focus to UCI interoperability. While I had only planned import and export of UCI configuration at first, I’ve realized that a two-way binding between UCI and ECE (i.e. an API-compatible libuci replacement/extension that will use ECE as backend) will be necessary for ECE to find acceptance. This will also allow to continue to use existing configuration tools like LuCI with UCI configuration converted to ECE.

I also plan to have OpenWrt/LEDE packages for ECE ready soon, so you can play around with the current implementation yourselves. Maybe I’ll also set up a public host with ECE Laughing

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