ROADMAP

[psolymos]

This is the roadmap for revising the R/rstats templates for OpenFaaS.

Base images

We need the following base image options (BASEIMAGE below):

• Debian based rocker/r-base: consistency for most adopted base images, call this base;
• Ubuntu based rocker/r-ubuntu: long term support can be important in corporate context and it jives with RSPM, call this ubuntu;
• Alpine based r-hub/r-minimal: small size is always a good thing, call this minimal.

Watchdog version

• Classic watchdog with stdin/stdout: call these images rstats-BASEIMAGE;
• of-watchdog with http support: call these images rstats-BASEIMAGE-FRAMEWORK.

Existing server frameworks

The following are server frameworks capable of running R based APIs:

• Rserve: very bare-bones implementation (RestRserve wraps this), rstats-BASEIMAGE-rserve;
  • RestRserve: a full-fledged API framework based on Rserve, rstats-BASEIMAGE-restserve;
• httpuv: the most popular server option behind other frameworks, rstats-BASEIMAGE-httpuv;
  • plumber: rstats-BASEIMAGE-plumber;
  • opencpu: rstats-BASEIMAGE-opencpu;
  • fiery: rstats-BASEIMAGE-fiery;
  • beakr: rstats-BASEIMAGE-beakr.

Template structure and workflows

• template.yml: yaml file for OpenFaaS, docker user, function name etc might have to be edited, see OpenFaaS config.
• Dockerfile: usually does not need editing.
• index.R: this file abstracts the server framework. Templates are set up for JSON in JSON out re/res types. This file only needs to be edited if the mime type depends on different midlewear, headers need to be changed etc.
• function/PACKAGES: file listing required packages and remotes to be installed for the function/handler.R file, plus additional sysreqs.
• function/handler.R: R script implementing the handler:
  • load libraries;
  • load data;
  • define functions/methods as needed;
  • it should include the handle = function(req, res) { ... } function called by index.R.

I really like how the r-minimal image implements remotes::install_deps() with the _R_SHLIB_STRIP_=true envvar. This behavior should be implemented for other templates through the Dockerfile as added by @mrchypark for the r-minimal template.