R Interface with Google Compute Engine.

README

0. Create a Google Appengine project in the US region (only region that supports flexible containers at the moment)
1. Create a scheduled script e.g. schedule.R - you can use auth from environment files specified in app.yaml.
2. Make an API out of the script by using plumber - example:

library(googleAuthR)         ## authentication
library(googleCloudStorageR)  ## google cloud storage
library(readr)                ## 
## gcs auto authenticated via environment file 
## pointed to via sys.env GCS_AUTH_FILE

#* @get /demoR
demoScheduleAPI <- function(){
  
  ## download or do something
  something <- tryCatch({
      gcs_get_object("schedule/test.csv", 
                     bucket = "mark-edmondson-public-files")
    }, error = function(ex) {
      NULL
    })
      
  something_else <- data.frame(X1 = 1,
                               time = Sys.time(), 
                               blah = paste(sample(letters, 10, replace = TRUE), collapse = ""))
  something <- rbind(something, something_else)
  
  tmp <- tempfile(fileext = ".csv")
  on.exit(unlink(tmp))
  write.csv(something, file = tmp, row.names = FALSE)
  ## upload something
  gcs_upload(tmp, 
             bucket = "mark-edmondson-public-files", 
             name = "schedule/test.csv")
  
  cat("Done", Sys.time())
}

3. Create Dockerfile. If using containerit then replace FROM with trestletech/plumber and add the below lines to use correct AppEngine port:

Example:

library(containerit)

dockerfile <- dockerfile("schedule.R", copy = "script_dir", soft = TRUE)
write(dockerfile, file = "Dockerfile")

Then change/add these lines:

EXPOSE 8080
ENTRYPOINT ["R", "-e", "pr <- plumber::plumb(commandArgs()[4]); pr$run(host='0.0.0.0', port=8080)"]
CMD ["schedule.R"]

Example output:

FROM trestletech/plumber
LABEL maintainer="mark"
RUN export DEBIAN_FRONTEND=noninteractive; apt-get -y update \
 && apt-get install -y libcairo2-dev \
	libcurl4-openssl-dev \
	libgmp-dev \
	libpng-dev \
	libssl-dev \
	libxml2-dev \
	make \
	pandoc \
	pandoc-citeproc \
	zlib1g-dev
RUN ["install2.r", "-r 'https://cloud.r-project.org'", "readr", "googleCloudStorageR", "Rcpp", "digest", "crayon", "withr", "mime", "R6", "jsonlite", "xtable", "magrittr", "httr", "curl", "testthat", "devtools", "hms", "shiny", "httpuv", "memoise", "htmltools", "openssl", "tibble", "remotes"]
RUN ["installGithub.r", "MarkEdmondson1234/googleAuthR@7917351", "hadley/rlang@ff87439"]
WORKDIR /payload/
COPY [".", "./"]

EXPOSE 8080
ENTRYPOINT ["R", "-e", "pr <- plumber::plumb(commandArgs()[4]); pr$run(host='0.0.0.0', port=8080)"]
CMD ["schedule.R"]

3. Specify app.yaml with any environment vars such as auth files, that will be included in same folder. Also limit instances if needed to make sure errors down't spawn hundreds of VMs.

Example:

runtime: custom
env: flex

env_variables:
  GCS_AUTH_FILE: auth.json

4. Specify cron.yaml for the schedule needed:

cron:
- description: "test cron"
  url: /demoR
  schedule: every 1 hours

5. Deploy via gcloud app deploy --project your-project

Deploy new cron via gcloud app deploy cron.yaml --project your-project

6. App should then be deployed on https://your-project.appspot.com/ - every GET request to https://your-project.appspot.com/demoR (or other endpoints you have specified in R script) will run the R code. The cron will run every hour to this endpoint as specified by the cron file above. Logs for the instance are found here.