R/plumber.R

In googleCloudRunner: R Scripts in the Google Cloud via Cloud Run, Cloud Build and Cloud Scheduler

#' Plumber - Pub/Sub parser
#'
#' A function to use in plumber scripts to accept Pub/Sub messages
#'
#' @param message The pubsub message
#' @param pass_f An R function that will work with the data parsed out of the pubsub \code{message$data} field.
#'
#' @details
#'
#' This function is intended to be used within \link[plumber]{plumb} API scripts.  It needs to be annotated with a \code{@post} URL route and a \code{@param message The pubsub message} as per the plumber documentation.
#'
#' \code{pass_f} should be a function you create that accepts one argument, the data from the pubsub \code{message$data} field.  It is unencoded for you.  Make sure the function returns a 200 response otherwise pub/sub will keep resending the message!  \code{return(TRUE)} is adequate.
#'
#' The Docker container for the API will need to include \code{googleCloudRunner} installed in its R environment to run this function.  This is available in the public \code{gcr.io/gcer-public/cloudrunner} image.
#'
#' Use \link{cr_pubsub} to test this function once deployed.
#'
#' @export
#' @examples
#' \dontrun{
#'
#' # within a plumber api.R script:
#'
#' # example function echos back pubsub message
#' pub <- function(x) {
#'   paste("Echo:", x)
#' }
#'
#' #' Recieve pub/sub message
#' #' @post /pubsub #nolint
#' #' @param message a pub/sub message
#' function(message = NULL) {
#'   googleCloudRunner::cr_plumber_pubsub(message, pub)
#' }
#' }
#' @seealso \href{https://cloud.google.com/run/docs/tutorials/pubsub}{Google Pub/Sub tutorial for Cloud Run}.  You can set up Pub/Sub messages from Google Cloud Storage buckets via \link[googleCloudStorageR]{gcs_create_pubsub}
#' @family Cloud Run functions
cr_plumber_pubsub <- function(message = NULL,
                              pass_f = function(x) x) {
  #
  if (is.null(message)) stop("pub/sub message not found")
  stopifnot(
    is.list(message),
    !is.null(message$data)
  )

  the_data <- rawToChar(jsonlite::base64_dec(message$data))

  pass_f(the_data)
}

#' Send a message to pubsub
#'
#' Useful for testing Cloud Run pubsub deployments
#'
#' @param payload Will be base64 encoded and placed in \code{message$data}
#' @param endpoint The url endpoint of the PubSub service
#'
#' @export
#' @importFrom httr content POST
#' @importFrom jsonlite base64_enc
cr_pubsub <- function(endpoint, payload = jsonlite::toJSON("hello")) {
  content(
    POST(endpoint,
      body = list(message = list(
        data = base64_enc(payload)
      )),
      encode = "json"
    )
  )
}

cran_check_plumber <- function() {
  plumber::available_apis()
}