r2lambda update to support multi-file projects and renv projects

Deploy a project with multiple R scripts and {renv}-managed environment to AWS Lambda

It has been a while since I’ve had the chance to work on my {r2lambda} project. In particular, there were a couple of good points made by a user on GitHub about functionality that is missing from the package. The option to deploy multiple files, e.g., one runtime function that depends on helpers in the same project organized in different files. And another, to enable {renv} management of the R environment within the AWS Lambda docker image. Both excellent points that I wished I addressed earlier. But better late than never.

Both of these features required minor adjustments to the codebase. Copying additional supports scripts and restoring the {renv} environment should both happen when the AWS Lambda docker image is built, so the logic to create the Dockerfile needed to be updated. Accordinly, the r2lambda::build_lambda function now has two additional arguments:

#' @param support_path path to the support files (if any). Either NULL 
#' (the default) if all needed code is in the same `runtime_path` script, or a 
#' character vector of paths to additional files needed by the runtime script.
#' @param renvlock_path path to the renv.lock file (if any). Default is NULL.
#' 
#' @details Use either `renvlock_path` or `dependencies` to install required
#' packages, not both. By default, both are `NULL`, so the Docker image will
#' have no additional packages installed.

To include any support scripts, provide a character vector script paths to the support_path argument when building the Lambda docker image locally with build_lamdba.

[Note that, multi-file project was supported previously as well, although perhaps not explicitly. An approach that I like is to create an ‘R’ package that exports the runtime function needed for the Lambda. Then one just needs to make that custom R package a dependency of the project and either install in the AWS Lambda docker image it through dependencies or renvlock_path.]

To use an existing renv.lock for installation of dependencies, provide its path to the renvlock_path argument to build_lambda. This instructs the code to copy the renv.lock file to the image and run renv::restore() which will reconstruct the R environment inside the docker image. I really like this feature, as it minimizes the size of the Dockefile and removes some potential headaches with R package dependencies from different repositories (CRAN, BioConductor, GitHub, etc).

Demo code

Assuming we have a folder with the following structure:

~/Desktop$ ls -1 iris-lambda/
renv/
renv.lock
runtime.r
support.r
test-code.r

Where, support.r defines some function that runtime.r uses for the Lambda:

get_iris_summary_by_species <- function(species) {
    iris |>
    dplyr::filter(Species == species) |>
    dplyr::summarise(
      mean = mean(Sepal.Length),
      sd = sd(Sepal.Length)
    )
}

Then runtime.r, sources the support script, and calls the function defined there:

source("support.r")

iris_summary <- function(species) {
  get_iris_summary_by_species(species)
}

lambdr::start_lambda()

Then the following should work, passing the support script and renv.lock to r2lambda::build_lambda:

dir("~/Desktop/iris-lambda")
runtime_function <- "iris_summary"
runtime_path <- "~/Desktop/iris-lambda/runtime.r"
support_path <- "~/Desktop/iris-lambda/support.r"
renvlock_path <- "~/Desktop/iris-lambda/renv.lock"
dependencies <- NULL

# Might take a while, its building a docker image
build_lambda(
  tag = "my_iris_lambda",
  runtime_function = runtime_function,
  runtime_path = runtime_path,
  support_path = support_path,
  renvlock_path = renvlock_path,
  dependencies = dependencies
)

# test
payload <- list(species = "setosa")
tag <- "my_iris_lambda"
test_lambda(tag = tag, payload)


# deploy

# Might take a while, its pushing it to a remote repository
deploy_lambda(
  tag = "my_iris_lambda",
  Timeout = 30
)

invoke_lambda(
  function_name = "my_iris_lambda",
  invocation_type = "RequestResponse",
  payload = list(species = "versicolor"),
  include_logs = FALSE
)

invoke_lambda(
  function_name = "my_iris_lambda",
  invocation_type = "RequestResponse",
  payload = list(species = "setosa"),
  include_logs = FALSE
)