tar_resources_repository_cas: Target resources for custom storage formats

In targets: Dynamic Function-Oriented 'Make'-Like Declarative Pipelines

Target resources for custom storage formats

Description

Create the repository_cas argument of tar_resources() to specify optional target settings for custom storage formats.

Usage

tar_resources_repository_cas(
  envvars = targets::tar_option_get("resources")$repository_cas$envvars
)

Arguments

envvars

Named character vector of environment variables. These environment variables are temporarily set just before each call to the storage methods you define in tar_format(). Specific methods like read can retrieve values from these environment variables using Sys.getenv(). Set envvars to NULL to omit entirely.

Details

tar_resources_repository_cas() accepts target-specific settings to customize tar_repository_cas() storage repositories.

Value

Object of class "tar_resources_repository_cas", to be supplied to the repository_cas argument of tar_resources().

Resources

Functions tar_target() and tar_option_set() each takes an optional resources argument to supply non-default settings of various optional backends for data storage and high-performance computing. The tar_resources() function is a helper to supply those settings in the correct manner.

In targets version 0.12.2 and above, resources are inherited one-by-one in nested fashion from tar_option_get("resources"). For example, suppose you set tar_option_set(resources = tar_resources(aws = my_aws)), where my_aws equals tar_resources_aws(bucket = "x", prefix = "y"). Then, ⁠tar_target(data, get_data()⁠ will have bucket "x" and prefix "y". In addition, if new_resources equals ⁠tar_resources(aws = tar_resources_aws(bucket = "z")))⁠, then tar_target(data, get_data(), resources = new_resources) will use the new bucket "z", but it will still use the prefix "y" supplied through tar_option_set(). (In targets 0.12.1 and below, options like prefix do not carry over from tar_option_set() if you supply non-default resources to tar_target().)

See Also

Other resources: tar_resources(), tar_resources_aws(), tar_resources_clustermq(), tar_resources_crew(), tar_resources_custom_format(), tar_resources_feather(), tar_resources_fst(), tar_resources_future(), tar_resources_gcp(), tar_resources_network(), tar_resources_parquet(), tar_resources_qs(), tar_resources_url()

Examples

# Somewhere in you target script file (usually _targets.R):
tar_target(
  name = target_name,
  command = data.frame(x = 1),
  repository = tar_repository_cas(
    upload = function(key, path) {
      if (dir.exists(path)) {
        stop("This CAS repository does not support directory outputs.")
      }
      if (!file.exists("cas")) {
        dir.create("cas", recursive = TRUE)
      }
      file.copy(path, file.path("cas", key))
    },
    download = function(key, path) {
      file.copy(file.path("cas", key), path)
    },
    exists = function(key) {
      file.exists(file.path("cas", key))
    }
  ),
  resources = tar_resources(
    repository_cas = tar_resources_repository_cas(
      envvars = c(AUTHENTICATION_CREDENTIALS = "...")
    )
  )
)

targets documentation built on Oct. 3, 2024, 1:11 a.m.