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05. Configuration

Source: vignettes/e-config.Rmd
e-config.Rmd

Two Ways to Manage Production vs Development Mode

golem provides two separate mechanisms for managing production and development modes in your Shiny applications:

  1. R Options Approach: Using options(golem.app.prod = TRUE/FALSE) which is checked by app_prod() and app_dev() functions. This approach controls the behavior of golem’s development-aware utility functions like cat_dev(), print_dev(), message_dev(), and similar tools.

  2. Configuration File Approach: Using the golem-config.yml file to store configuration values (including an app_prod setting) that can be retrieved in your application code using get_golem_config().

Important: These two mechanisms are independent and serve different purposes. The R option controls golem’s built-in development tools, while the config file provides a flexible way to store and retrieve application-specific settings. This vignette focuses on the configuration file approach.

About inst/golem-config.yml

When you start a new golem application, you’ll find a file called golem-config.yml in the inst/ folder.

By default, this file contains the name of your app, its version, and the default working directory (which is the root of your package).

This config file is based on the {config} format, which allows you to create configuration files for different application contexts. Please refer to this package documentation for more information.

Setting golem-config

Here is what the default config file looks like:

default:
  golem_name: golex
  golem_version: 0.0.0.9000
  app_prod: no

production:
  app_prod: yes

dev:
  golem_wd: !expr golem::pkg_path()
  • default/golem_name, default/golem_version, default/app_prod can be used across the whole life of your golem app: while developing, and also when in production.
  • production/app_prod can be used to add elements that are to be used once the app is in production.
  • dev/golem_wd is in a dev config because the only moment you might reliably use this config is while developing your app. Use the app_sys() function if you want to rely on the package path once the app is deployed.

The good news is that if you don’t want/need to use config, you can safely ignore this file, just leave it where it is: it is used internally by the golem functions.

These options are globally set with:

set_golem_options()
#> ── Setting {golem} options in `golem-config.yml` ───────────────────────────────
#> ✔ Setting `golem_name` to golex
#> ✔ Setting `golem_wd` to golem::pkg_path()
#> You can change golem working directory with set_golem_wd('path/to/wd')
#> ✔ Setting `golem_version` to 0.0.0.9000
#> ✔ Setting `app_prod` to FALSE
#> ── Setting {usethis} project as `golem_wd` ─────────────────────────────────────
#> ✔ Setting active project to "/tmp/Rtmpoi8F31/golex".
default:
  golem_name: golex
  golem_version: 0.0.0.9000
  app_prod: no
production:
  app_prod: yes
dev:
  golem_wd: !expr golem::pkg_path()

The functions reading the options in this config file are:

get_golem_name()
#> [1] "golex"
get_golem_wd()
#> [1] "/tmp/Rtmpoi8F31/golex"
get_golem_version()
#> [1] "0.0.0.9000"

You can set these with:

default:
  golem_name: golex
  golem_version: 0.0.0.9000
  app_prod: no
production:
  app_prod: yes
dev:
  golem_wd: !expr golem::pkg_path()

Using golem-config

If you’re already familiar with the config package, you can use this file just as any config file.

golem comes with an amend_golem_config() function to add elements to it.

amend_golem_config(
  key = "where",
  value = "indev"
)
#> ✔ Setting `where` to indev
amend_golem_config(
  key = "where",
  value = "inprod",
  config = "production"
)
#> ✔ Setting `where` to inprod

Will result in a golem-config.yml file as such:

default:
  golem_name: golex
  golem_version: 0.0.0.9000
  app_prod: no
  where: indev
production:
  app_prod: yes
  where: inprod
dev:
  golem_wd: !expr golem::pkg_path()

app_config.R

In R/app_config.R, you’ll find a get_golem_config() function that allows you to retrieve config from this config file:

pkgload::load_all()
#> ℹ Loading golex
get_golem_config(
  "where"
)
#> [1] "indev"
get_golem_config(
  "where",
  config = "production"
)
#> [1] "inprod"

Or using the env var (default config behavior):

Sys.setenv("R_CONFIG_ACTIVE" = "production")
get_golem_config("where")
#> [1] "inprod"

golem_config vs golem_options

There are two ways to configure golem apps:

  • The golem_opts in the run_app() function
  • The golem-config.yml file

The main difference between these two is that the golem options from run_app() are meant to be configured during runtime: you’ll be doing run_app(val = "this"), whereas the golem-config is meant to be used in the backend, and will not be linked to the parameters passed to run_app() (even if this is technically possible, this is not the main objective).

The golem-config.yml file is also linked to the R_CONFIG_ACTIVE environment variable, just as any config file.

Additionally, the golem-config.yml file is shareable across golem projects (whereas golem_opts are application specific), and will be tracked by version control systems.

Connecting Back to the R Options Approach

As mentioned at the beginning of this vignette, golem uses two separate mechanisms for production/development configuration. While this vignette has focused on the golem-config.yml file, it’s important to understand how this relates to the R options approach.

The R Options Mechanism

The R option options(golem.app.prod) is used by golem’s development-aware functions:

These functions check getOption("golem.app.prod") directly and do not read from the config file.

Important: The Two Mechanisms Are Independent

The app_prod value in golem-config.yml and the options(golem.app.prod) R option are not automatically synchronized. They serve different purposes:

  • Config file app_prod: A persistent configuration value that you can retrieve using get_golem_config("app_prod") to use in your own application logic. This value can vary by environment (default, production, dev) using the R_CONFIG_ACTIVE environment variable.

  • R option golem.app.prod: A session-level setting that controls golem’s built-in development tools. This must be explicitly set in your code or launch configuration (e.g., in Docker CMD or run_dev.R).

Best Practices

  • Set the R option explicitly: When deploying to production, ensure you set options(golem.app.prod = TRUE) in your app’s launch script or Docker configuration. The golem Dockerfile templates handle this automatically.

  • Use the config file for your app’s logic: If you need environment-specific configuration in your application code (e.g., different API endpoints for dev vs production), use get_golem_config() to retrieve values from golem-config.yml.

  • Keep them in sync if needed: If you want the config file’s app_prod setting to match your R option, you’ll need to manage this synchronization in your own code. For example, in your run_app() function, you could set the option based on the config value:

# Example: sync config to R option (optional)
if (get_golem_config("app_prod")) {
  options(golem.app.prod = TRUE)
}

Note for {golem} < 0.2.0 users

If you’ve built an app with golem before the version 0.2.0, this config file doesn’t exist: you’ll be prompted to create it if you update a newer version of golem.