Example functions and configuration files for using the config package to simplify connecting to a database

config.yml

default:
  gis:
    drv: !expr RPostgres::Postgres()
    db: mydatabase
    port: 5432
    host: somehost.dev.example.com
prod:
  gis:
    drv: !expr RPostgres::Postgres()
    db: proddb
    port: 5432
    host: somehost.prod.example.com

functions.R

connect_to_db <- function(dbname = "gis", file = "config.yml", override_params = list()) {
  # grab configuration values
  params <- config::get(dbname, file = file)
  
  # update list values / allow an "override" from the caller
  final_params <- purrr::list_modify(params, !!!override_params)
  
  # make connection by passing in arguments from a list
  con <- do.call(DBI::dbConnect, args = final_params)
}

# the exact same function, except the user is read from an environment variable or whatever else you want
connect_to_db_user_from_env_var <- function(dbname = "gis", file = "config.yml") {
  connect_to_db(
    dbname = dbname, 
    file = file, 
    override_params = list(
      "user" = Sys.getenv("DB_USER"),
      "password" = Sys.getenv("DB_PASSWORD")
    )
  )
}

# create template file
# if creating these config files is annoying... add a helper to create them for you!
create_template <- function(dbname = "gis", file = "test.yml") {
  raw <- yaml::as.yaml(
    x = list(
      "default" = list(
        "gis" = list(
          "drv" = "XXhacky_workaroundXX",
          "db" = dbname,
          "port" = "5432",
          "host" = "placeholder"
        )
      )
    )
  )
  # hacky workaround because the yaml package wants to quote "!expr"
  updated <- stringr::str_replace_all(raw, "XXhacky_workaroundXX", "!expr RPostgres::Postgres()")
  writeLines(updated, file)
}