Internal Values

Internal values are static or dynamic configuration values that can be referenced by environment variables, files, or other internal variables to compose values. An example common usecase is building a database connection string which requires a database host, username, password, etc. that may come from difference sources.

Using Internal Values

Internal values are declared in the waypoint.hcl file in the config stanza. The example below configures an internal value that reads a database username and host from a Terraform output and then combines them in an environment variable:

config {
  internal = {
    "db_host" = dynamic("terraform-cloud", {
      organization = "mycorp"
      workspace = "databases"
      output = "db_host"
    })

    "db_user" = dynamic("terraform-cloud", {
      organization = "mycorp"
      workspace = "databases"
      output = "db_user"
    })
  }

  env = {
    "DB_ADDR" = "${config.internal.db_user}@${config.internal.db_host}"
  }
}

The internal values db_host and db_user are never exposed directly to the application. Instead, only the combined value created in the DB_ADDR env var is exposed.

If the dynamic value of the database host or user changes, the environment variable will subsequently be updated and the application will be restarted using standard application restart behavior.

Caveats

Configsourcer plugins must return string type values to be used as internal values. With the terraform-cloud configsourcer, always specify an output, and only use outputs that of the type string.