Module to provide helpers to access environment variables defined by antikythera.

Environments and deployments

Antikythera instances and gears may run in the following two modes:

• As a mix project, when invoked by running iex or mix command-line tool.
• As an OTP release, which is generated by e.g. antikythera_core.generate_release task.

In general there are multiple deployments per antikythera instance. To distingish the target deployment from code, antikythera defines the following environment variables:

• At compile time (for metaprogramming): ANTIKYTHERA_COMPILE_ENV must be appropriately set; the value can be retrieved by compile_env/0.
• At runtime: ANTIKYTHERA_RUNTIME_ENV must be appropriately set; the value can be retrieved by runtime_env/0.

It is the responsibility of antikythera instance administrators to correctly set these environment variables when compiling/running antikythera and gears. Possible values returned by compile_env/0 and runtime_env/0 are:

• names of deployments given by :deployments application config
• :local (running an OTP release at local machine for testing purpose)
• :undefined

As an example, if you set :dev and :prod in :deployments, then you get:

|                           | Mix.env() at compile-time              | Mix.env() at runtime    | compile_env(), runtime_env() |
|---------------------------+----------------------------------------+-------------------------+------------------------------|
| $ iex -S mix              | :dev  (toplevel), :prod (dependencies) | :dev                    | :undefined                   |
| $ mix test                | :test (toplevel), :prod (dependencies) | :test                   | :undefined                   |
| $ mix antikythera_local.* | :prod                                  | (:mix is not available) | :local                       |
| :dev deployment           | :prod                                  | (:mix is not available) | :dev                         |
| :prod deployment          | :prod                                  | (:mix is not available) | :prod                        |

You can use these values to distinguish the current context from your code.