NervesTimeZones (nerves_time_zones v0.1.5) View Source

Local time support for Nerves devices

The nerves_time_zones application provides support for local time on Nerves devices. It does this by bundling a time zone database that's compatible with the zoneinfo library and providing logic to set the local time zone with the C runtime (and hence Erlang and Elixir).

To use, call NervesTimeZones.set_time_zone/1 with the any IANA time zone name (e.g., "America/New_York"). The time zone will be persisted so you won't need to set it again. It is safe to always set it on boot if your project will always be located in one time zone.

After this, calls to NaiveDateTime.local_now/1 will return the local time. If you would prefer DateTime struct, call DateTime.now(NervesTimeZones.get_time_zone()).

If running a non-BEAM program that is time zone aware, you may need to set environment variables for it to work right. See NervesTimeZones.tz_environment/0 for the proper settings.

Link to this section Summary

Functions

Return the current local time zone

Reset the time zone to the default

Set the local time zone

Return all known time zones

Return environment variables for running OS processes

Return whether a time zone is valid

Link to this section Functions

Specs

get_time_zone() :: String.t()

Return the current local time zone

Specs

reset_time_zone() :: :ok

Reset the time zone to the default

This cleans up any saved time zone information and reapplies the defaults. The default time zone is "Etc/UTC", but this can be changed by adding something like the following to your config.exs:

config :nerves_time_zones, default_time_zone: "Asia/Tokyo"
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set_time_zone(time_zone)

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Specs

set_time_zone(String.t()) :: :ok | {:error, any()}

Set the local time zone

Only known time zone names can be set. Others will return an error. "Etc/UTC" should always be available.

This time zone will be persisted and restored after a reboot.

Specs

time_zones() :: [String.t()]

Return all known time zones

This function scans the time zone database each time it's called. It's not slow, but if you just need to verify whether a time zone exists, call valid_time_zone?/1 instead.

Specs

tz_environment() :: %{required(String.t()) => String.t()}

Return environment variables for running OS processes

If you're using System.cmd/3 to start an OS process that is time zone aware, call this to set the environment appropriately. For example, System.cmd("my_program", [], env: NervesTimeZones.tz_environment())

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valid_time_zone?(time_zone)

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Specs

valid_time_zone?(String.t()) :: boolean()

Return whether a time zone is valid