tzif_loader

# tzif_loader

[![Package Version](https://img.shields.io/hexpm/v/tzif_loader)](https://hex.pm/packages/tzif_loader)
[![Hex Docs](https://img.shields.io/badge/hex-docs-ffaff3)](https://tzif-loader.hexdocs.pm/)

This package is a utility to load IANA Time Zone database files from the local
filesystem into `TzDatabase` records that can be used by the [tzif](https://tzif.hexdocs.pm/)
time zone package. 

Add to your project with the command:
```
gleam add tzif_loader@1
```

# Installing the zoneinfo data files
Time zone information is frequently updated, therefore it makes sense to use the
package manager for your operating system to keep the time zone database up to
date. All common unix variants have time zone database packages and install the
time zone database files into the `/usr/share/zoneinfo` directory by default.

If, however, your system does not have time zone data installed, you can use
the [zones](https://zones.hexdocs.pm/) package to install a database of
timezone data as a gleam library and dependency. To use the zones timezone
data get the database using the `zones.database` function rather than
`loader.load_from_os` or `loader.load_from_path`.

## MacOS
The files should be included in your operating system by default. Check the
`/usr/share/zoneinfo` directory and see if they are present.

## Ubuntu/Debian Linux Systems
The APT package manager can be used to install the compiled TZif files with the
following command:

```
sudo apt install tzdata
```

### Debian based docker containers
Installing and configuring the time zone database on a Debian or Ubuntu based
docker container can be done by adding the following to your `Dockerfile`:

```
# Use an ARG for the timezone, with a default of UTC
ARG TIMEZONE=Etc/UTC

# Set the TZ environment variable and install tzdata
RUN apt-get update && \
    export DEBIAN_FRONTEND=noninteractive && \
    ln -fs /usr/share/zoneinfo/${TIMEZONE} /etc/localtime && \
    apt-get install -y tzdata && \
    dpkg-reconfigure --frontend noninteractive tzdata
```

## Alpine Linux Systems
The Alpine Package Keeper can install the time zone database using the command:

```
sudo apk add tzdata
```

### Alpine based docker containers
Installing and configuring the time zone database on an Alpine based docker
container can be done by adding the following to your `Dockerfile`:

```
# Use an ARG for the timezone, with a default of UTC
ARG TIMEZONE=Etc/UTC

# 1. Install the tzdata package
# 2. Copy the correct timezone file to /etc/localtime
# 3. Set the TZ environment variable to be used by applications
RUN apk add --no-cache tzdata && \
    cp /usr/share/zoneinfo/${TIMEZONE} /etc/localtime && \
    echo "${TIMEZONE}" > /etc/timezone
```

## Red Hat/Rocky/Alma Linux Systems
You can use the YUM package manager or DNF to install the time zone database
on Red Hat variants. To use YUM run the command:

```
sudo yum install tzdata
```

Similarly, using DNF:

```
sudo dnf install tzdata
```

Further documentation can be found at <https://tzif-loader.hexdocs.pm/>.