more readme updates

Author: devries

README.md

@@ -7,8 +7,9 @@
 
 This package can be used to load the timezone database from the standard location
 (`/usr/share/zoneinfo`) on MacOS and Linux computers. It includes a parser for
-the `tzfile` format, as well as a utility functions to convert a timestamp from
-the [gleam_time](https://hexdocs.pm/gleam_time/) library into a date and time
+the Time Zone Information Format (TZif) or `tzfile` format, as well as utility
+functions to convert a timestamp from the
+[gleam_time](https://hexdocs.pm/gleam_time/) library into a date and time
 of day in the given timezone.
 
 > We could really do with a timezone database package with a
@@ -22,16 +23,74 @@ To use, add the following entry in your `gleam.toml` file dependencies:
 timezone = { git = "[email protected]:devries/timezone.git", ref = "main" }
 ```
 # Installing the zoneinfo data files
+Timezone information is frequently updated, therefore it makes sense to use the
+package manager for your operating system to keep the timezone database up to
+date. All common unix variants have timezone database packages and install the
+timezone database files into the `/usr/share/zoneinfo` directory by default.
 
 ## 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 timezone 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 timezone database using the command:
+
+```
+sudo apk add tzdata
+```
+
+### Alpine based docker containers
+Installing and configuring the timezone 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 timezone database
+on Red Hat variants. To use YUM run the command:
 
+```
+sudo yum install tzdata
+```
+
+Similarly, using DNF:
+
+```
+sudo dnf install tzdata
+```
 ## Windows
 At this time we have not tested the windows operating system.