---
date: 2018-05-07 14:04:43
tags: Tutorial Perl6 Sparrowdo GettingStarted
description: >
   Nondescript
---
= Sparrowdo - Getting started
:toc: preamble

https://github.com/melezhik/sparrowdo[Sparrowdo] is a Perl 6 project to
facilitate automatic configuration of systems. There's a
https://sparrowhub.org/[repository of useful modules] to make specific cases
easier to work with, but the
https://github.com/melezhik/sparrowdo/blob/master/core-dsl.md[Core DSL] can
already take care of many tasks. In this tutorial, I'll guide you through
setting up Sparrowdo, bootstrapping it onto your local system, writing a task
and running it.

== Install Sparrowdo
Sparrowdo is a http://perl6.org/[Perl 6] project, so you'll need to have Perl 6
installed. We'll also use the Perl 6 package manager
https://github.com/ugexe/zef/[zef] to install Sparrowdo itself. Luckily for us,
there's a stable distribution of Perl 6 with everything we need added to it,
called https://rakudo.org/files[Rakudo Star]. And to make it easier for
GNU+Linux users, I wrote a tool to fetch the latest Rakudo Star release, compile
it and install it, called https://github.com/Tyil/lonestar[LoneStar]. Since this
tutorial will aim at GNU+Linux users, I'll use that to install Perl 6.

=== Installing Perl 6 with LoneStar
LoneStar is a Bash application to download, compile and set up Perl 6. It's a
standalone application, meaning you don't have to install it to your system. You
can just run it from the source directory. First, we'll have to get the source
directory, which we'll do using `git`.

[source,sh]
----
mkdir -p ~/.local/src
git clone https://github.com/tyil/lonestar.git ~/.local/src/lonestar
cd !$
----

Now you have the LoneStar sources available in `~/.local/src/lonestar`. You can
run the application using `./bin/lonestar`. Running it, you'll get some help
output:

[source]
----
$ ./bin/lonestar
lonestar - Installation manager for Rakudo Star

Usage: lonestar <action> [arguments...]

Actions:
  help      [action]
  init      [version=latest]
  install   [version=latest]
  path      [version=latest]
  reinstall [version=latest]
  upgrade
----

We'll be needing the `install` action to get Perl 6 installed, and the `init`
action to configure the `$PATH` environment variable. Depending on your
hardware, `install` may take a couple minutes as it will compile Rakudo Perl 6
and install some base modules. You might want to grab a drink during this
period.

[source]
----
$ ./bin/lonestar install
$ eval $(./bin/lonestar init)
$ perl6 -v
This is Rakudo Star version 2018.04.1 built on MoarVM version 2018.04.1
implementing Perl 6.c.
----

[NOTE]
====
If there's a newer version available of Rakudo Star, the version numbers given
by `perl6 -v` will differ for you.
====

=== Installing Sparrowdo with zef
Now that you have Perl 6 available and installed, you can continue on using
`zef` to install Sparrowdo. `zef` is bundled with Rakudo Star, so you don't have
to do anything to get it working.

[source,sh]
----
zef install Sparrowdo
----

This will instruct `zef` to install Sparrowdo and all its dependencies. This can
take a couple minutes, again depending on the hardware of your machine.

== Bootstrapping your system
The first step to working with Sparrowdo is bootstrapping the system you wish to
use it with. In this case, that'll be the local system. There's a `--bootstrap`
option to do this automatically.

[source,sh]
----
sparrowdo --bootstrap
----

[TIP]
====
If you wish to bootstrap a remote system, you can use the `--host` option to
specify the system. For example: `sparrowdo --host=192.168.1.2 --bootstrap`.
====

Now your system is ready to be configured automatically using Sparrowdo!

== Sparrowfiles
Sparrowfiles are the files that describe the tasks Sparrow should execute to
get you the configuration you want. They are valid Perl 6 code, and call the
subroutines (or _sparrowtasks_) that will handle the actual actions. By default,
when running `sparrowdo`, it will look for a file named `sparrowfile` in the
current directory.

To make our sample, we'll create a new directory to work in, so we have clean
directory that can be shared easily. You can also keep this directory under
version control, so you can distribute the `sparrowfile` with all its templates.

[TIP]
====
If you just want to create an empty directory to test things in, without
"polluting" the rest of your system, just call `cd -- "$(mktemp -d)"`. This will
create a temporary directory and change the working directory to there.
====

I'll be using `~/.local/sparrowdo/local-dns` to work in, as I'll be setting up a
local dns cache with http://www.thekelleys.org.uk/dnsmasq/doc.html[dnsmasq] for
the sample code.

=== Writing a `sparrowfile`
As noted in the previous paragraph, for the sake of a demo I'll guide you
through creating a `sparrowfile` to install and configure `dnsmasq` as a local
DNS cache. Using your favourite `$EDITOR`, write the following to `sparrowfile`:

[source,perl6]
----
package-install "dnsmasq";
directory "/etc/dnsmasq.d";
file-create "/etc/dnsmasq.conf", %(content => slurp "dnsmasq.conf");
file-create "/etc/dnsmasq.d/resolv.conf", %(content => slurp "resolv.conf");
service-start "dnsmasq";
----

This `sparrowfile` will set up the following configuration for `dnsmasq`:

- Install the `dnsmasq` package
- Create the `/etc/dnsmasq.d` directory in which we'll store configuration files
  for `dnsmasq`
- Create the configuration files `dnsmasq.conf` at `/etc/dnsmasq.conf`
- Create the `resolv.conf` in the `dnsmasq.d` directory
- Start the `dnsmasq` service

The configuration files will be created based on the configuration files in the
current directory. So for this to work, you'll need to also create the
appropriate configuration files. Let's start off with the main `dnsmasq`
configuration in `dnsmasq.conf`:

[source,conf]
----
listen-address=127.0.0.1

no-dhcp-interface=
resolv-file=/etc/dnsmasq.d/resolv.conf
----

This will make `dnsmasq` listen on the loopback interface, so it'll only be able
to be used by the local machine. Furthermore, DHCP functionality will be
disabled, and the upstream resolvers are read from `/etc/dnsmasq.d/resolv.conf`.
The contents of that file are as follows:

[source,conf]
----
nameserver 37.235.1.174
nameserver 37.235.1.177
----

These nameservers are part of the https://freedns.zone/en/[FreeDNS] project. You
can of course use whatever other DNS provider you want to use as your upstream
servers. Now, for `dnsmasq` to be used, you will also need to set your machine's
DNS resolvers to point to the `dnsmasq` service. This is defined in
`/etc/resolv.conf`, so lets append the following to our `sparrowfile` to set
that up.

[source,conf]
----
bash "chattr -i /etc/resolv.conf";
file-delete "/etc/resolv.conf";
file-create "/etc/resolv.conf", %(content => "nameserver 127.0.0.1");
bash "chattr +i /etc/resolv.conf";
----

This will remove the "immutable" attribute from `/etc/resolv.conf` if it's set.
Next it will remove the current `/etc/resolv.conf` and write out a new one which
only refers to the local machine as DNS resolver. This is to ensure an existing
`/etc/resolv.conf` gets recreated with the configuration we want. Finally, it
adds back the immutable attribute to the file, so other processes won't
overwrite it.

=== Running the `sparrowfile`
To run the `sparrowfile` and get the setup you desire, run the `sparrowdo`
command with `--local_mode` and wait.

[source]
----
sparrowdo --local_mode
----

[NOTE]
====
If you want to run this on a remote machine to configure that one instead, you
can use `--host=<ip>` instead of `--local_mode`.
====

You can check whether it actually worked by inspecting the files in
`/etc/dnsmasq.d` and your `/etc/resolv.conf`. The easiest way to check their
contents would be by using `cat`:

[source]
----
cat /etc/dnsmasq.d/dnsmasq.conf
cat /etc/dnsmasq.d/resolv.conf
cat /etc/resolv.conf
----

== Closing words

You should now have a working local DNS setup, configured programmatically
through Sparrowdo. This allows you easily get it working on other machines as
well, and updates can be done in a much simpler fashion for all of them
together.

If you have more interest in automating configuration with Sparrowdo, go check
their website, https://sparrowdo.wordpress.com/.
