News from the Puppet-Mgmt Translator

CfgMgmtCamp 2018, Gent

Felix Frank, Systems Architect
The unbelievable Machine Company GmbH

Look who's talking

Felix (not an actual feline)

• codes things, but ops-es for a living
• Puppet nerd, writes things
• Berlin-izen, somehow not an expat

But why

enthused by mgmt since the initial presentations

James is a good chap

let ops tools be a happy family

Looking back on Part I

range("0", "93").each |$index| {
  if $index % 3 == 0 and $index % 5 == 0 {
    file { "/tmp/fizzbuzz/$index": ensure => present }
  } elsif $index % 3 == 0 {
    file { "/tmp/fizz/$index": ensure => present }
  } elsif $index % 5 == 0 {
    file { "/tmp/buzz/$index": ensure => present }
  }
}

Everyday Puppet (apply)

The approach

PuppetX::CatalogTranslation::Type.new :package do
  emit :pkg

  spawn :name do
    @resource[:name]
  end

  rename :ensure, :state do |value|
    case value
    when :installed, :present
      :installed
    when :purged, :absent
      :uninstalled
    else
      ...  

Demo! (Good!)

So what's new?

Now translating augeas resources

augeas {
  "enable replication":
    incl => "/etc/mysql/my.cnf",
    lens => "mysql.lns",
    changes => [
      "set target[3]/port 3307",
      "set target[3]/bind-address 127.0.0.1",
    ],
}

...except like this

augeas {
  "re-enable dns":
    incl => "/etc/mysql/my.cnf",
    lens => "mysql.lns",
    changes => [
      "rm target[3]/skip_name_resolve",
    ],
}

...or this...

augeas {
  "ensure InnoDB":
    changes => [
      "set /files/etc/mysql/my.cnf/target[3]/default_storage_engine InnoDB",
    ],
}

Otherwise, translator code
would look like this

  rename :incl, :file

Instead this happens

  spawn :file do
    if @resource[:incl]
      @resource[:incl]
    else
      translation_failure "does not use the 'incl' parameter, which mgmt needs"
      nil
    end
  end
  ignore :incl

Let's see some more demo (good!)

Also, AWS

mgmt now has native support
for managing EC2 instances

Puppet gets this through the puppetlabs/aws module

The translator copes

PuppetX::CatalogTranslation::Type.new :ec2_instance do
  emit :"aws:ec2"
  ...

Let's look at the list of supported parameters

mgmt EC2 parameters

• State
• Region
• Type
• ImageID
• WatchListenAddr (for SNS)
• UserData

Puppet EC2 parameters

well...

Translator input is potentially
rather more elaborate than the output

This must be communicated to the user

Let's see things break (bad!)

Severity levels

Warning: mgmt won't do it all,
but manage the essentials

Error: mgmt won't behave quite like Puppet

Works with small manifests and one-liners

Overwhelming at scale

It's about to get weird, folks

In light of this, let's take a step back

Do we want to run arbitrary manifests?

Do we want an established language?

Is it even feasible for mgmt
to become a Puppet stand-in?

Let's figure it out

See you at the hack day

Thanks

Attributions

• "Napster Bad" by Camp Chaos