Tips and Patterns

Module Layout and Naming

Generally the Playbooks behave as you would expect any modern Puppet function or data type.

You place the Playbook mymod::mybook in modules/mymod/plans/mybook.pp and in there you need plan mymod::mybook. Naming of Playbooks are subject to the same naming rules as Puppet, for example you cannot have a - in the Playbook name.

When running in this mode Puppet has a number of changes in behaviour for example strict variable checks are enabled by default and templates are disabled. I cannot find a list of these behaviour changes but it’s something to be aware of.

Interacting With Task Results

When a task is run it returns an instance of Choria::TaskResults which contains one of more Choria::TaskResult for every node that was affected by the task.

Each Choria::TaskResult has the following properties you can use:

Property / Method Type Description
host Choria::Node The hostname this result apply to
result Data The data that was returned from the task, this depends on the type of task
error Optional[Error] A Puppet standard Error object if the task failed
ok Boolean If the task was successful, always true when fail_ok is given
type String[1] The type of task that this result represents, like mcollective
$r["foo"] Data Utility to access the data of the result if it’s a hash
value Data The entire value that the task produced

Each Choria::TaskResults has the following properties you can use:

Property / Method Type Description
results Array[Choria::TaskResult] The individual results
count Integer How many results are contained in this set
empty Boolean If no results are contained in this set
error_set Choria::TaskResults A new result set with only failing nodes
ok_set Choria::TaskResults A new result set with only passing nodes
ok Boolean If all contained results were ok
fail_ok Boolean If failures are ignored when checking ok
hosts Choria::Nodes List of nodes in this result set
message String A short descriptive message about the outcome
find("some.node") Optional[Choria::TaskResult] Finds the Choria::TaskResult for a specific node
first Optional[Choria::TaskResult] Returns just the first Choria::TaskResult

With these you can do complex error and result handling, display statusses you like, send to Slack etc.

$result = choria::task("action" => "", "nodes" => $nodes, "fail_ok" => true)

if $result.error_set.empty {
  notice(sprintf("Ping reached %d nodes", $result.count))
  notice(sprintf("Outcome: %s", $result.message))
} else {
  notice(sprintf("Ping failed on: %s", $result.error_set.hosts.join(", "))

If you return these from a plan - or the last statement in your plan is a choria::task you can interact and error handle plans based on these.

Nodes on the CLI

Generally nodes come from node sets but you can also use a input to mimic a node set to some extend.

plan example::cli_nodes (
  Array[String] $nodes
) {
  # use $nodes

You can now supply nodes like this:

$ mco playbook run playbook.yaml --nodes --nodes

You can also load nodes from some file like this:

$ mco playbook run playbook.yaml --input @nodes.json

Your JSON would just have a array of node names in JSON format, you can also use YAML format by naming the file nodes.yaml

Error Handling Strategies

By default when you run a playbook any failure will just fail the playbook, but you might want to handle failures and branch to recovery code after failure, here’s a Playbook that handles failures and success, I’ll show a few possible syntaxes of the same thing:

The key to error handling is to pass _catch_errors => true to choria::run_playbook which would avoid raising errors instead giving you a chance to handle them.

choria::run_playbook("example::app_upgrade", _catch_errors => true,
  "action" => "appmgr.restart",
  "nodes" => $nodes)

    .choria::on_error |$err| {
      notice("Application upgrade failed: ${err.message}, recovering using example::recover")

        "cluster" => $cluster

      fail("deploying cluster ${cluster} failed, recovery run succesfully")}

    .choria::on_success |$results| {
      notice("deployment succesful on cluster ${cluster}")}

This syntax might be a bit foreign to Puppet users, here’s another approach but now you need temporary variables which can be very annoying:

$result = choria::task("mcollective", _catch_errors => true,
  "action" => "appmgr.restart",
  "nodes" => $nodes

$result.choria::on_error |$results| {
    "cluster" => $cluster

  fail("deploying cluster ${cluster} failed, recovery run succesfully")

$result.choria::on_success |$results| {
  notice("deployment succesful on cluster ${cluster}")

The Base Example page shows this in action where one Playbook wraps another and provides custom error handling.

These functions are clever enough to only trigger for Choria::TaskResults so if you wish to handle failures AND return non Choria::TaskResults from a Plan that’s totally ok.

plan example::update {
  $nodes = choria::discover(
    # ....

    # ...

$nodes = choria::run_playbook("example::update", _catch_errors => true)
  .on_error |$err| {
    # handle

notice($nodes.join(", "))

In this example your $nodes is an array or strings, the example::update returns the nodes and you print it using join which only works with arrays. However if the task failed you’d get a Choria::TaskResults back and the error handling will deal with that failure for you.

Utility Functions and Playbooks

These playbooks tend to be made up of a lot of basic building blocks. For example I find I often need to disable Puppet and wait for them to idle, lets look how we can make this reusable.

plan example::puppet::disable_and_wait (
  String $message = sprintf("Disabled by Choria Playbook $s", $facts["choria"]["playbook"]),
  Integer $checks = 20,
  Integer $sleep = 10
  $nodes = choria::discover(
    "discovery_method" => "choria",
    "test" => true,
    "agents" => ["puppet"],

    "action" => "puppet.disable",
    "nodes" => $nodes,
    "fail_ok" => true,
    "silent" => true,
    "properties" => {
      "message" => $message

    "action"    => "puppet.status",
    "nodes"     => $nodes,
    "assert"    => "idling=true",
    "tries"     => $checks,
    "silent"    => true,
    "try_sleep" => $sleep,
    "pre_sleep" => 5,

You can now use this Playbook wherever you need this functionality or indeed from the CLI. This is the benefit of using a Playbook as the abstraction rather than functions since they can be called from the CLI.

$results = choria::run_playbook("example::puppet::disable_and_wait",
  "message" => "Disabled while restarting Puppet Server",
$ mco playbook run example::puppet::disable_and_wait --message "disabled while testing"

For things that clearly have no standalone value functions can be made:

function example::plan_rc(String $key) >> String {
  choria::data($key, {
    "type"   => "file",
    "file"   => "~/.plans.rc",
    "format" => "yaml"

Here you can just call $something = example::plan_rc("something") whenever you want to fetch some data from your data source.

Iterating Subsets of Node Sets

There’s a small utility function that can iterate over arrays and call a provided block with a subset of the whole array, this is handy for performing multiple actions on batches.

$nodes.choria::in_groups_of(10) |$n| {
  # here $n is 10 nodes or fewer
  # see the example in the basics section for this in action

Validating Playbook syntax

You can use the standard Puppet CLI to validate your Playbook syntax if you pass –tags like puppet parser validate --tasks playbook.pp

Documentation using Puppet Strings

You can document your plans using the normal Puppet Strings, when generating documents for a module with Playbooks in it just pass –tags like puppet strings generate --tasks 'example/**/*.pp'