Function Library — Context

The remaining C members give a JavaScript script identifiers, shared values and a way to emit a diagnostic message.

Member	Signature	Returns
`C.Misc.uuidv4`	`()`	A random UUID
`C.Misc.uuidv5`	`(name, namespace)`	A deterministic UUID
`C.Misc.validateUUID`	`(value)`	`true` for a well-formed UUID of any version
`C.Misc.getUUIDVersion`	`(uuid)`	The version number, or `undefined`
`C.Misc.zip`	`(keys, values, target)`	An object built from two parallel arrays
`C.os.hostname`	`()`	The Director's host name
`C.vars.<name>`	—	A configured shared value
`C.env.<name>`	—	An environment variable
`C.version`	—	The Director's version string
`C.confVersion`	—	The configuration version
`C.WorkerGroupId`	—	The worker group identifier
`C.log`	`(message, data)`	Nothing; writes to the Director's log
`debug`	`(message, data)`	Nothing; writes to the Director's log

Details

Identifiers

C.Misc.uuidv4() generates a random identifier — the right choice for tagging an event that has none.

C.Misc.uuidv5() derives an identifier from a name, so the same name always produces the same UUID. That makes it a way to give a recurring entity a stable identifier without storing a mapping. The namespace argument takes DNS, URL, OID, X500 or a UUID of your own; anything else throws.

Give each host a stable identifier...

- script:
    lang: js
    source: |
        if (__e.host) {
          __e['host.id'] = C.Misc.uuidv5(__e.host, 'DNS');
        }

Building an Object

C.Misc.zip() pairs two arrays into an object, stopping at the shorter of the two. Pass a third argument to add the pairs to an existing object rather than a new one.

__e.attributes = C.Misc.zip(__e.field_names, __e.field_values);

Shared Values

C.vars holds values configured on the Director and visible to every script — thresholds, allow lists, mappings that would otherwise be repeated in each pipeline.

if (C.vars.blocked_hosts.includes(__e.host)) {
  __e.blocked = true;
}

C.vars is read-only from a script. Assigning to it fails, so it cannot be used to pass a value between events. Reads return a copy, so modifying a nested object you read from it changes nothing.

Environment and Host

C.os.hostname() returns the host name of the Director running the pipeline, which is how an event is attributed to a node in a cluster.

C.env exposes environment variables as properties.

warning

C.env carries the Director process's entire environment, not a filtered subset. Anything passed to the process as an environment variable — including credentials — is readable by any script in any pipeline. Do not treat it as a safe place to read configuration from, and keep secrets in the Vault instead.

Version Values

C.version, C.confVersion and C.WorkerGroupId are fixed strings, useful for stamping an event with the deployment that produced it. C.confVersion reads as undefined where no configuration version is set.

Logging

C.log() and debug() both write a message to the Director's log, visible under Console Logs. Both take a message and an optional value. Neither throws, and neither returns anything useful.

debug('unexpected payload shape', __e._raw);

There is no console object — these two are the only way a script can emit a message. Use them while developing a script and remove them afterwards: a message written for every event is expensive and buries everything else in the log.

Details​

Identifiers​

Building an Object​

Shared Values​

Environment and Host​

Version Values​

Logging​