Output the Date and Time in AutoPkg Recipes

Posted on by Matthew Warren

I recently needed to use the date and time of an AutoPkg run from within the context of recipe.

While AutoPkg itself is aware of the date and time of a run, that information is not accessible to other processors within the recipe.

To fill this need, I wrote a new AutoPkg processor: DatetimeOutputter.

DatetimeOutputter helps you reference the current date and time as a variable within your AutoPkg recipes. Additionally, it can calculate future and past dates to enhance advanced workflows.

Current date and time

At its core, DatetimeOutputter adds a datetime variable to an AutoPkg recipe execution. The datetime is outputted in ISO 8601 format relevant to the local time of the computer running the recipe.

Calling the processor using Shared Processor syntax, with no arguments, invokes this default behavior. Here are examples in both XML and YAML recipe format.

XML:

<key>Process</key>
<array>
    <dict>
        <key>Processor</key>
        <string>com.github.haircut.processors/DatetimeOutputter</string>
    </dict>
</array>

YAML:

Process:
  - Processor: com.github.haircut.processors/DatetimeOutputter

This will output a new datetime variable you can use in subsequent processors. datetime will look something like 2022-03-01T09:45:45.544391 by default.

You can control the output format by supplying a datetime_format argument. The processor accepts any strftime-compatible format.

Additionally, you can pass the use_utc argument as True to output the datetime relative to UTC rather than your computer's local time.

This example illustrates both concepts:

Process:
  - Processor: com.github.haircut.processors/DatetimeOutputter
    Arguments:
      datetime_format: "%A, %B %e, %Y at %l:%M %p"
      use_utc: True

This would output something like Tuesday, March 1, 2022 at 1:45 PM based on UTC time.

Past and future dates

It's handy to know when a recipe runs, but determining past and future dates – e.g. one week from now, or 3 days ago – can augment many workflows.

DatetimeOutputter can generate an arbitrary number of datetime "deltas." A datetime delta adds or subtracts time from the current datetime and outputs a variable in your preferred format.

Outputting a delta requires specifying a few arguments.

The interval argument accepts any number of keyword arguments compatible with Python's timedelta object, as listed above. This means you may need to convert far-future or past intervals to "weeks" or "days;" e.g. instead of specifying months: 2, use weeks: 8.

Here's an example of outputting two deltas:

- Processor: com.github.haircut.processors/DatetimeOutputter
  Arguments:
    deltas:
      - output_name: one_week_in_future
        direction: future
        datetime_format: "%Y-%m-%d 00:00:00"
        interval:
          weeks: 1
      - output_name: two_days_six_hours_twelve_minutes_ago
        direction: past
        datetime_format: "%A, %B %e, at %Y %H:%M:%S"
        interval:
          days: 2
          hours: 6
          minutes: 12

This would output two new variables as follows:

You can output as many deltas as you need by simply adding new dictionaries to the deltas array of the processor. Each will be available for use by later processors via variable substitution.

Deltas always respect the use_utc option of the processor, if set. In a single run of DatetimeOutputter you cannot output UTC- and non-UTC-based datetimes. If you have a need for this, run DatetimeOutputter multiple times in your recipe, setting use_utc accordingly.

Example use cases

Keep it simple with just the date and time

In the simplest use case, you might wish to note the date a package was uploaded by JamfUploader within the Jamf Pro package notes field. Call DatetimeOutputter first to generate the datetime variable, then reference that variable as %datetime% in the next processor like so:

Process:
  - Processor: com.github.haircut.processors/DatetimeOutputter
  - Processor: com.github.grahampugh.jamf-upload.processors/JamfPackageUploader
    Arguments:
      pkg_notes: "Uploaded via AutoPkg %datetime%"

Output a future datetime for use with Munki's "force install after date" feature

Munki includes a feature to force installation of a package after a specified date. Setting the force_install_after_date key in a package's pkginfo dictionary will cause client Macs to forcefully logout or restart to install the software after that (local) date and time.

If you use this functionality, Munki recommends setting the force_install_after_date to at least 2 weeks in the future.

DatetimeOutputter can help you generate this future date in the required format:

- Processor: com.github.haircut.processors/DatetimeOutputter
  Arguments:
    format: "%Y-%m-%dT%H:%M:%SZ"
    deltas:
      - output_name: force_after
        direction: future
        interval:
          weeks: 2

- Processor: MunkiImporter
  Arguments:
    MUNKI_REPO: <path to Munki repo>
    pkg_path: "%pkg%"
    pkginfo:
      force_install_after_date: "%force_after%"

This will automate the calculation of a two-week window after uploading the package during which users will be prompted – but not forced – to install the package. After force_date passes, users will be forced to install the software.

Output a future date for use with a Jamf Pro policy activation date

You might wish to delay the installation of an application update for some number of days after release. One way to do this is to configure a Jamf Pro policy to include the "Activation Date/Time" server-side limitation. This prevents the policy from running before the configured date and time.

DatetimeOutputter can generate a dynamic datetime stamp n number of days in the future. This means the new version of an application will be uploaded to your Jamf Pro server, and the installation policy ready to go when the Activation Date/Time rolls around. Automatically!

First, we add an activation_date key to the date_time_limitations of a policy template. We populate the key with an %activation_date% substitution variable we will later define within the associated AutoPkg recipe.

Install-after-1-week.xml

<?xml version="1.0" encoding="UTF-8"?>
<policy>
    <general>
        <name>Install %NAME% 1 Week After Release</name>
        <enabled>true</enabled>
        <trigger>CHECKIN</trigger>
        <trigger_checkin>true</trigger_checkin>
        <frequency>Once per computer</frequency>
        <date_time_limitations>
            <activation_date>%activation_date%</activation_date>
        </date_time_limitations>
    </general>
    <scope>
        <all_computers>false</all_computers>
        <computer_groups>
            <computer_group>
                <name>%UPDATE_GROUP_NAME%</name>
            </computer_group>
        </computer_groups>
    </scope>
    <self_service>
        <use_for_self_service>false</use_for_self_service>
    </self_service>
    <package_configuration>
        <packages>
            <size>1</size>
            <package>
                <name>%pkg_name%</name>
                <action>install</action>
            </package>
        </packages>
    </package_configuration>
</policy>

Next, we'll use DatetimeOutputter to generate a datestamp 1 week in the future from the time of the AutoPkg run, in the format Jamf Pro expects for midnight on that date. We set the output_name to activation_date to match what the policy template expects.

- Processor: StopProcessingIf
  Arguments:
    predicate: "pkg_uploaded == False"

- Processor: com.github.haircut.processors/DatetimeOutputter
  Arguments:
    deltas:
      - output_name: activation_date
        direction: future
        datetime_format: "%Y-%m-%d 00:00:00"
        interval:
          weeks: 1

- Processor: com.github.grahampugh.jamf-upload.processors/JamfPolicyUploader
  Arguments:
    policy_name: "Install %NAME% 1 Week After Release"
    policy_template: "Install-after-1-week.xml"

This will create a policy that installs the uploaded package, but remains inactive until 1 week in the future. At that future date, the policy will automatically activate and install on eligible Macs.

More info

These are just a few of the potential use cases for this processor. Please check the full details in the README. And as always – pull requests are open if you have an improvement or correction!


Questions or comments?

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