Skip to main content

Writing puppet manifests that can remove resources as well as adding them

I use puppet to manage the configuration of the machines I manage. So far, I've been rolling out new resources to machines but recently I've wanted to remove resources from machines. Here's how I modified my cron classes so I could remove cron jobs as well as create them.

When I first wrote my cron classes, I created a separate class for each cron job, eg.

class app::queue_processor::cron::cacheload {    include        user::base    cron { cacheload:        command => '/usr/bin/php /app/queue_processor/utils/cacheload.php account > /dev/null 2>&1',        hour    => '0',        minute  => '0',        user    => 'app',        require => User['app']    }}

I then created another class for each profile which includes all the required cron jobs, eg:

class profile::partition::cron {    include        app::queue_processor::cron::cacheload        app::queue_processor::cron::send_move_backlog}

This all works fine and the cron jobs are installed as required. However, I recently needed to remove the cacheload cron job from all machines.

This is simply a matter of specifying "ensure => absent" to the cron type. I therefore needed some way of passing this to the cron job classes.

I did this by creating a higher-level cron class, app::queue_processor::cron containing a definition app::queue_processor::cron::job which takes an ensure parameter that defaults to "present" if not specified. It looks like this:

class app::queue_processor::cron {}define app::queue_processor::cron::job($ensure = present) {    include user::base    case $name {        cacheload: {            cron { $name:                command => '/usr/bin/php /app/queue_processor/utils/cacheload.php account > /dev/null 2>&1',                hour    => '0',                minute  => '0',                user    => 'app',                require => User['app']                ensure  => $ensure            }        }        send_move_backlog: {            cron { $name:                # similar cron definition here            }        }        default: { fail("Unknown queue_processor cron job type: $name") }    }}

I use this new define in the profile::partition::cron class like this:

class profile::partition::cron {    include app::queue_processor::cron    app::queue_processor::cron::job{ send_move_backlog: }    app::queue_processor::cron::job{ cacheload: ensure => absent }}
Labels:

Comments

Post a Comment

Popular posts from this blog

Python logging with rich - writing to stderr - plain output when writing to file

Rich is a Python library for writing rich text (with color and style) to the terminal, and for displaying advanced content such as tables, markdown, and syntax highlighted code. Rich provides RichHandler , a logging handler for python's logging module which will format and colorize text written by the module. However, RichHandler writes to stdout by default. More specifically, it writes to a rich Console object which, by default, writes to stdout. To make RichHandler write to stderr by default, you must pass in a Console object which has been configured to write to stderr: import logging from rich.console import Console from rich.logging import RichHandler DATEFMT = "%Y-%m- %d T%H:%M:%SZ" FORMAT = " %(message)s " logging . basicConfig( level = "NOTSET" , format = FORMAT, datefmt = DATEFMT, handlers = [RichHandler(console = Console(stderr = True ))], ) logger = logging . getLogger(__name__) logger . i...
Post a Comment
Read more

Fix python import order on save in vim with ruff and ale

My IDE of choice is vim. I use various tools to perform linting and code formatting, and configure them all with ALE  (the Asynchronous Lint Engine). After using several discrete tools ( black , isort , flake8 , etc) I have settled on using Ruff to do my python code formatting and linting. Here's the relevant fragment of my ALE config in my .vimrc: " ALE config let g :ale_fixers = { \ 'python' : [ 'ruff' , 'ruff_format' ], \} let g :ale_linters = { \ 'python' : [ 'ruff' ], \} let g :ale_python_ruff_use_global = 1 One of the last remaining wrinkles I had was getting Ruff to automatically sort import statements. Sorting imports is performed by the Ruff linter, not the formatter, which is documented here . The fix on the command line is to add an option, like this: ruff check --select I --fix The difficulty I had was getting this to happen in the editor when the file was saved. It turns out, all I needed to do was ...
Post a Comment
Read more

Escaping special characters in wget username or password

I recently offered to help out with the hosting of a WordPress  site. It’s currently hosted somewhere with no shell access – just ftp – and there are a lot of images to transfer. I quickly figured out I could use wget to mirror the site, using something like: wget -m ftp://username:password@example.com However, this broke in this case because the username for the site contained an @ character (the username was user@example.com ). Turns out the solution was to encode the special chars using HTML notation. This is the command that did the trick: wget -m ftp://user%40example.com:password@example.com
Post a Comment
Read more