Quantum

Cron-like job scheduler for Elixir.

• Setup
• Usage
  • Named jobs
  • Nodes
  • Timezone
  • Crontab format
  • Special expressions
  • Override default settings
• Contribution
• License

Setup

To use Quantum in your project, edit the mix.exs file and add Quantum to both

1. the list of dependencies:

defp deps do
  [{:quantum, ">= 1.7.0"}]
end

2. and the list of applications:

def application do
  [applications: [:quantum]]
end

Usage

Configure your cronjobs in your config/config.exs like this:

config :quantum, cron: [
    # Every minute
    "* * * * *":      {"Heartbeat", :send},
    # Every 15 minutes
    "*/15 * * * *":   fn -> System.cmd("rm", ["/tmp/tmp_"]) end,
    # Runs on 18, 20, 22, 0, 2, 4, 6:
    "0 18-6/2 * * *": fn -> :mnesia.backup('/var/backup/mnesia') end,
    # Runs every midnight:
    "@daily":         &Backup.backup/0
]

or like this:

config :quantum, cron: [
    # Every minute
    "* * * * *": {MyApp.MyModule, :my_method}
]

or you can provide module as a string:

config :quantum, cron: [
    # Every minute
    "* * * * *": {"MyApp.MyModule", :my_method}
]

Or even use cron-like format (useful with conform / exrm / edeliver):

config :quantum, cron: [
    # Every minute
    "* * * * * MyApp.MyModule.my_method"
]

If you want to add jobs on runtime, this is possible too:

Quantum.add_job("1 * * * *", fn -> :ok end)

Named jobs

Job struct:

%Quantum.Job{
  name: :job_name, # is set automatically on adding a job
  schedule: "1 * * * *", # required
  task: {MyApp.MyModule, :my_method}, # required
  args: [:a, :b] # optional, default: []
  state: :active, # is used for internal purposes
  nodes: [:node@host], # default: [node()]
  overlap: false, # run even if previous job is still running?, default: true
  pid: nil # PID of last executed task
}

You can define named jobs in your config like this:

config :quantum, cron: [
  news_letter: [
    schedule: "@weekly",
    task: "MyApp.NewsLetter.send", # {MyApp.NewsLetter, :send} is supported too
    args: [:whatever]
  ]
]

Possible options:

• schedule cron schedule, ex: "@weekly" or "1 * * * *"
• task function to be performed, ex: "MyApp.MyModule.my_method" or {MyApp.MyModule, :my_method}
• args arguments list to be passed to task
• nodes nodes list the task should be run on, default: [node()]
• overlap set to false to prevent next job from being executed if previous job is still running, default: true

So now you can control your jobs behavior on runtime.

For runtime configuration, job names are not restricted to be atoms. Strings, atoms and charlists are allowed as job names.

Add named jobs on runtime:

job = %Quantum.Job{schedule: "* * * * *", task: fn -> IO.puts "tick" end}
Quantum.add_job("ticker", job)

Deactivate job (will not be performed until activation):

Quantum.deactivate_job(:ok_job)
Quantum.deactivate_job(:news_letter)

Activate inactive job:

Quantum.activate_job(:ok_job)
Quantum.activate_job(:news_letter)

Find job:

Quantum.find_job(:ok_job)
# %Quantum.Job{...}
Quantum.find_job(:news_letter)
# %Quantum.Job{...}

Delete job:

Quantum.delete_job(:ok_job)
# %Quantum.Job{...}
Quantum.delete_job(:news_letter)
# %Quantum.Job{...}

Nodes

If you need to run a job on a certain node you can define:

config :quantum, cron: [
  news_letter: [
    # your job config
    nodes: [:app1@myhost, "app2@myhost"]
  ]
]

NOTE If nodes is not defined current node is used and a job is performed on all nodes.

Timezone

Please note that Quantum uses UTC timezone and not local timezone by default.

To use local timezone, add the following timezone option to your configuration:

config :quantum,
  cron: [
    # Your cronjobs
  ],
  timezone: :local

Crontab format

| Field | Allowed values | ———— | ————– | minute | 0-59 | hour | 0-23 | day of month | 1-31 | month | 1-12 (or names) | day of week | 0-6 (0 is Sunday, or use names)

Names can also be used for the month and day of week fields. Use the first three letters of the particular day or month (case does not matter).

Special expressions

Instead of the first five fields, one of these special strings may be used:

| String | Description | ———– | ———– | @annually | Run once a year, same as "0 0 1 1 *" or @yearly | @daily | Run once a day, same as "0 0 * * *" or @midnight | @hourly | Run once an hour, same as "0 * * * *" | @midnight | Run once a day, same as "0 0 * * *" or @daily | @monthly | Run once a month, same as "0 0 1 * *" | @reboot | Run once, at startup | @weekly | Run once a week, same as "0 0 * * 0" | @yearly | Run once a year, same as "0 0 1 1 *" or @annually

Override default settings

The default job settings can be configured as shown in the example below. So if you have a lot of jobs and do not want to override the default setting in every job, you can set them globally.

config :quantum,
  cron: [
    # Your cronjobs
  ],
  default_schedule: "* * * * *",
  default_args: ["my api key"],
  default_nodes: [:app1@myhost],
  default_overlap: false

Contribution

This project uses the C4.1 process for all code changes.

“Everyone, without distinction or discrimination, SHALL have an equal right to become a Contributor under the terms of this contract.”

tl;dr

1. Check for open issues or open a new issue to start a discussion around a problem.
2. Issues SHALL be named as “Problem: description of the problem“.
3. Fork the quantum-elixir repository on GitHub to start making your changes
4. If possible, write a test which shows that the problem was solved.
5. Send a pull request.
6. Pull requests SHALL be named as “Solution: description of your solution“
7. Your pull request is merged and you are added to the list of contributors

License

Apache License, Version 2.0