# README

krontab

A crontab replacement for kubernetes.

You can use it to create cron jobs on a kubernetes cluster in a familiar crontab format. Krontab works by allowing you to create job templates which are used in kubernetes. Then create specific cron jobs using the crontab. Example:

# template: default
0 1 * * * echo hello  # name: test

Installation

Linux (x86 64-bit)

curl -L https://github.com/jacobtomlinson/krontab/releases/download/{LATEST VERSION}/krontab-linux-x86_64 -o /usr/local/bin/krontab
chmod +x /usr/local/bin/krontab

Linux (arm 32-bit)

curl -L https://github.com/jacobtomlinson/krontab/releases/download/{LATEST VERSION}/krontab-linux-arm -o /usr/local/bin/krontab
chmod +x /usr/local/bin/krontab

OS X (64-bit)

curl -L https://github.com/jacobtomlinson/krontab/releases/download/{LATEST VERSION}/krontab-darwin-x86_64 -o /usr/local/bin/krontab
chmod +x /usr/local/bin/krontab

Configuration

Krontab is configured with environment variables.

Env var	Default	Description
`KRONTAB_NAMESPACE`	`default`	The kubernetes namespace to use.
`KRONTAB_OWNER`	N/A	The owner of a cronjob. This will be used when creating jobs and will be used as a filter when listing them.

Usage

$ krontab help
Krontab is a crontab replacement for kubernetes.

You can use it to create cron jobs on a kubernetes cluster in a familiar crontab format.
Krontab works by allowing you to create job templates which are used in kubernetes. Then create
specific cron jobs using the crontab. Example krontab:

# Crontab example

# template: default
0 1 * * * echo hello  # name: test

Usage:
  krontab [flags]
  krontab [command]

Available Commands:
  create      Create a krontab resource
  delete      Delete a krontab resource
  edit        Edit a krontab resource
  get         Get krontab resources
  help        Help about any command
  list        List krontab resources
  run         Run a krontab job
  version     Print the version number of krontab

Flags:
  -e, --edit-crontab   Edit the crontab
  -h, --help           help for krontab
  -l, --list-crontab   List the crontab

Use "krontab [command] --help" for more information about a command.

Templates

Krontab uses templates to turn your crontab into Kubernetes CronJob resources. You will get a default template which you can view with krontab get template default. You can create, edit and delete your own templates too.

$ krontab get template default
apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: test
spec:
  schedule: 0 */6 * * *
  jobTemplate:
    metadata:
      name: test
      krontabTemplate: default
    spec:
      template:
        metadata:
        spec:
          restartPolicy: Never
          containers:
            - name: test
              image: busybox
              command: ["echo", "hello"]
              resources:
                limits:
                  cpu: "1"
                  memory: 2G
                requests:
                  cpu: "0.25"
                  memory: 0.5G

Crontab

Krontab will automatically generate a crontab from your existing Kubernetes CronJob resources. You can edit them with krontab -e or krontab edit crontab. Adding new lines to your crontab will be mapped into new CrobJob resources. Editing lines will update them and deleteing lines will remove them.

$ krontab -e
# Welcome to krontab, a crontab like editor for Kubernetes cron jobs.
#
# This is a virtual file and was generated from the kubernetes API. Any edits you make here will be
# sent back to the kubernetes API to create/update/delete CronJob resources. Next time you open this crontab
# you may notice different formatting and comments to how you save it. Comments are meaningful and contain
# metadata about the job.
#
# Example job
# -----------
#
# # template: default
# 0 1 * * * echo hello world  # name: hello-world
#
# Templates
# ---------
#
# Krontab uses templates to turn your your crontab into kubernetes compliant CronJob resources. You will find
# a default template by running 'krontab get template default'. This is a minimal CrobJob resource with runs your
# command in a ubuntu container. When krontab creates your jobs it will replace the container command and schedule pattern
# in the template with the command and schedule pattern from the crontab.
#
# All cronjobs following a '# template: <name>' comment will be created using that template. If no template comments exist
# then the default template will be used.
#
# Names
# -----
# Kubernetes requires each job to have a name and is specified at the end of a job with a '# name: <name>' comment.
# If you do not specify a name one will be autogenerated.


# template: default
0 1 * * * echo hello world  # name: test

Contributing

Environment

This project requires Go to be installed. On OS X with Homebrew you can just run brew install go.

Running it then should be as simple as:

$ make
$ ./bin/krontab

Testing

$ make test

Releasing

Decide the new release version. Check out the current releases and follow SemVer to work out what it will be. Then run make release which will ask for the tag in the form v{major}.{minor}.{patch}. This will create the tag and push it to GitHub, Travis CI will then build the binaries and push them to github along with some autogenerated release notes.

$ make release