Batch process scheduling on a single UNIX machines has historically been managed by cron and its derivatives. But if you have many batches, complex dependencies between batches, or many machines, maintaining config files across them may be difficult. Tron solves this problem by centralizing the configuration and scheduling of jobs to a single daemon.

The Tron system is split into four commands:


Daemon responsible for scheduling, running, and saving state. Provides an HTTP interface to tools.


View job state and output.


Start, stop, enable, disable, and otherwise control jobs.


Change Tron’s configuration while the daemon is still running.

The config file uses YAML syntax, and is further described in Configuration.

Nodes, Jobs and Actions

Tron’s orders consist of jobs. Jobs contain actions which may depend on other actions in the same job and run on a schedule.

trond is given access (via public key SSH) to one or more nodes on which to run jobs. For example, this configuration has two nodes, each of which is responsible for a single job:

    hostname: 'localhost'
  - name: node1
    hostname: 'batch1'
  - name: node2
    hostname: 'batch2'

    node: node1
    schedule: "cron * * * * *"
        command: "sleep 3; echo asdfasdf"
    node: node2
    schedule: "cron * * * * *"
        command: "cat big.txt; sleep 10"

How the nodes are set up and assigned to jobs is entirely up to you. They may have different operating systems, access to different databases, different privileges for the Tron user, etc.

See also:

Node Pools

Nodes can be grouped into pools. To continue the previous example:

    - name:pool
      nodes: [node1, node2]

  # ...
    node: pool
    schedule: "cron * * * * *"
        command: "ls /; sleep 1"
      command: "echo 'all done'"

job2’s action will be run on a random node from pool every 5 seconds. When pool_action is complete, cleanup_action will run on the same node.

For more information, see Jobs.


While Tron solves many scheduling-related problems, there are a few things to watch out for.

Tron keeps an SSH connection open for the entire lifespan of a process. This means that to upgrade trond, you have to either wait until no jobs are running, or accept an inconsistent state. This limitation is being worked on, and should be improved in later releases.

Tron is under active development. This means that some things will change. Whenever possible these changes will be backwards compatible, but in some cases there may be non-backwards compatible changes.

Tron does not support unicode. Tron is built using twisted which does not support unicode.