Having job run on only one node in cluster

[krisleech]

I noticed that a job is seems to be run either zero, once or more than once on each node in a cluster on my local machine.

The configuration is:

config :export, Export.Scheduler,
  jobs: [
    [
      schedule: "* * * * *", 
      task: fn -> IO.puts("hello #{inspect(DateTime.utc_now())}") end
    ]
  ]

If I start three nodes then I get the following output:

alice node

[debug] file=lib/quantum/execution_broadcaster.ex  Scheduling job for execution
hello ~U[2024-11-05 14:41:00.663749Z]
[debug] file=lib/quantum/executor.ex  Task for job started on node
[debug] file=lib/quantum/executor.ex  Execute started for job
[debug] file=lib/quantum/executor.ex  Execution ended for job

Runs onces.

bob node

[debug] file=lib/quantum/execution_broadcaster.ex  Scheduling job for execution
[debug] file=lib/quantum/executor.ex  Task for job started on node
hello ~U[2024-11-05 14:41:00.049222Z]
[debug] file=lib/quantum/executor.ex  Execute started for job
[debug] file=lib/quantum/executor.ex  Execution ended for job
hello ~U[2024-11-05 14:41:00.567387Z]
[debug] file=lib/quantum/executor.ex  Execute started for job
[debug] file=lib/quantum/executor.ex  Execution ended for job

Runs twice.

kris node

[debug] file=lib/quantum/execution_broadcaster.ex  Scheduling job for execution
[debug] file=lib/quantum/executor.ex  Task for job started on node

Runs zero times.

I tried adding the Quantum.RunStrategy.Random as the run strategy (which I thought was the default anyway) but got the following error:

config :export, Export.Scheduler,
  run_strategy: Quantum.RunStrategy.Random
  jobs: [
    [
      schedule: "* * * * *", 
      task: fn -> IO.puts("hello #{inspect(DateTime.utc_now())}") end
    ]
  ]

# (FunctionClauseError) no function clause matching in Quantum.RunStrategy.Random.normalize_config!/1
            (quantum 3.5.3) lib/quantum/run_strategy/random.ex:33: Quantum.RunStrategy.Random.normalize_config!(nil)
            (elixir 1.17.3) lib/keyword.ex:1144: Keyword.update!/4
            (elixir 1.17.3) lib/keyword.ex:1148: Keyword.update!/4
            (export 0.1.0) /Users/kris/dev/nimbus/apps/abacus/deps/quantum/lib/quantum.ex:416: Export.Scheduler.__new_job__/2

Any help would be much appreciated!

I am using libcluster to enrol the nodes in a cluster and can see in Node.list() that this is the case.