Run on an on-prem cluster (expert)

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Integrate your own cluster

Lightning provides an interface for providing your own definition of a cluster environment. It mainly consists of parsing the right environment variables to access information such as world size, global and local rank (process id), and node rank (node id). Here is an example of a custom ClusterEnvironment:

import os
from lightning.pytorch.plugins.environments import ClusterEnvironment


class MyClusterEnvironment(ClusterEnvironment):
    @property
    def creates_processes_externally(self) -> bool:
        """Return True if the cluster is managed (you don't launch processes yourself)"""
        return True

    def world_size(self) -> int:
        return int(os.environ["WORLD_SIZE"])

    def global_rank(self) -> int:
        return int(os.environ["RANK"])

    def local_rank(self) -> int:
        return int(os.environ["LOCAL_RANK"])

    def node_rank(self) -> int:
        return int(os.environ["NODE_RANK"])

    def main_address(self) -> str:
        return os.environ["MASTER_ADDRESS"]

    def main_port(self) -> int:
        return int(os.environ["MASTER_PORT"])


trainer = Trainer(plugins=[MyClusterEnvironment()])