Project Earth Livestream Code Samples

1-helloworld.py

from random import randint
from time import sleep

import prefect
from prefect import Task, task


class AddTask(Task):
    def __init__(self, default: int, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.default = default

    def run(self, x: int, y: int = None) -> int:
        if y is None:
            y = self.default
        result = x + y
        self.logger.info("Result: {}".format(result))
        return x + y


add = AddTask(default=1)


@task
def sleepy_task(sleep_seconds: int) -> int:
    logger = prefect.context.get("logger")
    logger.info("Sleepy..... {}".format(sleep_seconds))
    sleep(sleep_seconds)
    return randint(1, 100)


from prefect import Flow

with Flow("My first flow!") as flow:
    first_int = sleepy_task(5)
    first_result = add(first_int, y=2)
    second_int = sleepy_task(8)
    second_result = add(x=second_int, y=100)
    third_result = add(x=first_result, y=second_result)


if __name__ == "__main__":
    flow.register("your-project-name-here")

2-start_core_server.sh

# you must have docker installed - go install for your OS at https://www.docker.com/get-started

# you must have prefect > 0.10.0
# install with whatever your package manager is - here I've used pip
# this was not shown as the demo as I had already installed 0.10.0
# pip install --upgrade "prefect>=0.10.0"

# configure your install to use the local backend
prefect backend server

# start the server
prefect server start

# in a new terminal window, register your flow
python helloworld.py

# start an agent
prefect agent start

# go click the run button for your flow at localhost:8080!

3-flip_to_cloud.sh

# configure your install to use the Cloud backend
prefect backend cloud

# authenticate to cloud as per
# https://docs.prefect.io/orchestration/tutorial/configure.html#authenticating-with-prefect-cloud
# this was not shown in the demo as I was already authenticated
# prefect auth login -t $YOUR_PREFECT_USER_AUTH_TOKEN

# register your flow. 
# this was not explicitly shown in the demo but you must have a matching project name in Cloud 
# for whatever your register() method in this file specifies
python helloworld.py

# start an agent
prefect agent start -t $PREFECT__CLOUD__AGENT__AUTH_TOKEN

# go click the run button for your flow at https://cloud.prefect.io!

Annotated code transcript from the demo at https://www.youtube.com/watch?v=k9arDAr1GeA

1. 1-helloworld.py is the flow I use for the demo of both server and core
2. 2-start_core_server.sh commands were shown first starting at 5:50
3. 3-flip_to_core.sh commands were shown following 18:00