Hi folks, quick API question — in this query I can grab a particular parameter (awesome) but would love to be able to filter on a particular value, e.g. “company_slug=acmecorp” — is this possible today? Thanks 🙏

query {
  flow_run {
    name
    parameters(path: "company_slug")
  }
}

I'm registering a Flow with two Schedules, my intent is to have the same Flow run twice but with different Parameters for each run:

schedule=Schedule(
            clocks=[
                IntervalClock(
                    start_date=pendulum.datetime(2020, 1, 1, tz='UTC'),
                    interval=datetime.timedelta(days=1),
                    parameter_defaults=dict(
                        sfdc_listener_name='CustomerService',
                        sfdc_report_url='...'
                    )
                ),
                IntervalClock(
                    start_date=pendulum.datetime(2020, 1, 1, tz='UTC'),
                    interval=datetime.timedelta(days=1),
                    parameter_defaults=dict(
                        sfdc_listener_name='OneSupport',
                        sfdc_report_url='...'
                    )
                )
            ]
        ),

However, it seems that when this registered with Prefect Cloud, only the first Schedule is setup. Do I need to create two different Flows to have the same logic execute with different parameters on a schedule?

Is there a way to have a

Parameter

whose default is the value of another

Parameter

? Something like

from prefect import task, Flow, Parameter

@task
def add(x, y):
    return x + y

with Flow('flow') as flow:
    a = Parameter('a', default=0)
    b = Parameter('b', default=a)
    c = add(a, b)

Hi folks, I lead an ML and data science team, and I’m evaluating a bunch of tools in this space. Prefect looks very nice indeed, but I am having trouble understanding exactly what I get with a paid plan vs the open source core. I have looked at all the feature lists I can find, but I guess I’m missing one of those classic “feature comparison tables” that one often sees. Can someone point me in the direction of something like that?

Hello everyone! I'm using a

switch

. Is it possible to access the results of the switch in a subsequent task? For example, I have a list of data (some of which contain latitude/longitude and others don't). My switch consists of getting lat/long for the records that are missing it, while records that do have coordinates are simply returned. How can I access the final, joined list after the switch?

Hello there 👋, I'm a new user of Prefect, coming from the Airflow world when I happily used it for 3+ years. 🎂 I want to begin by saying that the project, the quality of the code and the quality of the documentation are outstanding 🤩 But I need some help about finding the good way to use it and the good practice 🤓 I have a standard ELT flow with a big json file (1GB) as input. For my task to run successfully on my medium machine, I combine ijson and iterator to read and write the file on disk chunk by chunk and not overload the memory (I can't stuck a 1GB json dict in memory) Then I load the file directly into my DB, without passing via python. What is the prefect-way of handling a similar usecase here? 🤔 Prefect encourage passing data from task to task in-memory but here, I offload it to disk and only pass the path of the file between task. Is there a way to pass an iterator between task instead of a single object? One way I'm thinking of doing it in a industrialized way is maybe to share a file cache between tasks. What do you guys think about it?

Has anyone had success using a large Docker base image? I'm trying to convert a Selenium script into a Prefect Flow .. for Selenium, it requires a full install of Google Chrome which makes the base image around 700MB with a ton of layers

selenium/standalone-chrome

. But when I try to build through the CLI, it's giving me trouble (essentially spun the CPU fan for an hour, and eventually gave up because

Traceback (most recent call last):=============================>]  143.3MB/143.3MB
  File "example-selenium.py", line 473, in <module>
    parameters=dict(
  File "/opt/anaconda3/envs/fastapi-async-sqlalchemy/lib/python3.7/site-packages/prefect/core/flow.py", line 1419, in register
    no_url=no_url,
  File "/opt/anaconda3/envs/fastapi-async-sqlalchemy/lib/python3.7/site-packages/prefect/client/client.py", line 623, in register
    serialized_flow = flow.serialize(build=build)  # type: Any
  File "/opt/anaconda3/envs/fastapi-async-sqlalchemy/lib/python3.7/site-packages/prefect/core/flow.py", line 1228, in serialize
    storage = self.storage.build()  # type: Optional[Storage]
  File "/opt/anaconda3/envs/fastapi-async-sqlalchemy/lib/python3.7/site-packages/prefect/environments/storage/docker.py", line 282, in build
    self._build_image(push=push)
  File "/opt/anaconda3/envs/fastapi-async-sqlalchemy/lib/python3.7/site-packages/prefect/environments/storage/docker.py", line 312, in _build_image
    self.pull_image()
  File "/opt/anaconda3/envs/fastapi-async-sqlalchemy/lib/python3.7/site-packages/prefect/environments/storage/docker.py", line 520, in pull_image
    raise InterruptedError(line.get("error"))
InterruptedError: write /var/lib/docker/tmp/GetImageBlob079036145: no space left on device

Hello there 👋, I got my first ELTC (Extract, Load, Transform, Cleanup) flow working on Prefect Core 🤩 But now I got a question: I would like to run the flow at the launch of the python app, but also to apply a schedule for every night at 3. So basically, I want a

CronClock

combine to a launch at startup. Is there an easy way to achieve this? 🧐 I think the fact that the scheduler wait for the next schedule raise the need for a "fire_at_start" parameter. In my case, if my schedule is programmed every day at 3 o'clock, I don't want to wait X hours before my DB is loaded up with data. 🕒 Does it make sense?

Hi Cloud users, interested in your suggestions. I have a Flow that executes great on my local dev machine. However, some of the logic within the Flow leverages a different application (XVBF & Google Chrome) that's also installed on my local dev machine. When I attempt to serialize the Flow into a Docker image, it doesn't run because the required application(s) aren't installed in the Docker image the

.register

generates. I can get the dependent application(s) to run inside a Docker image with supervisord, but that would require the entrypoint of Docker to somehow trigger supervisord before it attempts to execute the Flow. I couldn't find an API in Prefect to allow for this type of functionality? Another option is to provide the dependent application(s) as a native cloud service, and communicate over the network to access the same way I do it on my local dev machine.. but that'd be overkill for this one Flow. Curious if anyone has been successful in wrapping another (non-Python) application inside a serialized Flow to deploy on Prefect Cloud.

Hi Prefect Team, we have noticed that even without caching, that the results from tasks in a scheduled flow don’t fall out of scope (and therefore eligible for garbage collection) until the 3rd run. Is there a way to stop this behaviour? With large extract functions this can mean a lot of memory being held.

Hi Prefect Team, I am new to Prefect. I am facing a very basic issue where in i am unable to start the prefect core server on my local machine. I am able to create/run basic prefect flow in a python IDE. But unable to start prefect core server and Web UI on local machine. is there any prerequisites i need to install to run prefect core server? i dont have docker installed on my machine.

Hi everyone, I'm sure there will be an official announcement too, but just wanted to drop a quick congratulations to the Prefect team on getting the 0.10.0 release out that includes the UI and database! Last night I did a quick

pip install -U prefect

then

prefect server start

and brought up the UI in a browser without any trouble. This is a huge milestone and one that the community will benefit from greatly. Anyone can now run the fully open source Prefect Core and have a UI to manage and monitor flows. This gives folks a greater spectrum of options for running Prefect, from fully open source and no cost with Core to commercial with additional features with Cloud. Great work to the Prefect team!

seeing issues with the docs today

How would you debug a problem with the serialized Flow, after it's been packaged into a Docker storage? I have a Flow that executes fine when running locally, but when I do a

flow.register()

and it gets orchestrated to run in Cloud, it fails with the

result_handler

. I'd like to simulate running the serialized flow within the Docker image it generated locally, to see if I can figure out what's different between that environment and my local machine. Is there a proper way to do this?

Hi all! I saw that some folks here are interested in contributing their expertise to #COVID efforts, and we've been ramping up http://ProjectDomino.org on scalable social techniques for behavior change and combating misinformation, taking inspiration by techniques from public health (HIV), social media marketing, & security/fraud threat intelligence + autoresponse . We recently adopted Prefect.io as part of our orchestration layer (continuous data integration + autoresponse to alert community leaders & safety teams platforms on misinformation before the 'blast radius' gets big), and chances are, if you're here, you can have a big impact, esp. as we're getting the pipeline layers smoothed out 🙂 If relevant, just drop into the Slack channel linked above. Stay safe everyone!

Prefect-team, do you have extra guidance you can provide (or point me at examples for other open core projects ) of how to understand your "using the Software, or any derivative works thereof, to make available any software-as-a-service [etc etc]" langauge? What I'm trying to understand where "multi-user" crosses over to "excluded" - I would already assume "selling something" as excluded, but what about if I set up in my companies cloud and multiple people in my company use it? That loosely feels like it might be software-as-service, just that there isn't money (though in a company setting I could imagine department chargebacks and the like) - is that use in appropriate? (while I'm mostly talking about the contract, I'm also would like to know what you intended the spirit to be, I.E. even if this is allowable by the letter of the contract, is that something you intended? (you-all have done good work, and I want to honor what you intend too! 🙂)

Congratulations and thanks for opensourcing Prefect UI! Question: is there a way of setting an alternative port for the postgres instance started by

prefect server?

I have an instance of postgres running on the default port…

Really happy to see prefect opened up, even if it's not a real FOSS license this makes it way easier to adopt. I do wonder how you are planning on making money now though.

hello team prefect! We are reviewing snowflake task and are finding a number of limitations. Having to connect each time creates quite a bit of overhead and we are unable to run multisql statements as per https://docs.snowflake.com/en/user-guide/python-connector-api.html#

Hello! I just tried local UI with "prefect server start", but http://localhost:8080/ returns just a blank page. Console says:

vue-apollo.js:14 Uncaught TypeError: Cannot read property 'substr' of undefined
    at Module.56d7 (vue-apollo.js:14)
    at c (bootstrap:89)
    at Object.0 (app.e76c6ad2.js:1)
    at c (bootstrap:89)
    at t (bootstrap:45)
    at bootstrap:267
    at app.e76c6ad2.js:1

Hi, does anyone know how I can get the result of one task to be passed to another task further downstream with the imperative api?

flow = Flow('foo', tasks=[t1,t2,t3, t4])

flow.add_edge(t1,t2, key='x')
flow.add_edge(t2,t3)
flow.add_edge(t3,t4)

# now t4 needs the results of t1 not t2 or t3

What is an unreasonable number of tasks to be mapping over? If I have a table with millions of rows and need to transform each one of them (for example), can I generate a task for each row? Or would I need to export "pages" and process each of these in a task?

Question on the Q&A Fireside chat tomorrow — will it be recorded for those of us that cannot attend “in person”? Thanks! 🙏

Hey everybody, first of all: having access to an open-source UI is great, big thank you to the team! 👍🎊 I've managed to start the server and registering my flow, but trying to run a local agent using

prefect agent start

gives me this exception:

prefect.utilities.exceptions.AuthorizationError: No agent API token provided.

Any suggestions? I had already registered an agent with Prefect Cloud and an API token before.

Hi Run my first hello world on local server. Success ! with the new local instance server, are you planning to get the local agent to be called by the server rather than the agent polling the server Thanks

Is there a way to activate a conda environment inside of a Docker image before Prefect tries to pip install prefect? And also before it tries to run the flow in that container?

I would love to spin up the prefect webserver in k8s, but all of the tutorials point to using docker + docker-compose...is there any way that I can bootstrap it myself without having to run docker within docker in k8s?

Anyone could help me with this seemingly simple hurdle? I have

with Flow("My Flow") as flow:
    my_param = Parameter("my_param", default='a default value')
    ...

flow.run()
# flow.run(parameters={"my_param": "overwritten value"})

When I run this, I get

raise ValueError(
ValueError: Flow.run received the following unexpected parameters: my_param

What am I missing?

I'm sorry to ask, its probably really dumb. I cloned the git repo, did pip --upgrade, ran "prefect backend server".. Copied the hello-world script, instead of flow.run(), I did flow.register(). I got this message back:

Result Handler check: OK
/home/ec2-user/venv/prefect/lib64/python3.7/site-packages/prefect/core/task.py:258: UserWarning: DEPRECATED: all cache_* options on a Task will be deprecated in 0.11.0, and removed in 0.12.0; the options will be moved to a Task's prefect.engine.Result object.
  UserWarning,
Flow: <http://localhost:8080/flow/ef63906a-6e2b-4b7b-aba5-6e9303560e5f>

But I dont see anything changing in the UI, and dont see anything under the "Flows" link. I have this running on an ec2 machine so I dont use "localhost", but can reach the UI.. Just looks like it knows nothing about the flow. What have I missed?

Hi! Quick question: I'm using the GCSResultHandler with a task and I'd like to write the URI safe value of the result handler to a database. Is it possible during flow runtime to access a ResultHandler to persist the safe value?