Hi, I'm having trouble with Prefect Server. It came up, I was able to register a project in it, and I was also able to register a flow. But when I try to run the flow, I get an error:

agent@prefect-agent:~/.prefect/results$ prefect run flow --name 'My first Flow' --project test
    Traceback (most recent call last):
      File "/home/agent/.pyenv/versions/3.7.3/bin/prefect", line 10, in <module>
        sys.exit(cli())
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/click/core.py", line 829, in __call__
        return self.main(*args, **kwargs)
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/click/core.py", line 782, in main
        rv = self.invoke(ctx)
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/click/core.py", line 1259, in invoke
        return _process_result(sub_ctx.command.invoke(sub_ctx))
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/click/core.py", line 1259, in invoke
        return _process_result(sub_ctx.command.invoke(sub_ctx))
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/click/core.py", line 1066, in invoke
        return ctx.invoke(self.callback, **ctx.params)
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/click/core.py", line 610, in invoke
        return callback(*args, **kwargs)
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/prefect/cli/run.py", line 186, in flow
        run_name=run_name,
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/prefect/client/client.py", line 1094, in create_flow_run
        res = self.graphql(create_mutation, variables=dict(input=inputs))
      File "/home/agent/.pyenv/versions/3.7.3/lib/python3.7/site-packages/prefect/client/client.py", line 319, in graphql
        raise ClientError(result["errors"])
    prefect.utilities.exceptions.ClientError: [{'message': "Required parameters were not supplied: {'numbers'}", 'locations': [{'line': 2, 'column': 5}], 'path': ['create_flow_run'], 'extensions': {'code': 'INTERNAL_SERVER_ERROR', 'exception': {'message': "Required parameters were not supplied: {'numbers'}"}}}]

I checked the Docker logs and found this GraphQL error:

GraphQL request:2:3
    1 | mutation ($input: create_flow_run_input!) {
    2 |   create_flow_run(input: $input) {
      |   ^
    3 |     id
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/site-packages/graphql/execution/execute.py", line 628, in await_result
        return await result
      File "/prefect-server/src/prefect_server/graphql/extensions.py", line 52, in resolve
        result = await result
      File "/prefect-server/src/prefect_server/graphql/runs.py", line 119, in resolve_create_flow_run
        run_config=input.get("run_config"),
      File "/prefect-server/src/prefect_server/api/runs.py", line 74, in create_flow_run
        run_config=run_config,
      File "/prefect-server/src/prefect_server/api/runs.py", line 215, in _create_flow_run
        raise ValueError(f"Required parameters were not supplied: {missing}")
    ValueError: Required parameters were not supplied: {'numbers'}

It looks like your flow takes a parameter,

numbers

. It doesn’t look like there is a default value, so Server is erroring out because there isn’t a parameter value. You should be able to solve this in one of two ways: • Add a default value for the parameter so that you can create a flow run without specifying a value for

numbers

• Create your flow run with a value for

numbers

If you’re wanting to continue to use the

cli

to run your flow, specify the

--ps

option, which is a stringified JSON object that holds values for your paramters. I’d guess yours should look something like:

prefect run flow --name 'My first Flow --project test --ps '{"numbers": [1, 2, 3]}'

It worked. Thanks!

Is that the same address that your UI is located at? I believe that URL that’s returned is built using the UI address, not where your API address is (since those things can be run on different machines altogether)

I'm running the Docker image, which I believe has the API, UI, Postgres, and more.

So you started Server via the prefect cli, so those would all be on the same machine (running within docker-compose as an FYI). I’m not familiar with what a

docker-proxy

process does for you offhand, does it just forward traffic from one location to another? Like do you have this set up externally to Server so that traffic at

localhost:8080

gets forwarded to one of the services specifically?

I have no idea. I just ran

prefect server start

, it started the Docker images, and I was able to connect to the API from the other machine with no additional configuration.

Ah okay, that was a piece I missed (you’re not running this all on one machine). Did you run the

prefect run flow

command on the same machine running your Server? Because if that’s the case, I’m guessing the CLI is seeing that Server is on localhost. Additionally, do you have a configuration file with the value for`server.ui.endpoint` ? Or are you using the default?

No, I ran

prefect run flow

on the other machine, where the Agent is set up.

The UI’s address is specified server side, however (I believe) you also then need to update the value for the configuration on the client side as well, otherwise it’ll use the default values. If your agent isn’t running on the same machine as your Server, I’m guessing that the agent’s configuration is the one you need to look at Can you start a new thread with the flow stuck in “Scheduled” in the

#prefect-community

channel? It’ll likely be solved more quickly there!

Ok.