Apart from some minor things that could be written better, these are critical ones.. When following the instructions to the letter (apart from using your own github token), one will not be able to get past "_Option 1: import jobs from Meltano_" 1. Dagster requires Meltano library installed in its env for it to be able to run

load_jobs_from_meltano_project

function. I do not know, if this is by design or not, but it is not installed with

dagster_meltano

. Maybe the blog assumes this module to be available globally and in $PATH? One will be be presented with following error in terminal's stdout

..dag-melt/dagster/dag-venv/lib/python3.10/site-packages/dagster/_core/workspace/context.py:589: UserWarning: Error loading repository location dag_melt_project:FileNotFoundError: [Errno 2] No such file or directory: 'meltano'

No jobs will be visible in http://127.0.0.1:3000/locations/dag_melt_project/jobs To fix this, one would

source ~/dag-melt/dagster/dag-venv/bin/activate && pip install meltano && deactivate

then restart

dagster dev

2. One would not be able to run the job that now is available with fix in #1 because of following error

dagster._check.CheckError: Value in dict mismatches expected type for key MELTANO_CLI_LOG_CONFIG. Expected value of type <class 'str'>. Got value /Users/janispuris/dag-melt/dagster/dag-venv/lib/python3.10/site-packages/dagster_meltano/logging.yaml of type <class 'pathlib.PosixPath'>.

I do not know, if this is a breaking change in Meltano (because the tutorial tells the user to install the latest version or something else).. anyhow, I have not been able to work around this yet. Honestly would not think anyone to continue with a tutorial at this point.

Thanks for the specific feedback @JP!

This fixes the problem..

dag-melt/dagster/dag-venv/lib/python3.10/site-packages/dagster_meltano/meltano_resource.py

change line 34 from

"MELTANO_CLI_LOG_CONFIG": Path(__file__).parent / "logging.yaml",

to

"MELTANO_CLI_LOG_CONFIG": str(Path(__file__).parent / "logging.yaml"),

The meltano job runs without issues.. I now suspect this may be a breaking change in Python 3.11. I'll try to reproduce this with 3.10

From looks of it the default_env property is always used, its type hints say it returns a

dict

with

str

for keys and values, however

Path(__file__).parent / "logging.yaml"

does not return a

str

, but a

PosixPath

object, hence the error.. I've checked this on Python 3.11, 3.10 and 3.9 🤷 From what I can tell from git blame, this property was introduced back in Feb 18, 2023 as part of New dagster_meltano package #15 and therefore I'm clueless as to how this was working at the time of writing the blog post 😞 Would you suggest me to open github issue on this?

Looks like this is a bug in

dagster-meltano

where it was allowing non-string entries to exist in the dict, which was "fine" until a change in

dagster

package in dagster/python_modules/dagster/dagster/_check/__init__.py at master · dagster-io/dagster · GitHub I suspect previously the dict values were not validated, but now they are, hence the error. Specifically this function file:

dagster/_check/__init__.py

function:

_check_mapping_entries

It is little too late to go further down the rabbit hole on this. I'll open a PR on

dagster-meltano

sometime tomorrow on 🤷

Wanted to tag @Jules Huisman (Quantile) as well since he’s the main contributor to that project.