Including another file in Dataflow Python flex template, ImportError

Question

Is there an example of a Python Dataflow Flex Template with more than one file where the script is importing other files included in the same folder?

My project structure is like this:

├── pipeline
│   ├── __init__.py
│   ├── main.py
│   ├── setup.py
│   ├── custom.py

I'm trying to import custom.py inside of main.py for a dataflow flex template.

I receive the following error in the pipeline execution:

"ModuleNotFoundError: No module named 'custom'"

The pipeline works fine if I include all of the code in a single file and don't make any imports.

Example Dockerfile:

FROM gcr.io/dataflow-templates-base/python3-template-launcher-base

ARG WORKDIR=/dataflow/template/pipeline
RUN mkdir -p ${WORKDIR}
WORKDIR ${WORKDIR}

COPY pipeline /dataflow/template/pipeline

COPY spec/python_command_spec.json /dataflow/template/

ENV DATAFLOW_PYTHON_COMMAND_SPEC /dataflow/template/python_command_spec.json

RUN pip install avro-python3 pyarrow==0.11.1 apache-beam[gcp]==2.24.0

ENV FLEX_TEMPLATE_PYTHON_SETUP_FILE="${WORKDIR}/setup.py"
ENV FLEX_TEMPLATE_PYTHON_PY_FILE="${WORKDIR}/main.py"

Python spec file:

{
    "pyFile":"/dataflow/template/pipeline/main.py"
}
  

I am deploying the template with the following command: gcloud builds submit --project=${PROJECT} --tag ${TARGET_GCR_IMAGE} .

Any help is appreciated.

Answer 1

I actually solved this by passing an additional parameter setup_file to the template execution. Also need to add setup_file parameter to the template metadata

--parameters setup_file="/dataflow/template/pipeline/setup.py"

Apparently the command ENV FLEX_TEMPLATE_PYTHON_SETUP_FILE="${WORKDIR}/setup.py" in the Dockerfile is useless and doesnt actually pick up the setup file.

My setup file looked like this:

import setuptools

setuptools.setup(
    packages=setuptools.find_packages(),
    install_requires=[
        'apache-beam[gcp]==2.24.0'
    ],
 )

Answer 2

After some tests I found out that for some unknown reasons phyton files at working directory (WORKDIR) cannot be referenced with an import. But it works if you create a subfolder and move the python dependencies into it. I tested and it worked, for example, in your use case you can have the following structure:

??? pipeline
?   ??? main.py
?   ??? setup.py
?   ??? mypackage
?   ?   ??? __init__.py
?   ?   ??? custom.py

And you will be able to reference: import mypackage.custom. The Docker file should move in the custom.py to proper directory.

RUN mkdir -p ${WORKDIR}/mypackage
RUN touch ${WORKDIR}/mypackage/__init__.py
COPY custom.py ${WORKDIR}/mypackage

And the dependecy will be added to the python installation directory:

$ docker exec -it <container> /bin/bash
# find / -name custom.py
/usr/local/lib/python3.7/site-packages/mypackage/custom.py

Answer 3

@pavan-kumar-kattamuri asked me to post my solution, so here it is.

FROM gcr.io/dataflow-templates-base/python3-template-launcher-base:flex_templates_base_image_release_20210120_RC00

ARG WORKDIR=/dataflow/template
RUN mkdir -p ${WORKDIR}
WORKDIR ${WORKDIR}

COPY requirements.txt .


# Read https://stackoverflow.com/questions/65766066/can-i-make-flex-template-jobs-take-less-than-10-minutes-before-they-start-to-pro#comment116304237_65766066
# to understand why apache-beam is not being installed from requirements.txt
RUN pip install --no-cache-dir -U apache-beam==2.26.0
RUN pip install --no-cache-dir -U -r ./requirements.txt

COPY mymodule.py setup.py ./
COPY protoc_gen protoc_gen/

ENV FLEX_TEMPLATE_PYTHON_REQUIREMENTS_FILE="${WORKDIR}/requirements.txt"
ENV FLEX_TEMPLATE_PYTHON_PY_FILE="${WORKDIR}/mymodule.py"
ENV FLEX_TEMPLATE_PYTHON_SETUP_FILE="${WORKDIR}/setup.py"

and here is my setup.py:

import setuptools

setuptools.setup(
    packages=setuptools.find_packages(),
    install_requires=[],
    name="my df job modules",
)

Answer 4

Ok with apache beam 2.27 it seems that we need to follow the original practice of passing a setup_file parameter .... shame..

Answer 5

@Akshay, answering your original question with a working example for rest of the community.

A working example of a Python Dataflow Flex Template with more than one file where the script is importing other files included in the same folder could be found here: https://github.com/toransahu/apache-beam-eg/tree/main/python/using_flex_template_adv1

Answer 6

For me I didn't need to integrate the setup_file in the command to trigger the flex template, here is my Dockerfile:

FROM gcr.io/dataflow-templates-base/python38-template-launcher-base

ARG WORKDIR=/dataflow/template
RUN mkdir -p ${WORKDIR}
WORKDIR ${WORKDIR}

COPY . .

ENV FLEX_TEMPLATE_PYTHON_PY_FILE="${WORKDIR}/main.py"
ENV FLEX_TEMPLATE_PYTHON_SETUP_FILE="${WORKDIR}/setup.py"

# Install apache-beam and other dependencies to launch the pipeline
RUN pip install apache-beam[gcp]
RUN pip install -U -r ./requirements.txt

This is the command:

gcloud dataflow flex-template run "job_ft" --template-file-gcs-location "$TEMPLATE_PATH" --parameters paramA="valA" --region "europe-west1"