Deploy a pipeline with Airflow and Google Composer

Before you can deploy a pipeline, you will need to install dlt and create a pipeline.

tip

While this walkthrough deals specifically with Google Composer, it will generate DAGs and configuration files that you can use on any Airflow deployment. DAGs are generated using dlt Airflow helper that maps dlt resources into Airflow tasks, provides clean working environment, retry mechanism, metrics and logging via Airflow loggers.

1. Add your dlt project directory to GitHub

You will need a GitHub repository for your project. If you don't have one yet, you need to initialize a Git repository in your dlt project directory and push it to GitHub as described in Adding locally hosted code to GitHub.

2. Ensure your pipeline works

Before you can deploy, you must run your pipeline locally at least once.

python3 {pipeline_name}_pipeline.py

This should successfully load data from the source to the destination once and allows dlt to gather required information for the deployment.

3. Initialize deployment

First you need to add additional dependencies that deploy command requires:

pip install "dlt[cli]"

then:

dlt deploy {pipeline_name}_pipeline.py airflow-composer

This command checks if your pipeline has run successfully before and creates the following folders:

• build

  • This folder contains a file called cloudbuild.yaml with a simple configuration for cloud deployment. We will use it below.

• dags

  • This folder contains the Python script dag_{pipeline_name}.py, which is an example of a simple serialized DAG using the Airflow PipelineTasksGroup wrapper.

  Note: This folder is only needed to store DAG scripts, but it is not the Airflow dags_folder. Please refer to the Troubleshooting section for more information.

By default, the dlt deploy command shows you the deployment credentials in ENV format.

💡 When you run the dlt deploy command, you will get the relevant info in your CLI about how you can deploy credentials.

Example with the pipedrive pipeline

1. Run the deploy command

dlt deploy pipedrive_pipeline.py airflow-composer

where pipedrive_pipeline.py is the pipeline script that you just ran and airflow-composer is a deployment method. The command will create deployment files and provide instructions to set up the credentials.

Your airflow-composer deployment for pipeline pipedrive is ready!
* The airflow cloudbuild.yaml file was created in build.
* The dag_pipedrive.py script was created in dags.

You must prepare your repository first:
1. Import your sources in dag_pipedrive.py, change default_task_args if necessary.
2. Run airflow pipeline locally.
See Airflow getting started: https://airflow.apache.org/docs/apache-airflow/stable/start.html

If you are planning run the pipeline with Google Cloud Composer, follow the next instructions:

1. Read this doc and set up the Environment: https://dlthub.com/docs/running-in-production/orchestrators/airflow-gcp-cloud-composer
2. Set _BUCKET_NAME up in build/cloudbuild.yaml file.
3. Add the following toml-string to the Airflow UI as the dlt_secrets_toml variable.

[sources.pipedrive]
pipedrive_api_key = "c66..."

💡 deploy command will use Airflow variable called dlt_secrets_toml to store all the required secrets as toml fragment. You can also use environment variables by passing --secrets-format env option:

dlt deploy pipedrive_pipeline.py airflow-composer --secrets-format env

which will output the environment variable names and their values.

3. Add the following secret values (typically stored in ./.dlt/secrets.toml):
SOURCES__PIPEDRIVE__PIPEDRIVE_API_KEY

in ENVIRONMENT VARIABLES using Google Composer UI

Name:
SOURCES__PIPEDRIVE__PIPEDRIVE_API_KEY
Secret:
c66c..

2. Modify DAG file

In directory dags/ you can find the file dag_pipedrive.py that you need to edit. It has the following structure:

import dlt
from airflow.decorators import dag
from dlt.common import pendulum
from dlt.helpers.airflow_helper import PipelineTasksGroup

# Modify the dag arguments
default_task_args = {
    'owner': 'airflow',
    'depends_on_past': False,
    'email': 'test@test.com',
    'email_on_failure': False,
    'email_on_retry': False,
    'retries': 0,

}

@dag(
    schedule=None,
    start_date=pendulum.datetime(2021, 1, 1),
    catchup=False,
    max_active_runs=1,
    default_args=default_task_args
)
def load_data():
    # Set `use_data_folder` to True to store temporary data on the `data` bucket.
    # Use only when it does not fit on the local storage
    tasks = PipelineTasksGroup("pipeline_name", use_data_folder=False, wipe_local_data=True)

    # Import your source from pipeline script
    from pipeline_or_source_script import source

    # Modify the pipeline parameters
    pipeline = dlt.pipeline(
        pipeline_name='pipeline_name',
        dataset_name='dataset_name',
        destination='duckdb',
        full_refresh=False # must be false if we decompose
    )
    # Create the source, the "serialize" decompose option
    # will convert dlt resources into Airflow tasks.
    # Use "none" to disable it.
    tasks.add_run(
        pipeline,
        source(),
        decompose="serialize",
        trigger_rule="all_done",
        retries=0,
        provide_context=True
    )

    # The "parallel" decompose option will convert dlt
    # resources into parallel Airflow tasks, except the
    # first one, which will be executed before any other tasks.
    # All the tasks will be executed in the same pipeline state.
    # tasks.add_run(
    #   pipeline,
    #   source(),
    #   decompose="parallel",
    #   trigger_rule="all_done",
    #   retries=0,
    #   provide_context=True
    # )

    # The "parallel-isolated" decompose option will convert dlt
    # resources into parallel Airflow tasks, except the
    # first one, which will be executed before any other tasks.
    # In this mode, all the tasks will use separate pipeline states.
    # tasks.add_run(
    #   pipeline,
    #   source(),
    #   decompose="parallel-isolated",
    #   trigger_rule="all_done",
    #   retries=0,
    #   provide_context=True
    # )

load_data()

• Customize the PipelineTaskGroup:

  • change the name from “pipeline_name” to yours, for example, “pipedrive”.

  • change runtime settings: data_folder, logging, retry policy etc. For example, let’s wipe all the data created by pipeline (wipe_local_data=True), redirect dlt logger into task logger (use_task_logger=True) and set the retry policy as a Retrying class object with three restart attempts.

    from tenacity import Retrying, stop_after_attempt
    
    # Set `use_data_folder` to True to store temporary data on the `data` bucket.
    # Use only when it does not fit on the local storage
    tasks = PipelineTasksGroup(
        pipeline_name="pipedrive",
        use_data_folder=False,
        wipe_local_data=True,
        use_task_logger=True,
        retry_policy=Retrying(stop=stop_after_attempt(3), reraise=True),
    )
    tip

    When you run load_data DAG above, Airflow will call source function every 30 seconds (by default) to be able to monitor the tasks. Make sure that your source function does not do any long lasting operations ie. reflecting source database. In case of sql_database we added an option to delay database reflection until data is accessed by a resource.

3. Import sources and move the relevant code from the pipeline script

You should now move your working code from the pipeline script you previously ran to the newly created DAG script.

• Import your sources from your existing pipeline script - after task group is created:

  # Import your source from pipeline script
  from pipedrive import pipedrive_source

  If you create your pipeline, instance in your source in the “main” function in your script then copy it here. For example, look at the load_from_start_date function in pipedrive_pipeline.py:

  """Example to incrementally load activities limited to items updated after a given date"""
  
  pipeline = dlt.pipeline(
    pipeline_name="pipedrive", destination='duckdb', dataset_name="pipedrive_data"
  )
  
  # First source configure to load everything except activities from the beginning
  source = pipedrive_source()
  source.resources["activities"].selected = False
  
  # Another source configured to activities starting at the given date (custom_fields_mapping is included to translate custom field hashes to names)
  activities_source = pipedrive_source(
    since_timestamp="2023-03-01 00:00:00Z"
  ).with_resources("activities", "custom_fields_mapping")

  Copy this part of the code to the dags/dag_pipedrive.py script.

  Note: Task ids in the task group should be still unique globally, so we have to exclude "custom_fields_mapping” from activities_source. See Troubleshooting section.

• Pass your pipeline instance and source instance to the add_run method of tasks.

  Note: PipelineTasksGroup can’t handle the list of sources (e.g. data=[source, activities_source]), so we have to add them sequentially. See Troubleshooting section.

  # Create the source,
  # the "serialize" decompose option will convert
  # dlt resources into Airflow tasks.
  # Use "none" to disable it
  tasks.add_run(
      pipeline=pipeline,
      data=source,
      decompose="serialize",
      trigger_rule="all_done",
      retries=0,
      provide_context=True
  )
  
  # PipelineTasksGroup can’t handle the list of
  # sources (e.g. data=[source, activities_source]),
  # so we have to add them sequentially
  tasks.add_run(
      pipeline=pipeline,
      data=activities_source,
      decompose="serialize",
      trigger_rule="all_done",
      retries=0,
      provide_context=True
  )

• Customize the name of Airflow DAG by changing the name of the load_data function to your desired name, for example to load_pipedrive_data.

• Modify the @dag arguments. Set up schedule, start_date, default_task_args.

As a result, we will get a script of the following form:

import dlt
from airflow.decorators import dag
from dlt.common import pendulum
from dlt.helpers.airflow_helper import PipelineTasksGroup

# Modify the dag arguments
default_task_args = {
    'owner': 'airflow',
    'depends_on_past': False,
    'email': 'test@test.com',
    'email_on_failure': False,
    'email_on_retry': False,
    'retries': 0,

}

@dag(
    schedule=None,
    start_date=pendulum.datetime(2021, 1, 1),
    catchup=False,
    max_active_runs=1,
    default_args=default_task_args
)
def load_pipedrive_data():
    from tenacity import Retrying, stop_after_attempt

    # Set `use_data_folder` to True to store temporary data on the `data` bucket.
    # Use only when it does not fit on the local storage.
    tasks = PipelineTasksGroup(
        pipeline_name="pipedrive",
        use_data_folder=False,
        wipe_local_data=True,
        use_task_logger=True,
        retry_policy=Retrying(stop=stop_after_attempt(3), reraise=True),
    )

    # Import your source from pipeline script
    from pipedrive import pipedrive_source

    """Example to incrementally load activities limited to items updated after a given date"""

    pipeline = dlt.pipeline(
        pipeline_name="pipedrive", destination='duckdb', dataset_name="pipedrive_data"
    )

    # First source configure to load everything
    # except activities from the beginning
    source = pipedrive_source()
    source.resources["activities"].selected = False

    # Another source configured to activities
    # starting at the given date (custom_fields_mapping is included to
    # translate custom field hashes to names)
    activities_source = pipedrive_source(
        since_timestamp="2023-03-01 00:00:00Z"
    ).with_resources("activities")

    # Create the source, the "serialize" decompose option
    # will convert dlt resources into Airflow tasks.
    # Use "none" to disable it.
    tasks.add_run(
        pipeline=pipeline,
        data=source,
        decompose="serialize",
        trigger_rule="all_done",
        retries=0,
        provide_context=True
    )

    # PipelineTasksGroup can’t handle the list of sources
    # (e.g. data=[source, activities_source]),
    # so we have to add them sequentially.
    tasks.add_run(
        pipeline=pipeline,
        data=activities_source,
        decompose="serialize",
        trigger_rule="all_done",
        retries=0,
        provide_context=True
    )

load_pipedrive_data()

4. Add credentials

There are two ways to pass the credentials

1. in the dlt_secrets_toml Airflow variable.

   • During the execution of the deploy command with --secrets-format toml, secret variables will be displayed in the output:

     3. Add the following toml-string to the Airflow UI as the dlt_secrets_toml variable.
     
     [sources.pipedrive]
     pipedrive_api_key = "c66c..."

   • Launch the Airflow UI, head to Admin top level menu and select Variables

   • Add a new variable with a name dlt_secrets_toml

   • Paste the toml fragment displayed by the deploy command.

   • 💡 the content of this variable will be used by dlt Airflow helper instead of local secrets.toml which you are familiar with. If your local secrets file contains anything else you want to access on Airflow, you are good to just copy the local secrets.toml content to dlt_secrets_toml variable.

2. as ENVIRONMENT VARIABLES.

   • During the execution of the deploy command with --secrets-format env (by default), environment variables will be displayed in the output:

     3. Add the following secret values (typically stored in ./.dlt/secrets.toml):
     SOURCES__PIPEDRIVE__PIPEDRIVE_API_KEY
     
     in ENVIRONMENT VARIABLES using Google Composer UI
     
     Name:
     SOURCES__PIPEDRIVE__PIPEDRIVE_API_KEY
     Secret:
     c66c...

   • Copy capitalized variables and add it into airflow’s env variables, save it. Now, dlt can pick it up.

     

5. Configure build/cloudbuild.yaml to run it with Google Cloud Platform [Cloud Composer]

• Read our doc How to deploy the main branch of your airflow project from GitHub to Cloud Composer.

  There you can find:

  • How to set up the Cloud Composer Environment.
  • How to create trigger.
  • How to add the libraries needed.

• Set _BUCKET_NAME up in build/cloudbuild.yaml file.

  The file has the following structure:

  steps:
  - name: 'gcr.io/google.com/cloudsdktool/cloud-sdk'
    entrypoint: 'bash'
    args:
    - '-c'
    - gsutil -m rsync -d -r ./ gs://${_BUCKET_NAME}/dags
  
  substitutions:
    _BUCKET_NAME: "set me up!"
  options:
    logging: CLOUD_LOGGING_ONLY

  This code copies the whole pipeline repository into the bucket’s DAGs folder.

  To fill it, we need to get the name of the DAGs bucket from Cloud Composer, so we know where to deploy.

  • Go to Cloud Composer, click on the DAGs folder, and get the bucket name.

    

  • In your cloudbuild.yaml, set _BUCKET_NAME up in the substitutions section.

    substitutions:
      _BUCKET_NAME: "set me up!"

6. Finish the Airflow deploying

1. Commit and push the pipeline files to GitHub.

   Add stage deployment files to commit. Use your Git UI or the following command:

   git add dags/dag_pipedrive.py build/cloudbuild.yaml

   Commit the files above. Use your Git UI or the following command:

   git commit -m 'initiate pipedrive pipeline with Airflow'

   Push changes to GitHub. Use your Git UI or the following command:

   git push origin

2. Run the trigger you build (in Cloud Build).

   

3. Wait a minute, and check if your files arrived in the bucket. In our case, we added a whole repository with pipedrive project, and we can see it appeared.

Troubleshooting

This section will cover the most common probable errors and exceptions.

1. ModuleNotFoundError: No module named ‘{source_name}’

If you got this error, then make sure that your repository has been completely copied to the DAGs folder.

If you run it locally, then check your airflow.cfg file (line 4):

# The folder where your airflow pipelines live, most likely a
# subfolder in a code repository. This path must be absolute.
# default: dags_folder = ~/airflow/dags
dags_folder = absolute_path_to_your_project

dags_folder should not lead to the absolute_path_to_your_project/dags folder.

2. ValueError: Can only decompose dlt sources

In this case you perhaps passed a list of sources to the method add_run as data or another unacceptable data structure and provided decompose = "serialize".

For example:

tasks.add_run(
    pipeline=pipeline,
    data=[source, activities_source],
    decompose="serialize",
)

If data is a DltSource and decompose is “serialize” it will decompose the source into disjoint connected components (isolated group of resources) and execute them one after another as separate Airflow tasks.

PipelineTasksGroup can't handle the list of sources in the “serialize” mode, it can only decompose DltSource, so we have to add them sequentially:

tasks.add_run(
    pipeline=pipeline,
    data=source,
    decompose="serialize",
)
tasks.add_run(
    pipeline=pipeline,
    data=activities_source,
    decompose="serialize",
)

Or you should set the decompose = "none” to run it as the one Airflow task.

3. DuplicateTaskIdFound: Task id ‘{your_task_id}’ has already been added to the DAG

In case of pipedrive pipeline we tried to load data from “custom_fields_mapping” twice.

# First source configure to load everything except activities from the beginning
source = pipedrive_source()
source.resources["activities"].selected = False

# Another source configured to activities starting at the given date
# (custom_fields_mapping is included to translate custom field hashes to names)
activities_source = pipedrive_source(
    since_timestamp="2023-03-01 00:00:00Z"
).with_resources("activities", "custom_fields_mapping")

Because of this we got the following error:

airflow.exceptions.DuplicateTaskIdFound:
Task id ‘pipedrive.pipedrive_custom_fields_mapping’ has already been added to the DAG

Task ids in the task group should be still unique globally, so in this case we have to exclude “custom_fields_mapping” from activities_source. “custom_fields_mapping” will be taken from the current state to translate custom field hashes to names:

activities_source = pipedrive_source(
    since_timestamp="2023-03-01 00:00:00Z"
).with_resources("activities")