dbt-glue 0.2.0

dbt (data build tool) adapter for Aws Glue

dbt enables data analysts and engineers to transform their data using the same practices that software engineers use to build applications. dbt is the T in ELT. Organize, cleanse, denormalize, filter, rename, and pre-aggregate the raw data in your warehouse so that it's ready for analysis.

dbt-glue

The dbt-glue package implements the dbt adapter protocol for AWS Glue's Spark engine. It supports running dbt against Spark, through the new Glue Interactive Sessions API.

Installation

The package can be installed from PyPI with:

$ pip install dbt-glue

For further (and more likely up-to-date) info, see the README

Connection Methods

Configuring your AWS profile for Glue Interactive Session

There are two IAM principals used with interactive sessions.

• Client principal: The princpal (either user or role) calling the AWS APIs (Glue, Lake Formation, Interactive Sessions) from the local client. This is the principal configured in the AWS CLI and likely the same.
• Service role: The IAM role that AWS Glue uses to execute your session. This is the same as AWS Glue ETL.

Read this documentation to configure these principals.

You will find bellow a least privileged policy to enjoy all features of dbt-glue adapter.

Please to update variables between <>, here are explanations of these arguments:

Args	Description
region	The region where you're Glue database is stored
AWS Account	The AWS account where you run your pipeline
dbt output database	The database updated by dbt (this is the database configured in the profile.yml of your dbt environment)
dbt source database	All databases used as source
dbt output bucket	The bucket name where the data will be generate dbt (the location configured in the profile.yml of your dbt environment)
dbt source bucket	The bucket name of source databases (if they are not managed by Lake Formation)

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "Read_and_write_databases",
            "Action": [
                "glue:SearchTables",
                "glue:BatchCreatePartition",
                "glue:CreatePartitionIndex",
                "glue:DeleteDatabase",
                "glue:GetTableVersions",
                "glue:GetPartitions",
                "glue:DeleteTableVersion",
                "glue:UpdateTable",
                "glue:DeleteTable",
                "glue:DeletePartitionIndex",
                "glue:GetTableVersion",
                "glue:UpdateColumnStatisticsForTable",
                "glue:CreatePartition",
                "glue:UpdateDatabase",
                "glue:CreateTable",
                "glue:GetTables",
                "glue:GetDatabases",
                "glue:GetTable",
                "glue:GetDatabase",
                "glue:GetPartition",
                "glue:UpdateColumnStatisticsForPartition",
                "glue:CreateDatabase",
                "glue:BatchDeleteTableVersion",
                "glue:BatchDeleteTable",
                "glue:DeletePartition",
                "lakeformation:ListResources",
                "lakeformation:BatchGrantPermissions",
                "lakeformation:ListPermissions"
            ],
            "Resource": [
                "arn:aws:glue:<region>:<AWS Account>:catalog",
                "arn:aws:glue:<region>:<AWS Account>:table/<dbt output database>/*",
                "arn:aws:glue:<region>:<AWS Account>:database/<dbt output database>"
            ],
            "Effect": "Allow"
        },
        {
            "Sid": "Read_only_databases",
            "Action": [
                "glue:SearchTables",
                "glue:GetTableVersions",
                "glue:GetPartitions",
                "glue:GetTableVersion",
                "glue:GetTables",
                "glue:GetDatabases",
                "glue:GetTable",
                "glue:GetDatabase",
                "glue:GetPartition",
                "lakeformation:ListResources",
                "lakeformation:ListPermissions"
            ],
            "Resource": [
                "arn:aws:glue:<region>:<AWS Account>:table/<dbt source database>/*",
                "arn:aws:glue:<region>:<AWS Account>:database/<dbt source database>",
                "arn:aws:glue:<region>:<AWS Account>:database/default",
                "arn:aws:glue:<region>:<AWS Account>:database/global_temp"
            ],
            "Effect": "Allow"
        },
        {
            "Sid": "Storage_all_buckets",
            "Action": [
                "s3:GetBucketLocation",
                "s3:ListBucket"
            ],
            "Resource": [
                "arn:aws:s3:::<dbt output bucket>",
                "arn:aws:s3:::<dbt source bucket>"
            ],
            "Effect": "Allow"
        },
        {
            "Sid": "Read_and_write_buckets",
            "Action": [
                "s3:PutObject",
                "s3:PutObjectAcl",
                "s3:GetObject",
                "s3:DeleteObject"
            ],
            "Resource": [
                "arn:aws:s3:::<dbt output bucket>"
            ],
            "Effect": "Allow"
        },
        {
            "Sid": "Read_only_buckets",
            "Action": [
                "s3:GetObject"
            ],
            "Resource": [
                "arn:aws:s3:::<dbt source bucket>"
            ],
            "Effect": "Allow"
        }
    ]
}

Configuration of the local environment

Because dbt and dbt-glue adapter are compatible with Python versions 3.7, 3.8, and 3.9, check the version of Python:

$ python3 --version

Configure a Python virtual environment to isolate package version and code dependencies:

$ sudo yum install git
$ python3 -m venv dbt_venv
$ source dbt_venv/bin/activate
$ python3 -m pip install --upgrade pip

Configure the last version of AWS CLI

$ curl "https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip" -o "awscliv2.zip"
$ unzip awscliv2.zip
$ sudo ./aws/install

Configure the aws-glue-session package

$ sudo yum install gcc krb5-devel.x86_64 python3-devel.x86_64 -y
$ pip3 install —upgrade boto3
$ pip3 install —upgrade aws-glue-sessions

Example config

type: glue
query-comment: This is a glue dbt example
role_arn: arn:aws:iam::1234567890:role/GlueInteractiveSessionRole
region: us-east-1
workers: 2
worker_type: G.1X
idle_timeout: 10
schema: "dbt_demo"
database: "dbt_demo"
session_provisioning_timeout_in_seconds: 120
location: "s3://dbt_demo_bucket/dbt_demo_data"

The table below describes all the options.

Option	Description	Mandatory
project_name	The dbt project name. This must be the same as the one configured in the dbt project.	yes
type	The driver to use.	yes
query-comment	A string to inject as a comment in each query that dbt runs.	no
role_arn	The ARN of the interactive session role created as part of the CloudFormation template.	yes
region	The AWS Region were you run the data pipeline.	yes
workers	The number of workers of a defined workerType that are allocated when a job runs.	yes
worker_type	The type of predefined worker that is allocated when a job runs. Accepts a value of Standard, G.1X, or G.2X.	yes
schema	The schema used to organize data stored in Amazon S3.	yes
database	The database in Lake Formation. The database stores metadata tables in the Data Catalog.	yes
session_provisioning_timeout_in_seconds	The timeout in seconds forT AWS Glue interactive session provisioning.	yes
location	The Amazon S3 location of your target data.	yes
query_timeout_in_seconds	The timeout in seconds for a signle query. Default is 300	no
idle_timeout	The AWS Glue session idle timeout in minutes. (The session stops after being idle for the specified amount of time.)	no
glue_version	The version of AWS Glue for this session to use. Currently, the only valid options are 2.0 and 3.0. The default value is 2.0.	no
security_configuration	The security configuration to use with this session.	no
connections	A comma-separated list of connections to use in the session.	no

Configs

Configuring tables

When materializing a model as table, you may include several optional configs that are specific to the dbt-spark plugin, in addition to the standard model configs.

Option	Description	Required?	Example
file_format	The file format to use when creating tables (parquet, csv, json, text, jdbc or orc).	Optional	parquet
partition_by	Partition the created table by the specified columns. A directory is created for each partition.	Optional	date_day
clustered_by	Each partition in the created table will be split into a fixed number of buckets by the specified columns.	Optional	country_code
buckets	The number of buckets to create while clustering	Required if clustered_by is specified	8
custom_location	By default, the adapter will store your data in the following path: location path/database/table. If you don't want to follow that default behaviour, you can use this parameter to set your own custom location on S3	No	s3://mycustombucket/mycustompath

Incremental models

dbt seeks to offer useful, intuitive modeling abstractions by means of its built-in configurations and materializations.

For that reason, the dbt-glue plugin leans heavily on the incremental_strategy config. This config tells the incremental materialization how to build models in runs beyond their first. It can be set to one of three values:

• append (default): Insert new records without updating or overwriting any existing data.
• insert_overwrite: If partition_by is specified, overwrite partitions in the table with new data. If no partition_by is specified, overwrite the entire table with new data.
• merge (Apache Hudi only): Match records based on a unique_key; update old records, insert new ones. (If no unique_key is specified, all new data is inserted, similar to append.)

Each of these strategies has its pros and cons, which we'll discuss below. As with any model config, incremental_strategy may be specified in dbt_project.yml or within a model file's config() block.

Notes: The default strategie is insert_overwrite

The append strategy

Following the append strategy, dbt will perform an insert into statement with all new data. The appeal of this strategy is that it is straightforward and functional across all platforms, file types, connection methods, and Apache Spark versions. However, this strategy cannot update, overwrite, or delete existing data, so it is likely to insert duplicate records for many data sources.

Source code

{{ config(
    materialized='incremental',
    incremental_strategy='append',
) }}

--  All rows returned by this query will be appended to the existing table

select * from {{ ref('events') }}
{% if is_incremental() %}
  where event_ts > (select max(event_ts) from {{ this }})
{% endif %}

Run Code

create temporary view spark_incremental__dbt_tmp as

    select * from analytics.events

    where event_ts >= (select max(event_ts) from {{ this }})

;

insert into table analytics.spark_incremental
    select `date_day`, `users` from spark_incremental__dbt_tmp

The insert_overwrite strategy

This strategy is most effective when specified alongside a partition_by clause in your model config. dbt will run an atomic insert overwrite statement that dynamically replaces all partitions included in your query. Be sure to re-select all of the relevant data for a partition when using this incremental strategy.

If no partition_by is specified, then the insert_overwrite strategy will atomically replace all contents of the table, overriding all existing data with only the new records. The column schema of the table remains the same, however. This can be desirable in some limited circumstances, since it minimizes downtime while the table contents are overwritten. The operation is comparable to running truncate + insert on other databases. For atomic replacement of Delta-formatted tables, use the table materialization (which runs create or replace) instead.

Source Code

{{ config(
    materialized='incremental',
    partition_by=['date_day'],
    file_format='parquet'
) }}

/*
  Every partition returned by this query will be overwritten
  when this model runs
*/

with new_events as (

    select * from {{ ref('events') }}

    {% if is_incremental() %}
    where date_day >= date_add(current_date, -1)
    {% endif %}

)

select
    date_day,
    count(*) as users

from events
group by 1

Run Code

create temporary view spark_incremental__dbt_tmp as

    with new_events as (

        select * from analytics.events


        where date_day >= date_add(current_date, -1)


    )

    select
        date_day,
        count(*) as users

    from events
    group by 1

;

insert overwrite table analytics.spark_incremental
    partition (date_day)
    select `date_day`, `users` from spark_incremental__dbt_tmp

Specifying insert_overwrite as the incremental strategy is optional, since it's the default strategy used when none is specified.

The merge strategy

Usage notes: The merge incremental strategy requires:

• file_format: hudi
• AWS Glue runtime 2 with hudi libraries as extra jars

You can add hudi libraries as extra jars in the classpath using extra_jars options in your profiles.yml. Here is an example:

extra_jars: "s3://dbt-glue-hudi/Dependencies/hudi-spark.jar,s3://dbt-glue-hudi/Dependencies/spark-avro_2.11-2.4.4.jar"

dbt will run an atomic merge statement which looks nearly identical to the default merge behavior on Snowflake and BigQuery. If a unique_key is specified (recommended), dbt will update old records with values from new records that match on the key column. If a unique_key is not specified, dbt will forgo match criteria and simply insert all new records (similar to append strategy).

Source Code

{{ config(
    materialized='incremental',
    incremental_strategy='merge',
    unique_key='user_id',
    file_format='hudi'
) }}

with new_events as (

    select * from {{ ref('events') }}

    {% if is_incremental() %}
    where date_day >= date_add(current_date, -1)
    {% endif %}

)

select
    user_id,
    max(date_day) as last_seen

from events
group by 1

Persisting model descriptions

Relation-level docs persistence is supported since dbt v0.17.0. For more information on configuring docs persistence, see the docs.

When the persist_docs option is configured appropriately, you'll be able to see model descriptions in the Comment field of describe [table] extended or show table extended in [database] like '*'.

Always schema, never database

Apache Spark uses the terms "schema" and "database" interchangeably. dbt understands database to exist at a higher level than schema. As such, you should never use or set database as a node config or in the target profile when running dbt-glue.

If you want to control the schema/database in which dbt will materialize models, use the schema config and generate_schema_name macro only.

Tests

To perform a functional test:

1. Install dev requirements:

$ pip install -r dev_requirements.txt

2. Install dev locally

$ python setup.py build && python setup.py install_lib

3. Export variables

$ export DBT_S3_LOCATION=s3://mybucket/myprefix
$ export DBT_ROLE_ARN=arn:aws:iam::1234567890:role/GlueInteractiveSessionRole

4. Run the test

$ python3 -m pytest tests/functional

For more information, check the dbt documentation about testing a new adapter.

Caveats

Supported Functionality

Most dbt Core functionality is supported, but some features are only available with Apache Hudi.

Apache Hudi-only features:

1. Incremental model updates by unique_key instead of partition_by (see merge strategy)

Some dbt features, available on the core adapters, are not yet supported on Glue:

1. Persisting column-level descriptions as database comments
2. Snapshots

---

For more information on dbt:

• Read the introduction to dbt.
• Read the dbt viewpoint.
• Join the dbt community.

---

Security

See CONTRIBUTING for more information.

License

This project is licensed under the Apache-2.0 License.