dagrules - dbt DAG rule creator and validator
Project description
dagrules
dagrules is a tool that allows you to write your own dbt dag rules and check that your dbt project is conforming to those rules.
Overview
While the dbt community has established some excellent guidelines for
how to structure dbt
projects,
those conventions are not automatically enforced. Those
conventions are simply guidelines, and each team may decide on a
slightly different set of conventions that work best for their
particular set up. dagrules was developed to allow you to write your
own conventions in a simple yaml
document, and have those
conventions enforced via your CI system.
To use dagrules, all you need is a dbt project and a dagrules.yml
file located in the root of the dbt project (e.g.,
dbt/dagrules.yml
). The yaml file should look like (for a more
complete example, see tests/dagrules.yml:
---
version: '1'
rules:
- name: The name of my rule
subject:
... # How to select nodes to check that they satisfy the rules
must:
... # Define the rules that must be followed
- name: Another one of my rules
...
Installation and running rules
dagrules can be installed using pip:
pip install dagrules
And then run dagrules
with the --check
argument from your dbt project root:
dagrules --check
dagrules assumes that it is being executed from the dbt project root and that there is
a target/manifest.json
file already present (so the dbt project must be compiled
any time the dag is changed before dagrules can be run). These defaults can
be overridden by setting the DBT_ROOT
and DAGRULES_YAML
environment variable to
point to other locations.
Subjects
For every rule, a subject should be declared that defines how to select nodes of the dbt dag to use for rule validation. Omitting the subject means that the rule will be applied to every dbt model. dagrules currently supports two ways to select subjects: 1) by node type (source, snapshot, model) and 2) by tags. For example, the follow subject includes all models that are tagged "staging":
rules:
- name: All staging models must ...
subject:
type: model
tags: staging
must:
...
Tag selection
Tag selection applies both to subject
and must
section of the
dagrules yaml spec. Tags can be defined several ways.
Single string - Selecting with a single tag can be expressed as a simple string
tags: staging
List of tags: match any - A list of tags can also be specified, and
dagrules will match nodes with any of the tags in the list. The
example below will match nodes having either base
or intermediate
tags.
tags:
- base
- intermediate
Include: match all with exclusions - When you need to select nodes
that match all tags in a list, and possibly exclude nodes with
some tags as well, you can use include/exclude. The example below
will select any nodes that have both "staging" and "finance" tags, but
that don't also have the base
tag.
tags:
include:
- staging
- finance
exclude:
- base
The arguments to include
and exclude
can either be a list or single strings.
Combine any/all - We can also combine any and all syntaxes at once. The following will select all nodes that are either "non-base staging", "core", or "mart" models.:
tags:
- include: staging
exclude: base
- core
- mart
Musts
"Musts" define the rules that must be adhered to by the subjects defined in the subject
section. Multiple "musts" may be included in a rule definition, and all must be
satisfied for the rule to pass.
Match name - The match-name
rule requires that each subject adhere to a
particular naming pattern. dagrules currently only supports regular expression matching.
For example, the following rule enforces that all snapshot models must be named with
a snap_
prefix:
rules:
- name: Snapshot must be prefixed with snap_
subject:
type: snapshot
must:
match-name: /snap_.*/
Have tags - The have-tags-any
rule requires that all selected models must have
one of any of the listed tags. The following example specifies that all nodes in the dag
must have at least one of the tags listed:
rules:
- name: All models must be tagged either snapshot, base, staging, intermediate, core, mart
# Omit subject to include all nodes
must:
have-tags-any:
- snaphost
- base
- staging
- intermediate
- core
- mart
Have parent or child relationship - The have-child-relationship
and have-parent-relationship
rules require that the subjects have a
certain kind of relationship to either their immediate children or
parents. The types of relationship can involve:
cardinality
- The cardinality of the relationship between a subject and its child/parent can either beone_to_one
orone_to_many
(default). Ifone_to_one
is selected, that a subject may only have one child/parent.required
- Indicates whether a child/parent relationship is required or not. The default isTrue
, meaning that if a relationship is defined, all subject must have at least one child or parent node. IfFalse
, then a subject may have 0 children/parents.require-tags-any
- Contains a list of tags that the parent/child must have (with syntax defined in the "Tag selection" section above).require-node-type
- Indicates the node type (source, snapshot, model) that the child/parent must be in order to pass.select-tags-any
- Contains a list of tags that restricts the selection of parents/children involved in the rule.select-node-type
- Indicates that only the parents/children with the specified node type are to be considered when checking the rule.
For example,
rules:
- name: Snapshots must have 0 or 1 children, which must all be base models
subject:
type: snapshot
must:
have-child-relationship:
cardinality: one_to_one
required: false
require-tags-any:
- base
- name: Intermediate models may only depend on non-base staging, core, mart, or other intermediate models
subject:
tags:
include: intermediate
must:
have-parent-relationship:
require-tags-any:
- include: staging
exclude: base
- core
- mart
- intermediate
Contributing
We welcome contributors! Please submit any suggests or pull requests in Github.
Developer setup
Create an appropriate python environment. I like miniconda, but use whatever you like:
conda create --name dagrules python=3.9
conda activate dagrules
Then install pip packages
pip install pip-tools
pip install --ignore-installed -r requirements.txt
run tests via
inv test
and the linter via
inv lint
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