feat: Add Job traits (combine)

Author: Alan Christie

decoder/decoder.py

@@ -13,6 +13,10 @@
 import jsonschema
 import yaml
 
+# Supported 'traits'
+TRAIT_COMBINE: str = "combine"
+ALL_TRAITS: Set[str] = {TRAIT_COMBINE}
+
 # The decoding engine implementations.
 # The modules are expected to be called 'decode_<TextEncoding.lower()>'
 from . import decode_jinja2_3_0
@@ -360,6 +364,12 @@ def get_image(job_definition: Dict[str, Any]) -> Tuple[str, str]:
     return image_name, image_tag
 
 
+def get_traits(job_definition: Dict[str, Any]) -> List[Dict[str, Any]]:
+    """Returns the array of Job traits. Each trait proeprty name can be found
+    in the module's ALL_TRAITS set."""
+    return job_definition.get("traits", [])
+
+
 def decode(
     template_text: str,
     variable_map: Optional[Dict[str, str]],

decoder/job-definition-schema.yaml

@@ -101,6 +101,13 @@ definitions:
         $ref: '#/definitions/job-test'
       replaces:
         $ref: '#/definitions/replace-list'
+      # Traits - a list of Job characteristics or behaviours.
+      # These can be used by automated tools to drive the Job.
+      traits:
+        type: array
+        items:
+          anyOf:
+          - $ref: '#/definitions/trait-combine'
     required:
     - name
     - version
@@ -181,6 +188,26 @@ definitions:
     type: string
     pattern: '^([1-9][0-9]{2,3}Mi|[1-9][0-9]{0,1}Gi)$'
 
+  # The 'combine' trait.
+  # This declares the name of an input that is typically
+  # a series of files that the job combines, producing a single output.
+  # A job with a 'combine' trait is esentially a "combiner" - somewthing
+  # that processes a number of files, all presented to the Job via
+  # the named variable. If the Job combines files using its "--source"
+  # input property it would have a "combine: source" trait.
+  #
+  # The value of the "combine" property should be the name of an
+  # input variable declared in the Job's "variables" block.
+  trait-combine:
+    type: object
+    additionalProperties: false
+    properties:
+      combine:
+        type: string
+        pattern: '^[a-zA-Z]{1}[a-zA-Z0-9-_]{0,79}$'
+    required:
+    - combine
+
   # Image environment definitions.
   environment:
     type: array

tests/test_get_traits.py

@@ -0,0 +1,41 @@
+# Tests for the decoder's get_traits() function.
+from typing import Dict
+
+import pytest
+
+pytestmark = pytest.mark.unit
+
+from decoder import decoder
+
+
+def test_check_all_traits():
+    # Arrange
+
+    # Act
+
+    # Assert
+    assert len(decoder.ALL_TRAITS) == 1
+    assert decoder.TRAIT_COMBINE in decoder.ALL_TRAITS
+
+
+def test_get_traits_when_none():
+    # Arrange
+    job_definition: Dict = {}
+
+    # Act
+    traits = decoder.get_traits(job_definition)
+
+    # Assert
+    assert traits == []
+
+
+def test_get_traits_when_combine():
+    # Arrange
+    job_definition: Dict = {"traits": [{"combine": "source"}]}
+
+    # Act
+    traits = decoder.get_traits(job_definition)
+
+    # Assert
+    assert len(traits) == 1
+    assert traits[0] == {"combine": "source"}