Add support for pydantic v2 (#795)

**Pull Request Checklist**
- [x] Fixes #713
- [ ] Tests added
- [ ] Documentation/examples added
- [x] [Good commit messages](https://cbea.ms/git-commit/) and/or PR
title

**Description of PR**
WIP, but wanted to get the bulk of it up for any feedback while I:
- add a test run in CI with pydantic v1 installed (to ensure existing
users are covered - they passed manually)
- add a couple more tests and try to support serializing v1 *and* v2
user-defined models (not just the v1 models from either version - I
think this should be possible).
- update the model generation to update the Field import

---

This PR updates hera to support use with either pydantic v1 or v2
installed. All hera internal code now imports pydantic objects from
`hera.shared._pydantic` (extended and renamed from `_base_model`). This
module ensures that we're always using v1 compatible objects, which
allows us to support codebases installing either pydantic v1 or v2
(although the models passed to Hera must be v1 for pydantic v1 and v2
for pydantic v2).

---------

Signed-off-by: Jacob Hayes <[email protected]>
Signed-off-by: Matt Rose <[email protected]>
Signed-off-by: Sambhav Kothari <[email protected]>
Co-authored-by: Matt Rose <[email protected]>
Co-authored-by: Sambhav Kothari <[email protected]>

.github/workflows/cicd.yaml

@@ -34,7 +34,7 @@ jobs:
 
       - name: Install dependencies
         run: poetry install
-    
+
       - name: run ci checks
         run: make ci
 
@@ -53,6 +53,44 @@ jobs:
         with:
           path: dist/*.whl
 
+  # Run tests against pydantic v1 until we drop support.
+  test-pydantic-v1:
+    name: test py${{ matrix.python-version }} (pydantic v1) on ${{ matrix.os }}
+    timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest]
+        python-version: ["3.8", "3.9", "3.10", "3.11"]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: checkout
+        uses: actions/checkout@v3
+
+      - name: Install poetry
+        run: pipx install poetry
+
+      - name: setup python ${{ matrix.python-version }}
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+          cache: "poetry"
+
+      - name: Install dependencies
+        run: |
+          poetry install
+          poetry run pip install "pydantic<2"
+
+      - name: run ci checks
+        run: make ci
+
+      - name: Upload coverage
+        uses: codecov/codecov-action@v3
+        with:
+          file: ./coverage.xml
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref || github.run_id }}
   cancel-in-progress: true

Makefile

@@ -55,11 +55,15 @@ workflows-models: ## Generate the Workflows models portion of Argo Workflows
 		--snake-case-field \
 		--target-python-version 3.8 \
 		--output src/hera/workflows/models \
-		--base-class hera.shared._base_model.BaseModel \
+		--output-model-type pydantic.BaseModel \
+		--base-class hera.shared._pydantic.BaseModel \
+		--input-file-type jsonschema \
 		--wrap-string-literal \
 		--disable-appending-item-suffix \
 		--disable-timestamp \
 		--use-default-kwarg
+	@find src/hera/workflows/models/ -name '*.py' -exec sed -i.bak 's/from pydantic import Field/from hera.shared._pydantic import Field/' {} +
+	@find src/hera/workflows/models/ -name '*.bak' -delete
 	@poetry run python scripts/models.py $(OPENAPI_SPEC_URL) workflows
 	@poetry run stubgen -o src -p hera.workflows.models && find src/hera/workflows/models -name '__init__.pyi' -delete
 	@rm $(SPEC_PATH)
@@ -74,11 +78,15 @@ events-models: ## Generate the Events models portion of Argo Workflows
 		--snake-case-field \
 		--target-python-version 3.8 \
 		--output src/hera/events/models \
-		--base-class hera.shared._base_model.BaseModel \
+		--output-model-type pydantic.BaseModel \
+		--base-class hera.shared._pydantic.BaseModel \
+		--input-file-type jsonschema \
 		--wrap-string-literal \
 		--disable-appending-item-suffix \
 		--disable-timestamp \
 		--use-default-kwarg
+	@find src/hera/events/models/ -name '*.py' -exec sed -i.bak 's/from pydantic import Field/from hera.shared._pydantic import Field/' {} +
+	@find src/hera/events/models/ -name '*.bak' -delete
 	@poetry run python scripts/models.py $(OPENAPI_SPEC_URL) events
 	@poetry run stubgen -o src -p hera.events.models && find src/hera/events/models -name '__init__.pyi' -delete
 	@rm $(SPEC_PATH)

docs/examples/workflows/scripts/callable_script.md

@@ -10,6 +10,8 @@
     ```python linenums="1"
     from typing import List, Union
 
+    from hera.shared.serialization import serialize
+
     try:
         from typing import Annotated  # type: ignore
     except ImportError:
@@ -99,7 +101,7 @@
     with Workflow(name="my-workflow") as w:
         with Steps(name="my-steps") as s:
             my_function(arguments={"input": Input(a=2, b="bar", c=42)})
-            str_function(arguments={"input": Input(a=2, b="bar", c=42).json()})
+            str_function(arguments={"input": serialize(Input(a=2, b="bar", c=42))})
             another_function(arguments={"inputs": [Input(a=2, b="bar", c=42), Input(a=2, b="bar", c=42.0)]})
             function_kebab(arguments={"a-but-kebab": 3, "b-but-kebab": "bar"})
             function_kebab_object(arguments={"input-value": Input(a=3, b="bar", c="42")})

examples/workflows/scripts/callable_script.py

@@ -1,5 +1,7 @@
 from typing import List, Union
 
+from hera.shared.serialization import serialize
+
 try:
     from typing import Annotated  # type: ignore
 except ImportError:
@@ -89,7 +91,7 @@ def function_kebab_object(annotated_input_value: Annotated[Input, Parameter(name
 with Workflow(name="my-workflow") as w:
     with Steps(name="my-steps") as s:
         my_function(arguments={"input": Input(a=2, b="bar", c=42)})
-        str_function(arguments={"input": Input(a=2, b="bar", c=42).json()})
+        str_function(arguments={"input": serialize(Input(a=2, b="bar", c=42))})
         another_function(arguments={"inputs": [Input(a=2, b="bar", c=42), Input(a=2, b="bar", c=42.0)]})
         function_kebab(arguments={"a-but-kebab": 3, "b-but-kebab": "bar"})
         function_kebab_object(arguments={"input-value": Input(a=3, b="bar", c="42")})