fix: remove PyYAML runtime dependency from Bazel flow scripts

.gitattributes

@@ -1,2 +1,3 @@
 # Make Github ignore the designs folder when determining repo language
 flow/designs/src/* linguist-vendored
+flow/scripts/variables.json linguist-generated=true

.github/workflows/github-actions-yaml-test.yml

@@ -15,18 +15,25 @@ jobs:
         fetch-depth: 1
         sparse-checkout: |
           flow/scripts/generate-variables-docs.py
+          flow/scripts/yaml_to_json.py
+          flow/scripts/variables.yaml
+          flow/scripts/variables.json
           docs/user/FlowVariables.md
           yamlfix.toml
+    - name: Install dependencies
+      run: |
+        python3 -m venv venv
+        venv/bin/pip install --quiet pyyaml yamlfix==1.17.0
     - name: Run generate-variables-docs.py
       run: |
-        python3 flow/scripts/generate-variables-docs.py
+        venv/bin/python3 flow/scripts/generate-variables-docs.py
     - name: Check if FlowVariables.md is up to date
       run: |
         git diff --exit-code docs/user/FlowVariables.md
-    - name: Install dependencies
+    - name: Check variables.json is up to date
       run: |
-        python3 -m venv venv
-        venv/bin/pip install --quiet yamlfix==1.17.0
+        venv/bin/python3 flow/scripts/yaml_to_json.py
+        git diff --exit-code flow/scripts/variables.json
     - name: Run yamlfix check
       run: |
         source venv/bin/activate

flow/BUILD.bazel

@@ -2,6 +2,7 @@ load("@bazel-orfs//:openroad.bzl", "orfs_pdk")
 
 # files shared between scripts/synth.sh and scripts/flow.sh steps
 MAKEFILE_SHARED = [
+    "scripts/variables.json",
     "scripts/*.py",
     "scripts/*.sh",
     "scripts/*.yaml",

flow/scripts/defaults.py

@@ -1,13 +1,13 @@
 #!/usr/bin/env python3
 
+import json
 import os
-import yaml
 
 dir_path = os.path.dirname(os.path.realpath(__file__))
 
-yaml_path = os.path.join(dir_path, "variables.yaml")
-with open(yaml_path, "r") as file:
-    data = yaml.safe_load(file)
+json_path = os.path.join(dir_path, "variables.json")
+with open(json_path, "r") as file:
+    data = json.load(file)
 
 for key, value in data.items():
     if value.get("default", None) is None:

flow/scripts/non_stage_variables.py

@@ -5,15 +5,15 @@
 #
 # This script generates a list of variables known
 # not to be in the current stage.
+import json
 import os
 import sys
-import yaml
 
 dir_path = os.path.dirname(os.path.realpath(__file__))
 
-yaml_path = os.path.join(dir_path, "variables.yaml")
-with open(yaml_path, "r") as file:
-    data = yaml.safe_load(file)
+json_path = os.path.join(dir_path, "variables.json")
+with open(json_path, "r") as file:
+    data = json.load(file)
 
 for key, value in data.items():
     if "stages" not in value: