.gitlab-ci.yml: add --no-cache for apk, remove update step

.gitignore

@@ -1,6 +1,10 @@
+# Editor swap files
 *~*
 *.swp
 *.tmp
-wwwuser
-openbox/*
+
+# .gitlab-ci.yml pre-commit directory
+.cache/**
+
+# Symlink
 install.run

.gitlab-ci.yml

@@ -0,0 +1,16 @@
+# Based on https://pre-commit.com
+image: python:alpine
+gitlab-ci-pre-commit:
+  stage: build
+  before_script:
+    - apk add --no-cache git gcc musl-dev go
+    - pip install pre-commit
+  script:
+    - pre-commit run --all-files --show-diff-on-failure
+  variables:
+    # Remember to gitignore .cache/**
+    PRE_COMMIT_HOME: ${CI_PROJECT_DIR}/.cache/pre-commit
+    TERM: dumb
+  cache:
+    paths:
+      - ${PRE_COMMIT_HOME}

.pre-commit-config.yaml

@@ -43,13 +43,13 @@ repos:
   #     - id: mypy
 
   # GitHub Actions etc. configuration validity checking
-  # - repo: https://github.com/python-jsonschema/check-jsonschema
-  #   rev: 0.23.0
-  #   hooks:
+  - repo: https://github.com/python-jsonschema/check-jsonschema
+    rev: 0.23.0
+    hooks:
       #- id: check-dependabot
       #- id: check-github-actions
       #- id: check-github-workflows
-  #     - id: check-gitlab-ci
+      - id: check-gitlab-ci
 
   # - repo: https://github.com/jumanjihouse/pre-commit-hooks
   #   rev: 3.0.0