add yamllint

.drone.yml

@@ -0,0 +1,15 @@
+---
+kind: pipeline
+type: docker
+name: pull_request
+image_pull_secrets:
+  - dockerconfigjson
+
+steps:
+  - name: lint yaml
+    image: registry.fedy95.com/baseimage-yamllint:latest
+    commands:
+      - yamllint -c /yamllint/relaxed.yaml docker-compose.yml
+    when:
+      event: pull_request
+...

Makefile

@@ -0,0 +1,14 @@
+MAKEFLAGS += --silent
+.PHONY: *
+
+REGISTRY=registry.fedy95.com
+YAMLLINT_TAG=baseimage-yamllint:latest
+
+lint: lint-yaml
+
+LINT-YAML-CMD=docker run --rm -it -v $(PWD):/data ${REGISTRY}/${YAMLLINT_TAG}
+lint-yaml:
+	docker pull ${REGISTRY}/${YAMLLINT_TAG}
+	$(LINT-YAML-CMD) docker-compose.yml
+
+.DEFAULT_GOAL := lint