Add DroneCI pipeline stage to validate loki example configs; create example configuration files

.drone/drone.jsonnet

@@ -284,6 +284,9 @@ local manifest(apps) = pipeline('manifest') {
         image: 'koalaman/shellcheck-alpine:stable',
         commands: ['apk add make bash && make lint-scripts'],
       },
+      make('loki', container=false) { depends_on: ['clone'] },
+      make('validate-example-configs', container=false) { depends_on: ['loki'] },
+      make('check-example-config-doc', container=false) { depends_on: ['clone'] },
     ],
   },
 ] + [

.drone/drone.yml

@@ -46,6 +46,27 @@ steps:
   commands:
   - apk add make bash && make lint-scripts
 
+- name: loki
+  image: grafana/loki-build-image:0.17.0
+  commands:
+  - make BUILD_IN_CONTAINER=false loki
+  depends_on:
+  - clone
+
+- name: validate-example-configs
+  image: grafana/loki-build-image:0.17.0
+  commands:
+  - make BUILD_IN_CONTAINER=false validate-example-configs
+  depends_on:
+  - loki
+
+- name: check-example-config-doc
+  image: grafana/loki-build-image:0.17.0
+  commands:
+  - make BUILD_IN_CONTAINER=false check-example-config-doc
+  depends_on:
+  - clone
+
 ---
 kind: pipeline
 name: docker-amd64
@@ -973,6 +994,6 @@ get:
 
 ---
 kind: signature
-hmac: b70be41d1a7f91c11af945a34bdbdc7a4f7613cf830c13f5438dba0bf33a1ec5
+hmac: f1681daaa15376eb15eae5dd623a3ec19544b0447506aba2d59a92f0fd8fee49
 
 ...

Makefile

@@ -7,6 +7,7 @@
 .PHONY: bigtable-backup, push-bigtable-backup
 .PHONY: benchmark-store, drone, check-mod
 .PHONY: migrate migrate-image lint-markdown ragel
+.PHONY: validate-example-configs generate-example-config-doc check-example-config-doc
 
 SHELL = /usr/bin/env bash
 
@@ -635,3 +636,30 @@ format:
 		-type f -name '*.go' -exec gofmt -w -s {} \;
 	find . $(DONT_FIND) -name '*.pb.go' -prune -o -name '*.y.go' -prune -o -name '*.rl.go' -prune -o \
 		-type f -name '*.go' -exec goimports -w -local github.com/grafana/loki {} \;
+
+###################
+# Example Configs #
+###################
+
+# Validate the example configurations that we provide in ./docs/sources/configuration/examples
+validate-example-configs: loki
+	for f in ./docs/sources/configuration/examples/*.yaml; do echo "Validating provided example config: $$f" && ./cmd/loki/loki -config.file=$$f -verify-config || exit 1; done
+
+# Dynamically generate ./docs/sources/configuration/examples.md using the example configs that we provide.
+# This target should be run if any of our example configs change.
+generate-example-config-doc:
+	echo "Removing existing doc at loki/docs/configuration/examples.md and re-generating. . ."
+	# Title and Heading
+	echo -e "---\ntitle: Examples\n---\n # Loki Configuration Examples" > ./docs/sources/configuration/examples.md
+	# Append each configuration and its file name to examples.md
+	for f in ./docs/sources/configuration/examples/*.yaml; do echo -e "\n## $$(basename $$f)\n\n\`\`\`yaml\n$$(cat $$f)\n\`\`\`\n" >> ./docs/sources/configuration/examples.md; done
+
+# Fail our CI build if changes are made to example configurations but our doc is not updated
+check-example-config-doc: generate-example-config-doc
+	@if ! (git diff --exit-code ./docs/sources/configuration/examples.md); then \
+		echo -e "\nChanges found in generated example configuration doc"; \
+		echo "Run 'make generate-example-config-doc' and commit the changes to fix this error."; \
+		echo "If you are actively developing these files you can ignore this error"; \
+		echo -e "(Don't forget to check in the generated files when finished)\n"; \
+		exit 1; \
+	fi