Add support for extensions in Docker environment (#3042)

By default, the container starts without extensions. But if for some reasons,
you need to add them without copying or moving some code, you can embed them
while starting the container. The syntax is:
```
make start extensions="/full/path/to/extension/1 /full/path/to/extension/2"
```

1 files changed, 2 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 6e77de8a9..566fd3c10 100644
--- a/Makefile
+++ b/Makefile
@@ -38,9 +38,11 @@ build: ## Build a Docker image
 
 .PHONY: start
 start: ## Start the development environment (use Docker)
+	$(foreach extension,$(extensions),$(eval volumes=$(volumes) --volume $(extension):/var/www/FreshRSS/extensions/$(notdir $(extension)):z))
 	docker run \
 		--rm \
 		--volume $(shell pwd):/var/www/FreshRSS:z \
+		$(volumes) \
 		--publish $(PORT):80 \
 		--env FRESHRSS_ENV=development \
 		--name freshrss-dev \