Improve documentation on Debugging source controller

Expands on the current documentation to help contributors debug the controller
regardless of all its existing dependencies.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

DEVELOPMENT.md

@@ -128,3 +128,31 @@ Deploy `source-controller` into the cluster that is configured in the local kube
 ```sh
 make deploy
 ```
+
+### Debugging controller with VSCode
+
+Create a `.vscode/launch.json` file:
+```json
+{
+ "version": "0.2.0",
+ "configurations": [
+ {
+ "name": "Launch Package",
+ "type": "go",
+ "request": "launch",
+ "mode": "auto",
+ "envFile": "${workspaceFolder}/build/.env",
+ "program": "${workspaceFolder}/main.go"
+ }
+ ]
+}
+```
+
+Create the environment file containing details on how to load 
+`libgit2` dependencies:
+```bash
+make env
+```
+
+Start debugging by either clicking `Run` > `Start Debugging` or using
+the relevant shortcut.

Makefile

@@ -241,19 +241,30 @@ endef
 
 # Build fuzzers
 fuzz-build: $(LIBGIT2)
- rm -rf $(shell pwd)/build/fuzz/
- mkdir -p $(shell pwd)/build/fuzz/out/
+ rm -rf $(BUILD_DIR)/fuzz/
+ mkdir -p $(BUILD_DIR)/fuzz/out/
 
  docker build . --tag local-fuzzing:latest -f tests/fuzz/Dockerfile.builder
  docker run --rm \
  -e FUZZING_LANGUAGE=go -e SANITIZER=address \
  -e CIFUZZ_DEBUG='True' -e OSS_FUZZ_PROJECT_NAME=fluxcd \
- -v "$(shell pwd)/build/fuzz/out":/out \
+ -v "$(BUILD_DIR)/fuzz/out":/out \
  local-fuzzing:latest
 
 fuzz-smoketest: fuzz-build
  docker run --rm \
- -v "$(shell pwd)/build/fuzz/out":/out \
+ -v "$(BUILD_DIR)/fuzz/out":/out \
  -v "$(shell pwd)/tests/fuzz/oss_fuzz_run.sh":/runner.sh \
  local-fuzzing:latest \
  bash -c "/runner.sh"
+
+# Creates an env file that can be used to load all source-controller's dependencies
+# this is handy when you want to run adhoc debug sessions on tests or start the 
+# controller in a new debug session.
+env: $(LIBGIT2)
+ echo 'GO_ENABLED="1"' > $(BUILD_DIR)/.env
+ echo 'PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)"' >> $(BUILD_DIR)/.env
+ echo 'LIBRARY_PATH="$(LIBRARY_PATH)"' >> $(BUILD_DIR)/.env
+ echo 'CGO_CFLAGS="$(CGO_CFLAGS)"' >> $(BUILD_DIR)/.env
+ echo 'CGO_LDFLAGS="$(CGO_LDFLAGS)"' >> $(BUILD_DIR)/.env
+ echo 'KUBEBUILDER_ASSETS=$(KUBEBUILDER_ASSETS)' >> $(BUILD_DIR)/.env