remove hostess tool + add extra_hosts entry to oncall backend containers

Makefile

@@ -62,12 +62,6 @@ define run_engine_docker_command
 endef
 
 # touch SQLITE_DB_FILE if it does not exist and DB is eqaul to SQLITE_PROFILE
-#
-# hostess installation (crossplatform/idempotent modification of /etc/hosts file)
-# see here (https://github.com/cbednarski/hostess#installation) for docs
-# basically this is needed because oncall api has been configured locally to communicate w/ grafana @
-# http://grafana:3000. This becomes a problem in certain parts of OnCall where we generate "public" URLs
-# and the user tries to access them via their browser.
 start:
 ifeq ($(DB),$(SQLITE_PROFILE))
 	@if [ ! -f $(SQLITE_DB_FILE) ]; then \
@@ -75,17 +69,6 @@ ifeq ($(DB),$(SQLITE_PROFILE))
 	fi
 endif
 
-	@if [ ! -x "$$(command -v hostess)" ]; then \
-		echo "installing hostess"; \
-		git clone https://github.com/cbednarski/hostess "${HOME}/hostess"; \
-		cd "${HOME}/hostess"; \
-		make install; \
-	fi
-
-	@if ! hostess has grafana; then \
-		sudo hostess add grafana 127.0.0.1; \
-	fi
-
 	$(call run_docker_compose_command,up --remove-orphans -d)
 
 init:
@@ -168,4 +151,4 @@ backend-command:
 	$(call backend_command,$(CMD))
 
 backend-manage-command:
-	$(call backend_command,python manage.py $(CMD))
+	$(call backend_command,python manage.py $(CMD))

docker-compose-developer.yml

@@ -20,7 +20,19 @@ x-env-files: &oncall-env-files
 
 x-env-vars: &oncall-env-vars
   BROKER_TYPE: ${BROKER_TYPE}
-  GRAFANA_API_URL: http://grafana:3000
+  GRAFANA_API_URL: http://localhost:3000
+
+# basically this is needed because the oncall backend containers have been configured to communicate w/ grafana via
+# http://localhost:3000 (GRAFANA_API_URL). This URL is used in two scenarios:
+# 1. oncall backend -> grafana API communication (happens within docker)
+# 2. accessing templated URLs generated by the oncall backend - meant to be accessed via a browser on your host machine
+# The alternative is to set GRAFANA_API_URL to http://grafana:3000. However, this would only work in scenario #1
+# as http://grafana:3000 would not be resolvable on the host machine (without modifying /etc/hosts)
+#
+# by adding this extra_host entry to the oncall backend containers any calls to localhost will get routed to the docker
+# gateway, onto the host machine, where localhost:3000 points to grafana
+x-extra-hosts: &oncall-extra-hosts
+  - "localhost:host-gateway"
 
 services:
   oncall_ui:
@@ -49,6 +61,7 @@ services:
     env_file: *oncall-env-files
     environment: *oncall-env-vars
     volumes: *oncall-volumes
+    extra_hosts: *oncall-extra-hosts
     ports:
       - "8080:8080"
     depends_on:
@@ -68,6 +81,7 @@ services:
     env_file: *oncall-env-files
     environment: *oncall-env-vars
     volumes: *oncall-volumes
+    extra_hosts: *oncall-extra-hosts
     profiles:
       # no need to start this except from within the Makefile
       - _engine_commands
@@ -81,6 +95,7 @@ services:
     env_file: *oncall-env-files
     environment: *oncall-env-vars
     volumes: *oncall-volumes
+    extra_hosts: *oncall-extra-hosts
     depends_on:
       oncall_db_migration:
         condition: service_completed_successfully
@@ -95,6 +110,7 @@ services:
     env_file: *oncall-env-files
     environment: *oncall-env-vars
     volumes: *oncall-volumes
+    extra_hosts: *oncall-extra-hosts
     depends_on:
       postgres:
         condition: service_healthy