Add possibility to use env vars for settings

The environment variables that are considered are:
- TANGO_HOST
- NETWORK_MODE
- MYSQL_HOST

docker-compose/Makefile

@@ -17,10 +17,12 @@ else ifeq (attach,$(firstword $(MAKECMDGOALS)))
     ifndef NETWORK_MODE
         $(error NETWORK_MODE must specify the network to attach to, e.g., make NETWORK_MODE=tangonet-powersupply ...)
     endif
+
     ifndef TANGO_HOST
         $(error TANGO_HOST must specify the Tango database device, e.g., make TANGO_HOST=powersupply-databaseds:10000 ...)
     endif
 endif
+
 ifdef SERVICE_TARGET
     # .. then use the rest as arguments for the make target
     SERVICE := $(wordlist 2,$(words $(MAKECMDGOALS)),$(MAKECMDGOALS))
@@ -46,6 +48,7 @@ ifeq ($(OS),Windows_NT)
     $(error Sorry, Windows is not supported yet)
 else
     UNAME_S := $(shell uname -s)
+
     ifeq ($(UNAME_S),Linux)
         DISPLAY ?= :0.0
         NETWORK_MODE ?= host
@@ -53,8 +56,7 @@ else
         XAUTHORITY ?= /hosthome/.Xauthority
         # /bin/sh (=dash) does not evaluate 'docker network' conditionals correctly
         SHELL := /bin/bash
-	endif
-	ifeq ($(UNAME_S),Darwin)
+    else ifeq ($(UNAME_S),Darwin)
         IF_INTERFACE := $(shell scutil --nwi | grep 'Network interfaces:' | cut -d' ' -f3)
         IP_ADDRESS := $(shell scutil --nwi | grep 'address' | cut -d':' -f2 | tr -d ' ' | head -n1)
         DISPLAY := $(IP_ADDRESS):0
@@ -62,7 +64,11 @@ else
         # allows X access from our Docker containers.
         ADD_TO_XHOST := $(shell xhost +$(IP_ADDRESS))
         # network_mode = host doesn't work on MacOS, so fix to the internal network
-		NETWORK_MODE ?= tangonet
+        ifeq ($(NETWORK_MODE),)
+            NETWORK_MODE := tangonet
+        else
+            NETWORK_MODE := $(NETWORK_MODE)
+        endif
         XAUTHORITY_MOUNT := $(HOME)/.Xauthority:/hosthome/.Xauthority:ro
         XAUTHORITY := /hosthome/.Xauthority
     endif
@@ -76,13 +82,29 @@ ifeq ($(NETWORK_MODE),host)
     TANGO_HOST := $(shell hostname):10000
     MYSQL_HOST := $(shell hostname):3306
 else
+    ifeq ($(TANGO_HOST),)
         TANGO_HOST := $(CONTAINER_NAME_PREFIX)databaseds:10000
+    else
+        TANGO_HOST := $(TANGO_HOST)
+    endif
+
+    ifeq ($(MYSQL_HOST),)
         MYSQL_HOST := $(CONTAINER_NAME_PREFIX)tangodb:3306
+    else
+        MYSQL_HOST := $(MYSQL_HOST)
+    endif
 endif
 
-DOCKER_COMPOSE_ARGS := DISPLAY=$(DISPLAY) XAUTHORITY=$(XAUTHORITY) TANGO_HOST=$(TANGO_HOST) \
-		NETWORK_MODE=$(NETWORK_MODE) XAUTHORITY_MOUNT=$(XAUTHORITY_MOUNT) TANGO_SKA_CONTAINER_MOUNT=$(TANGO_SKA_CONTAINER_MOUNT) TANGO_LOFAR_CONTAINER_MOUNT=$(TANGO_LOFAR_CONTAINER_MOUNT) TANGO_LOFAR_CONTAINER_DIR=${TANGO_LOFAR_CONTAINER_DIR} MYSQL_HOST=$(MYSQL_HOST) \
-		CONTAINER_NAME_PREFIX=$(CONTAINER_NAME_PREFIX) COMPOSE_IGNORE_ORPHANS=true
+DOCKER_COMPOSE_ARGS := DISPLAY=$(DISPLAY) \
+    XAUTHORITY=$(XAUTHORITY) \
+    TANGO_HOST=$(TANGO_HOST) \
+    NETWORK_MODE=$(NETWORK_MODE) \
+    XAUTHORITY_MOUNT=$(XAUTHORITY_MOUNT) \
+    TANGO_SKA_CONTAINER_MOUNT=$(TANGO_SKA_CONTAINER_MOUNT) \
+    TANGO_LOFAR_CONTAINER_MOUNT=$(TANGO_LOFAR_CONTAINER_MOUNT) \
+    TANGO_LOFAR_CONTAINER_DIR=${TANGO_LOFAR_CONTAINER_DIR} MYSQL_HOST=$(MYSQL_HOST) \
+    CONTAINER_NAME_PREFIX=$(CONTAINER_NAME_PREFIX) \
+    COMPOSE_IGNORE_ORPHANS=true
 
 
 .PHONY: up down minimal start stop status clean pull help
@@ -127,4 +149,3 @@ clean: down  ## clear all TANGO database entries
 
 help:   ## show this help.
 	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'
-