Add possibility to use env vars for settings

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

docker-compose/Makefile

@@ -9,23 +9,25 @@ ATTACH_COMPOSE_FILE_ARGS := $(foreach yml,$(filter-out tango.yml,$(COMPOSE_FILES
 
 # If the first make argument is "start" or "stop"...
 ifeq (start,$(firstword $(MAKECMDGOALS)))
-  SERVICE_TARGET = true
+    SERVICE_TARGET = true
 else ifeq (stop,$(firstword $(MAKECMDGOALS)))
-  SERVICE_TARGET = true
+    SERVICE_TARGET = true
 else ifeq (attach,$(firstword $(MAKECMDGOALS)))
-  SERVICE_TARGET = true
-ifndef NETWORK_MODE
-$(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
+    SERVICE_TARGET = true
+    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))
-  # ...and turn them into do-nothing targets
-  $(eval $(SERVICE):;@:)
+    # .. then use the rest as arguments for the make target
+    SERVICE := $(wordlist 2,$(words $(MAKECMDGOALS)),$(MAKECMDGOALS))
+    # ...and turn them into do-nothing targets
+    $(eval $(SERVICE):;@:)
 endif
 
 #
@@ -35,37 +37,41 @@ endif
 # time.
 #
 ifneq ($(CI_JOB_ID),)
-NETWORK_MODE := tangonet-$(CI_JOB_ID)
-CONTAINER_NAME_PREFIX := $(CI_JOB_ID)-
+    NETWORK_MODE := tangonet-$(CI_JOB_ID)
+    CONTAINER_NAME_PREFIX := $(CI_JOB_ID)-
 else
-CONTAINER_NAME_PREFIX :=
-$(info Network mode cannot be host for the archiver! It won't work unless you set the env var CI_JOB_ID=local)
+    CONTAINER_NAME_PREFIX :=
+    $(info Network mode cannot be host for the archiver! It won't work unless you set the env var CI_JOB_ID=local)
 endif
 
 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
-		XAUTHORITY_MOUNT := /tmp/.X11-unix:/tmp/.X11-unix
-		XAUTHORITY ?= /hosthome/.Xauthority
-		# /bin/sh (=dash) does not evaluate 'docker network' conditionals correctly
-		SHELL := /bin/bash
-	endif
-	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
-		# Make sure that Darwin, especially from macOS Catalina on,
-		# 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
-		XAUTHORITY_MOUNT := $(HOME)/.Xauthority:/hosthome/.Xauthority:ro
-		XAUTHORITY := /hosthome/.Xauthority
-	endif
+    UNAME_S := $(shell uname -s)
+
+    ifeq ($(UNAME_S),Linux)
+        DISPLAY ?= :0.0
+        NETWORK_MODE ?= host
+        XAUTHORITY_MOUNT := /tmp/.X11-unix:/tmp/.X11-unix
+        XAUTHORITY ?= /hosthome/.Xauthority
+        # /bin/sh (=dash) does not evaluate 'docker network' conditionals correctly
+        SHELL := /bin/bash
+    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
+        # Make sure that Darwin, especially from macOS Catalina on,
+        # 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
+        ifeq ($(NETWORK_MODE),)
+            NETWORK_MODE := tangonet
+        else
+            NETWORK_MODE := $(NETWORK_MODE)
+        endif
+        XAUTHORITY_MOUNT := $(HOME)/.Xauthority:/hosthome/.Xauthority:ro
+        XAUTHORITY := /hosthome/.Xauthority
+    endif
 endif
 
 #
@@ -73,16 +79,32 @@ endif
 # machine rather than at the container.
 #
 ifeq ($(NETWORK_MODE),host)
-	TANGO_HOST := $(shell hostname):10000
-	MYSQL_HOST := $(shell hostname):3306
+    TANGO_HOST := $(shell hostname):10000
+    MYSQL_HOST := $(shell hostname):3306
 else
-	TANGO_HOST := $(CONTAINER_NAME_PREFIX)databaseds:10000
-	MYSQL_HOST := $(CONTAINER_NAME_PREFIX)tangodb:3306
+    ifeq ($(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}'
-