add: ACME domain, .env generator; minor code refactoring

Makefile

@@ -1,35 +1,35 @@
+# app custom Makefile
+
 SHELL         = /bin/sh
-CFG           =.env
+CFG           = .env
 
 SOURCES      ?= $(wildcard *.sql)
 OBJECTS       = $(SOURCES:.sql=.done)
 OBJECTSDIRECT = $(SOURCES:.sql=.direct)
 
 # ------------------------------------------------------------------------------
-# шаблон файла .env
+# app custom config
+# comments prefixed with '#- ' will be copied to $(CFG).sample
 
-define CONFIG_DEF
-# dcape-dns config file, generated by make $(CFG)
+#- Postgresql container name (access via docker)
+PG_CONTAINER ?= dcape_db_1
 
-# Postgresql container name (access via docker)
-PG_CONTAINER=dcape_db_1
+#- PowerDNS DB user name
+PGUSER       ?= pdns
 
-# PowerDNS DB user name
-PGUSER=pdns
+#- PowerDNS DB name
+PGDATABASE   ?= pdns
 
-# PowerDNS DB name
-PGDATABASE=pdns
+#- Used ONLY for direct DB access without docker (update-direct)
+PGPASSWORD   ?=
 
-# Used ONLY for direct DB access without docker (start-direct)
-PGPASSWORD=
-
-endef
-export CONFIG_DEF
-
-all: help
+#- ACME zone suffix
+ACME_DOMAIN  ?=
 
 # ------------------------------------------------------------------------------
 
+all: help
+
 -include $(CFG)
 export
 
@@ -38,41 +38,69 @@ export
 
 start-hook: update
 
-start-direct: update-direct
-
 stop:
 
-$(CFG): $(CFG).sample
-	@[ -f $@ ] || cp $< $@
-
 # ------------------------------------------------------------------------------
+## Usage
+#:
 
+## Load updated zone files via running PG container
 update: $(OBJECTS)
 
 %.done: %.sql
 	@echo "*** $< ***"
 	@csum=$$(md5sum $< | sed 's/ .*//') ; \
-	  cat $< | docker exec -i $$PG_CONTAINER psql -U $$PGUSER -d $$PGDATABASE -vcsum=$$csum > $@
-
-# ------------------------------------------------------------------------------
+	  cat $< | docker exec -i $$PG_CONTAINER psql -U $$PGUSER -d $$PGDATABASE -vcsum=$$csum -vACME_DOMAIN=$(ACME_DOMAIN) > $@
 
+## Load updated zone files via psql connection
 update-direct: $(CFG) $(OBJECTSDIRECT)
 
 %.direct: %.sql
 	@echo "*** $< ***"
 	@source $(CFG) && cat $< | PGPASSWORD=$$PGPASSWORD psql -h localhost -U $$PGUSER > $@
 
-# ------------------------------------------------------------------------------
-
+## Run psql via running PG container
 psql:
 	@docker exec -it $$PG_CONTAINER psql -U $$PGUSER $$PGDATABASE
 
-clean:
-	rm -rf *.done
+# ------------------------------------------------------------------------------
+## Other
+#:
 
-$(CFG).sample:
-	@echo "*** $@ ***"
-	@[ -f $@ ] || echo "$$CONFIG_DEF" > $@
+# This code generates $(CFG).sample from Makefile vars with previous comment line(s)
+# See https://gist.github.com/LeKovr/2697fe02504d7c081b0bf79427c93db6
+
+# Internal: generate config sample data
+.env.temp.mk:
+	@echo "define CFVAR" > $@
+	@grep -A 1 -h "^#- " $(MAKEFILE_LIST) | grep -vE "^--" \
+	  | sed -E 's/^([^\n ]+)\ *\??=([^\n]*)$$/\1=$$(\1)\n/ ; s/^(#)-/\1/' >> $@
+	@echo "endef" >> $@
+
+ifneq ($(findstring $(MAKECMDGOALS),config $(CFG).sample),)
+include .env.temp.mk
+endif
+
+# Internal: generate config sample
+$(CFG).sample: .env.temp.mk
+	@echo "# dcape-dns config file, generated by 'make config'\n" > $@
+	@echo "$$CFVAR" >> $@
+	@rm -f $<
 
 ## generate sample config
 config: $(CFG).sample
+
+# ------------------------------------------------------------------------------
+
+## Remove .done files
+clean:
+	rm -rf *.done
+
+# This code handles group header and target comment with one or two lines only
+## list Makefile targets
+## (this is default target)
+help:
+	@grep -A 1 -h "^## " $(MAKEFILE_LIST) \
+  | sed -E 's/^--$$// ; /./{H;$$!d} ; x ; s/^\n## ([^\n]+)\n(## (.+)\n)*(.+):(.*)$$/"    " "\4" "\1" "\3"/' \
+  | sed -E 's/^"    " "#" "(.+)" "(.*)"$$/"" "" "" ""\n"\1 \2" "" "" ""/' \
+  | xargs printf "%s\033[36m%-15s\033[0m %s %s\n"