Fix SQL race condition

When running "wait-for-mysql.sh", the "echo 'show tables' | manage.py
dbshell" command is always considered a success, even if the database is
unreachable ($? == 0). So we replace this command by a global system
check.

This closes #3.

Makefile

@@ -11,8 +11,8 @@ build:
 	docker-compose build
 
 migrate:
-	docker-compose run --rm lms bash -c "./wait-for-mysql.sh && ./manage.py lms --settings=production migrate"
-	docker-compose run --rm cms bash -c "./wait-for-mysql.sh && ./manage.py cms --settings=production migrate"
+	docker-compose run --rm lms bash -c "./wait-for-greenlight.sh && ./manage.py lms --settings=production migrate"
+	docker-compose run --rm cms bash -c "./wait-for-greenlight.sh && ./manage.py cms --settings=production migrate"
 
 assets:
 	docker-compose run --rm lms paver update_assets lms --settings=production

edxapp/Dockerfile

@@ -47,7 +47,7 @@ COPY ./config/lms.auth.json /openedx/
 COPY ./config/cms.auth.json /openedx/
 
 # Copy convenient script
-COPY ./wait-for-mysql.sh .
+COPY ./wait-for-greenlight.sh .
 
 ############ End of code common to lms & cms
 

edxapp/wait-for-greenlight.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+echo "Checking system..."
+until ./manage.py lms --settings=production check
+do
+  printf "."
+  sleep 1
+done
+
+echo -e "\nSystem is ready \\o/"

edxapp/wait-for-mysql.sh

@@ -1,10 +0,0 @@
-#!/bin/bash
-
-echo "Waiting for mysql database"
-until echo "show tables;" | ./manage.py lms --settings=production dbshell
-do
-  printf "."
-  sleep 1
-done
-
-echo -e "\nmysql database ready"