separate docker-db from init-db

so we don't need docker on Travis

test-db-upgrade/docker-db.sh

@@ -1,19 +1,44 @@
 #!/usr/bin/env bash
-set -e
-NAME="hub-test-$DB"
-docker rm -f $NAME 2>/dev/null || true
+# source this file to setup postgres and mysql
+# for local testing (as similar as possible to docker)
 
-case $DB in
-mysql)
-  ARGS="-p 13306:3306 -e MYSQL_ROOT_PASSWORD=x -e MYSQL_DATABASE=jupyterhub mysql:5.7"
-  ;;
-postgres)
-  ARGS="-p 15432:5432 -e POSTGRES_DB=jupyterhub postgres:9.5"
-  ;;
-*)
-  echo "must be mysql or postgres"
-  exit -1
-esac
+DOCKER="docker run --rm -d --name"
 
-set -x
-docker run --rm --name $NAME -d $ARGS
+export MYSQL_HOST=127.0.0.1
+export PGHOST=127.0.0.1
+
+set -ex
+docker rm -f hub-test-mysql hub-test-postgres 2>/dev/null || true
+
+$DOCKER hub-test-mysql -e MYSQL_ALLOW_EMPTY_PASSWORD=1 -p 3306:3306 mysql:5.7
+$DOCKER hub-test-postgres -p 5432:5432 postgres:9.5
+set +x
+
+echo -n 'waiting for postgres'
+for i in {1..60}; do
+  if psql --user postgres -c '\q' 2>/dev/null; then
+    echo 'done'
+    break
+  else
+    echo -n '.'
+    sleep 1
+  fi
+done
+
+echo -n 'waiting for mysql'
+for i in {1..60}; do
+  if mysql --user root -e '\q' 2>/dev/null; then
+    echo 'done'
+    break
+  else
+    echo -n '.'
+    sleep 1
+  fi
+done
+
+echo -e "
+Set these environment variables:
+
+    export MYSQL_HOST=127.0.0.1
+    export PGHOST=127.0.0.1
+"