Add MySQL instance to docker-compose (#1303)

* Fix flaky service account tests
Sometimes, the SA tests fail with the "service account already exists" error
The issue is due to the fact that Grafana sometimes 500s on SA POSTs, but the SA is actually created, so on the retry, there's a conflict
This PR changes the retry process so that if we 500, we try to find the SA and "import" it before retrying

* Add MySQL instance to `docker-compose`
SQLite is pretty unstable. Gettings lots of `database is locked` errors which are fixed by this DB switch

Author: julienduchesne

docker-compose.yml

@@ -1,10 +1,32 @@
 version: '3'
 services:
+  mysql:
+    ports:
+      - 3306:3306
+    image: mysql:8.3
+    environment:
+      - MYSQL_ROOT_PASSWORD=${MYSQL_ROOT_PASSWORD:-root}
+      - MYSQL_DATABASE=${MYSQL_DATABASE:-grafana}
+      - MYSQL_USER=${MYSQL_USER:-grafana}
+      - MYSQL_PASSWORD=${MYSQL_PASSWORD:-grafana}
+    healthcheck:
+      test: mysqladmin ping -h localhost
+      interval: 10s
+      retries: 10
+      start_period: 10s
   grafana:
+    depends_on:
+      mysql:
+        condition: service_healthy
     ports:
       - 3000:3000
     image: ${GRAFANA_IMAGE:-grafana/grafana}:${GRAFANA_VERSION}
     environment:
+      - GF_DATABASE_TYPE=mysql
+      - GF_DATABASE_HOST=mysql
+      - GF_DATABASE_NAME=${MYSQL_DATABASE:-grafana}
+      - GF_DATABASE_USER=${MYSQL_USER:-grafana}
+      - GF_DATABASE_PASSWORD=${MYSQL_PASSWORD:-grafana}
       - GF_SERVER_ROOT_URL=${GRAFANA_URL}
       - GF_ENTERPRISE_LICENSE_TEXT=${GF_ENTERPRISE_LICENSE_TEXT:-}
       - GF_SERVER_SERVE_FROM_SUB_PATH=${GF_SERVER_SERVE_FROM_SUB_PATH:-}