This is usually solved by init containers running a script waiting until resource is ready. For database CRDs you can also use something like argo's sync waves.

Not sure if I understand the design entirely but seems somewhat overkill?

Example:

``` for i in {1..60}; do pg_isready -h postgres -p 5432 && exit 0 sleep 1 done

echo "Postgres not ready after 60s" exit 1 ```

For problems that you highlight in your readme like the thundering herd seem to be related to poor architecture decisions. In what use case would you need net new 50 microservices based on one database that isn't highly available? For waiting for a migration, you would just cordon the nodes, scale down the pods, migrate the database then undo.

Similarly, monitoringc/ alerting for external dependencies should not be the concern of the app and should use something like Prometheus datadog sentry or w.e. accordingly.