by adding targets and curl wait loops to services to ensure services
are not started before their depended services are reachable.
Extra targets cfssl-online.target and kube-apiserver-online.target
syncronize starts across machines and node-online.target ensures
docker is restarted and ready to deploy containers on after flannel
has discussed the network cidr with apiserver.
Since flannel needs to be started before addon-manager to configure
the docker interface, it has to have its own rbac bootstrap service.
The curl wait loops within the other services exists to ensure that when
starting the service it is able to do its work immediately without
clobbering the log about failing conditions.
By ensuring kubernetes.target is only reached after starting the
cluster it can be used in the tests as a wait condition.
In kube-certmgr-bootstrap mkdir is needed for it to not fail to start.
The following is the relevant part of systemctl list-dependencies
default.target
● ├─certmgr.service
● ├─cfssl.service
● ├─docker.service
● ├─etcd.service
● ├─flannel.service
● ├─kubernetes.target
● │ ├─kube-addon-manager.service
● │ ├─kube-proxy.service
● │ ├─kube-apiserver-online.target
● │ │ ├─flannel-rbac-bootstrap.service
● │ │ ├─kube-apiserver-online.service
● │ │ ├─kube-apiserver.service
● │ │ ├─kube-controller-manager.service
● │ │ └─kube-scheduler.service
● │ └─node-online.target
● │ ├─node-online.service
● │ ├─flannel.target
● │ │ ├─flannel.service
● │ │ └─mk-docker-opts.service
● │ └─kubelet.target
● │ └─kubelet.service
● ├─network-online.target
● │ └─cfssl-online.target
● │ ├─certmgr.service
● │ ├─cfssl-online.service
● │ └─kube-certmgr-bootstrap.service
to protect services from crashing and clobbering the logs when
certificates are not in place yet and make sure services are activated
when certificates are ready.
To prevent errors similar to "kube-controller-manager.path: Failed to
enter waiting state: Too many open files"
fs.inotify.max_user_instances has to be increased.
The overwriteprotocol option can be used to force Nextcloud to generate
URLs with the given protocol. This is useful for instances behind
reverse proxies that serve Nextcloud with HTTPS.
In this case Nextcloud can't determine the proper protocol and it needs
to be configured manually.
https://github.com/golang/go/issues/9334 describes how net.Listen (as used by Alertmanager):
* listens on 127.0.0.1 if the listenAddress is "localhost"
* listens on all interfaces if the listenAddress is ""
