* Accept experimental CNI `networking` mode "cilium"
* Run Cilium v1.8.0-rc4 with overlay vxlan tunnels and a
minimal set of features. We're interested in:
* IPAM: Divide pod_cidr into /24 subnets per node
* CNI networking pod-to-pod, pod-to-external
* BPF masquerade
* NetworkPolicy as defined by Kubernetes (no L7 Policy)
* Continue using kube-proxy with Cilium probe mode
* Firewall changes:
* Require UDP 8472 for vxlan (Linux kernel default) between nodes
* Optional ICMP echo(8) between nodes for host reachability
(health)
* Optional TCP 4240 between nodes for endpoint reachability (health)
Known Issues:
* Containers with `hostPort` don't listen on all host addresses,
these workloads must use `hostNetwork` for now
https://github.com/cilium/cilium/issues/12116
* Erroneous warning on Fedora CoreOS
https://github.com/cilium/cilium/issues/10256
Note: This is experimental. It is not listed in docs and may be
changed or removed without a deprecation notice
Related:
* https://github.com/poseidon/terraform-render-bootstrap/pull/192
* https://github.com/cilium/cilium/issues/12217
* Change the Calico VXLAN interface for MTU from 1450 to 1410
* VXLAN on Azure should support MTU 1450. However, there is
history where performance measures have shown that 1410 is
needed to have expected performance. Flatcar Linux has the
same MTU 1410 override and note
* FCOS 31.20200323.3.2 was known to perform fine with 1450, but
now in 31.20200517.3.0 the right value seems to be 1410
* Remove node label `node.kubernetes.io/master` from controller nodes
* Use `node.kubernetes.io/controller` (present since v1.9.5,
[#160](https://github.com/poseidon/typhoon/pull/160)) to node select controllers
* Rename controller NoSchedule taint from `node-role.kubernetes.io/master` to
`node-role.kubernetes.io/controller`
* Tolerate the new taint name for workloads that may run on controller nodes
and stop tolerating `node-role.kubernetes.io/master` taint
* Generated Kubelet TLS certificate and key are not longer
used or distributed to machines since Kubelet TLS bootstrap
is used instead. Remove the certificate and key from state
* Set a consistent MCS level/range for Calico install-cni
* Note: Rebooting a node was a workaround, because Kubelet
relabels /etc/kubernetes(/cni/net.d)
Background:
* On SELinux enforcing systems, the Calico CNI install-cni
container ran with default SELinux context and a random MCS
pair. install-cni places CNI configs by first creating a
temporary file and then moving them into place, which means
the file MCS categories depend on the containers SELinux
context.
* calico-node Pod restarts creates a new install-cni container
with a different MCS pair that cannot access the earlier
written file (it places configs every time), causing the
init container to error and calico-node to crash loop
* https://github.com/projectcalico/cni-plugin/issues/874
```
mv: inter-device move failed: '/calico.conf.tmp' to
'/host/etc/cni/net.d/10-calico.conflist'; unable to remove target:
Permission denied
Failed to mv files. This may be caused by selinux configuration on
the
host, or something else.
```
Note, this isn't a host SELinux configuration issue.
Related:
* https://github.com/poseidon/terraform-render-bootstrap/pull/186
* Enable bootstrap token authentication on kube-apiserver
* Generate the bootstrap.kubernetes.io/token Secret that
may be used as a bootstrap token
* Generate a bootstrap kubeconfig (with a bootstrap token)
to be securely distributed to nodes. Each Kubelet will use
the bootstrap kubeconfig to authenticate to kube-apiserver
as `system:bootstrappers` and send a node-unique CSR for
kube-controller-manager to automatically approve to issue
a Kubelet certificate and kubeconfig (expires in 72 hours)
* Add ClusterRoleBinding for bootstrap token subjects
(`system:bootstrappers`) to have the `system:node-bootstrapper`
ClusterRole
* Add ClusterRoleBinding for bootstrap token subjects
(`system:bootstrappers`) to have the csr nodeclient ClusterRole
* Add ClusterRoleBinding for bootstrap token subjects
(`system:bootstrappers`) to have the csr selfnodeclient ClusterRole
* Enable NodeRestriction admission controller to limit the
scope of Node or Pod objects a Kubelet can modify to those of
the node itself
* Ability for a Kubelet to delete its Node object is retained
as preemptible nodes or those in auto-scaling instance groups
need to be able to remove themselves on shutdown. This need
continues to have precedence over any risk of a node deleting
itself maliciously
Security notes:
1. Issued Kubelet certificates authenticate as user `system:node:NAME`
and group `system:nodes` and are limited in their authorization
to perform API operations by Node authorization and NodeRestriction
admission. Previously, a Kubelet's authorization was broader. This
is the primary security motivation.
2. The bootstrap kubeconfig credential has the same sensitivity
as the previous generated TLS client-certificate kubeconfig.
It must be distributed securely to nodes. Its compromise still
allows an attacker to obtain a Kubelet kubeconfig
3. Bootstrapping Kubelet kubeconfig's with a limited lifetime offers
a slight security improvement.
* An attacker who obtains the kubeconfig can likely obtain the
bootstrap kubeconfig as well, to obtain the ability to renew
their access
* A compromised bootstrap kubeconfig could plausibly be handled
by replacing the bootstrap token Secret, distributing the token
to new nodes, and expiration. Whereas a compromised TLS-client
certificate kubeconfig can't be revoked (no CRL). However,
replacing a bootstrap token can be impractical in real cluster
environments, so the limited lifetime is mostly a theoretical
benefit.
* Cluster CSR objects are visible via kubectl which is nice
4. Bootstrapping node-unique Kubelet kubeconfigs means Kubelet
clients have more identity information, which can improve the
utility of audits and future features
Rel: https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet-tls-bootstrapping/
Rel: https://github.com/poseidon/terraform-render-bootstrap/pull/185
Dalton Hubble