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weave/prog/weave-kube/weave-daemonset.yaml
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Damien Lespiau 8d44f49edd kubernetes: Morph the livenessProbe into readinessProbe
The liveness probe has the not-so-great side effect of killing the weave pods
if anything goes wrong, making debugging really difficult.

Not only that, we also bumped into the livenessProbe killing pods before they
had a chance to start (see below for the full story).

The readinessProbe is only used for Kubernetes Services: no traffic will be
routed to non-Ready pods when using the Service IP. We can use to to signal the
user something in wrong with Weave Net while not having Kubernetes delete the
pods behind our backs.

I removed the ininitialDelaySeconds field as Kurbernetes won't kill the pod if
not ready.

Notes from a debugging session:

Some nodes may have a vast amount of iptables rules, making each iptables
command take a few seconds (~5-10s). At startup, when the weave container
creates its chains, it runs quite a few iptables commands and the total time of
execution was > 30s.

It's important to note that, at this point, the weave process hasn't started as
those iptables commands are run by an initial script.

Kubernetes was trying to check for the container liveness, was failing, and
then proceeded to kill the weave pods before they had a chance to fully start.
2018-09-28 15:50:39 +01:00

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YAML

apiVersion: v1
kind: List
items:
- apiVersion: v1
kind: ServiceAccount
metadata:
name: weave-net
labels:
name: weave-net
namespace: kube-system
- apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: weave-net
labels:
name: weave-net
namespace: kube-system
spec:
template:
metadata:
annotations:
scheduler.alpha.kubernetes.io/tolerations: >-
[{"key":"dedicated","operator":"Equal","value":"master","effect":"NoSchedule"}]
labels:
name: weave-net
spec:
containers:
- name: weave
command:
- /home/weave/launch.sh
env:
- name: HOSTNAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.nodeName
image: 'weaveworks/weave-kube:latest'
imagePullPolicy: Always
readinessProbe:
httpGet:
host: 127.0.0.1
path: /status
port: 6784
resources:
requests:
cpu: 10m
securityContext:
privileged: true
volumeMounts:
- name: weavedb
mountPath: /weavedb
- name: cni-bin
mountPath: /host/opt
- name: cni-bin2
mountPath: /host/home
- name: cni-conf
mountPath: /host/etc
- name: dbus
mountPath: /host/var/lib/dbus
- name: lib-modules
mountPath: /lib/modules
- name: weave-npc
env:
- name: HOSTNAME
valueFrom:
fieldRef:
apiVersion: v1
fieldPath: spec.nodeName
image: 'weaveworks/weave-npc:latest'
imagePullPolicy: Always
resources:
requests:
cpu: 10m
securityContext:
privileged: true
hostNetwork: true
hostPID: true
restartPolicy: Always
securityContext:
seLinuxOptions: {}
serviceAccountName: weave-net
volumes:
- name: weavedb
hostPath:
path: /var/lib/weave
- name: cni-bin
hostPath:
path: /opt
- name: cni-bin2
hostPath:
path: /home
- name: cni-conf
hostPath:
path: /etc
- name: dbus
hostPath:
path: /var/lib/dbus
- name: lib-modules
hostPath:
path: /lib/modules