Failing K8s rabbitmq-peer-discovery-k8s clustering - kubernetes

Question

I'm trying to bring up a RabbitMQ cluster on Kubernetes using Rabbitmq-peer-discovery-k8s plugin and I always have only on pod running and ready but the next one always fails.
I tried multiple changes to my configuration and this is what got at least one pod running
---
apiVersion: v1
kind: ServiceAccount
metadata:
name: rabbitmq
namespace: namespace-dev
---
kind: Role
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: endpoint-reader
namespace: namespace-dev
rules:
- apiGroups: [""]
resources: ["endpoints"]
verbs: ["get"]
---
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: endpoint-reader
namespace: namespace-dev
subjects:
- kind: ServiceAccount
name: rabbitmq
roleRef:
apiGroup: rbac.authorization.k8s.io
kind: Role
name: endpoint-reader
---
apiVersion: v1
kind: PersistentVolume
metadata:
name: "rabbitmq-data"
labels:
name: "rabbitmq-data"
release: "rabbitmq-data"
namespace: "namespace-dev"
spec:
capacity:
storage: 5Gi
accessModes:
- "ReadWriteMany"
nfs:
path: "/path/to/nfs"
server: "xx.xx.xx.xx"
persistentVolumeReclaimPolicy: Retain
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: "rabbitmq-data-claim"
namespace: "namespace-dev"
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 5Gi
selector:
matchLabels:
release: rabbitmq-data
---
# headless service Used to access pods using hostname
kind: Service
apiVersion: v1
metadata:
name: rabbitmq-headless
namespace: namespace-dev
spec:
clusterIP: None
# publishNotReadyAddresses, when set to true, indicates that DNS implementations must publish the notReadyAddresses of subsets for the Endpoints associated with the Service. The default value is false. The primary use case for setting this field is to use a StatefulSet's Headless Service to propagate SRV records for its Pods without respect to their readiness for purpose of peer discovery. This field will replace the service.alpha.kubernetes.io/tolerate-unready-endpoints when that annotation is deprecated and all clients have been converted to use this field.
# Since access to the Pod using DNS requires Pod and Headless service to be started before launch, publishNotReadyAddresses is set to true to prevent readinessProbe from finding DNS when the service is not started.
publishNotReadyAddresses: true
ports:
- name: amqp
port: 5672
- name: http
port: 15672
selector:
app: rabbitmq
---
# Used to expose the dashboard to the external network
kind: Service
apiVersion: v1
metadata:
namespace: namespace-dev
name: rabbitmq-service
spec:
type: NodePort
ports:
- name: http
protocol: TCP
port: 15672
targetPort: 15672
nodePort: 31672
- name: amqp
protocol: TCP
port: 5672
targetPort: 5672
nodePort: 30672
selector:
app: rabbitmq
---
apiVersion: v1
kind: ConfigMap
metadata:
name: rabbitmq-config
namespace: namespace-dev
data:
enabled_plugins: |
[rabbitmq_management,rabbitmq_peer_discovery_k8s].
rabbitmq.conf: |
cluster_formation.peer_discovery_backend = rabbit_peer_discovery_k8s
cluster_formation.k8s.host = kubernetes.default.svc.cluster.local
cluster_formation.k8s.address_type = hostname
cluster_formation.node_cleanup.interval = 10
cluster_formation.node_cleanup.only_log_warning = true
cluster_partition_handling = autoheal
queue_master_locator=min-masters
loopback_users.guest = false
cluster_formation.randomized_startup_delay_range.min = 0
cluster_formation.randomized_startup_delay_range.max = 2
cluster_formation.k8s.service_name = rabbitmq-headless
cluster_formation.k8s.hostname_suffix = .rabbitmq-headless.namespace-dev.svc.cluster.local
vm_memory_high_watermark.absolute = 1.6GB
disk_free_limit.absolute = 2GB
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: rabbitmq
namespace: rabbitmq
spec:
serviceName: rabbitmq-headless # Must be the same as the name of the headless service, used for hostname propagation access pod
selector:
matchLabels:
app: rabbitmq # In apps/v1, it needs to be the same as .spec.template.metadata.label for hostname propagation access pods, but not in apps/v1beta
replicas: 3
template:
metadata:
labels:
app: rabbitmq # In apps/v1, the same as .spec.selector.matchLabels
# setting podAntiAffinity
annotations:
scheduler.alpha.kubernetes.io/affinity: >
{
"podAntiAffinity": {
"requiredDuringSchedulingIgnoredDuringExecution": [{
"labelSelector": {
"matchExpressions": [{
"key": "app",
"operator": "In",
"values": ["rabbitmq"]
}]
},
"topologyKey": "kubernetes.io/hostname"
}]
}
}
spec:
serviceAccountName: rabbitmq
terminationGracePeriodSeconds: 10
containers:
- name: rabbitmq
image: rabbitmq:3.7.10
resources:
limits:
cpu: "0.5"
memory: 2Gi
requests:
cpu: "0.3"
memory: 2Gi
volumeMounts:
- name: config-volume
mountPath: /etc/rabbitmq
- name: rabbitmq-data
mountPath: /var/lib/rabbitmq/mnesia
ports:
- name: http
protocol: TCP
containerPort: 15672
- name: amqp
protocol: TCP
containerPort: 5672
livenessProbe:
exec:
command: ["rabbitmqctl", "status"]
initialDelaySeconds: 60
periodSeconds: 60
timeoutSeconds: 5
readinessProbe:
exec:
command: ["rabbitmqctl", "status"]
initialDelaySeconds: 20
periodSeconds: 60
timeoutSeconds: 5
imagePullPolicy: IfNotPresent
env:
- name: HOSTNAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: RABBITMQ_USE_LONGNAME
value: "true"
- name: RABBITMQ_NODENAME
value: "rabbit#$(HOSTNAME).rabbitmq-headless.namespace-dev.svc.cluster.local"
# If service_name is set in ConfigMap, there is no need to set it again here.
# - name: K8S_SERVICE_NAME
# value: "rabbitmq-headless"
- name: RABBITMQ_ERLANG_COOKIE
value: "mycookie"
volumes:
- name: config-volume
configMap:
name: rabbitmq-config
items:
- key: rabbitmq.conf
path: rabbitmq.conf
- key: enabled_plugins
path: enabled_plugins
- name: rabbitmq-data
persistentVolumeClaim:
claimName: rabbitmq-data-claim
I only get one pod running and ready instead of the 3 replicas
[admin#devsvr3 yaml]$ kubectl get pods
NAME READY STATUS RESTARTS AGE
rabbitmq-0 1/1 Running 0 2m2s
rabbitmq-1 0/1 Running 1 43s
Inspecting the failing pod I got this.
[admin#devsvr3 yaml]$ kubectl logs rabbitmq-1
## ##
## ## RabbitMQ 3.7.10. Copyright (C) 2007-2018 Pivotal Software, Inc.
########## Licensed under the MPL. See http://www.rabbitmq.com/
###### ##
########## Logs: <stdout>
Starting broker...
2019-02-06 21:09:03.303 [info] <0.211.0>
Starting RabbitMQ 3.7.10 on Erlang 21.2.3
Copyright (C) 2007-2018 Pivotal Software, Inc.
Licensed under the MPL. See http://www.rabbitmq.com/
2019-02-06 21:09:03.315 [info] <0.211.0>
node : rabbit#rabbitmq-1.rabbitmq-headless.namespace-dev.svc.cluster.local
home dir : /var/lib/rabbitmq
config file(s) : /etc/rabbitmq/rabbitmq.conf
cookie hash : XhdCf8zpVJeJ0EHyaxszPg==
log(s) : <stdout>
database dir : /var/lib/rabbitmq/mnesia/rabbit#rabbitmq-1.rabbitmq-headless.namespace-dev.svc.cluster.local
2019-02-06 21:09:10.617 [error] <0.219.0> Unable to parse vm_memory_high_watermark value "1.6GB"
2019-02-06 21:09:10.617 [info] <0.219.0> Memory high watermark set to 103098 MiB (108106919116 bytes) of 257746 MiB (270267297792 bytes) total
2019-02-06 21:09:10.690 [info] <0.221.0> Enabling free disk space monitoring
2019-02-06 21:09:10.690 [info] <0.221.0> Disk free limit set to 2000MB
2019-02-06 21:09:10.698 [info] <0.224.0> Limiting to approx 1048476 file handles (943626 sockets)
2019-02-06 21:09:10.698 [info] <0.225.0> FHC read buffering: OFF
2019-02-06 21:09:10.699 [info] <0.225.0> FHC write buffering: ON
2019-02-06 21:09:10.702 [info] <0.211.0> Node database directory at /var/lib/rabbitmq/mnesia/rabbit#rabbitmq-1.rabbitmq-headless.namespace-dev.svc.cluster.local is empty. Assuming we need to join an existing cluster or initialise from scratch...
2019-02-06 21:09:10.702 [info] <0.211.0> Configured peer discovery backend: rabbit_peer_discovery_k8s
2019-02-06 21:09:10.702 [info] <0.211.0> Will try to lock with peer discovery backend rabbit_peer_discovery_k8s
2019-02-06 21:09:10.702 [info] <0.211.0> Peer discovery backend does not support locking, falling back to randomized delay
2019-02-06 21:09:10.702 [info] <0.211.0> Peer discovery backend rabbit_peer_discovery_k8s does not support registration, skipping randomized startup delay.
2019-02-06 21:09:10.710 [info] <0.211.0> Failed to get nodes from k8s - {failed_connect,[{to_address,{"kubernetes.default.svc.cluster.local",443}},
{inet,[inet],nxdomain}]}
2019-02-06 21:09:10.711 [error] <0.210.0> CRASH REPORT Process <0.210.0> with 0 neighbours exited with reason: no case clause matching {error,"{failed_connect,[{to_address,{\"kubernetes.default.svc.cluster.local\",443}},\n {inet,[inet],nxdomain}]}"} in rabbit_mnesia:init_from_config/0 line 164 in application_master:init/4 line 138
2019-02-06 21:09:10.711 [info] <0.43.0> Application rabbit exited with reason: no case clause matching {error,"{failed_connect,[{to_address,{\"kubernetes.default.svc.cluster.local\",443}},\n {inet,[inet],nxdomain}]}"} in rabbit_mnesia:init_from_config/0 line 164
{"Kernel pid terminated",application_controller,"{application_start_failure,rabbit,{bad_return,{{rabbit,start,[normal,[]]},{'EXIT',{{case_clause,{error,\"{failed_connect,[{to_address,{\\"kubernetes.default.svc.cluster.local\\",443}},\n {inet,[inet],nxdomain}]}\"}},[{rabbit_mnesia,init_from_config,0,[{file,\"src/rabbit_mnesia.erl\"},{line,164}]},{rabbit_mnesia,init_with_lock,3,[{file,\"src/rabbit_mnesia.erl\"},{line,144}]},{rabbit_mnesia,init,0,[{file,\"src/rabbit_mnesia.erl\"},{line,111}]},{rabbit_boot_steps,'-run_step/2-lc$^1/1-1-',1,[{file,\"src/rabbit_boot_steps.erl\"},{line,49}]},{rabbit_boot_steps,run_step,2,[{file,\"src/rabbit_boot_steps.erl\"},{line,49}]},{rabbit_boot_steps,'-run_boot_steps/1-lc$^0/1-0-',1,[{file,\"src/rabbit_boot_steps.erl\"},{line,26}]},{rabbit_boot_steps,run_boot_steps,1,[{file,\"src/rabbit_boot_steps.erl\"},{line,26}]},{rabbit,start,2,[{file,\"src/rabbit.erl\"},{line,815}]}]}}}}}"}
Kernel pid terminated (application_controller) ({application_start_failure,rabbit,{bad_return,{{rabbit,start,[normal,[]]},{'EXIT',{{case_clause,{error,"{failed_connect,[{to_address,{\"kubernetes.defau
Crash dump is being written to: /var/log/rabbitmq/erl_crash.dump...done
[admin#devsvr3 yaml]$
What did I do wrong here?

Answer 1

finally i fixed it by adding this in /etc/resolv.conf of my pods:
[my-rabbit-svc].[my-rabbitmq-namespace].svc.[cluster-name]
to add this in my pod i used this setting in my StatefulSet:
dnsConfig:
searches:
- [my-rabbit-svc].[my-rabbitmq-namespace].svc.[cluster-name]
full documentation here

Answer 2

Try to set:
cluster_formation.k8s.host = [your kubernetes endpoint ip addres]
cluster_formation.k8s.port = [your kubernetes endpoint port]
because it seems that your pod cannot solve this name:
kubernetes.default.svc.cluster.local

Answer 3

Try using this stable helm chart https://github.com/helm/charts/tree/master/stable/rabbitmq

Answer 4

One of the possible solution here, instead of attaching dns config to pod - use k8s proxy sidecar. So, instead of solving
kubernetes.default.svc.cluster.local
You could setup sidecar container like
- name: "k8s-api-sidecar"
image: "tommyvn/kubectl-proxy:latest"
in statefullset/deployment
And change configmap to use it
cluster_formation.peer_discovery_backend = rabbit_peer_discovery_k8s
cluster_formation.k8s.host = localhost
cluster_formation.k8s.port = 8001
cluster_formation.k8s.scheme = http
If you take a look into this repository https://github.com/tommyvn/kubectl-proxy , you will find that it is just a call kubectl proxy.