This guide describes how to configure KafkaCluster
to deploy Apache Kafka clusters which use pre-provisioned volumes instead of dynamically provisioned ones. Using static volumes is useful in environments where dynamic volume provisioning is not supported.
Koperator
uses persistent volume claim Kubernetes resources to dynamically provision volumes for the Kafka broker log directories.
Kubernetes provides a feature which allows binding persistent volume claims to existing persistent volumes either through the volumeName
or the selector
field. This allows
Koperator
to use pre-created persistent volumes as Kafka broker log directories instead of dynamically provisioning persistent volumes. For this binding to work:
- the configuration fields specified under
storageConfigs.pvcSpec
(such asaccessModes
,storageClassName
) must match the specification of the pre-created persistent volume, and - the
resources.requests.storage
must fit onto the capacity of the persistent volume.
For further details on how the persistent volume claim binding works, consult the Kubernetes documentation.
In the following example, it is assumed that you (or your administrator) have already created four persistent volumes. The example shows you how to create a Kafka cluster with two brokers, each broker configured with two log directories to use the four pre-provisioned volumes:
apiVersion: v1
kind: PersistentVolume
metadata:
labels:
namespace: kafka # namespace of the kafka cluster this volume is for in case there are multiple kafka clusters with the same name in different namespaces
kafka_cr: kafka # name of the kafka cluster this volume is for
brokerId: "0" # the id of the broker this volume is for
mountPath: kafka-logs-1 # path mounted as broker log dir
spec:
...
capacity:
storage: 10Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: my-storage-class
...
---
apiVersion: v1
kind: PersistentVolume
metadata:
labels:
namespace: kafka # namespace of the kafka cluster this volume is for in case there are multiple kafka clusters with the same name in different namespaces
kafka_cr: kafka # name of the kafka cluster this volume is for
brokerId: "0" # the id of the broker this volume is for
mountPath: kafka-logs-2 # path mounted as broker log dir
spec:
...
capacity:
storage: 10Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: my-storage-class
...
---
apiVersion: v1
kind: PersistentVolume
metadata:
labels:
namespace: kafka # namespace of the kafka cluster this volume is for in case there are multiple kafka clusters with the same name in different namespaces
kafka_cr: kafka # name of the kafka cluster this volume is for
brokerId: "1" # the id of the broker this volume is for
mountPath: kafka-logs-1 # path mounted as broker log dir
spec:
...
capacity:
storage: 10Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: my-storage-class
...
---
apiVersion: v1
kind: PersistentVolume
metadata:
labels:
namespace: kafka # namespace of the kafka cluster this volume is for in case there are multiple kafka clusters with the same name in different namespaces
kafka_cr: kafka # name of the kafka cluster this volume is for
brokerId: "1" # the id of the broker this volume is for
mountPath: kafka-logs-2 # path mounted as broker log dir
spec:
...
capacity:
storage: 10Gi
volumeMode: Filesystem
accessModes:
- ReadWriteOnce
storageClassName: my-storage-class
...
Broker-level storage configuration to use pre-provisioned volumes 🔗︎
The storageConfigs
specified at the broker level to use the above described pre-created persistent volumes as broker log dirs:
apiVersion: kafka.banzaicloud.io/v1beta1
kind: KafkaCluster
metadata:
namespace: kafka
name: kafka
spec:
...
brokers:
- id: 0
brokerConfigGroup: default
brokerConfig:
storageConfigs:
- mountPath: /kafka-logs-1
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: "0"
# strip '/' from mount path as label selector values
# has to start with an alphanumeric character': https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
mountPath: '{{ trimPrefix "/" .MountPath }}'
storageClassName: my-storage-class
- mountPath: /kafka-logs-2
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: "0"
# strip '/' from mount path as label selector values
# has to start with an alphanumeric character': https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
mountPath: '{{ trimPrefix "/" .MountPath }}'
storageClassName: my-storage-class
- id: 1
brokerConfigGroup: default
brokerConfig:
storageConfigs:
- mountPath: /kafka-logs-1
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: "1"
# strip '/' from mount path as label selector values
# has to start with an alphanumeric character': https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
mountPath: '{{ trimPrefix "/" .MountPath }}'
storageClassName: my-storage-class
- mountPath: /kafka-logs-2
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: "1"
# strip '/' from mount path as label selector values
# has to start with an alphanumeric character': https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
mountPath: '{{ trimPrefix "/" .MountPath }}'
storageClassName: my-storage-class
Broker configuration group level storage config to use pre-provisioned volumes 🔗︎
The storageConfigs
specified at the broker configuration group level to use the above described pre-created persistent volumes as broker log dirs:
apiVersion: kafka.banzaicloud.io/v1beta1
kind: KafkaCluster
metadata:
namespace: kafka
name: kafka
spec:
brokerConfigGroups:
default:
storageConfigs:
- mountPath: /kafka-logs-1
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: '{{ .BrokerId }}'
# strip '/' from mount path as label selector values
# has to start with an alphanumeric character': https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
mountPath: '{{ trimPrefix "/" .MountPath }}'
storageClassName: my-storage-class
- mountPath: /kafka-logs-2
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: '{{ .BrokerId }}'
# strip '/' from mount path as label selector values
# has to start with an alphanumeric character': https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
mountPath: '{{ trimPrefix "/" .MountPath }}'
storageClassName: my-storage-class
- mountPath: /mountpath/that/exceeds63characters/kafka-logs-123456789123456789
pvcSpec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
selector: # bind to pre-provisioned persistent volumes by labels
matchLabels:
namespace: kafka
kafka_cr: kafka
brokerId: '{{ .BrokerId }}'
# use sha1sum of mountPath to not exceed the 63 char limit for label selector values
mountPath: '{{ .MountPath | sha1sum }}'
storageClassName: my-storage-class
...
Storage config data fields 🔗︎
The following data fields are supported in the storage config:
.BrokerID
- resolves to the current broker’s Id.MountPath
- resolves to the value of themountPath
field of the current storage config
Under the hood, go-templates
enhanced with Sprig functions are used to resolve these fields to values that allow alterations to the resulting value (for examples, see above the use of trimPrefix
and sha1sum
template functions).