deploy/clickhouse

ClickHouse packaged by Bitnami

ClickHouse is an open-source column-oriented OLAP database management system. Use it to boost your database performance while providing linear scalability and hardware efficiency.

Overview of ClickHouse

Trademarks: This software listing is packaged by Bitnami. The respective trademarks mentioned in the offering are owned by the respective companies, and use of them does not imply any affiliation or endorsement.

TL;DR

helm repo add my-repo https://charts.bitnami.com/bitnami
helm install my-release my-repo/clickhouse

Introduction

Bitnami charts for Helm are carefully engineered, actively maintained and are the quickest and easiest way to deploy containers on a Kubernetes cluster that are ready to handle production workloads.

This chart bootstraps a ClickHouse Deployment in a Kubernetes cluster using the Helm package manager.

Bitnami charts can be used with Kubeapps for deployment and management of Helm Charts in clusters.

Learn more about the default configuration of the chart.

Prerequisites

• Kubernetes 1.19+
• Helm 3.2.0+
• PV provisioner support in the underlying infrastructure
• ReadWriteMany volumes for deployment scaling

If you are using Kubernetes 1.18, the following code needs to be commented out. seccompProfile: type: "RuntimeDefault"

Installing the Chart

To install the chart with the release name my-release:

helm repo add my-repo https://charts.bitnami.com/bitnami
helm install my-release my-repo/clickhouse

The command deploys ClickHouse on the Kubernetes cluster in the default configuration. The Parameters section lists the parameters that can be configured during installation.

Tip: List all releases using helm list

Uninstalling the Chart

To uninstall/delete the my-release deployment:

helm delete my-release

The command removes all the Kubernetes components associated with the chart and deletes the release.

Parameters

Global parameters

Name	Description	Value
global.imageRegistry	Global Docker image registry	""
global.imagePullSecrets	Global Docker registry secret names as an array	[]
global.storageClass	Global StorageClass for Persistent Volume(s)	""

Common parameters

Name	Description	Value
kubeVersion	Override Kubernetes version	""
nameOverride	String to partially override common.names.name	""
fullnameOverride	String to fully override common.names.fullname	""
namespaceOverride	String to fully override common.names.namespace	""
commonLabels	Labels to add to all deployed objects	{}
commonAnnotations	Annotations to add to all deployed objects	{}
clusterDomain	Kubernetes cluster domain name	cluster.local
extraDeploy	Array of extra objects to deploy with the release	[]
diagnosticMode.enabled	Enable diagnostic mode (all probes will be disabled and the command will be overridden)	false
diagnosticMode.command	Command to override all containers in the deployment	["sleep"]
diagnosticMode.args	Args to override all containers in the deployment	["infinity"]

ClickHouse Parameters

Name	Description	Value
image.registry	ClickHouse image registry	docker.io
image.repository	ClickHouse image repository	bitnami/clickhouse
image.tag	ClickHouse image tag (immutable tags are recommended)	23.3.1-debian-11-r0
image.digest	ClickHouse image digest in the way sha256:aa.... Please note this parameter, if set, will override the tag	""
image.pullPolicy	ClickHouse image pull policy	IfNotPresent
image.pullSecrets	ClickHouse image pull secrets	[]
image.debug	Enable ClickHouse image debug mode	false
shards	Number of ClickHouse shards to deploy	2
replicaCount	Number of ClickHouse replicas per shard to deploy	3
containerPorts.http	ClickHouse HTTP container port	8123
containerPorts.https	ClickHouse HTTPS container port	8443
containerPorts.tcp	ClickHouse TCP container port	9000
containerPorts.tcpSecure	ClickHouse TCP (secure) container port	9440
containerPorts.keeper	ClickHouse keeper TCP container port	2181
containerPorts.keeperSecure	ClickHouse keeper TCP (secure) container port	3181
containerPorts.keeperInter	ClickHouse keeper interserver TCP container port	9444
containerPorts.mysql	ClickHouse MySQL container port	9004
containerPorts.postgresql	ClickHouse PostgreSQL container port	9005
containerPorts.interserver	ClickHouse Interserver container port	9009
containerPorts.metrics	ClickHouse metrics container port	8001
livenessProbe.enabled	Enable livenessProbe on ClickHouse containers	true
livenessProbe.initialDelaySeconds	Initial delay seconds for livenessProbe	10
livenessProbe.periodSeconds	Period seconds for livenessProbe	10
livenessProbe.timeoutSeconds	Timeout seconds for livenessProbe	1
livenessProbe.failureThreshold	Failure threshold for livenessProbe	3
livenessProbe.successThreshold	Success threshold for livenessProbe	1
readinessProbe.enabled	Enable readinessProbe on ClickHouse containers	true
readinessProbe.initialDelaySeconds	Initial delay seconds for readinessProbe	10
readinessProbe.periodSeconds	Period seconds for readinessProbe	10
readinessProbe.timeoutSeconds	Timeout seconds for readinessProbe	1
readinessProbe.failureThreshold	Failure threshold for readinessProbe	3
readinessProbe.successThreshold	Success threshold for readinessProbe	1
startupProbe.enabled	Enable startupProbe on ClickHouse containers	false
startupProbe.initialDelaySeconds	Initial delay seconds for startupProbe	10
startupProbe.periodSeconds	Period seconds for startupProbe	10
startupProbe.timeoutSeconds	Timeout seconds for startupProbe	1
startupProbe.failureThreshold	Failure threshold for startupProbe	3
startupProbe.successThreshold	Success threshold for startupProbe	1
customLivenessProbe	Custom livenessProbe that overrides the default one	{}
customReadinessProbe	Custom readinessProbe that overrides the default one	{}
customStartupProbe	Custom startupProbe that overrides the default one	{}
resources.limits	The resources limits for the ClickHouse containers	{}
resources.requests	The requested resources for the ClickHouse containers	{}
podSecurityContext.enabled	Enabled ClickHouse pods' Security Context	true
podSecurityContext.fsGroup	Set ClickHouse pod's Security Context fsGroup	1001
podSecurityContext.seccompProfile.type	Set ClickHouse container's Security Context seccomp profile	RuntimeDefault
containerSecurityContext.enabled	Enabled ClickHouse containers' Security Context	true
containerSecurityContext.runAsUser	Set ClickHouse containers' Security Context runAsUser	1001
containerSecurityContext.runAsNonRoot	Set ClickHouse containers' Security Context runAsNonRoot	true
containerSecurityContext.allowPrivilegeEscalation	Set ClickHouse container's privilege escalation	false
containerSecurityContext.capabilities.drop	Set ClickHouse container's Security Context runAsNonRoot	["ALL"]
auth.username	ClickHouse Admin username	default
auth.password	ClickHouse Admin password	""
auth.existingSecret	Name of a secret containing the Admin password	""
auth.existingSecretKey	Name of the key inside the existing secret	""
logLevel	Logging level	information

ClickHouse keeper configuration parameters

Name	Description	Value
keeper.enabled	Deploy ClickHouse keeper. Support is experimental.	false
defaultConfigurationOverrides	Default configuration overrides (evaluated as a template)	""
existingOverridesConfigmap	The name of an existing ConfigMap with your custom configuration for ClickHouse	""
extraOverrides	Extra configuration overrides (evaluated as a template) apart from the default	""
extraOverridesConfigmap	The name of an existing ConfigMap with extra configuration for ClickHouse	""
extraOverridesSecret	The name of an existing ConfigMap with your custom configuration for ClickHouse	""
initdbScripts	Dictionary of initdb scripts	{}
initdbScriptsSecret	ConfigMap with the initdb scripts (Note: Overrides initdbScripts)	""
startdbScripts	Dictionary of startdb scripts	{}
startdbScriptsSecret	ConfigMap with the startdb scripts (Note: Overrides startdbScripts)	""
command	Override default container command (useful when using custom images)	["/scripts/setup.sh"]
args	Override default container args (useful when using custom images)	[]
hostAliases	ClickHouse pods host aliases	[]
podLabels	Extra labels for ClickHouse pods	{}
podAnnotations	Annotations for ClickHouse pods	{}
podAffinityPreset	Pod affinity preset. Ignored if affinity is set. Allowed values: soft or hard	""
podAntiAffinityPreset	Pod anti-affinity preset. Ignored if affinity is set. Allowed values: soft or hard	soft
nodeAffinityPreset.type	Node affinity preset type. Ignored if affinity is set. Allowed values: soft or hard	""
nodeAffinityPreset.key	Node label key to match. Ignored if affinity is set	""
nodeAffinityPreset.values	Node label values to match. Ignored if affinity is set	[]
affinity	Affinity for ClickHouse pods assignment	{}
nodeSelector	Node labels for ClickHouse pods assignment	{}
tolerations	Tolerations for ClickHouse pods assignment	[]
updateStrategy.type	ClickHouse statefulset strategy type	RollingUpdate
podManagementPolicy	Statefulset Pod management policy, it needs to be Parallel to be able to complete the cluster join	Parallel
priorityClassName	ClickHouse pods' priorityClassName	""
topologySpreadConstraints	Topology Spread Constraints for pod assignment spread across your cluster among failure-domains. Evaluated as a template	[]
schedulerName	Name of the k8s scheduler (other than default) for ClickHouse pods	""
terminationGracePeriodSeconds	Seconds Redmine pod needs to terminate gracefully	""
lifecycleHooks	for the ClickHouse container(s) to automate configuration before or after startup	{}
extraEnvVars	Array with extra environment variables to add to ClickHouse nodes	[]
extraEnvVarsCM	Name of existing ConfigMap containing extra env vars for ClickHouse nodes	""
extraEnvVarsSecret	Name of existing Secret containing extra env vars for ClickHouse nodes	""
extraVolumes	Optionally specify extra list of additional volumes for the ClickHouse pod(s)	[]
extraVolumeMounts	Optionally specify extra list of additional volumeMounts for the ClickHouse container(s)	[]
sidecars	Add additional sidecar containers to the ClickHouse pod(s)	[]
initContainers	Add additional init containers to the ClickHouse pod(s)	[]
tls.enabled	Enable TLS traffic support	false
tls.autoGenerated	Generate automatically self-signed TLS certificates	false
tls.certificatesSecret	Name of an existing secret that contains the certificates	""
tls.certFilename	Certificate filename	""
tls.certKeyFilename	Certificate key filename	""
tls.certCAFilename	CA Certificate filename	""

Traffic Exposure Parameters

Name	Description	Value
service.type	ClickHouse service type	ClusterIP
service.ports.http	ClickHouse service HTTP port	8123
service.ports.https	ClickHouse service HTTPS port	443
service.ports.tcp	ClickHouse service TCP port	9000
service.ports.tcpSecure	ClickHouse service TCP (secure) port	9440
service.ports.keeper	ClickHouse keeper TCP container port	2181
service.ports.keeperSecure	ClickHouse keeper TCP (secure) container port	3181
service.ports.keeperInter	ClickHouse keeper interserver TCP container port	9444
service.ports.mysql	ClickHouse service MySQL port	9004
service.ports.postgresql	ClickHouse service PostgreSQL port	9005
service.ports.interserver	ClickHouse service Interserver port	9009
service.ports.metrics	ClickHouse service metrics port	8001
service.nodePorts.http	Node port for HTTP	""
service.nodePorts.https	Node port for HTTPS	""
service.nodePorts.tcp	Node port for TCP	""
service.nodePorts.tcpSecure	Node port for TCP (with TLS)	""
service.nodePorts.keeper	ClickHouse keeper TCP container port	""
service.nodePorts.keeperSecure	ClickHouse keeper TCP (secure) container port	""
service.nodePorts.keeperInter	ClickHouse keeper interserver TCP container port	""
service.nodePorts.mysql	Node port for MySQL	""
service.nodePorts.postgresql	Node port for PostgreSQL	""
service.nodePorts.interserver	Node port for Interserver	""
service.nodePorts.metrics	Node port for metrics	""
service.clusterIP	ClickHouse service Cluster IP	""
service.loadBalancerIP	ClickHouse service Load Balancer IP	""
service.loadBalancerSourceRanges	ClickHouse service Load Balancer sources	[]
service.externalTrafficPolicy	ClickHouse service external traffic policy	Cluster
service.annotations	Additional custom annotations for ClickHouse service	{}
service.extraPorts	Extra ports to expose in ClickHouse service (normally used with the sidecars value)	[]
service.sessionAffinity	Control where client requests go, to the same pod or round-robin	None
service.sessionAffinityConfig	Additional settings for the sessionAffinity	{}
service.headless.annotations	Annotations for the headless service.	{}
externalAccess.enabled	Enable Kubernetes external cluster access to ClickHouse	false
externalAccess.service.type	Kubernetes Service type for external access. It can be NodePort, LoadBalancer or ClusterIP	LoadBalancer
externalAccess.service.ports.http	ClickHouse service HTTP port	80
externalAccess.service.ports.https	ClickHouse service HTTPS port	443
externalAccess.service.ports.tcp	ClickHouse service TCP port	9000
externalAccess.service.ports.tcpSecure	ClickHouse service TCP (secure) port	9440
externalAccess.service.ports.keeper	ClickHouse keeper TCP container port	2181
externalAccess.service.ports.keeperSecure	ClickHouse keeper TCP (secure) container port	3181
externalAccess.service.ports.keeperInter	ClickHouse keeper interserver TCP container port	9444
externalAccess.service.ports.mysql	ClickHouse service MySQL port	9004
externalAccess.service.ports.postgresql	ClickHouse service PostgreSQL port	9005
externalAccess.service.ports.interserver	ClickHouse service Interserver port	9009
externalAccess.service.ports.metrics	ClickHouse service metrics port	8001
externalAccess.service.loadBalancerIPs	Array of load balancer IPs for each ClickHouse . Length must be the same as replicaCount	[]
externalAccess.service.loadBalancerAnnotations	Array of load balancer annotations for each ClickHouse . Length must be the same as replicaCount	[]
externalAccess.service.loadBalancerSourceRanges	Address(es) that are allowed when service is LoadBalancer	[]
externalAccess.service.nodePorts.http	Node port for HTTP	[]
externalAccess.service.nodePorts.https	Node port for HTTPS	[]
externalAccess.service.nodePorts.tcp	Node port for TCP	[]
externalAccess.service.nodePorts.tcpSecure	Node port for TCP (with TLS)	[]
externalAccess.service.nodePorts.keeper	ClickHouse keeper TCP container port	[]
externalAccess.service.nodePorts.keeperSecure	ClickHouse keeper TCP container port (with TLS)	[]
externalAccess.service.nodePorts.keeperInter	ClickHouse keeper interserver TCP container port	[]
externalAccess.service.nodePorts.mysql	Node port for MySQL	[]
externalAccess.service.nodePorts.postgresql	Node port for PostgreSQL	[]
externalAccess.service.nodePorts.interserver	Node port for Interserver	[]
externalAccess.service.nodePorts.metrics	Node port for metrics	[]
externalAccess.service.labels	Service labels for external access	{}
externalAccess.service.annotations	Service annotations for external access	{}
externalAccess.service.extraPorts	Extra ports to expose in the ClickHouse external service	[]
ingress.enabled	Enable ingress record generation for ClickHouse	false
ingress.pathType	Ingress path type	ImplementationSpecific
ingress.apiVersion	Force Ingress API version (automatically detected if not set)	""
ingress.hostname	Default host for the ingress record	clickhouse.local
ingress.ingressClassName	IngressClass that will be be used to implement the Ingress (Kubernetes 1.18+)	""
ingress.path	Default path for the ingress record	/
ingress.annotations	Additional annotations for the Ingress resource. To enable certificate autogeneration, place here your cert-manager annotations.	{}
ingress.tls	Enable TLS configuration for the host defined at ingress.hostname parameter	false
ingress.selfSigned	Create a TLS secret for this ingress record using self-signed certificates generated by Helm	false
ingress.extraHosts	An array with additional hostname(s) to be covered with the ingress record	[]
ingress.extraPaths	An array with additional arbitrary paths that may need to be added to the ingress under the main host	[]
ingress.extraTls	TLS configuration for additional hostname(s) to be covered with this ingress record	[]
ingress.secrets	Custom TLS certificates as secrets	[]
ingress.extraRules	Additional rules to be covered with this ingress record	[]

Persistence Parameters

Name	Description	Value
persistence.enabled	Enable persistence using Persistent Volume Claims	true
persistence.storageClass	Storage class of backing PVC	""
persistence.labels	Persistent Volume Claim labels	{}
persistence.annotations	Persistent Volume Claim annotations	{}
persistence.accessModes	Persistent Volume Access Modes	["ReadWriteOnce"]
persistence.size	Size of data volume	8Gi
persistence.selector	Selector to match an existing Persistent Volume for WordPress data PVC	{}
persistence.dataSource	Custom PVC data source	{}

Init Container Parameters

Name	Description	Value
volumePermissions.enabled	Enable init container that changes the owner/group of the PV mount point to runAsUser:fsGroup	false
volumePermissions.image.registry	Bitnami Shell image registry	docker.io
volumePermissions.image.repository	Bitnami Shell image repository	bitnami/bitnami-shell
volumePermissions.image.tag	Bitnami Shell image tag (immutable tags are recommended)	11-debian-11-r101
volumePermissions.image.pullPolicy	Bitnami Shell image pull policy	IfNotPresent
volumePermissions.image.pullSecrets	Bitnami Shell image pull secrets	[]
volumePermissions.resources.limits	The resources limits for the init container	{}
volumePermissions.resources.requests	The requested resources for the init container	{}
volumePermissions.containerSecurityContext.runAsUser	Set init container's Security Context runAsUser	0

Other Parameters

Name	Description	Value
serviceAccount.create	Specifies whether a ServiceAccount should be created	true
serviceAccount.name	The name of the ServiceAccount to use.	""
serviceAccount.annotations	Additional Service Account annotations (evaluated as a template)	{}
serviceAccount.automountServiceAccountToken	Automount service account token for the server service account	true
metrics.enabled	Enable the export of Prometheus metrics	false
metrics.podAnnotations	Annotations for metrics scraping	{}
metrics.serviceMonitor.enabled	if true, creates a Prometheus Operator ServiceMonitor (also requires metrics.enabled to be true)	false
metrics.serviceMonitor.namespace	Namespace in which Prometheus is running	""
metrics.serviceMonitor.annotations	Additional custom annotations for the ServiceMonitor	{}
metrics.serviceMonitor.labels	Extra labels for the ServiceMonitor	{}
metrics.serviceMonitor.jobLabel	The name of the label on the target service to use as the job name in Prometheus	""
metrics.serviceMonitor.honorLabels	honorLabels chooses the metric's labels on collisions with target labels	false
metrics.serviceMonitor.interval	Interval at which metrics should be scraped.	""
metrics.serviceMonitor.scrapeTimeout	Timeout after which the scrape is ended	""
metrics.serviceMonitor.metricRelabelings	Specify additional relabeling of metrics	[]
metrics.serviceMonitor.relabelings	Specify general relabeling	[]
metrics.serviceMonitor.selector	Prometheus instance selector labels	{}

External Zookeeper paramaters

Name	Description	Value
externalZookeeper.servers	List of external zookeeper servers to use	[]
externalZookeeper.port	Port of the Zookeeper servers	2888

Zookeeper subchart parameters

Name	Description	Value
zookeeper.enabled	Deploy Zookeeper subchart	true
zookeeper.replicaCount	Number of Zookeeper instances	3
zookeeper.service.ports.client	Zookeeper client port	2181

See https://github.com/bitnami-labs/readme-generator-for-helm to create the table.

The above parameters map to the env variables defined in bitnami/clickhouse. For more information please refer to the bitnami/clickhouse image documentation.

Specify each parameter using the --set key=value[,key=value] argument to helm install. For example,

helm install my-release \
  --set auth.username=admin \
  --set auth.password=password \
    my-repo/clickhouse

The above command sets the ClickHouse administrator account username and password to admin and password respectively.

NOTE: Once this chart is deployed, it is not possible to change the application's access credentials, such as usernames or passwords, using Helm. To change these application credentials after deployment, delete any persistent volumes (PVs) used by the chart and re-deploy it, or use the application's built-in administrative tools if available.

Alternatively, a YAML file that specifies the values for the above parameters can be provided while installing the chart. For example,

helm install my-release -f values.yaml my-repo/clickhouse

Tip: You can use the default values.yaml

Configuration and installation details

Rolling VS Immutable tags

It is strongly recommended to use immutable tags in a production environment. This ensures your deployment does not change automatically if the same tag is updated with a different image.

Bitnami will release a new chart updating its containers if a new version of the main container, significant changes, or critical vulnerabilities exist.

ClickHouse keeper support

You can set keeper.enabled to use ClickHouse keeper. If keeper.enabled=true, Zookeeper settings will not be ignore.

External Zookeeper support

You may want to have ClickHouse connect to an external zookeeper rather than installing one inside your cluster. Typical reasons for this are to use a managed database service, or to share a common database server for all your applications. To achieve this, the chart allows you to specify credentials for an external database with the externalZookeeper parameter. You should also disable the Zookeeper installation with the zookeeper.enabled option. Here is an example:

zookeper.enabled=false
externalZookeeper.host=myexternalhost
externalZookeeper.user=myuser
externalZookeeper.password=mypassword
externalZookeeper.database=mydatabase
externalZookeeper.port=3306

TLS secrets

The chart also facilitates the creation of TLS secrets for use with the Ingress controller, with different options for certificate management. Learn more about TLS secrets).

Persistence

The Bitnami ClickHouse image stores the ClickHouse data and configurations at the /bitnami path of the container. Persistent Volume Claims are used to keep the data across deployments. This is known to work in GCE, AWS, and minikube.

Additional environment variables

In case you want to add extra environment variables (useful for advanced operations like custom init scripts), you can use the extraEnvVars property.

clickhouse:
  extraEnvVars:
    - name: LOG_LEVEL
      value: error

Alternatively, you can use a ConfigMap or a Secret with the environment variables. To do so, use the extraEnvVarsCM or the extraEnvVarsSecret values.

Sidecars

If additional containers are needed in the same pod as ClickHouse (such as additional metrics or logging exporters), they can be defined using the sidecars parameter. If these sidecars export extra ports, extra port definitions can be added using the service.extraPorts parameter. Learn more about configuring and using sidecar containers.

Ingress without TLS

For using ingress (example without TLS):

ingress:
  ## If true, ClickHouse server Ingress will be created
  ##
  enabled: true

  ## ClickHouse server Ingress annotations
  ##
  annotations: {}
  #   kubernetes.io/ingress.class: nginx
  #   kubernetes.io/tls-acme: 'true'

  ## ClickHouse server Ingress hostnames
  ## Must be provided if Ingress is enabled
  ##
  hosts:
    - clickhouse.domain.com

Ingress TLS

If your cluster allows automatic creation/retrieval of TLS certificates (e.g. kube-lego), please refer to the documentation for that mechanism.

To manually configure TLS, first create/retrieve a key & certificate pair for the address(es) you wish to protect. Then create a TLS secret (named clickhouse-server-tls in this example) in the namespace. Include the secret's name, along with the desired hostnames, in the Ingress TLS section of your custom values.yaml file:

ingress:
  ## If true, ClickHouse server Ingress will be created
  ##
  enabled: true

  ## ClickHouse server Ingress annotations
  ##
  annotations: {}
  #   kubernetes.io/ingress.class: nginx
  #   kubernetes.io/tls-acme: 'true'

  ## ClickHouse server Ingress hostnames
  ## Must be provided if Ingress is enabled
  ##
  hosts:
    - clickhouse.domain.com

  ## ClickHouse server Ingress TLS configuration
  ## Secrets must be manually created in the namespace
  ##
  tls:
    - secretName: clickhouse-server-tls
      hosts:
        - clickhouse.domain.com

Using custom scripts

For advanced operations, the Bitnami ClickHouse chart allows using custom init and start scripts that will be mounted in /docker-entrypoint.initdb.d and /docker-entrypoint.startdb.d . The init scripts will be run on the first boot whereas the start scripts will be run on every container start. For adding the scripts directly as values use the initdbScripts and startdbScripts values. For using Secrets use the initdbScriptsSecret and startdbScriptsSecret.

initdbScriptsSecret: init-scripts-secret
startdbScriptsSecret: start-scripts-secret

Pod affinity

This chart allows you to set your custom affinity using the affinity parameter. Find more information about Pod affinity in the kubernetes documentation.

As an alternative, use one of the preset configurations for pod affinity, pod anti-affinity, and node affinity available at the bitnami/common chart. To do so, set the podAffinityPreset, podAntiAffinityPreset, or nodeAffinityPreset parameters.

Troubleshooting

Find more information about how to deal with common errors related to Bitnami's Helm charts in this troubleshooting guide.

Upgrading

To 2.0.0

This major updates the Zookeeper subchart to it newest major, 11.0.0. For more information on this subchart's major, please refer to zookeeper upgrade notes.

License

Copyright © 2023 Bitnami

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.