Spring Cloud Configuration Server - Spring Cloud Apache ZooKeeper
Spring Cloud Configuration Server is able to use Apache ZooKeeper to locate properties and settings.
Support is provided via the following dependency in the WAR overlay:
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<dependency>
<groupId>org.apereo.cas</groupId>
<artifactId>cas-server-support-configuration-cloud-zookeeper</artifactId>
<version>${cas.version}</version>
</dependency>
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implementation "org.apereo.cas:cas-server-support-configuration-cloud-zookeeper:${project.'cas.version'}"
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dependencyManagement {
imports {
mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
}
}
dependencies {
implementation "org.apereo.cas:cas-server-support-configuration-cloud-zookeeper"
}
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dependencies {
/*
The following platform references should be included automatically and are listed here for reference only.
implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
*/
implementation "org.apereo.cas:cas-server-support-configuration-cloud-zookeeper"
}
The configuration modules provide here may also be used verbatim inside a CAS server overlay and do not exclusively belong to a Spring Cloud Configuration server. While this module is primarily useful when inside the Spring Cloud Configuration server, it nonetheless may also be used inside a CAS server overlay directly to fetch settings from a source.
You will need to map CAS settings to ZooKeeper’s nodes that contain values. The parent node for all settings should
match the configuration root value provided to CAS. Under the root, you could have folders such
as cas
, cas,dev
, cas,local
, etc where dev
and local
are Spring profiles.
To create nodes and values in Apache ZooKeeper, try the following commands as a sample:
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zookeeper-client -server zookeeper1:2181
create /cas cas
create /cas/config cas
create /cas/config/cas cas
create /cas/config/cas/settingName casuser::Test
Creating nodes and directories in Apache ZooKeeper may require providing a value. The above sample commands show that
the value cas
is provided when creating directories. Always check with the official Apache ZooKeeper guides. You may not need to do that step.
Finally in your CAS properties, the new settingName
setting can be used as a reference.
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# cas.something.something=${settingName}
…where ${settingName}
gets the value of the contents of the Apache ZooKeeper node cas/config/cas/settingName
.
The following settings and properties are available from the CAS configuration catalog:
spring.cloud.zookeeper.base-sleep-time-ms=50
Initial amount of time to wait between retries.
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spring.cloud.zookeeper.block-until-connected-unit=
The unit of time related to blocking on connection to Zookeeper.
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spring.cloud.zookeeper.block-until-connected-wait=10
Wait time to block on connection to Zookeeper.
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spring.cloud.zookeeper.config.default-context=application
The name of the default context.
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spring.cloud.zookeeper.config.enabled=true
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spring.cloud.zookeeper.config.fail-fast=true
Throw exceptions during config lookup if true, otherwise, log warnings.
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spring.cloud.zookeeper.config.name=
Alternative to spring.application.name to use in looking up values in zookeeper.
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spring.cloud.zookeeper.config.profile-separator=,
Separator for profile appended to the application name.
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spring.cloud.zookeeper.config.root=config
Root folder where the configuration for Zookeeper is kept.
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spring.cloud.zookeeper.connect-string=localhost:2181
Connection string to the Zookeeper cluster.
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spring.cloud.zookeeper.connection-timeout=
The configured connection timeout in milliseconds.
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spring.cloud.zookeeper.enabled=true
Is Zookeeper enabled.
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spring.cloud.zookeeper.max-retries=10
Max number of times to retry.
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spring.cloud.zookeeper.max-sleep-ms=500
Max time in ms to sleep on each retry.
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spring.cloud.zookeeper.session-timeout=
The configured/negotiated session timeout in milliseconds. Please refer to Curator's Tech Note 14 to understand how Curator implements connection sessions. @see Curator's Tech Note 14
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Configuration Metadata
The collection of configuration properties listed in this section are automatically generated from the CAS source and components that contain the actual field definitions, types, descriptions, modules, etc. This metadata may not always be 100% accurate, or could be lacking details and sufficient explanations.
Be Selective
This section is meant as a guide only. Do NOT copy/paste the entire collection of settings into your CAS configuration; rather pick only the properties that you need. Do NOT enable settings unless you are certain of their purpose and do NOT copy settings into your configuration only to keep them as reference. All these ideas lead to upgrade headaches, maintenance nightmares and premature aging.
YAGNI
Note that for nearly ALL use cases, declaring and configuring properties listed here is sufficient. You should NOT have to explicitly massage a CAS XML/Java/etc configuration file to design an authentication handler, create attribute release policies, etc. CAS at runtime will auto-configure all required changes for you. If you are unsure about the meaning of a given CAS setting, do NOT turn it on without hesitation. Review the codebase or better yet, ask questions to clarify the intended behavior.
Naming Convention
Property names can be specified in very relaxed terms. For instance cas.someProperty
, cas.some-property
, cas.some_property
are all valid names. While all
forms are accepted by CAS, there are certain components (in CAS and other frameworks used) whose activation at runtime is conditional on a property value, where
this property is required to have been specified in CAS configuration using kebab case. This is both true for properties that are owned by CAS as well as those
that might be presented to the system via an external library or framework such as Spring Boot, etc.
When possible, properties should be stored in lower-case kebab format, such as cas.property-name=value
.
The only possible exception to this rule is when naming actuator endpoints; The name of the
actuator endpoints (i.e. ssoSessions
) MUST remain in camelCase mode.
Settings and properties that are controlled by the CAS platform directly always begin with the prefix cas
. All other settings are controlled and provided
to CAS via other underlying frameworks and may have their own schemas and syntax. BE CAREFUL with
the distinction. Unrecognized properties are rejected by CAS and/or frameworks upon which CAS depends. This means if you somehow misspell a property definition
or fail to adhere to the dot-notation syntax and such, your setting is entirely refused by CAS and likely the feature it controls will never be activated in the
way you intend.
Validation
Configuration properties are automatically validated on CAS startup to report issues with configuration binding, specially if defined CAS settings cannot be
recognized or validated by the configuration schema. The validation process is on by default and can be skipped on startup using a special system
property SKIP_CONFIG_VALIDATION
that should be set to true
. Additional validation processes are also handled
via Configuration Metadata and property migrations applied automatically on
startup by Spring Boot and family.
Indexed Settings
CAS settings able to accept multiple values are typically documented with an index, such as cas.some.setting[0]=value
. The index [0]
is meant to be
incremented by the adopter to allow for distinct multiple configuration blocks.