cassandra/examples/startup-checks

== Cassandra Startup Check Example

An implementation of `StartupCheck` interface will create custom startup check. For the purposes of this example,
there will be one startup check with the name `my_check`.

If you want to code your own startup check without patching Cassandra yourself, you need to do the following:

1. Code against interface `org.apache.cassandra.service.StartupCheck`.
2. Put the class implementing this interface to `META-INF/services/org.apache.cassandra.service.StartupCheck`
3. Build a JAR both with the implementation and `META-INF` resources, as show in this example, and put this JAR onto
Cassandra's classpath.
4. When Cassandra starts, it will auto-detect new check by loading `MyCustomStartupCheck` in your JAR.
5. You can code more check classes and add them all into one jar, just add another entry into file in step 2.

You can also configure the checks loaded like this in cassandra.yaml under `startup_checks` section,
like following:

----
startup_checks:
  my_check:
    key: value
----

You can get these options from `StartupChecksConfiguration`, by check's `name()`.

=== Installation

----
$ cd <cassandra_src_dir>/examples/startup-checks
$ ant install
----

It will build the startup check and will copy it to `lib` as well as to `build/lib/jars`.

You remove it from everywhere by

----
$ cd <cassandra_src_dir>/examples/startup-checks
$ ant clean
----

=== Usage

Follow the logs, you will see the output of the check. You can
play with options in cassandra.yaml to see what is propagated to that check.