Spring Boot sample with Redis export for metrics.

Start redis, e.g. with [Docker Compose]()

[source,indent=0]
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	$ docker-compose up
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Run the app and ping the home page (http://localhost:8080) a few times. Go and look at
the result in Redis, e.g.

[source,indent=0]
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	$ redis-cli
	127.0.0.1:6379> keys *
	1) "keys.spring.metrics"
	2) "spring.metrics.counter.status.200.root"
	3) "spring.metrics.gauge.response.root"
	127.0.0.1:6379> zrange keys.spring.metrics 0 0 WITHSCORES
	1) "spring.metrics.counter.status.200.root"
	2) "4"
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