ElasticMeterRegistry: template index pattern is hardcoded to metrics*

[micheljung]

The index name is configurable:

micrometer/implementations/micrometer-registry-elastic/src/main/java/io/micrometer/elastic/ElasticMeterRegistry.java

Lines 291 to 294 in a0e46fd

	protected String indexName() {
	ZonedDateTime dt = ZonedDateTime.ofInstant(new Date(config().clock().wallTime()).toInstant(), ZoneOffset.UTC);
	return config.index() + config.indexDateSeparator() + indexDateFormatter.format(dt);
	}

However, the index pattern in the template is not:

micrometer/implementations/micrometer-registry-elastic/src/main/java/io/micrometer/elastic/ElasticMeterRegistry.java

Lines 93 to 95 in a0e46fd

	private static final String TEMPLATE_BODY_BEFORE_VERSION_7 = "{\"template\":\"metrics*\",\"mappings\":{\"_default_\":{\"_all\":{\"enabled\":false}," + TEMPLATE_PROPERTIES + "}}}";
	private static final String TEMPLATE_BODY_AFTER_VERSION_7 = "{\n" +
	" \"index_patterns\": [\"metrics*\"],\n" +

This results in two issues:

1. If my custom index-pattern doesn't start with metrics, the template won't apply
2. The template pattern metrics* is too broad and prevents me from using indices like metrics-something-* in other applications (in my case, the config of _source breaks the other application. See Configurable _source.enabled Elastic mapping property #1629)

Making the template index-pattern configurable solves these issues.

[izeye]

@micheljung Thanks for the issue. This seems to be an oversight. I created #2197 to try to resolve this.

[micheljung]

Thanks for the quick fix! #2197 looks exactly as it should be :-)