Change node_name to be a tag in aerospike input

[danielnelson]

Without this all nodes would create conflicting series.

fixes #2917

Required for all PRs:

• Associated README.md updated.
• Has appropriate unit tests.

[danielnelson]

@popov-ilya Can you test this change? Here is the amd64 build.

[popov-ilya]

ilya-popov@dev01:~$ curl 192.168.1.18:9127/metrics | grep aerospike_node_objects
# HELP aerospike_node_objects Telegraf collected metric
# TYPE aerospike_node_objects untyped
aerospike_node_objects{aerospike_host="localhost:3000",host="dev01",node_name="BB92F7E6C005452"} 7919
aerospike_node_objects{aerospike_host="localhost:3000",host="dev01",node_name="BB947F50D005452"} 7532
aerospike_node_objects{aerospike_host="localhost:3000",host="dev01",node_name="BB9B84A3B005452"} 7367
aerospike_node_objects{aerospike_host="localhost:3000",host="dev01",node_name="BB9F1EA1A005452"} 7144

Now it gives 4 times more series, but i can finally get correct data. Thank you!

[danielnelson]

I didn't see a way to determine which node is the "local" one using aerospike-client-go, though I didn't look too deeply. If we did have a way we could potentially add an option to allow switching between full cluster and local node only mode, similar to what we have for elasticsearch.

This is technically a breaking change, but I think it must be done since otherwise this input is totally unusable with multiple nodes.

[popov-ilya]

Don't know about other outputs, but in prometheus i can drop unnecessary series when pulling it from telegraf. So tottally fine for me.

[danielnelson]

Great, it is also possible for any output/input to use the tagpass/tagdrop options to prevent some of the series from being output.

[kportertx]

I didn't see a way to determine which node is the "local" one using aerospike-client-go, though I didn't look too deeply.

@danielnelson You cold use RequesInfo() and pass a connection to localhost (or another target address).