compute: allow "instance" label name to be set (behind a flag)

[jjo]

Fixes #262.

What

Allow instance label name to be set via new -compute.instance-label flag.

Why

See #262 for the rationale and discussion.

How

• for each compute Collector, create new collectorMetrics type containing compute metrics (moved from global var), to let each Collector own an allocated instance obtained via newCollectorMetrics(instanceLabel)

• changing metrics from global var to dynamically allocated object is needed for:

  • setting its label at runtime
  • allowing tests to be self-contained, else the 1st test to run would "own" setting instanceLabel
  • pave the way to also fixing #263, where we'd also need to (optionally) add a spot={true,false} label

• there's a new config.CommonConfig type, currently only having a single field ComputeInstanceLabel, which is passed down from cmd/ to each instantiated Provider, then to each compute Collector

Testing

Adapted testing with a couple ComputeInstanceLabel="node" changes, although it should be improved to test changes to the label name.

-- Signed-off-by: JuanJo Ciarlante juanjosec@gmail.com

[jjo]

BTW also manually tested it locally with:

$ ./cloudcost-exporter  --aws.profile $DEV_PROFILE --aws.region us-east-1 --aws.services ec2 --compute.instance-label node
[...]

$ curl -s http://localhost:8080/metrics | egrep ^cloudcost_aws
[...]
cloudcost_aws_ec2_instance_total_usd_per_hour{cluster_name="<EDITED>",family="General purpose",machine_type="m6g.xlarge",node="ip-10-60-5-156.us-east-2.compute.internal",price_tier="ondemand",region="us-east-2"} 0.154
cloudcost_aws_ec2_instance_total_usd_per_hour{cluster_name="<EDITED>",family="General purpose",machine_type="m7g.2xlarge",node="ip-10-60-11-138.us-east-2.compute.internal",price_tier="spot",region="us-east-2a"} 0.1292
cloudcost_aws_ec2_instance_total_usd_per_hour{cluster_name="<EDITED>",family="General purpose",machine_type="m7g.2xlarge",node="ip-10-60-3-71.us-east-2.compute.internal",price_tier="spot",region="us-east-2a"} 0.1292
[...]

[jjo]

Closing as this was intended as a PoC / exploration to sense the feasibility and complexity on adding such flag, then we also agreed on not moving fwd with this approach.