Incorrectly assuming that job label is always there when replacing %%juju_topology%%

[sed-i]

Bug Description

When using LogForwarder, it is incorrect to replace the topology stub with a job matcher.

Following up on #332, we can no longer assume that the job label would always be there, because pebble does not create it.

loki-k8s-operator/lib/charms/loki_k8s/v0/loki_push_api.py

Lines 768 to 771 in 0f6b870

	alert_rule["expr"] = self.tool.inject_label_matchers(
	re.sub(r"%%juju_topology%%", r'job=~".+"', alert_rule["expr"]),
	self.topology.label_matcher_dict,
	)

Originally reported by @saltiyazan.

Related:

• Add juju_charm label to logs grafana-agent-operator#111

To Reproduce

NTA

Environment

NTA

Relevant log output

NTA

Additional context

No response

[saltiyazan]

Thanks for opening this @sed-i I wasn't sure if it was a bug or a misconfiguration on my side :)

[PietroPasotti]

this happened because in the pebble log forwarder never added the 'job' and 'instance' labels. --> @barrettj12

hopefully it will be fixed and the fix backported to the pebbles in juju 3.4 and up

[sed-i]

Just realized that our lib should probably be the one creating it, just like we do all other labels:

loki-k8s-operator/lib/charms/loki_k8s/v1/loki_push_api.py

Lines 2426 to 2435 in 3ddd54e

	log_target.update(
	{
	"labels": {
	"product": "Juju",
	"charm": topology._charm_name,
	"juju_model": topology._model,
	"juju_model_uuid": topology._model_uuid,
	"juju_application": topology._application,
	"juju_unit": topology._unit,
	},

[barrettj12]

Personally I supported adding job and instance labels by default to Pebble, but I know there was some opposition to this and we ultimately decided against it.

Is it possible for the charm just to manually set these labels in the Pebble plan?