These signatures can be provided by arbitrary Varlink backends symlinked
into /run/systemd/report/sign.
Also add a proper Varlink IDL for the upload interface, since we are
extended it now.
let's name the dir "/run/systemd/report.upload/" (rather than
"/run/systemd/metrics-upload/"). After all, these are reports that we
upload, not indiviudual metrics. And it would be particular confusing
since the dir to pick up metrics is called /run/systemd/report/, rather
than /run/systemd/metrics/. Hence the thing that deals with reports is
nmamed metrics, and the thing that deals in metrics is named reports...
We really want to use io.systemd.Report for the interface
provided by systemd-report itself, not by its backend. hence, rename the
interface that uploading plugins shall implement to
io.systemd.Report.Uploader.
Note that we ideally should have a varlink interface definition for that
interface. if we had, we'd have noticed that earlier.
Two new verbs are added: "generate" and "upload". The first one just
creates a "report", i.e. puts the metrics into a structured JSON object
that in the future is intended to carry additional data like a
signature:
$ build/systemd-report generate io.systemd.Manager.UnitsTotal
{
"mediaType" : "application/vnd.io.systemd.report",
"timestamp" : "Tue 2026-04-28 22:30:09 UTC",
"metrics" : [
{
"name" : "io.systemd.Manager.UnitsTotal",
"value" : 520
}
]
}
The second verb can be used to upload or otherwise process the report.
It builds on the code added in 0a8560eed8.
In /run/systemd/metrics-upload/ we expect a set of sockets. We'll call
out to each one of them. This allows the data to be processed in custom
ways, incl. writing to storage or sending over the network.
Each socket must provide a single interface:
io.systemd.Metrics.Upload {"report":$data}
This gets rid of the duality in the cmdline interface and various
APIs. The general plan is collect both "facts" and "metrics" in a
single list. We have various producers which respond on the
io.systemd.Facts endpoint. Those will need to be adjusted to respond
to io.systemd.Metrics.
Cmdline interface:
'metrics' (unchanged)
'describe-metrics' → 'describe'
'facts' → merged into 'metrics'
'describe-facts' → merged into 'describe'
Let's prepare for a future where the "systemd-report" tool can do more
than enumerate metrics: let's introduce our usual "verbs" style
interface.
Let's also add a second command right-away: "describe-metrics" shows the
description of the metrics.
Lennart Poettering
Zbigniew Jędrzejewski-Szmek
Yu Watanabe