Open5GS has a lightweight HTTP server (already used for `/metrics`) embedded in each NF.
New optional JSON endpoints were added:
| NF | Endpoint | Content |
| --- | --- | --- |
| **SMF** | `/pdu-info` | All currently connected UEs + their PDU sessions (IMSI/SUPI, DNN, IPs, S-NSSAI, QoS, state, etc.) |
| **AMF** | `/gnb-info` | All currently connected gNBs and their supported TAs, PLMNs, SCTP info, number of UEs |
| **AMF** | `/ue-info` | All currently connected NR UEs and their info, active gNB, tai, security, slices, am_policy |
| **MME** | `/enb-info` | All currently connected eNBs and their supported TAs, PLMNs, SCTP info, number of UEs |
| **MME** | `/ue-info` | All currently connected LTE UEs and their info, active eNB, tai, pdn info |
They are exposed on the same HTTP port used by Prometheus metrics (default `:9090`).
To reduce processor load when there are a large number of devices, the API includes a pager that limits output.
`/ue-info?page=0&page_size=100`
page in the range 0-n (0 is default),
`page=-1` to avoid paging
`page_size=100` (default and MAX)
Without this change, using metrics with core setup configurations
(configs/vonr.yaml for example) would not be possible. Having one
metrics section for whole config file causes every NF to start metrics
server on same port causing an abort.
Recent commit re-enabling SBI HTTP/1.1 support
(10bdf39505cf525b95886c140b3c2e82e7427d29) started using libmicrohttpd's
API MHD_create_response_from_buffer_with_free_callback(), which is only
available starting from v0.9.61.
As a result, compilation in xUbuntu 18.04 started failing with errors
about the function not being found, since it ships with libmicrohttpd
v0.9.59.
Depending on 0.9.61 is fine since it's quite old (november 2018) and all
major current distros should for sure have an >= one. Let's simply bump
the version check so that it fails in an informative manner.
* Initial metrics support based on Prometheus
This commit introduces initial support for metrics in open5gs.
The metrics code is added as libogsmetrics (lib/metrics/), with a well
defined opaque API to manage different types of metrics, allowing for
different implementations for different technologies to scrap the
metrics (placed as lib/metrics/<impl>/. The implementation is right now
selected at build time, in order to be able to opt-out the related dependencies
for users not interested in the features. 2 implementations are already
provided in this commit to start with:
* void: Default implementation. Empty stubs, acts as a NOOP.
* prometheus: open5gs processes become Prometheus servers, offering
states through an http server to the Prometheus scrappers. Relies on
libprom (prometheus-client-ci [1] project) to track the metrics and format
them during export, and libmicrohttpd to make the export possible through
HTTP.
[1] https://github.com/digitalocean/prometheus-client-c
The prometheus-client-c is not well maintained nowadays in upstream, and
furthermore it uses a quite peculiar mixture of build systems (autolib
on the main dir, cmake for libprom in a subdir). This makes it difficult
to have it widely available in distros, and difficult to find it if it
is installed in the system. Hence, the best is to include it as a
meson subproject like we already do for freeDiameter. An open5gs fork is
requried in order to have an extra patch adding a top-level
CMakeList.txt in order to be able to includ eit from open5gs's meson
build. Furthermore, this allows adding bugfixes to the subproject if any
are found in the future.
* [SMF] Initial metrics support
* [SMF] Add metrics at gtp_node level
* docs: Add tutorial documenting metrics with Prometheus
