Three stacked lessons, each proved live 2026-10-21:
- the image's ENTRYPOINT is /bin/blackbox_exporter, so Exec= repeating the
binary made it a positional arg: 'unexpected /bin/blackbox_exporter'.
- the podman gateway 169.254.1.2 is NOT bindable from the host netns - it
exists only inside each rootless netns: 'bind: cannot assign requested
address'. The scrape path does not need it bound: a bridge container
dialing the gateway lands on the host LOOPBACK (proved 200 from the
prometheus container), so the exporter binds 127.0.0.1 + LAN.
- HealthCmd shell form ('/bin/sh -c "..."') is passed as one quoted token
and quadlet folds the following --health-interval/--health-retries (and
the image) into the command string; the plain exec form the sibling units
use is correct.
Prometheus.md bind law corrected (gateway is a forward-to-loopback, not a
bind address); deploy-remote gate stays loopback, which is now honest.
Third boot failure: the exporter exited 100 ms in with 'unknown long
flag --listen-address' (proved against the pinned image, plus --help).
The bind semantics were right; the flag name was invented. --web.listen-address
is repeatable - one per address - so the dual gateway+LAN bind stands.
Proven again pre-deploy with the real argv: the run starts and dies
only on the deliberate /dev/null placeholder config.
The deploy died at 'Unit blackbox-exporter.service not found': a
.container without Image= is not generated at all, and the header
argued for Network=host it never declared. Completes the unit (digest
pinned prom/blackbox-exporter, Network=host) and fixes the bind
topology the first cut got wrong:
- Prometheus is bridge-networked and the netavark hairpin gap bars it
from its own host's LAN IP, so a LAN-only prober bind is unscrapable
and a loopback-only bind was claimed to ride the gateway on faith.
The prober now binds 9115 on the podman gateway (scrape path) AND
the LAN (healthcheck/diagnostics); the listen_address line leaves
blackbox.yml so config and Exec cannot disagree.
- comfyui probe target http://comfyui:8188 -> http://127.0.0.1:8188:
bridge container names do not resolve in the host netns; the
published 0.0.0.0:8188 answers on loopback there.
- New seam: every observability unit must declare Image= (red on the
shipped file by name); copier test pinned module presence instead
of the removed listen line. Docs updated to the real topology.
Prometheus 3 refuses HTML scrape bodies, so the comfyui/services probe
jobs were structurally dead targets reading as outages. HTTP liveness
now rides a blackbox exporter (shared/blackbox/blackbox.yml, loopback
bind, http_2xx module); prometheus.yml probes SearXNG, OpenWebUI and
ComfyUI via __param_target relabeling. The unit is a boot-persistent,
self-healing root quadlet.
Frank