monitoring: systemd services, domain expiry, DNS correctness, public endpoints
Four more check types, 42 endpoints, taking the estate from 39 to 81.
── systemd services (infra/401) ────────────────────────────────────────────
Every unit we deploy, checked every 5 minutes with a 16-minute heartbeat.
This closes the gap that let a real bug run unnoticed earlier today: a backup
script left forgejo, lnbits, headscale and memos stopped, and NOTHING caught
it. The dumps exited 0, the artefacts were correct, the deploy said failed=0,
and liveness only proves the HOST is up - not that anything on it serves.
One endpoint PER UNIT but only ONE timer per host: the check iterates that
host's units and pushes a result for each, the way check-backups.sh reports per
source. Four units on vipy would otherwise mean four scripts, services and
timers. A single host-level red light would also say "something on vipy is
down" without saying which, which is not the question anyone has.
Keys are host-qualified because unit names collide - caddy runs on four
machines. Which units a host runs lives in host_vars/<host>/monitored_services,
because "what runs here" is a property of the machine, the same reasoning as
the cross-host ports.
nut-driver-enumerator is deliberately excluded: it is a oneshot generator that
is `enabled` but always `inactive`, so it would report down forever. Checked
live before excluding it.
── domain, DNS and public endpoints (infra/402) ────────────────────────────
The first checks that PULL rather than push, and that is the right way round:
all three are about how the outside world sees us, so they must be measured
from outside. Nothing is installed anywhere - no script, no timer, no token.
They also have no heartbeat, because a heartbeat answers "did the reporter
report"; when Gatus does the checking itself, failure is immediate.
domain 1 endpoint, 24h, [DOMAIN_EXPIRATION] > 336h (two weeks)
dns 11 endpoints, 24h, [DNS_RCODE] == NOERROR and [BODY] == the IP
public 14 endpoints, 5m, 11 HTTPS + 3 TCP
Expected A records are derived from inventory (hostvars[host].ansible_host),
not written down again. The estate's recurring bug is an address recorded in a
second place and left behind when the machine moved; asserting against
inventory means a renumbered box is one edit, not two.
Expected HTTP status was checked live per site rather than assumed. Two return
401 - the Gatus dashboard and the DATUM dashboard, both behind basic auth - and
that is what is asserted: expecting 200 there would go green precisely when the
auth broke. headscale asserts /health rather than /, which is a 404 by design.
Every HTTPS check also carries [CERTIFICATE_EXPIRATION] > 168h, which is free
on an endpoint already being polled and catches a renewal that silently stops.
Two things learned the hard way, both now in comments:
* A domain-expiry endpoint needs a URL SCHEME. Gatus derives the endpoint type
from the prefix (endpoint.Type()), so a bare "contrapeso.xyz" is UNKNOWN and
the whole config is rejected. It is https:// plus a DOMAIN_EXPIRATION
condition and no status assertion, so the registrar's parking page at the
apex is irrelevant. Upstream also enforces a 5m minimum interval for that
placeholder, because it uses a free whois service.
* That rejection proved skip-invalid-config-update was worth adding. Gatus
logged "the configuration file was updated, but it is not valid, the old
configuration will continue being used" and kept running. Without it the
reload path calls panic() and one malformed contributed file takes the
monitor down.
Verified: 15/15 service endpoints UP; 26/27 public-facing UP. The single DOWN is
public_memos, correctly - memos-box is powered off, and the condition result
reads [STATUS] (502) == 200. memos-box and arbret-staging-box were shut down
deliberately from the Proxmox UI to test the liveness endpoints; their endpoints
stay registered and will go green when the VMs return.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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83
ansible/infra/401_service_monitoring.yml
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83
ansible/infra/401_service_monitoring.yml
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@ -0,0 +1,83 @@
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---
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# Is each systemd-deployed service actually running?
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#
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# Every 5 minutes, with a 16-minute Gatus heartbeat - three missed runs before
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# it alarms, so a reboot or a slow check does not page anyone, but a host that
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# stops reporting does.
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#
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# This closes the gap that let a real bug run unnoticed: a backup script left
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# forgejo, lnbits, headscale and memos stopped, and NOTHING caught it. The dumps
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# exited 0, the artefacts were correct, the deploy said failed=0, and liveness
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# only proves the HOST is up - not that anything on it is serving.
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#
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# One endpoint PER UNIT, not per host. A host running four services needs four
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# endpoints, or a single red light says "something on vipy is down" without
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# saying which - and that is the question you actually have at 3am. But only ONE
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# timer per host: the check iterates that host's units and pushes a result for
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# each, the same way check-backups.sh reports per source. Four units on vipy
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# would otherwise mean four scripts, four services and four timers.
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#
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# Which units each host runs is in host_vars/<host>/main.yml as
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# monitored_services, because "what runs here" is a property of the machine.
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#
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# Keys are host-qualified because unit names collide - caddy runs on four
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# machines. Gatus computes sanitize(group)_sanitize(name), so group "services"
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# and name "vipy/caddy" give services_vipy-caddy.
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# ─────────────────────────────────────────────────────────────────────────────
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# Register one endpoint per unit. Runs first: Gatus reloads within 30s, and the
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# host play above takes minutes, so every endpoint exists before its first push.
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# ─────────────────────────────────────────────────────────────────────────────
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- name: Register the service checks with Gatus
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hosts: observability
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become: yes
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tasks:
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# Two plain steps rather than one clever expression: first collect which
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# units each host declares, then flatten that into endpoints.
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- name: Collect the units each host declares
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ansible.builtin.set_fact:
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host_units: "{{ host_units | default([]) + [{'host': item, 'units': hostvars[item].monitored_services}] }}"
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loop: "{{ groups['managed'] | sort }}"
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when: hostvars[item].monitored_services | default([]) | length > 0
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- name: Build one endpoint per unit
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ansible.builtin.set_fact:
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service_endpoints: "{{ service_endpoints | default([]) + [{
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'name': (item.0.host | lower | regex_replace('[/_.,# +&]', '-')) ~ '/' ~ item.1,
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'group': 'services',
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'token': gatus_push_tokens[item.0.host],
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'heartbeat': '16m'}] }}"
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loop: "{{ host_units | subelements('units') }}"
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- name: Register the service endpoints
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ansible.builtin.include_role:
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name: gatus_endpoint
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vars:
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gatus_endpoint_name: services
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gatus_endpoint_external: "{{ service_endpoints }}"
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- name: Monitor systemd services on every host that has them
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hosts: managed
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become: yes
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vars:
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gatus_api: "https://{{ subdomains.gatus }}.{{ root_domain }}/api/v1/endpoints"
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host_key: "{{ inventory_hostname | lower | regex_replace('[/_.,# +&]', '-') }}"
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tasks:
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- name: Is every deployed service running?
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ansible.builtin.include_role:
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name: healthcheck
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vars:
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healthcheck_name: service-health
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healthcheck_description: "systemd services on {{ inventory_hostname }}"
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healthcheck_check: systemd-units
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healthcheck_units: "{{ monitored_services }}"
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healthcheck_units_key_prefix: "services_{{ host_key }}"
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healthcheck_interval: "5min"
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healthcheck_boot_delay: "2min"
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# The per-unit results go to keys under this collection; the role's own
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# single-result push is unused here, so only the base is set.
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healthcheck_push_base: "{{ gatus_api }}"
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healthcheck_push_token: "{{ gatus_push_tokens[inventory_hostname] }}"
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when: monitored_services | default([]) | length > 0
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125
ansible/infra/402_public_monitoring.yml
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125
ansible/infra/402_public_monitoring.yml
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@ -0,0 +1,125 @@
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---
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# Domain expiry, DNS correctness, and public endpoint reachability.
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#
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# These are the first checks in the estate that PULL rather than push, and that
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# is the right way round for them: all three are about how the outside world
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# sees us, so they must be measured from outside. Gatus polls from the
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# observability host and needs nothing installed anywhere else - there is no
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# script, no timer and no token, because nothing is reporting in.
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#
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# That also means these have no heartbeat. A heartbeat answers "did the thing
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# that was supposed to report in do so"; when Gatus does the checking itself,
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# failure is immediate and self-evident.
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- name: Register the public-facing checks with Gatus
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hosts: observability
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become: yes
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vars:
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# Expected A records, derived from inventory rather than written down again.
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# The estate's recurring bug is an address recorded in a second place and
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# then left behind when the machine moved, so the check asserts against
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# ansible_host - if a box is renumbered, inventory is the one edit.
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dns_records:
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- {sub: "{{ subdomains.gatus }}", host: monitoring}
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- {sub: "{{ subdomains.ntfy }}", host: watchtower}
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- {sub: "{{ subdomains.headscale }}", host: spacey}
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- {sub: "{{ subdomains.vaultwarden }}", host: vipy}
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- {sub: "{{ subdomains.forgejo }}", host: vipy}
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- {sub: "{{ subdomains.lnbits }}", host: vipy}
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- {sub: "{{ subdomains.ntfy_emergency_app }}", host: vipy}
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- {sub: "{{ subdomains.personal_blog }}", host: vipy}
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- {sub: "{{ subdomains.memos }}", host: vipy}
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- {sub: "{{ subdomains.mempool }}", host: vipy}
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- {sub: "{{ subdomains.datum_gateway }}", host: vipy}
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# A public resolver on purpose: this must test what the internet sees, not
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# what a local cache or the tailnet's MagicDNS happens to answer.
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dns_resolver: "1.1.1.1"
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# Expected status per site, checked live before being written down.
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# 401 is the CORRECT answer for the two behind basic auth - asserting 200
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# there would go green precisely when the auth broke.
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public_sites:
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- {name: gatus, sub: "{{ subdomains.gatus }}", path: "/", status: 401}
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- {name: ntfy, sub: "{{ subdomains.ntfy }}", path: "/", status: 200}
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- {name: headscale, sub: "{{ subdomains.headscale }}", path: "/health", status: 200}
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- {name: vaultwarden, sub: "{{ subdomains.vaultwarden }}", path: "/", status: 200}
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- {name: forgejo, sub: "{{ subdomains.forgejo }}", path: "/", status: 200}
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- {name: lnbits, sub: "{{ subdomains.lnbits }}", path: "/", status: 200}
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- {name: avisame, sub: "{{ subdomains.ntfy_emergency_app }}", path: "/", status: 200}
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- {name: blog, sub: "{{ subdomains.personal_blog }}", path: "/", status: 200}
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- {name: memos, sub: "{{ subdomains.memos }}", path: "/", status: 200}
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- {name: mempool, sub: "{{ subdomains.mempool }}", path: "/", status: 200}
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- {name: datum, sub: "{{ subdomains.datum_gateway }}", path: "/", status: 401}
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# Ports published from the edge host by socket_proxy.
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public_tcp:
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- {name: bitcoin-p2p, host: vipy, port: "{{ hostvars['knots_box_local'].bitcoin_p2p_port }}"}
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- {name: fulcrum-ssl, host: vipy, port: "{{ hostvars['fulcrum_box_local'].fulcrum_ssl_port }}"}
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- {name: datum-stratum, host: vipy, port: "{{ hostvars['knots_box_local'].datum_gateway_stratum_port }}"}
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tasks:
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# ── Domain expiry ────────────────────────────────────────────────────────
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- name: Build the domain endpoint
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ansible.builtin.set_fact:
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domain_endpoints:
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- name: "{{ root_domain }}"
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group: domain
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# Needs a scheme: Gatus derives the endpoint TYPE from the URL prefix
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# (endpoint.Type()), and a bare domain is UNKNOWN and rejected. The
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# apex points at the registrar's parking page, which is irrelevant -
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# the only condition here is the WHOIS expiry, and no status check is
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# asserted, so what the page serves does not matter.
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url: "https://{{ root_domain }}"
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# 24h, and upstream enforces a 5m minimum for DOMAIN_EXPIRATION
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# anyway because it uses a free whois service that must not be
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# hammered and whose data updates slowly.
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interval: 24h
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# 336h = 14 days. Renewal is manual at the registrar, so this needs
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# enough runway to act on.
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conditions:
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- "[DOMAIN_EXPIRATION] > 336h"
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# ── DNS ──────────────────────────────────────────────────────────────────
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- name: Build the DNS endpoints
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ansible.builtin.set_fact:
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dns_endpoints: "{{ dns_endpoints | default([]) + [{
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'name': item.sub ~ '.' ~ root_domain,
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'group': 'dns',
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'url': dns_resolver,
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'interval': '24h',
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'dns': {'query-type': 'A', 'query-name': item.sub ~ '.' ~ root_domain},
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'conditions': ['[DNS_RCODE] == NOERROR',
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'[BODY] == ' ~ hostvars[item.host].ansible_host]}] }}"
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loop: "{{ dns_records }}"
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# ── Public HTTP ──────────────────────────────────────────────────────────
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- name: Build the public HTTP endpoints
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ansible.builtin.set_fact:
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http_endpoints: "{{ http_endpoints | default([]) + [{
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'name': item.name,
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'group': 'public',
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'url': 'https://' ~ item.sub ~ '.' ~ root_domain ~ item.path,
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'interval': '5m',
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'conditions': ['[STATUS] == ' ~ item.status,
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'[CERTIFICATE_EXPIRATION] > 168h']}] }}"
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loop: "{{ public_sites }}"
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# ── Public TCP ───────────────────────────────────────────────────────────
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- name: Build the public TCP endpoints
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ansible.builtin.set_fact:
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tcp_endpoints: "{{ tcp_endpoints | default([]) + [{
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'name': item.name,
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'group': 'public',
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'url': 'tcp://' ~ hostvars[item.host].ansible_host ~ ':' ~ item.port,
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'interval': '5m',
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'conditions': ['[CONNECTED] == true']}] }}"
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loop: "{{ public_tcp }}"
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- name: Register the public-facing endpoints
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ansible.builtin.include_role:
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name: gatus_endpoint
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vars:
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gatus_endpoint_name: public
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gatus_endpoint_pulled: "{{ domain_endpoints + dns_endpoints + http_endpoints + tcp_endpoints }}"
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