diff --git a/data/common/common.yaml b/data/common/common.yaml
--- a/data/common/common.yaml
+++ b/data/common/common.yaml
@@ -3164,6 +3164,7 @@
 prometheus::server::listen_network: "%{lookup('internal_network')}"
 prometheus::server::listen_port: 9090
 prometheus::server::certname: pergamon.softwareheritage.org
+prometheus::server::fqdn: pergamon.internal.softwareheritage.org
 
 swh::deploy::environment: production
 
diff --git a/site-modules/profile/files/icinga2/plugins/check_belvedere_replication_lag.sh b/site-modules/profile/files/icinga2/plugins/check_belvedere_replication_lag.sh
deleted file mode 100644
--- a/site-modules/profile/files/icinga2/plugins/check_belvedere_replication_lag.sh
+++ /dev/null
@@ -1,28 +0,0 @@
-#!/bin/bash
-
-#
-# File managed by puppet. All modifications will be lost.
-
-# Wrapper calling check_prometheus_metric.sh with the harcoded prometheus query
-# incorrectly parsed when passed to vars.check_prometheus_metric_query
-
-PROGPATH=$(dirname $0)
-
-while getopts ':H:n:c:w:' OPT "$@"
-do
-    case ${OPT} in
-        H)  PROMETHEUS_SERVER="$OPTARG" ;;
-        n)  METRIC_NAME="$OPTARG" ;;
-        c)  CRITICAL_THRESHOLD=${OPTARG}
-            ;;
-        w) WARNING_THRESHOLD=${OPTARG}
-            ;;
-        *) echo "Invalid option ${OPT}"
-           exit 1
-           ;;
-    esac
-done
-
-QUERY='sum(sql_pg_stat_replication{instance="belvedere.internal.softwareheritage.org", host=":5433", application_name="softwareheritage_replica"})'
-
-${PROGPATH}/check_prometheus_metric.sh -H ${PROMETHEUS_SERVER} -q "${QUERY}" -w ${WARNING_THRESHOLD} -c ${CRITICAL_THRESHOLD} -n "${METRIC_NAME}" -t vector
diff --git a/site-modules/profile/files/icinga2/plugins/check_prometheus_metric.sh b/site-modules/profile/files/icinga2/plugins/check_prometheus_metric
rename from site-modules/profile/files/icinga2/plugins/check_prometheus_metric.sh
rename to site-modules/profile/files/icinga2/plugins/check_prometheus_metric
diff --git a/site-modules/profile/functions/icinga2/literal_var.pp b/site-modules/profile/functions/icinga2/literal_var.pp
new file mode 100644
--- /dev/null
+++ b/site-modules/profile/functions/icinga2/literal_var.pp
@@ -0,0 +1,5 @@
+function profile::icinga2::literal_var(String $argument) >> String {
+  # " => \"; \ => \\.
+  $escaped_argument = regsubst($argument, '(["\\\\])', '\\\\\\1', 'G')
+  "-:\"${escaped_argument}\""
+}
diff --git a/site-modules/profile/manifests/icinga2/objects/agent_checks.pp b/site-modules/profile/manifests/icinga2/objects/agent_checks.pp
--- a/site-modules/profile/manifests/icinga2/objects/agent_checks.pp
+++ b/site-modules/profile/manifests/icinga2/objects/agent_checks.pp
@@ -1,8 +1,9 @@
 # Checks that need to be supported on icinga2 agents
 class profile::icinga2::objects::agent_checks {
 
+  $prometheus_host = lookup('prometheus::server::fqdn')
   $prometheus_port = lookup('prometheus::server::listen_port')
-  $prometheus_url = "pergamon.internal.softwareheritage.org:${prometheus_port}"
+  $prometheus_url = "http://${prometheus_host}:${prometheus_port}"
 
   $plugins = {
     'check_journal' => {
@@ -50,29 +51,30 @@
       sudo => true,
       sudo_user => 'root',
     },
-    'check_prometheus_metric.sh' => {
+    'check_prometheus_metric' => {
       arguments => {
         '-H' => '$check_prometheus_metric_url$',
         '-q' => '$check_prometheus_metric_query$',
         '-w' => '$check_prometheus_metric_warning$',
         '-c' => '$check_prometheus_metric_critical$',
         '-n' => '$check_prometheus_metric_name$',
+        '-m' => '$check_prometheus_comparison_method$',
+        '-t' => '$check_prometheus_query_type$',
+        '-O' => {
+          'set_if' => '$check_prometheus_nan_ok$',
+        },
+        '-P' => {
+          'set_if' => '$check_prometheus_perfdata$',
+        },
       },
       vars => {
-        'check_prometheus_metric_url' => $prometheus_url,
+        'check_prometheus_metric_url'        => $prometheus_url,
+        'check_prometheus_comparison_method' => 'ge',
+        'check_prometheus_query_type'        => 'scalar',
+        'check_prometheus_nan_ok'            => false,
+        'check_prometheus_perfdat'           => true,
       }
     },
-    'check_belvedere_replication_lag.sh' => {
-      arguments => {
-        '-H' => '$check_prometheus_metric_url$',
-        '-w' => '$check_prometheus_metric_warning$',
-        '-c' => '$check_prometheus_metric_critical$',
-        '-n' => '$check_prometheus_metric_name$',
-      },
-      vars => {
-        'check_prometheus_metric_url' => $prometheus_url,
-      }
-    }
   }
 
   $plugin_dir = '/usr/lib/nagios/plugins'
diff --git a/site-modules/profile/manifests/icinga2/objects/static_checks.pp b/site-modules/profile/manifests/icinga2/objects/static_checks.pp
--- a/site-modules/profile/manifests/icinga2/objects/static_checks.pp
+++ b/site-modules/profile/manifests/icinga2/objects/static_checks.pp
@@ -110,13 +110,16 @@
     target        => $checks_file,
   }
 
-  $prometheus_host = lookup('prometheus::server::certname')
+  $prometheus_host = lookup('prometheus::server::fqdn')
   ::icinga2::object::service {'Postgresql replication lag (belvedere -> somerset)':
-    check_command => 'check_belvedere_replication_lag.sh',
+    check_command => 'check_prometheus_metric',
     target        => $checks_file,
     host_name     => 'belvedere.internal.softwareheritage.org',
     vars          => {
       check_prometheus_metric_name     => 'pg replication_lag belvedere somerset',
+      check_prometheus_query           => profile::icinga2::literal_var(
+        'sum(sql_pg_stat_replication{instance="belvedere.internal.softwareheritage.org", host=":5433", application_name="softwareheritage_replica"})'
+      ),
       check_prometheus_metric_warning  => '1073741824', # 1GiB 1*1024*1024*1024
       check_prometheus_metric_critical => '2147483648', # 2GiB 2*1024*1024*1024
     },