Модуль http_prometheus#

Собирает статистику Angie PRO, исходя из определенных в конфигурации шаблонов, и возвращает сформированные на основании этих шаблонов метрики в формате Prometheus.

Внимание

Чтобы собирать статистику, включите в нужных контекстах зону разделяемой памяти с помощью:

Пример конфигурации#

Три метрики для сбора статистики запросов к серверным зонам разделяемой памяти, объединенные в шаблон custom и опубликованные по пути /p8s:

http {

    prometheus_template custom {
        'angie_http_server_zones_requests_total{zone="$1"}' $p8s_value
            path=~^/http/server_zones/([^/]+)/requests/total$
            type=counter;

        'angie_http_server_zones_requests_processing{zone="$1"}' $p8s_value
            path=~^/http/server_zones/([^/]+)/requests/processing$
            type=gauge;

        'angie_http_server_zones_requests_discarded{zone="$1"}' $p8s_value
            path=~^/http/server_zones/([^/]+)/requests/discarded$
            type=counter;
    }

    # ...

    server {

        listen 80;

        location =/p8s {
            prometheus custom;
        }

        # ...

    }
}

В состав Angie PRO входит вспомогательный файл prometheus_all.conf, куда включен набор общеупотребимых метрик, сведенных в шаблон all:

Содержимое файла
prometheus_template all {

angie_connections_accepted $p8s_value
    path=/connections/accepted
    type=counter
    'help=The total number of accepted client connections.';

angie_connections_dropped $p8s_value
    path=/connections/dropped
    type=counter
    'help=The total number of dropped client connections.';

angie_connections_active $p8s_value
    path=/connections/active
    type=gauge
    'help=The current number of active client connections.';

angie_connections_idle $p8s_value
    path=/connections/idle
    type=gauge
    'help=The current number of idle client connections.';


'angie_slabs_pages_used{zone="$1"}' $p8s_value
    path=~^/slabs/([^/]+)/pages/used$
    type=gauge
    'help=The number of currently used memory pages in a slab zone.';

'angie_slabs_pages_free{zone="$1"}' $p8s_value
    path=~^/slabs/([^/]+)/pages/free$
    type=gauge
    'help=The number of currently free memory pages in a slab zone.';


'angie_slabs_pages_slots_used{zone="$1",size="$2"}' $p8s_value
    path=~^/slabs/([^/]+)/slots/([^/]+)/used$
    type=gauge
    'help=The number of currently used memory slots of a specific size in a slab zone.';

'angie_slabs_pages_slots_free{zone="$1",size="$2"}' $p8s_value
    path=~^/slabs/([^/]+)/slots/([^/]+)/free$
    type=gauge
    'help=The number of currently free memory slots of a specific size in a slab zone.';

'angie_slabs_pages_slots_reqs{zone="$1",size="$2"}' $p8s_value
    path=~^/slabs/([^/]+)/slots/([^/]+)/reqs$
    type=counter
    'help=The total number of attempts to allocate a memory slot of a specific size in a slab zone.';

'angie_slabs_pages_slots_fails{zone="$1",size="$2"}' $p8s_value
    path=~^/slabs/([^/]+)/slots/([^/]+)/fails$
    type=counter
    'help=The number of unsuccessful attempts to allocate a memory slot of a specific size in a slab zone.';


'angie_resolvers_queries{zone="$1",type="$2"}' $p8s_value
    path=~^/resolvers/([^/]+)/queries/([^/]+)$
    type=counter
    'help=The number of queries of a specific type to resolve in a resolver zone.';

'angie_resolvers_responses{zone="$1",status="$2"}' $p8s_value
    path=~^/resolvers/([^/]+)/responses/([^/]+)$
    type=counter
    'help=The number of resolution results with a specific status in a resolver zone.';


'angie_http_server_zones_ssl_handshaked{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/ssl/handshaked$
    type=counter
    'help=The total number of successful SSL handshakes in an HTTP server zone.';

'angie_http_server_zones_ssl_reuses{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/ssl/reuses$
    type=counter
    'help=The total number of session reuses during SSL handshakes in an HTTP server zone.';

'angie_http_server_zones_ssl_timedout{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/ssl/timedout$
    type=counter
    'help=The total number of timed-out SSL handshakes in an HTTP server zone.';

'angie_http_server_zones_ssl_failed{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/ssl/failed$
    type=counter
    'help=The total number of failed SSL handshakes in an HTTP server zone.';


'angie_http_server_zones_requests_total{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/requests/total$
    type=counter
    'help=The total number of client requests received in an HTTP server zone.';

'angie_http_server_zones_requests_processing{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/requests/processing$
    type=gauge
    'help=The number of client requests currently being processed in an HTTP server zone.';

'angie_http_server_zones_requests_discarded{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/requests/discarded$
    type=counter
    'help=The total number of client requests completed in an HTTP server zone without sending a response.';


'angie_http_server_zones_responses{zone="$1",code="$2"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/responses/([^/]+)$
    type=counter
    'help=The number of responses with a specific status in an HTTP server zone.';


'angie_http_server_zones_data_received{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/data/received$
    type=counter
    'help=The total number of bytes received from clients in an HTTP server zone.';

'angie_http_server_zones_data_sent{zone="$1"}' $p8s_value
    path=~^/http/server_zones/([^/]+)/data/sent$
    type=counter
    'help=The total number of bytes sent to clients in an HTTP server zone.';


'angie_http_location_zones_requests_total{zone="$1"}' $p8s_value
    path=~^/http/location_zones/([^/]+)/requests/total$
    type=counter
    'help=The total number of client requests in an HTTP location zone.';

'angie_http_location_zones_requests_discarded{zone="$1"}' $p8s_value
    path=~^/http/location_zones/([^/]+)/requests/discarded$
    type=counter
    'help=The total number of client requests completed in an HTTP location zone without sending a response.';


'angie_http_location_zones_responses{zone="$1",code="$2"}' $p8s_value
    path=~^/http/location_zones/([^/]+)/responses/([^/]+)$
    type=counter
    'help=The number of responses with a specific status in an HTTP location zone.';


'angie_http_location_zones_data_received{zone="$1"}' $p8s_value
    path=~^/http/location_zones/([^/]+)/data/received$
    type=counter
    'help=The total number of bytes received from clients in an HTTP location zone.';

'angie_http_location_zones_data_sent{zone="$1"}' $p8s_value
    path=~^/http/location_zones/([^/]+)/data/sent$
    type=counter
    'help=The total number of bytes sent to clients in an HTTP location zone.';


'angie_http_upstreams_peers_state{upstream="$1",peer="$2"}' $p8st_all_ups_state
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/state$
    type=gauge
    'help=The current state of an upstream peer in "HTTP": 1 - up, 2 - down, 3 - unavailable, 4 - recovering, 5 - unhealthy, 6 - checking, or 7 - draining.';


'angie_http_upstreams_peers_selected_current{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/selected/current$
    type=gauge
    'help=The number of requests currently being processed by an upstream peer in "HTTP".';

'angie_http_upstreams_peers_selected_total{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/selected/total$
    type=counter
    'help=The total number of attempts to use an upstream peer in "HTTP".';


'angie_http_upstreams_peers_responses{upstream="$1",peer="$2",code="$3"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/responses/([^/]+)$
    type=counter
    'help=The number of responses with a specific status received from an upstream peer in "HTTP".';


'angie_http_upstreams_peers_data_sent{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/data/sent$
    type=counter
    'help=The total number of bytes received from an upstream peer in "HTTP".';

'angie_http_upstreams_peers_data_received{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/data/received$
    type=counter
    'help=The total number of bytes sent to an upstream peer in "HTTP".';


'angie_http_upstreams_peers_health_fails{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/fails$
    type=counter
    'help=The total number of unsuccessful attempts to communicate with an upstream peer in "HTTP".';

'angie_http_upstreams_peers_health_unavailable{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/unavailable$
    type=counter
    'help=The number of times when an upstream peer in "HTTP" became "unavailable" due to reaching the max_fails limit.';

'angie_http_upstreams_peers_health_downtime{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/downtime$
    type=counter
    'help=The total time (in milliseconds) that an upstream peer in "HTTP" was "unavailable".';

'angie_http_upstreams_peers_health_header_time{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/header_time$
    type=gauge
    'help=Average time (in milliseconds) to receive the response headers from an upstream peer in "HTTP".';

'angie_http_upstreams_peers_health_response_time{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/response_time$
    type=gauge
    'help=Average time (in milliseconds) to receive the complete response from an upstream peer in "HTTP".';

'angie_http_upstreams_peers_health_probes_count{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/probes/count$
    type=counter
    'help=The total number of probes for this peer.';

'angie_http_upstreams_peers_health_probes_fails{upstream="$1",peer="$2"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/peers/([^/]+)/health/probes/fails$
    type=counter
    'help=The total number of failed probes for this peer.';


'angie_http_upstreams_keepalive{upstream="$1"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/keepalive$
    type=gauge
    'help=The number of currently cached keepalive connections for an HTTP upstream.';


'angie_http_upstreams_queue_queued{upstream="$1"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/queue/queued$
    type=counter
    'help=The total number of queued requests for an HTTP upstream.';

'angie_http_upstreams_queue_waiting{upstream="$1"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/queue/waiting$
    type=gauge
    'help=The number of requests currently waiting in an HTTP upstream queue.';

'angie_http_upstreams_queue_dropped{upstream="$1"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/queue/dropped$
    type=counter
    'help=The total number of requests dropped from an HTTP upstream queue because the client had prematurely closed the connection.';

'angie_http_upstreams_queue_timedout{upstream="$1"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/queue/timedout$
    type=counter
    'help=The total number of requests timed out from an HTTP upstream queue.';

'angie_http_upstreams_queue_overflows{upstream="$1"}' $p8s_value
    path=~^/http/upstreams/([^/]+)/queue/overflows$
    type=counter
    'help=The total number of requests rejected by an HTTP upstream queue because the size limit had been reached.';


'angie_http_caches_responses{zone="$1",status="$2"}' $p8s_value
    path=~^/http/caches/([^/]+)/([^/]+)/responses$
    type=counter
    'help=The total number of responses processed in an HTTP cache zone with a specific cache status.';

'angie_http_caches_bytes{zone="$1",status="$2"}' $p8s_value
    path=~^/http/caches/([^/]+)/([^/]+)/bytes$
    type=counter
    'help=The total number of bytes processed in an HTTP cache zone with a specific cache status.';

'angie_http_caches_responses_written{zone="$1",status="$2"}' $p8s_value
    path=~^/http/caches/([^/]+)/([^/]+)/responses_written$
    type=counter
    'help=The total number of responses written to an HTTP cache zone with a specific cache status.';

'angie_http_caches_bytes_written{zone="$1",status="$2"}' $p8s_value
    path=~^/http/caches/([^/]+)/([^/]+)/bytes_written$
    type=counter
    'help=The total number of bytes written to an HTTP cache zone with a specific cache status.';


'angie_http_caches_size{zone="$1"}' $p8s_value
    path=~^/http/caches/([^/]+)/size$
    type=gauge
    'help=The current size (in bytes) of cached responses in an HTTP cache zone.';


'angie_http_caches_shards_size{zone="$1",path="$2"}' $p8s_value
    path=~^/http/caches/([^/]+)/shards/([^/]+)/size$
    type=gauge
    'help=The current size (in bytes) of cached responses in a shard path of an HTTP cache zone.';


'angie_http_limit_conns{zone="$1",status="$2"}' $p8s_value
    path=~^/http/limit_conns/([^/]+)/([^/]+)$
    type=counter
    'help=The number of requests processed by an HTTP limit_conn zone with a specific result.';

'angie_http_limit_reqs{zone="$1",status="$2"}' $p8s_value
    path=~^/http/limit_reqs/([^/]+)/([^/]+)$
    type=counter
    'help=The number of requests processed by an HTTP limit_reqs zone with a specific result.';


'angie_stream_server_zones_ssl_handshaked{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/ssl/handshaked$
    type=counter
    'help=The total number of successful SSL handshakes in a stream server zone.';

'angie_stream_server_zones_ssl_reuses{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/ssl/reuses$
    type=counter
    'help=The total number of session reuses during SSL handshakes in a stream server zone.';

'angie_stream_server_zones_ssl_timedout{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/ssl/timedout$
    type=counter
    'help=The total number of timed-out SSL handshakes in a stream server zone.';

'angie_stream_server_zones_ssl_failed{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/ssl/failed$
    type=counter
    'help=The total number of failed SSL handshakes in a stream server zone.';


'angie_stream_server_zones_connections_total{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/connections/total$
    type=counter
    'help=The total number of client connections received in a stream server zone.';

'angie_stream_server_zones_connections_processing{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/connections/processing$
    type=gauge
    'help=The number of client connections currently being processed in a stream server zone.';

'angie_stream_server_zones_connections_discarded{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/connections/discarded$
    type=counter
    'help=The total number of client connections completed in a stream server zone without establishing a session.';


'angie_stream_server_zones_sessions{zone="$1",status="$2"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/sessions/([^/]+)$
    type=counter
    'help=The number of sessions finished with a specific status in a stream server zone.';


'angie_stream_server_zones_data_received{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/data/received$
    type=counter
    'help=The total number of bytes received from clients in a stream server zone.';

'angie_stream_server_zones_data_sent{zone="$1"}' $p8s_value
    path=~^/stream/server_zones/([^/]+)/data/sent$
    type=counter
    'help=The total number of bytes sent to clients in a stream server zone.';


'angie_stream_upstreams_peers_state{upstream="$1",peer="$2"}' $p8st_all_ups_state
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/state$
    type=gauge
    'help=The current state of an upstream peer in "stream": 1 - up, 2 - down, 3 - unavailable, or 4 - recovering.';


'angie_stream_upstreams_peers_selected_current{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/selected/current$
    type=gauge
    'help=The number of sessions currently being processed by an upstream peer in "stream".';

'angie_stream_upstreams_peers_selected_total{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/selected/total$
    type=counter
    'help=The total number of attempts to use an upstream peer in "stream".';


'angie_stream_upstreams_peers_data_sent{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/data/sent$
    type=counter
    'help=The total number of bytes received from an upstream peer in "stream".';

'angie_stream_upstreams_peers_data_received{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/data/received$
    type=counter
    'help=The total number of bytes sent to an upstream peer in "stream".';


'angie_stream_upstreams_peers_health_fails{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/fails$
    type=counter
    'help=The total number of unsuccessful attempts to communicate with an upstream peer in "stream".';

'angie_stream_upstreams_peers_health_unavailable{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/unavailable$
    type=counter
    'help=The number of times when an upstream peer in "stream" became "unavailable" due to reaching the max_fails limit.';

'angie_stream_upstreams_peers_health_downtime{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/downtime$
    type=counter
    'help=The total time (in milliseconds) that an upstream peer in "stream" was "unavailable".';

'angie_stream_upstreams_peers_health_connect_time{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/connect_time$
    type=gauge
    'help=Average time (in milliseconds) to connect to an upstream peer in "stream".';

'angie_stream_upstreams_peers_health_first_byte_time{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/first_byte_time$
    type=gauge
    'help=Average time (in milliseconds) to receive the first byte from an upstream peer in "stream".';

'angie_stream_upstreams_peers_health_last_byte_time{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/last_byte_time$
    type=gauge
    'help=Average time (in milliseconds) of the whole communication session with an upstream peer in "stream".';


'angie_stream_upstreams_peers_health_probes_count{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/probes/count$
    type=counter
    'help=The total number of probes for this peer.';

'angie_stream_upstreams_peers_health_probes_fails{upstream="$1",peer="$2"}' $p8s_value
    path=~^/stream/upstreams/([^/]+)/peers/([^/]+)/health/probes/fails$
    type=counter
    'help=The total number of failed probes for this peer.';
}

map $p8s_value $p8st_all_ups_state {
    volatile;
    "up"           1;
    "down"         2;
    "unavailable"  3;
    "recovering"   4;
    "unhealthy"    5;
    "checking"     6;
    "draining"     7;
    default        0;
}

Его использование:

http {

    include prometheus_all.conf;

    # ...

    server {

        listen 80;

        location =/p8s {
            prometheus all;
        }

        # ...

    }
}
$ curl localhost/p8s

    # Angie PRO Prometheus template "all"
    ...

Директивы#

prometheus#

Синтаксис:

prometheus имя_шаблона;

Умолчание:

Контекст:

location

Указывает для контекста location шаблон-обработчик, заданный директивой prometheus_template. При запросе этот location вычисляет и возвращает метрики шаблона в формате Prometheus.

location =/p8s {
    prometheus custom;
}
$ curl localhost/p8s

    # Angie PRO Prometheus template "custom"
    ...

prometheus_template#

Синтаксис:

prometheus_template имя_шаблона { … }

Умолчание:

Контекст:

http

Определяет именованный шаблон метрик, собираемых и экспортируемых Angie PRO, для использования с директивой prometheus.

Примечание

В состав Angie PRO также входит готовый шаблон all, куда включен набор наиболее общеупотребимых метрик.

Может содержать произвольное число определений метрик, каждая из которых имеет следующую структуру:
<имя_метрики> <переменная> [path=<строка_сопоставления>] [type=<тип>] [help=<справка>];

имя_метрики

Задает имя метрики, под которым она будет добавлена в формате Prometheus в ответ на запрос. Может содержать необязательную часть с метками ({...}), например:

http_requests_total{method="$1",code="$2"}

В значениях меток можно использовать переменные Angie PRO; если строка_сопоставления задана регулярным выражением, то можно также использовать определенные в этом выражении группы захвата. Такие переменные и группы вычисляются при получении значения метрики, которое задает переменная.

переменная

Задает имя переменной, которая будет вычислена и добавлена как значение метрики в ответ на запрос. Если переменной нет или результат вычисления пуст (""), метрика не добавляется.

Метрика вычисляется со значением, которое задает переменная; при успехе вычисления метрика добавляется в ответ, например:

'angie_time{version="$angie_version"}' $msec;
$ curl localhost/p8s

    angie_time{version="1.5.0"} 1695119820.562

path=строка_сопоставления

Сопоставляется со всеми конечными путями метрик в поддереве /status API-интерфейса Angie PRO, позволяя добавить в ответ сразу несколько экземпляров метрики.

При сопоставлении пути берутся с начальной косой чертой, но без конечной, например /angie/generation; при этом регистр символов не учитывается. Есть два способа сопоставления:

path=точное_соответствие

Проверяется посимвольным сравнением.

path=~регулярное_выражение

Проверяется при помощи библиотеки PCRE; может задавать группы захвата для использования в метках поля имя метрики.

Если строка_сопоставления соответствует какому-либо пути, то значение метрики Angie PRO по нему заносится в переменную $p8s_value, которую при заданном path= можно использовать в поле переменная.

В случае регулярного выражения совпадающих путей может быть несколько; метрика добавляется в ответ для каждого совпадения. В сочетании с группами захвата это позволяет получить ряд метрик с одним именем и разными метками, например:

'angie_slabs_slots_free{zone="$1",size="$2"}' $p8s_value
    path=~^/slabs/([^/]+)/slots/([^/]+)/free$;

Это определение добавляет метрики для всех зон и всех размеров, которые есть сейчас в конфигурации:

angie_slabs_slots_free{zone="one",size="8"} 502
angie_slabs_slots_free{zone="one",size="16"} 249
angie_slabs_slots_free{zone="one",size="32"} 122
angie_slabs_slots_free{zone="one",size="128"} 22
angie_slabs_slots_free{zone="one",size="512"} 4
angie_slabs_slots_free{zone="two",size="8"} 311
...

Если совпадений нет (при любом способе сопоставления), то метрика не добавляется.

Примечание

Параметр path= доступен только при сборке Angie PRO с модулем API.

type=тип, help=справка

Задают соответственно тип и справочную строку метрики в формате Prometheus, которые добавляются с ней в ответ без изменений и проверок.

Встроенные переменные#

В модуле http_prometheus есть встроенная переменная, получающая значение при сопоставлении путей метрик из раздела /status API-интерфейса Angie PRO с параметром строка_сопоставления метрик, заданных директивой prometheus_template.

$p8s_value#

Если строка_сопоставления метрики, заданной в prometheus_template, соответствует какому-либо пути, то значение метрики Angie PRO, находящееся по этому пути, заносится в переменную $p8s_value. Она предназначена для использования в поле переменная в определениях метрик, которые вычисляются на основе параметра path=.

Значения метрик Angie PRO, заносимые в переменную $p8s_value, не всегда отвечают потребностям формата Prometheus. Тогда можно воспользоваться директивой map, например для преобразования строк в числа:

map $p8s_value $ups_state_n {
    up           0;
    unavailable  1;
    down         2;
    default      3;
}

prometheus_template main {
    'angie_http_upstreams_state{upstream="$1",peer="$2"}' $ups_state_n
        path=~^/http/upstreams/([^/]+)/peers/([^/]+)/state$;
}

Если у метрики Angie PRO логическое значение, то есть true или false, переменная получает значение "1" или "0" соответственно; если значение метрики — null, то переменная будет равна "(null)". Для дат используется целочисленный формат эпохи UNIX.