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Updated TLSv1.3 support notes. Previous notes described some early development snapshot of OpenSSL 1.1.1 with disabled TLSv1.3 by default. It was then enabled in the first alpha. Further, the updated text covers later major releases such as OpenSSL 3.0.
author Sergey Kandaurov <pluknet@nginx.com>
date Thu, 30 Sep 2021 16:29:20 +0300
parents 375a3dfde23b
children
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<?xml version="1.0"?>

<!--
  Copyright (C) Nginx, Inc.
  -->

<!DOCTYPE module SYSTEM "../../../../dtd/module.dtd">

<module name="Module ngx_http_status_module"
        link="/en/docs/http/ngx_http_status_module.html"
        lang="en"
        rev="19">

<section id="summary">

<para>
The <literal>ngx_http_status_module</literal> module provides
access to various status information.
<note>
This module was available as part of our
<commercial_version>commercial subscription</commercial_version>
until 1.13.10.
It was superseded by the
<link doc="ngx_http_api_module.xml">ngx_http_api_module</link> module
in 1.13.3.
</note>
</para>

</section>


<section id="example" name="Example Configuration">

<para>
<example>
http {
    upstream <emphasis>backend</emphasis> {
        <emphasis>zone</emphasis> http_backend 64k;

        server backend1.example.com weight=5;
        server backend2.example.com;
    }

    proxy_cache_path /data/nginx/cache_backend keys_zone=<emphasis>cache_backend</emphasis>:10m;

    server {
        server_name backend.example.com;

        location / {
            proxy_pass  http://backend;
            proxy_cache cache_backend;

            health_check;
        }

        <emphasis>status_zone server_backend;</emphasis>
    }

    server {
        listen 127.0.0.1;

        location /upstream_conf {
            upstream_conf;
        }

        location /status {
            status;
        }

        location = /status.html {
        }
    }
}

stream {
    upstream <emphasis>backend</emphasis> {
        <emphasis>zone</emphasis> stream_backend 64k;

        server backend1.example.com:12345 weight=5;
        server backend2.example.com:12345;
    }

    server {
        listen      127.0.0.1:12345;
        proxy_pass  backend;
        <emphasis>status_zone server_backend;</emphasis>
        health_check;
    }
}
</example>
</para>

<para>
Examples of status requests with this configuration:
<example>
http://127.0.0.1/status
http://127.0.0.1/status/nginx_version
http://127.0.0.1/status/caches/cache_backend
http://127.0.0.1/status/upstreams
http://127.0.0.1/status/upstreams/backend
http://127.0.0.1/status/upstreams/backend/peers/1
http://127.0.0.1/status/upstreams/backend/peers/1/weight
http://127.0.0.1/status/stream
http://127.0.0.1/status/stream/upstreams
http://127.0.0.1/status/stream/upstreams/backend
http://127.0.0.1/status/stream/upstreams/backend/peers/1
http://127.0.0.1/status/stream/upstreams/backend/peers/1/weight
</example>
</para>

<para>
The simple monitoring page is shipped with this distribution,
accessible as “<literal>/status.html</literal>” in the default configuration.
It requires the locations “<literal>/status</literal>” and
“<literal>/status.html</literal>” to be configured as shown above.
</para>

</section>


<section id="directives" name="Directives">

<directive name="status">
<syntax/>
<default/>
<context>location</context>

<para>
The status information will be accessible from the surrounding location.
Access to this location should be
<link doc="ngx_http_core_module.xml" id="satisfy">limited</link>.
</para>

</directive>


<directive name="status_format">
<syntax><literal>json</literal></syntax>
<syntax><literal>jsonp</literal> [<value>callback</value>]</syntax>
<default>json</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
By default, status information is output in the JSON format.
</para>

<para>
Alternatively, data may be output as JSONP.
The <value>callback</value> parameter specifies the name of a callback function.
Parameter value can contain variables.
If parameter is omitted, or the computed value is an empty string,
then “<literal>ngx_status_jsonp_callback</literal>” is used.
</para>

</directive>


<directive name="status_zone">
<syntax><value>zone</value></syntax>
<default/>
<context>server</context>

<para>
Enables collection of virtual
<link doc="ngx_http_core_module.xml" id="server">http</link>
or
<link doc="../stream/ngx_stream_core_module.xml" id="server">stream</link>
(1.7.11) server status information in the specified <value>zone</value>.
Several servers may share the same zone.
</para>

</directive>

</section>


<section id="data" name="Data">

<para>
The following status information is provided:
<list type="tag">

<tag-name id="version"><literal>version</literal></tag-name>
<tag-desc>
Version of the provided data set.
The current version is 8.
</tag-desc>

<tag-name><literal>nginx_version</literal></tag-name>
<tag-desc>
Version of nginx.
</tag-desc>

<tag-name id="nginx_build"><literal>nginx_build</literal></tag-name>
<tag-desc>
Name of nginx build.
</tag-desc>

<tag-name><literal>address</literal></tag-name>
<tag-desc>
The address of the server that accepted status request.
</tag-desc>

<tag-name id="generation"><literal>generation</literal></tag-name>
<tag-desc>
The total number of configuration
<link doc="../control.xml" id="reconfiguration">reloads</link>.
</tag-desc>

<tag-name id="load_timestamp"><literal>load_timestamp</literal></tag-name>
<tag-desc>
Time of the last reload of configuration, in milliseconds since Epoch.
</tag-desc>

<tag-name><literal>timestamp</literal></tag-name>
<tag-desc>
Current time in milliseconds since Epoch.
</tag-desc>

<tag-name id="pid"><literal>pid</literal></tag-name>
<tag-desc>
The ID of the worker process that handled status request.
</tag-desc>

<tag-name id="ppid"><literal>ppid</literal></tag-name>
<tag-desc>
The ID of the master process that started
the <link id="pid">worker process</link>.
</tag-desc>

<tag-name id="processes"><literal>processes</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name id="respawned"><literal>respawned</literal></tag-name>
<tag-desc>
The total number of abnormally terminated and respawned
child processes.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>connections</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>accepted</literal></tag-name>
<tag-desc>
The total number of accepted client connections.
</tag-desc>

<tag-name><literal>dropped</literal></tag-name>
<tag-desc>
The total number of dropped client connections.
</tag-desc>

<tag-name><literal>active</literal></tag-name>
<tag-desc>
The current number of active client connections.
</tag-desc>

<tag-name><literal>idle</literal></tag-name>
<tag-desc>
The current number of idle client connections.
</tag-desc>

</list>
</tag-desc>

<tag-name id="ssl"><literal>ssl</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>handshakes</literal></tag-name>
<tag-desc>
The total number of successful SSL handshakes.
</tag-desc>

<tag-name><literal>handshakes_failed</literal></tag-name>
<tag-desc>
The total number of failed SSL handshakes.
</tag-desc>

<tag-name><literal>session_reuses</literal></tag-name>
<tag-desc>
The total number of session reuses during SSL handshake.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>requests</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>total</literal></tag-name>
<tag-desc>
The total number of client requests.
</tag-desc>

<tag-name><literal>current</literal></tag-name>
<tag-desc>
The current number of client requests.
</tag-desc>

</list>
</tag-desc>

<tag-name id="server_zones"><literal>server_zones</literal></tag-name>
<tag-desc>
For each <link id="status_zone"/>:
<list type="tag">

<tag-name><literal>processing</literal></tag-name>
<tag-desc>
The number of
client requests that are currently being processed.
</tag-desc>

<tag-name><literal>requests</literal></tag-name>
<tag-desc>
The total number of
client requests received from clients.
</tag-desc>

<tag-name><literal>responses</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>total</literal></tag-name>
<tag-desc>
The total number of
responses sent to clients.
</tag-desc>

<tag-name>
<literal>1xx</literal>,
<literal>2xx</literal>,
<literal>3xx</literal>,
<literal>4xx</literal>,
<literal>5xx</literal>
</tag-name>
<tag-desc>
The number of responses with status codes 1xx, 2xx, 3xx, 4xx, and 5xx.
</tag-desc>

</list>
</tag-desc>

<tag-name id="discarded"><literal>discarded</literal></tag-name>
<tag-desc>
The total number of requests completed without sending a response.
</tag-desc>

<tag-name><literal>received</literal></tag-name>
<tag-desc>
The total number of bytes received from clients.
</tag-desc>

<tag-name><literal>sent</literal></tag-name>
<tag-desc>
The total number of bytes sent to clients.
</tag-desc>

</list>
</tag-desc>

<tag-name id="slabs"><literal>slabs</literal></tag-name>
<tag-desc>
For each shared memory zone that uses slab allocator:
<list type="tag">

<tag-name><literal>pages</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>used</literal></tag-name>
<tag-desc>
The current number of used memory pages.
</tag-desc>

<tag-name><literal>free</literal></tag-name>
<tag-desc>
The current number of free memory pages.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>slots</literal></tag-name>
<tag-desc>
For each memory slot size (8, 16, 32, 64, 128, etc.)
the following data are provided:
<list type="tag">

<tag-name><literal>used</literal></tag-name>
<tag-desc>
The current number of used memory slots.
</tag-desc>

<tag-name><literal>free</literal></tag-name>
<tag-desc>
The current number of free memory slots.
</tag-desc>

<tag-name><literal>reqs</literal></tag-name>
<tag-desc>
The total number of attempts to allocate memory of specified size.
</tag-desc>

<tag-name><literal>fails</literal></tag-name>
<tag-desc>
The number of unsuccessful attempts to allocate memory of specified size.
</tag-desc>

</list>
</tag-desc>

</list>
</tag-desc>

<tag-name id="upstreams"><literal>upstreams</literal></tag-name>
<tag-desc>
For each
<link doc="ngx_http_upstream_module.xml" id="zone">dynamically
configurable</link>
<link doc="ngx_http_upstream_module.xml" id="upstream">group</link>,
the following data are provided:
<list type="tag">

<tag-name id="peers"><literal>peers</literal></tag-name>
<tag-desc>
For each
<link doc="ngx_http_upstream_module.xml" id="server"/>,
the following data are provided:
<list type="tag">

<tag-name id="id"><literal>id</literal></tag-name>
<tag-desc>
The ID of the server.
</tag-desc>

<tag-name><literal>server</literal></tag-name>
<tag-desc>
An
<link doc="ngx_http_upstream_module.xml" id="server">address</link>
of the server.
</tag-desc>

<tag-name id="name"><literal>name</literal></tag-name>
<tag-desc>
The name of the server specified in the
<link doc="ngx_http_upstream_module.xml" id="server"/>
directive.
</tag-desc>

<tag-name id="service"><literal>service</literal></tag-name>
<tag-desc>
The <link doc="ngx_http_upstream_module.xml" id="service"/>
parameter value of the
<link doc="ngx_http_upstream_module.xml" id="server"/> directive.
</tag-desc>

<tag-name><literal>backup</literal></tag-name>
<tag-desc>
A boolean value indicating whether the server is a
<link doc="ngx_http_upstream_module.xml" id="backup"/>
server.
</tag-desc>

<tag-name><literal>weight</literal></tag-name>
<tag-desc>
<link doc="ngx_http_upstream_module.xml" id="weight">Weight</link>
of the server.
</tag-desc>

<tag-name id="state"><literal>state</literal></tag-name>
<tag-desc>
Current state, which may be one of
“<literal>up</literal>”,
“<literal>draining</literal>”,
“<literal>down</literal>”,
“<literal>unavail</literal>”,
“<literal>checking</literal>”,
or
“<literal>unhealthy</literal>”.
</tag-desc>

<tag-name><literal>active</literal></tag-name>
<tag-desc>
The current number of active connections.
</tag-desc>

<tag-name id="max_conns"><literal>max_conns</literal></tag-name>
<tag-desc>
The <link doc="ngx_http_upstream_module.xml" id="max_conns"/> limit
for the server.
</tag-desc>

<tag-name><literal>requests</literal></tag-name>
<tag-desc>
The total number of
client requests forwarded to this server.
</tag-desc>

<tag-name><literal>responses</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>total</literal></tag-name>
<tag-desc>
The total number of
responses obtained from this server.
</tag-desc>

<tag-name>
<literal>1xx</literal>,
<literal>2xx</literal>,
<literal>3xx</literal>,
<literal>4xx</literal>,
<literal>5xx</literal>
</tag-name>
<tag-desc>
The number of responses with status codes 1xx, 2xx, 3xx, 4xx, and 5xx.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>sent</literal></tag-name>
<tag-desc>
The total number of bytes sent to this server.
</tag-desc>

<tag-name><literal>received</literal></tag-name>
<tag-desc>
The total number of bytes received from this server.
</tag-desc>

<tag-name><literal>fails</literal></tag-name>
<tag-desc>
The total number of
unsuccessful attempts to communicate with the server.
</tag-desc>

<tag-name><literal>unavail</literal></tag-name>
<tag-desc>
How many times
the server became unavailable for client requests
(state “<literal>unavail</literal>”)
due to the number of unsuccessful attempts reaching the
<link doc="ngx_http_upstream_module.xml" id="max_fails"/>
threshold.
</tag-desc>

<tag-name><literal>health_checks</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>checks</literal></tag-name>
<tag-desc>
The total number of
<link doc="ngx_http_upstream_hc_module.xml" id="health_check">health check</link>
requests made.
</tag-desc>

<tag-name><literal>fails</literal></tag-name>
<tag-desc>
The number of failed health checks.
</tag-desc>

<tag-name><literal>unhealthy</literal></tag-name>
<tag-desc>
How many times
the server became unhealthy (state “<literal>unhealthy</literal>”).
</tag-desc>

<tag-name><literal>last_passed</literal></tag-name>
<tag-desc>
Boolean indicating
if the last health check request was successful and passed
<link doc="ngx_http_upstream_hc_module.xml" id="match">tests</link>.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>downtime</literal></tag-name>
<tag-desc>
Total time
the server was in the “<literal>unavail</literal>”,
“<literal>checking</literal>”, and “<literal>unhealthy</literal>” states.
</tag-desc>

<tag-name><literal>downstart</literal></tag-name>
<tag-desc>
The time (in milliseconds since Epoch)
when the server became
“<literal>unavail</literal>”,
“<literal>checking</literal>”, or “<literal>unhealthy</literal>”.
</tag-desc>

<tag-name id="selected"><literal>selected</literal></tag-name>
<tag-desc>
The time (in milliseconds since Epoch)
when the server was last selected to process a request (1.7.5).
</tag-desc>

<tag-name id="header_time"><literal>header_time</literal></tag-name>
<tag-desc>
The average time to get the
<link doc="ngx_http_upstream_module.xml" id="var_upstream_header_time">response
header</link> from the server (1.7.10).
Prior to version 1.11.6,
the field was available only when using the
<link doc="ngx_http_upstream_module.xml" id="least_time"/>
load balancing method.
</tag-desc>

<tag-name id="response_time"><literal>response_time</literal></tag-name>
<tag-desc>
The average time to get the
<link doc="ngx_http_upstream_module.xml" id="var_upstream_response_time">full
response</link> from the server (1.7.10).
Prior to version 1.11.6,
the field was available only when using the
<link doc="ngx_http_upstream_module.xml" id="least_time"/>
load balancing method.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>keepalive</literal></tag-name>
<tag-desc>
The current number of
idle <link doc="ngx_http_upstream_module.xml" id="keepalive"/> connections.
</tag-desc>

<tag-name id="zombies"><literal>zombies</literal></tag-name>
<tag-desc>
The current number of servers removed
from the group but still processing active client requests.
</tag-desc>

<tag-name id="zone"><literal>zone</literal></tag-name>
<tag-desc>
The name of the shared memory
<link doc="ngx_http_upstream_module.xml" id="zone"/>
that keeps the group’s configuration and run-time state.
</tag-desc>

<tag-name id="queue"><literal>queue</literal></tag-name>
<tag-desc>
For the requests <link doc="ngx_http_upstream_module.xml" id="queue"/>,
the following data are provided:
<list type="tag">

<tag-name><literal>size</literal></tag-name>
<tag-desc>
The current number of requests in the queue.
</tag-desc>

<tag-name id="max_size"><literal>max_size</literal></tag-name>
<tag-desc>
The maximum number of requests that can be in the queue at the same time.
</tag-desc>

<tag-name><literal>overflows</literal></tag-name>
<tag-desc>
The total number of requests rejected due to the queue overflow.
</tag-desc>

</list>
</tag-desc>

</list>
</tag-desc>

<tag-name id="caches"><literal>caches</literal></tag-name>
<tag-desc>
For each cache (configured by
<link doc="ngx_http_proxy_module.xml" id="proxy_cache_path"/> and the likes):
<list type="tag">

<tag-name><literal>size</literal></tag-name>
<tag-desc>
The current size of the cache.
</tag-desc>

<tag-name><literal>max_size</literal></tag-name>
<tag-desc>
The limit on the maximum size of the cache specified in the configuration.
</tag-desc>

<tag-name><literal>cold</literal></tag-name>
<tag-desc>
A boolean value indicating whether the “cache loader” process is still loading
data from disk into the cache.
</tag-desc>

<tag-name>
    <literal>hit</literal>,
    <literal>stale</literal>,
    <literal>updating</literal>,
    <literal>revalidated</literal>
</tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>responses</literal></tag-name>
<tag-desc>
The total number of responses read from the cache (hits, or stale responses
due to <link doc="ngx_http_proxy_module.xml" id="proxy_cache_use_stale"/>
and the likes).
</tag-desc>

<tag-name><literal>bytes</literal></tag-name>
<tag-desc>
The total number of bytes read from the cache.
</tag-desc>

</list>
</tag-desc>

<tag-name>
    <literal>miss</literal>,
    <literal>expired</literal>,
    <literal>bypass</literal>
</tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>responses</literal></tag-name>
<tag-desc>
The total number of responses not taken from the cache (misses, expires, or
bypasses due to
<link doc="ngx_http_proxy_module.xml" id="proxy_cache_bypass"/>
and the likes).
</tag-desc>

<tag-name><literal>bytes</literal></tag-name>
<tag-desc>
The total number of bytes read from the proxied server.
</tag-desc>

<tag-name><literal>responses_written</literal></tag-name>
<tag-desc>
The total number of responses written to the cache.
</tag-desc>

<tag-name><literal>bytes_written</literal></tag-name>
<tag-desc>
The total number of bytes written to the cache.
</tag-desc>

</list>
</tag-desc>

</list>
</tag-desc>

<tag-name id="stream"><literal>stream</literal></tag-name>
<tag-desc>

<list type="tag">
<tag-name id="stream_server_zones"><literal>server_zones</literal></tag-name>
<tag-desc>
For each <link id="status_zone"/>:
<list type="tag">

<tag-name><literal>processing</literal></tag-name>
<tag-desc>
The number of
client connections that are currently being processed.
</tag-desc>

<tag-name><literal>connections</literal></tag-name>
<tag-desc>
The total number of
connections accepted from clients.
</tag-desc>

<tag-name id="sessions"><literal>sessions</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>total</literal></tag-name>
<tag-desc>
The total number of completed client sessions.
</tag-desc>

<tag-name>
<literal>2xx</literal>,
<literal>4xx</literal>,
<literal>5xx</literal>
</tag-name>
<tag-desc>
The number of sessions completed with
<link doc="../stream/ngx_stream_core_module.xml" id="var_status">status codes</link>
2xx, 4xx, or 5xx.
</tag-desc>

</list>
</tag-desc>

<tag-name id="stream_discarded"><literal>discarded</literal></tag-name>
<tag-desc>
The total number of connections completed without creating a session.
</tag-desc>

<tag-name><literal>received</literal></tag-name>
<tag-desc>
The total number of bytes received from clients.
</tag-desc>

<tag-name><literal>sent</literal></tag-name>
<tag-desc>
The total number of bytes sent to clients.
</tag-desc>

</list>
</tag-desc>

<tag-name id="stream_upstreams"><literal>upstreams</literal></tag-name>
<tag-desc>
For each
<link doc="../stream/ngx_stream_upstream_module.xml" id="zone">dynamically
configurable</link>
<link doc="../stream/ngx_stream_upstream_module.xml" id="upstream">group</link>,
the following data are provided:
<list type="tag">

<tag-name><literal>peers</literal></tag-name>
<tag-desc>
For each
<link doc="../stream/ngx_stream_upstream_module.xml" id="server"/>
the following data are provided:
<list type="tag">

<tag-name><literal>id</literal></tag-name>
<tag-desc>
The ID of the server.
</tag-desc>

<tag-name><literal>server</literal></tag-name>
<tag-desc>
An
<link doc="../stream/ngx_stream_upstream_module.xml" id="server">address</link>
of the server.
</tag-desc>


<tag-name id="stream_name"><literal>name</literal></tag-name>
<tag-desc>
The name of the server specified in the
<link doc="../stream/ngx_stream_upstream_module.xml" id="server"/> directive.
</tag-desc>

<tag-name id="stream_service"><literal>service</literal></tag-name>
<tag-desc>
The <link doc="../stream/ngx_stream_upstream_module.xml" id="service"/>
parameter value of the
<link doc="../stream/ngx_stream_upstream_module.xml" id="server"/> directive.
</tag-desc>

<tag-name><literal>backup</literal></tag-name>
<tag-desc>
A boolean value indicating whether the server is a
<link doc="../stream/ngx_stream_upstream_module.xml" id="backup"/>
server.
</tag-desc>

<tag-name><literal>weight</literal></tag-name>
<tag-desc>
<link doc="../stream/ngx_stream_upstream_module.xml" id="weight">Weight</link>
of the server.
</tag-desc>

<tag-name><literal>state</literal></tag-name>
<tag-desc>
Current state, which may be one of
“<literal>up</literal>”,
“<literal>down</literal>”,
“<literal>unavail</literal>”,
“<literal>checking</literal>”,
or
“<literal>unhealthy</literal>”.
</tag-desc>

<tag-name><literal>active</literal></tag-name>
<tag-desc>
The current number of connections.
</tag-desc>

<tag-name><literal>max_conns</literal></tag-name>
<tag-desc>
The <link doc="../stream/ngx_stream_upstream_module.xml" id="max_conns"/> limit
for the server.
</tag-desc>

<tag-name><literal>connections</literal></tag-name>
<tag-desc>
The total number of
client connections forwarded to this server.
</tag-desc>

<tag-name><literal>connect_time</literal></tag-name>
<tag-desc>
The average time to connect to the upstream server.
Prior to version 1.11.6,
the field was available only when using the
<link doc="../stream/ngx_stream_upstream_module.xml" id="least_time"/>
load balancing method.
</tag-desc>

<tag-name><literal>first_byte_time</literal></tag-name>
<tag-desc>
The average time to receive the first byte of data.
Prior to version 1.11.6,
the field was available only when using the
<link doc="../stream/ngx_stream_upstream_module.xml" id="least_time"/>
load balancing method.
</tag-desc>

<tag-name><literal>response_time</literal></tag-name>
<tag-desc>
The average time to receive the last byte of data.
Prior to version 1.11.6,
the field was available only when using the
<link doc="../stream/ngx_stream_upstream_module.xml" id="least_time"/>
load balancing method.
</tag-desc>

<tag-name><literal>sent</literal></tag-name>
<tag-desc>
The total number of bytes sent to this server.
</tag-desc>

<tag-name><literal>received</literal></tag-name>
<tag-desc>
The total number of bytes received from this server.
</tag-desc>

<tag-name><literal>fails</literal></tag-name>
<tag-desc>
The total number of
unsuccessful attempts to communicate with the server.
</tag-desc>

<tag-name><literal>unavail</literal></tag-name>
<tag-desc>
How many times
the server became unavailable for client connections
(state “<literal>unavail</literal>”)
due to the number of unsuccessful attempts reaching the
<link doc="../stream/ngx_stream_upstream_module.xml" id="max_fails"/>
threshold.
</tag-desc>

<tag-name><literal>health_checks</literal></tag-name>
<tag-desc>
<list type="tag">

<tag-name><literal>checks</literal></tag-name>
<tag-desc>
The total number of
<link doc="../stream/ngx_stream_upstream_hc_module.xml" id="health_check">health check</link>
requests made.
</tag-desc>

<tag-name><literal>fails</literal></tag-name>
<tag-desc>
The number of failed health checks.
</tag-desc>

<tag-name><literal>unhealthy</literal></tag-name>
<tag-desc>
How many times
the server became unhealthy (state “<literal>unhealthy</literal>”).
</tag-desc>

<tag-name><literal>last_passed</literal></tag-name>
<tag-desc>
Boolean indicating
if the last health check request was successful and passed
<link doc="../stream/ngx_stream_upstream_hc_module.xml" id="match">tests</link>.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>downtime</literal></tag-name>
<tag-desc>
Total time
the server was in the “<literal>unavail</literal>”,
“<literal>checking</literal>”, and “<literal>unhealthy</literal>” states.
</tag-desc>

<tag-name><literal>downstart</literal></tag-name>
<tag-desc>
The time (in milliseconds since Epoch)
when the server became
“<literal>unavail</literal>”,
“<literal>checking</literal>”, or “<literal>unhealthy</literal>”.
</tag-desc>

<tag-name><literal>selected</literal></tag-name>
<tag-desc>
The time (in milliseconds since Epoch)
when the server was last selected to process a connection.
</tag-desc>

</list>
</tag-desc>

<tag-name><literal>zombies</literal></tag-name>
<tag-desc>
The current number of servers removed
from the group but still processing active client connections.
</tag-desc>

<tag-name><literal>zone</literal></tag-name>
<tag-desc>
The name of the shared memory
<link doc="../stream/ngx_stream_upstream_module.xml" id="zone"/>
that keeps the group’s configuration and run-time state.
</tag-desc>

</list>
</tag-desc>

</list>
</tag-desc>

</list>
</para>

</section>

<section id="compatibility" name="Compatibility">

<para>
<list type="bullet">

<listitem>
The
<link id="zone"/> field in
<link id="upstreams">http</link> and <link id="stream_upstreams">stream</link>
upstreams
was added in <link id="version"/> 8.
</listitem>

<listitem>
The <link id="slabs"/> status data
were added in <link id="version"/> 8.
</listitem>

<listitem>
The
<link id="state">checking</link> state
was added in <link id="version"/> 8.
</listitem>

<listitem>
The
<link id="name"/> and <link id="service"/> fields in
<link id="upstreams">http</link> and <link id="stream_upstreams">stream</link>
upstreams
were added in <link id="version"/> 8.
</listitem>

<listitem>
The
<link id="nginx_build"/> and <link id="ppid"/> fields
were added in <link id="version"/> 8.
</listitem>

<listitem>
The
<link id="sessions"/> status data
and the <link id="stream_discarded">discarded</link> field in
stream <link id="stream_server_zones">server_zones</link>
were added in <link id="version"/> 7.
</listitem>

<listitem>
The <link id="zombies"/> field
was moved from nginx <link doc="../debugging_log.xml">debug</link> version
in <link id="version"/> 6.
</listitem>

<listitem>
The <link id="ssl"/> status data
were added in <link id="version"/> 6.
</listitem>

<listitem>
The
<link id="discarded"/> field in
<link id="server_zones"/>
was added in <link id="version"/> 6.
</listitem>

<listitem>
The <link id="queue"/> status data
were added in <link id="version"/> 6.
</listitem>

<listitem>
The
<link id="pid"/> field
was added in <link id="version"/> 6.
</listitem>

<listitem>
The list of servers in <link id="upstreams"/>
was moved into <link id="peers"/> in
<link id="version"/> 6.
</listitem>

<listitem>
The <literal>keepalive</literal> field of an upstream server
was removed in <link id="version"/> 5.
</listitem>

<listitem>
The <link id="stream">stream</link> status data
were added in <link id="version"/> 5.
</listitem>

<listitem>
The
<link id="generation"/> field
was added in <link id="version"/> 5.
</listitem>

<listitem>
The
<link id="respawned"/> field in
<link id="processes"/>
was added in <link id="version"/> 5.
</listitem>

<listitem>
The
<link id="header_time"/> and <link id="response_time"/> fields in
<link id="upstreams"/>
were added in <link id="version"/> 5.
</listitem>

<listitem>
The
<link id="selected"/> field in
<link id="upstreams"/>
was added in <link id="version"/> 4.
</listitem>

<listitem>
The <link id="state">draining</link> state in
<link id="upstreams"/>
was added in <link id="version"/> 4.
</listitem>

<listitem>
The
<link id="id"/> and <link id="max_conns"/> fields in
<link id="upstreams"/>
were added in <link id="version"/> 3.
</listitem>

<listitem>
The <literal>revalidated</literal> field in
<link id="caches"/>
was added in <link id="version"/> 3.
</listitem>

<listitem>
The <link id="server_zones"/>, <link id="caches"/>,
and <link id="load_timestamp"/> status data
were added in <link id="version"/> 2.
</listitem>

</list>
</para>

</section>

</module>