<?xml version="1.0"?>

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

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

<module name="Module ngx_http_grpc_module"
        link="/en/docs/http/ngx_http_grpc_module.html"
        lang="en"
        rev="9">

<section id="summary">

<para>
The <literal>ngx_http_grpc_module</literal> module allows passing requests
to a gRPC server (1.13.10).
The module requires the
<link doc="ngx_http_v2_module.xml">ngx_http_v2_module</link> module.
</para>

</section>


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

<para>
<example>
server {
    listen 9000 http2;

    location / {
        grpc_pass 127.0.0.1:9000;
    }
}
</example>
</para>

</section>


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

<directive name="grpc_bind">
<syntax>
    <value>address</value>
    [<literal>transparent </literal>] |
    <literal>off</literal></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Makes outgoing connections to a gRPC server originate
from the specified local IP address with an optional port.
Parameter value can contain variables.
The special value <literal>off</literal> cancels the effect
of the <literal>grpc_bind</literal> directive
inherited from the previous configuration level, which allows the
system to auto-assign the local IP address and port.
</para>

<para id="grpc_bind_transparent">
The <literal>transparent</literal> parameter allows
outgoing connections to a gRPC server originate
from a non-local IP address,
for example, from a real IP address of a client:
<example>
grpc_bind $remote_addr transparent;
</example>
In order for this parameter to work,
it is usually necessary to run nginx worker processes with the
<link doc="../ngx_core_module.xml" id="user">superuser</link> privileges.
On Linux it is not required as if
the <literal>transparent</literal> parameter is specified, worker processes
inherit the <literal>CAP_NET_RAW</literal> capability from the master process.
It is also necessary to configure kernel routing table
to intercept network traffic from the gRPC server.
</para>

</directive>


<directive name="grpc_buffer_size">
<syntax><value>size</value></syntax>
<default>4k|8k</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Sets the <value>size</value> of the buffer used for reading the response
received from the gRPC server.
The response is passed to the client synchronously, as soon as it is received.
</para>

</directive>


<directive name="grpc_connect_timeout">
<syntax><value>time</value></syntax>
<default>60s</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Defines a timeout for establishing a connection with a gRPC server.
It should be noted that this timeout cannot usually exceed 75 seconds.
</para>

</directive>


<directive name="grpc_hide_header">
<syntax><value>field</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
By default,
nginx does not pass the header fields <header>Date</header>,
<header>Server</header>, and
<header>X-Accel-...</header> from the response of a gRPC
server to a client.
The <literal>grpc_hide_header</literal> directive sets additional fields
that will not be passed.
If, on the contrary, the passing of fields needs to be permitted,
the <link id="grpc_pass_header"/> directive can be used.
</para>

</directive>


<directive name="grpc_ignore_headers">
<syntax><value>field</value> ...</syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Disables processing of certain response header fields from the gRPC server.
The following fields can be ignored: <header>X-Accel-Redirect</header>
and <header>X-Accel-Charset</header>.
</para>

<para>
If not disabled, processing of these header fields has the following
effect:
<list type="bullet" compact="no">

<listitem>
<header>X-Accel-Redirect</header> performs an
<link doc="ngx_http_core_module.xml" id="internal">internal
redirect</link> to the specified URI;
</listitem>

<listitem>
<header>X-Accel-Charset</header> sets the desired
<link doc="ngx_http_charset_module.xml" id="charset"/>
of a response.
</listitem>

</list>
</para>

</directive>


<directive name="grpc_intercept_errors">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Determines whether gRPC server responses with codes greater than or equal
to 300 should be passed to a client
or be intercepted and redirected to nginx for processing
with the <link doc="ngx_http_core_module.xml" id="error_page"/> directive.
</para>

</directive>


<directive name="grpc_next_upstream">
<syntax>
    <literal>error</literal> |
    <literal>timeout</literal> |
    <literal>invalid_header</literal> |
    <literal>http_500</literal> |
    <literal>http_502</literal> |
    <literal>http_503</literal> |
    <literal>http_504</literal> |
    <literal>http_403</literal> |
    <literal>http_404</literal> |
    <literal>http_429</literal> |
    <literal>non_idempotent</literal> |
    <literal>off</literal>
    ...</syntax>
<default>error timeout</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies in which cases a request should be passed to the next server:
<list type="tag">

<tag-name><literal>error</literal></tag-name>
<tag-desc>an error occurred while establishing a connection with the
server, passing a request to it, or reading the response header;</tag-desc>

<tag-name><literal>timeout</literal></tag-name>
<tag-desc>a timeout has occurred while establishing a connection with the
server, passing a request to it, or reading the response header;</tag-desc>

<tag-name><literal>invalid_header</literal></tag-name>
<tag-desc>a server returned an empty or invalid response;</tag-desc>

<tag-name><literal>http_500</literal></tag-name>
<tag-desc>a server returned a response with the code 500;</tag-desc>

<tag-name><literal>http_502</literal></tag-name>
<tag-desc>a server returned a response with the code 502;</tag-desc>

<tag-name><literal>http_503</literal></tag-name>
<tag-desc>a server returned a response with the code 503;</tag-desc>

<tag-name><literal>http_504</literal></tag-name>
<tag-desc>a server returned a response with the code 504;</tag-desc>

<tag-name><literal>http_403</literal></tag-name>
<tag-desc>a server returned a response with the code 403;</tag-desc>

<tag-name><literal>http_404</literal></tag-name>
<tag-desc>a server returned a response with the code 404;</tag-desc>

<tag-name><literal>http_429</literal></tag-name>
<tag-desc>a server returned a response with the code 429;</tag-desc>

<tag-name id="non_idempotent"><literal>non_idempotent</literal></tag-name>
<tag-desc>normally, requests with a
<link url="https://datatracker.ietf.org/doc/html/rfc7231#section-4.2.2">non-idempotent</link>
method
(<literal>POST</literal>, <literal>LOCK</literal>, <literal>PATCH</literal>)
are not passed to the next server
if a request has been sent to an upstream server;
enabling this option explicitly allows retrying such requests;
</tag-desc>

<tag-name><literal>off</literal></tag-name>
<tag-desc>disables passing a request to the next server.</tag-desc>

</list>
</para>

<para>
One should bear in mind that passing a request to the next server is
only possible if nothing has been sent to a client yet.
That is, if an error or timeout occurs in the middle of the
transferring of a response, fixing this is impossible.
</para>

<para>
The directive also defines what is considered an
<link doc="ngx_http_upstream_module.xml" id="max_fails">unsuccessful
attempt</link> of communication with a server.
The cases of <literal>error</literal>, <literal>timeout</literal> and
<literal>invalid_header</literal> are always considered unsuccessful attempts,
even if they are not specified in the directive.
The cases of <literal>http_500</literal>, <literal>http_502</literal>,
<literal>http_503</literal>, <literal>http_504</literal>,
and <literal>http_429</literal> are
considered unsuccessful attempts only if they are specified in the directive.
The cases of <literal>http_403</literal> and <literal>http_404</literal>
are never considered unsuccessful attempts.
</para>

<para>
Passing a request to the next server can be limited by
<link id="grpc_next_upstream_tries">the number of tries</link>
and by <link id="grpc_next_upstream_timeout">time</link>.
</para>

</directive>


<directive name="grpc_next_upstream_timeout">
<syntax><value>time</value></syntax>
<default>0</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Limits the time during which a request can be passed to the
<link id="grpc_next_upstream">next server</link>.
The <literal>0</literal> value turns off this limitation.
</para>

</directive>


<directive name="grpc_next_upstream_tries">
<syntax><value>number</value></syntax>
<default>0</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Limits the number of possible tries for passing a request to the
<link id="grpc_next_upstream">next server</link>.
The <literal>0</literal> value turns off this limitation.
</para>

</directive>


<directive name="grpc_pass">
<syntax><value>address</value></syntax>
<default/>
<context>location</context>
<context>if in location</context>

<para>
Sets the gRPC server address.
The address can be specified as a domain name or IP address,
and a port:
<example>
grpc_pass localhost:9000;
</example>
or as a UNIX-domain socket path:
<example>
grpc_pass unix:/tmp/grpc.socket;
</example>
Alternatively, the “<literal>grpc://</literal>” scheme can be used:
<example>
grpc_pass grpc://127.0.0.1:9000;
</example>
To use gRPC over SSL, the “<literal>grpcs://</literal>” scheme should be used:
<example>
grpc_pass grpcs://127.0.0.1:443;
</example>
</para>

<para>
If a domain name resolves to several addresses, all of them will be
used in a round-robin fashion.
In addition, an address can be specified as a
<link doc="ngx_http_upstream_module.xml">server group</link>.
</para>

<para>
Parameter value can contain variables (1.17.8).
In this case, if an address is specified as a domain name,
the name is searched among the described
<link doc="ngx_http_upstream_module.xml">server groups</link>,
and, if not found, is determined using a
<link doc="ngx_http_core_module.xml" id="resolver"/>.
</para>

</directive>


<directive name="grpc_pass_header">
<syntax><value>field</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Permits passing <link id="grpc_hide_header">otherwise disabled</link> header
fields from a gRPC server to a client.
</para>

</directive>


<directive name="grpc_read_timeout">
<syntax><value>time</value></syntax>
<default>60s</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Defines a timeout for reading a response from the gRPC server.
The timeout is set only between two successive read operations,
not for the transmission of the whole response.
If the gRPC server does not transmit anything within this time,
the connection is closed.
</para>

</directive>


<directive name="grpc_send_timeout">
<syntax><value>time</value></syntax>
<default>60s</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Sets a timeout for transmitting a request to the gRPC server.
The timeout is set only between two successive write operations,
not for the transmission of the whole request.
If the gRPC server does not receive anything within this time,
the connection is closed.
</para>

</directive>


<directive name="grpc_set_header">
<syntax><value>field</value> <value>value</value></syntax>
<default>Content-Length $content_length</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Allows redefining or appending fields to the request header
<link id="grpc_pass_request_headers">passed</link> to the gRPC server.
The <value>value</value> can contain text, variables, and their combinations.
These directives are inherited from the previous configuration level
if and only if there are no <literal>grpc_set_header</literal> directives
defined on the current level.
</para>

<para>
If the value of a header field is an empty string then this
field will not be passed to a gRPC server:
<example>
grpc_set_header Accept-Encoding "";
</example>
</para>

</directive>


<directive name="grpc_socket_keepalive">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>http</context>
<context>server</context>
<context>location</context>
<appeared-in>1.15.6</appeared-in>

<para>
Configures the “TCP keepalive” behavior
for outgoing connections to a gRPC server.
By default, the operating system’s settings are in effect for the socket.
If the directive is set to the value “<literal>on</literal>”, the
<c-def>SO_KEEPALIVE</c-def> socket option is turned on for the socket.
</para>

</directive>


<directive name="grpc_ssl_certificate">
<syntax><value>file</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies a <value>file</value> with the certificate in the PEM format
used for authentication to a gRPC SSL server.
</para>

<para>
Since version 1.21.0, variables can be used in the <value>file</value> name.
</para>

</directive>


<directive name="grpc_ssl_certificate_key">
<syntax><value>file</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies a <value>file</value> with the secret key in the PEM format
used for authentication to a gRPC SSL server.
</para>

<para>
The value
<literal>engine</literal>:<value>name</value>:<value>id</value>
can be specified instead of the <value>file</value>,
which loads a secret key with a specified <value>id</value>
from the OpenSSL engine <value>name</value>.
</para>

<para>
Since version 1.21.0, variables can be used in the <value>file</value> name.
</para>

</directive>


<directive name="grpc_ssl_ciphers">
<syntax><value>ciphers</value></syntax>
<default>DEFAULT</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies the enabled ciphers for requests to a gRPC SSL server.
The ciphers are specified in the format understood by the OpenSSL library.
</para>

<para>
The full list can be viewed using the
“<command>openssl ciphers</command>” command.
</para>

</directive>


<directive name="grpc_ssl_conf_command">
<syntax><value>name</value> <value>value</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>
<appeared-in>1.19.4</appeared-in>

<para>
Sets arbitrary OpenSSL configuration
<link url="https://www.openssl.org/docs/man1.1.1/man3/SSL_CONF_cmd.html">commands</link>
when establishing a connection with the gRPC SSL server.
<note>
The directive is supported when using OpenSSL 1.0.2 or higher.
</note>
</para>

<para>
Several <literal>grpc_ssl_conf_command</literal> directives
can be specified on the same level.
These directives are inherited from the previous configuration level
if and only if there are
no <literal>grpc_ssl_conf_command</literal> directives
defined on the current level.
</para>

<para>
<note>
Note that configuring OpenSSL directly
might result in unexpected behavior.
</note>
</para>

</directive>


<directive name="grpc_ssl_crl">
<syntax><value>file</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies a <value>file</value> with revoked certificates (CRL)
in the PEM format used to <link id="grpc_ssl_verify">verify</link>
the certificate of the gRPC SSL server.
</para>

</directive>


<directive name="grpc_ssl_name">
<syntax><value>name</value></syntax>
<default>host from grpc_pass</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Allows overriding the server name used to
<link id="grpc_ssl_verify">verify</link>
the certificate of the gRPC SSL server and to be
<link id="grpc_ssl_server_name">passed through SNI</link>
when establishing a connection with the gRPC SSL server.
</para>

<para>
By default, the host part from <link id="grpc_pass"/> is used.
</para>

</directive>


<directive name="grpc_ssl_password_file">
<syntax><value>file</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies a <value>file</value> with passphrases for
<link id="grpc_ssl_certificate_key">secret keys</link>
where each passphrase is specified on a separate line.
Passphrases are tried in turn when loading the key.
</para>

</directive>


<directive name="grpc_ssl_protocols">
<syntax>
    [<literal>SSLv2</literal>]
    [<literal>SSLv3</literal>]
    [<literal>TLSv1</literal>]
    [<literal>TLSv1.1</literal>]
    [<literal>TLSv1.2</literal>]
    [<literal>TLSv1.3</literal>]</syntax>
<default>TLSv1 TLSv1.1 TLSv1.2 TLSv1.3</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Enables the specified protocols for requests to a gRPC SSL server.
</para>

<para>
<note>
The <literal>TLSv1.3</literal> parameter is used by default
since 1.23.4.
</note>
</para>

</directive>


<directive name="grpc_ssl_server_name">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Enables or disables passing of the server name through
<link url="http://en.wikipedia.org/wiki/Server_Name_Indication">TLS
Server Name Indication extension</link> (SNI, RFC 6066)
when establishing a connection with the gRPC SSL server.
</para>

</directive>


<directive name="grpc_ssl_session_reuse">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>on</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Determines whether SSL sessions can be reused when working with
the gRPC server.
If the errors
“<literal>SSL3_GET_FINISHED:digest check failed</literal>”
appear in the logs, try disabling session reuse.
</para>

</directive>


<directive name="grpc_ssl_trusted_certificate">
<syntax><value>file</value></syntax>
<default/>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Specifies a <value>file</value> with trusted CA certificates in the PEM format
used to <link id="grpc_ssl_verify">verify</link>
the certificate of the gRPC SSL server.
</para>

</directive>


<directive name="grpc_ssl_verify">
<syntax><literal>on</literal> | <literal>off</literal></syntax>
<default>off</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Enables or disables verification of the gRPC SSL server certificate.
</para>

</directive>


<directive name="grpc_ssl_verify_depth">
<syntax><value>number</value></syntax>
<default>1</default>
<context>http</context>
<context>server</context>
<context>location</context>

<para>
Sets the verification depth in the gRPC SSL server certificates chain.
</para>

</directive>

</section>

</module>