Table of Contents

• Name
• Status
• Synopsis
• Description
• Directives
  • rds_json
  • rds_json_buffer_size
  • rds_json_format
  • rds_json_root
  • rds_json_success_property
  • rds_json_user_property
  • rds_json_errcode_key
  • rds_json_errstr_key
  • rds_json_ret
  • rds_json_content_type
• Installation
• Compatibility
• Author
• Copyright & License
• See Also

Status

This module is considered production ready.

We need your help! If you find this module useful and/or interesting, please consider joining the development! Commit bit can be freely delivered at your request ;)

Synopsis

server {
    location /mysql {
        drizzle_query 'select * from cats';
        drizzle_pass my_mysql_upstream;

        rds_json on;
    }

    location /foo {
        if ($arg_limit !~ '^\d{2}$') {
            rds_json_ret 400 'Bad "limit" argument';
        }

        drizzle_query "select * from dogs limit $arg_limit";
        drizzle_pass my_mysql_upstream;

        rds_json on;
    }
    ...
}

Description

This module provides an output filter that can format the RDS outputs generated by ngx_drizzle and ngx_postgres modules to JSON.

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Directives

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rds_json

syntax: rds_json on|off

default: rds_json off

context: http, server, location, if location

Enables or disables the output filter of this module.

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rds_json_buffer_size

syntax: rds_json_buffer_size <bytes>

default: rds_json_buffer_size <page-size>

context: http, server, location, if location

Controls the buffer size used by this module. default to the page size (4k/8k). The bigger the buffer size, the less streammy the conversion will be. But usually increasing the buffer size does help reduce CPU time.

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rds_json_format

syntax: rds_json_format normal|compact

default: rds_json_format normal

context: http, server, location, if location

Controls the output JSON format. A sample of the default "normal" format looks like this

 [{"id":1,"name":"marry"},{"id":2,"name":"bob"}]

while it looks like below when in the "compact" format

 [["id","name"],[1,"marry"],[2,"bob"]]

that is, the first row holds the column name list.

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rds_json_root

syntax: rds_json_root <key>

default: no

context: http, server, location, if location

Specifies the "root" key for data rows (if any). For example,

 rds_json on;
 rds_json_root rows;

will return JSON output like this:

 {"rows":[{"id":2,"name":null},{"id":3,"name":"bob"}]}

if rds_json_format compact is also specified, then the output will look like this:

 {"rows":[["id","name"],[2,null],[3,"bob"]]}

Nginx variables are not supported in the argument of this directive.

If this directive is not defined, neither are rds_json_success_property, nor rds_json_user_property, the JSON output for select queries will just be an array at the top level.

When either rds_json_success_property or rds_json_user_property are specified, this directive takes a default argument of "data".

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rds_json_success_property

syntax: rds_json_success_property <key>

default: no

context: http, server, location, if location

Specifies the top-level object property name used in the JSON output for indicating success or false of the query.

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rds_json_user_property

syntax: rds_json_user_property <key> <value>

default: no

context: http, server, location, if location

Specifies additonal user properties for the top-level object of the JSON output.

Multiple instances of this directives are allowed in a single scope.

Nginx variables are supported in the value argument.

Both of the key and value arguments will be automatically quoted according to JSON strings' notation.

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rds_json_errcode_key

syntax: rds_json_errcode_key <key>

default: rds_json_errcode_key errcode

context: http, server, location, if location

Specifies the errcode key name used in the JSON output.

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rds_json_errstr_key

syntax: rds_json_errstr_key <key>

default: rds_json_errstr_key errstr

context: http, server, location, if location

Specifies the errstr key name used in the JSON output.

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rds_json_ret

syntax: rds_json_ret <error-code> <descrption>

default: no

context: location, if location

This directive enables a content handler that simply emits an response body like this:

 {"errcode":<error-code>,"errstr":"<description>"}

while the <description> string will be properly quoted as a JSON string.

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rds_json_content_type

syntax: rds_json_content_type <mime-type>

default: rds_json_content_type application/json

context: http, server, location, if location

Controls the Content-Type header of the response generated by this module's output filter.

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Installation

You're recommended to install this module (as well as the Nginx core and many other goodies) via the OpenResty bundle. See the detailed instructions for downloading and installing OpenResty into your system. This is the easiest and most safe way to set things up.

Alternatively, you can install this module manually with the Nginx source:

Grab the nginx source code from nginx.org, for example, the version 1.13.6 (see nginx compatibility), and then build the source with this module:

 $ wget 'http://nginx.org/download/nginx-1.13.6.tar.gz'
 $ tar -xzvf nginx-1.13.6.tar.gz
 $ cd nginx-1.13.6/

 # Here we assume you would install you nginx under /opt/nginx/.
 $ ./configure --prefix=/opt/nginx \
     --add-module=/path/to/rds-json-nginx-module

 $ make -j2
 $ make install

Download the latest version of the release tarball of this module from rds-json-nginx-module file list.

Also, this module is included and enabled by default in the OpenResty bundle.

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Compatibility

The following versions of Nginx should work with this module:

• 1.13.x (last tested: 1.13.6)
• 1.12.x
• 1.11.x (last tested: 1.11.2)
• 1.10.x
• 1.9.x (last tested: 1.9.7)
• 1.8.x
• 1.7.x (last tested: 1.7.10)
• 1.6.x
• 1.5.x (last tested: 1.5.12)
• 1.4.x (last tested: 1.4.4)
• 1.2.x (last tested: 1.2.9)
• 1.1.x (last tested: 1.1.5)
• 1.0.x (last tested: 1.0.9)
• 0.9.x (last tested: 0.9.4)
• 0.8.x (last tested: 0.8.55)
• 0.7.x >= 0.7.46 (last tested: 0.7.68)

Earlier versions of Nginx like 0.6.x and 0.5.x will not work.

If you find that any particular version of Nginx above 0.7.44 does not work with this module, please consider reporting a bug.

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Author

Yichun "agentzh" Zhang (章亦春) <agentzh@gmail.com>, OpenResty Inc.

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Copyright & License

This module is licenced under the BSD license.

Copyright (C) 2009-2017, Yichun Zhang (agentzh) <agentzh@gmail.com>, OpenResty Inc.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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See Also

• ngx_drizzle
• ngx_postgres
• ngx_rds_csv