PostgreSQL LISTEN Exchange
A RabbitMQ exchange type that translates PostgreSQL NOTIFY messages to AMQP messages and publishes them to bound queues. The PostgreSQL NOTIFY message channel is used as the routing key for the message using direct exchange style routing mechanics.
Example
To publish Postgres notifications as AMQP messages into queues bound to a
x-pgsql-listen exchange with a binding key of test, run the following
command in psql:
postgres=# NOTIFY test, 'This is a test';Installation
Extract the contents of the release zip file into your RabbitMQ plugins
directory. Once extracted, run rabbitmq-plugins enable pgsql_listen_exchange.
Configuration
Argument Based Configuration
To connect to PostgreSQL using something other than the default
pgsql://postgres@localhost:5432/postgres connection, you can
add arguments when declaring the exchange:
| Setting | Description | Data Type |
|---|---|---|
| x-host | The PostgreSQL server hostname | String |
| x-port | The port to connect on | Number |
| x-dbname | The database name to connect to | String |
| x-user | The user to connect as | String |
| x-password | The password to use when connecting | String |
Policy Based Configuration
To apply configuration via a policy, the following settings are available:
| Setting | Description | Data Type |
|---|---|---|
| pgsql-listen-host | The PostgreSQL server hostname | String |
| pgsql-listen-port | The port to connect on | Number |
| pgsql-listen-dbname | The database name to connect to | String |
| pgsql-listen-user | The user to connect as | String |
| pgsql-listen-password | The password to use when connecting | String |
Configuration in rabbitmq.config
You can also change the default connection values in the rabbitmq.config file:
| Setting | Description | Data Type | Default Value |
|---|---|---|---|
| host | The PostgreSQL server hostname | list | "localhost" |
| port | The port to connect on | integer | 5432 |
| dbname | The database name to connect to | list | "postgres" |
| user | The user to connect as | list | "postgres" |
| password | The password to use when connecting | list | "" |
Example rabbitmq.config
[{pgsql_listen_exchange,
[
{host, "localhost"},
{port, 5432},
{dbname, "postgres"},
{user, "postgres"},
{password, ""}
]}
].Message Properties
The exchange will automatically add the following properties to messages:
| Property | Value |
|---|---|
| app_id | pgsql-listen-exchange |
| headers | See "Headers Properties Values" table below |
| timestamp | The UNIX epoch timestamp of the publishing server |
Headers Property Values
The following table details the values of the headers property that is set on each message.
| Key | Value |
|---|---|
| pgsql-channel | The PostgreSQL notification channel |
| pgsql-server | The host and port of the PostgreSQL server |
| source-exchange | The pgsql-listen-exchange that the notification was received by |
Specifying Other Properties
In addition to the automatically set message properties, the exchange can set
configured message properties. To set one of the supported message properties,
specify the property name and value when binding to the exchange. For example,
to set the content_type property, specify content_type and the value it
should be set to when binding a queue to the exchange. The following message
properties are supported:
| Property | Data Type |
|---|---|
| content_encoding | String |
| content_type | String |
| delivery_mode | Number |
| priority | Number |
| reply_to | String |
| type | String |
Building
Steps to custom build a version of the pgsql-listen-exchange plugin follow the development environment instructions at https://www.rabbitmq.com/build-server.html#prerequisites and then run the following:
make tests
make dist
zip -r pgsql-listen-exchange.zip plugins/epgsql-* plugins/pgsql-listen-exchange-*Unzip that file into the plugins directory for RabbitMQ and enable as you would any other plugin.