property file-based initialization

[rabbit-hunter]

This is a feature request for the RabbitMQ Java library.

It would be useful if we could initialize the ConnectionFactory via a properties file. Now, whenever we want to set a new configuration property, we have to change the code to call the setter. It would be more convenient if we just could alter the properties file.

You could take Hikari as an example, see https://github.com/brettwooldridge/HikariCP#initialization. A java.util.properties file can be provided. Whenever we want to alter the configuration, we just update the properties file, without being forced to alter the code.

// Examines both filesystem and classpath for .properties file
HikariConfig config = new HikariConfig("/some/path/hikari.properties");
HikariDataSource ds = new HikariDataSource(config);

[michaelklishin]

This can work for a limited number of (common) settings. I'm not sure what can be done about e.g. collections — should command separated lines be used?

And some values, e.g. a SocketConfigurator, would not be supported by this.

@acogoluegnes WDYT?

[acogoluegnes]

@michaelklishin Seems to me like a good idea. Like you said, we won't be able to support all the options (e.g. SocketConfigurator, ExceptionHandler) and have to use some conventions (e.g. comma-separated for URLs), but overall it should be straightforward.

[rrrrrrrrramba]

+1 for this, this would be very useful

[rrrrrrrrramba]

I will try to verify this in the next days.

[rrrrrrrrramba]

I did a quick test with 4.4.0-SNAPSHOT as of today.

I replaced following working code:

        final ConnectionFactory f = new ConnectionFactory();

        try {
            f.setUri("amqp://user:password@localhost:5672/vhost");
        } catch (Exception) {
            e.printStackTrace();
        }
        return f.newConnection();

by

        final ConnectionFactory f = new ConnectionFactory();
        final Properties p = new Properties();

        p.setProperty("uri", "amqp://user:password@localhost:5672/vhost");
        f.load(p);

        return f.newConnection();

Now I am getting:

java.net.ConnectException: Connection refused (Connection refused)

I did not do any further analysis so far.

Any idea?

[rrrrrrrrramba]

Please ignore previous comment. I did not see that there was a default prefix. Now, when setting rabbitmq.uri instead of uri, it works!

[michaelklishin]

@rrrrrrrrramba see the Networking guide. The best way to diagnose this kind of feature is to fire up a VisualVM or a debugger in your IDE and inspect ConnectionFactory object state directly.

[rrrrrrrrramba]

@michaelklishin I wasn't providing an uri, see previous comment. So it was probably falling back to some default credentials, which aren't allowed on my host (standard 3.6.x Docker image).

[rrrrrrrrramba]

@acogoluegnes FYI, I finished my tests, based on commit cb03deefea17364ed5d5631666734dc00142aae5 and it all seems to work fine!

[rrrrrrrrramba]

Will this also be merged in the 5.x master branch?

[michaelklishin]

All 4.x changes that can go into 5.x, will.

[rrrrrrrrramba]

Great!