Using DAPR Postgres Configuration Store

DAPR – PostGres Configuration Store .

With the help of DAPR Configuration building block we can fetch the configuration items from the configuration store and also subscribe for configuration updates .

A configuration item is often dynamic in nature and tightly coupled to the needs of the application that consumes it.

For Setup Postgres Configuration Store . Following the official Link : Postgres Configuration Store

1. Get Configuration Items from the Postgres Configuration Store.  To fetch the configuration item we can use the following code in JAVA to get the item.

 try (DaprClient client = (new DaprClientBuilder()).build()) {
            for (String configurationItem : CONFIGURATION_ITEMS) {
                ConfigurationItem item = client.getConfiguration(DAPR_CONFIGURATON_STORE, configurationItem).block();
                System.out.println("Configuration for " + configurationItem + ": {'value':'" + item.getValue() + "'}");
            }
        } catch (Exception e) {
            System.out.println("Could not get config item, err:" + e.getMessage());
            System.exit(1);
        }

2. Subscribe to configuration Updates from Postgres Configuration Store.

Since, we need to mention the name of PG-Notify channel to which we are subscribing , update the function with the following parameters .

try (DaprClient client = (new DaprClientBuilder()).build()) {

            // Create a Metadata for storing PG-notify channel name
            Map<String,String> metadata = new HashMap<>();
            metadata.put("pgNotifyChannel","config");

            // Subscribe for config changes
            // ********  Change the function parametes here ***********
            Flux subscription = client.subscribeConfiguration(DAPR_CONFIGURATON_STORE,
                    CONFIGURATION_ITEMS,metadata);

            // Read config changes for 20 seconds
            subscription.subscribe((response) -> {
                // First ever response contains the subscription id
                if (response.getItems() == null || response.getItems().isEmpty()) {
                    subscriptionId = response.getSubscriptionId();
                    System.out.println("App subscribed to config changes with subscription id: " + subscriptionId);
                } else {
                    response.getItems().forEach((k, v) -> {
                        System.out.println("Configuration update for " + k + ": {'value':'" + v.getValue() + "'}");
                    });
                }
            });

3 . Unsubscribe from Postgres configuration updates.

// Unsubscribe from config changes
UnsubscribeConfigurationResponse unsubscribe = client
        .unsubscribeConfiguration(subscriptionId, DAPR_CONFIGURATON_STORE).block();
if (unsubscribe.getIsUnsubscribed()) {
    System.out.println("App unsubscribed to config changes");
}