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https://issues.apache.org/jira/browse/CAMEL-15748?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17220034#comment-17220034
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Claus Ibsen commented on CAMEL-15748:
-------------------------------------
Can you try testing with setting the value to null.
Supervising route controller is the better way as otherwise having to build in
auto reconnection logic in 100+ components each with all kind of their own way
is not ideal, vs having camel route controller managing it which can also be
consistently managed and monitored.
And btw on cloud systems you have readiness checks where the cloud system will
restart / reschedule the app.
> Paho consumer never connects if the broker is not reachable at startup
> ----------------------------------------------------------------------
>
> Key: CAMEL-15748
> URL: https://issues.apache.org/jira/browse/CAMEL-15748
> Project: Camel
> Issue Type: Bug
> Components: camel-paho
> Affects Versions: 3.5.0, 3.4.4, 3.6.0
> Reporter: Marco Collovati
> Priority: Major
>
> Having a route with a paho consumer in a route, if the broker is not
> reachable at startup, camel context fail fast and shuts down.
> This can be avoided by setting the *SupervisingRouteController*, but this
> way, even if camel context does not fail, the consumer is never able to
> establish a connection.
> The reason is that when *PahoConsumer* starts for the first time, it creates
> a *MqttClient* and stores it into *client* field; the call to
> *client.connect* throws an exception due to broker down;
>
> {code:java}
>
> @Override
> protected void doStart() throws Exception {
> super.doStart(); connectOptions =
> PahoEndpoint.createMqttConnectOptions(getEndpoint().getConfiguration());
> if (client == null) {
> clientId = getEndpoint().getConfiguration().getClientId();
> if (clientId == null) {
> clientId = "camel-" + MqttClient.generateClientId();
> }
> stopClient = true;
> client = new MqttClient(
> getEndpoint().getConfiguration().getBrokerUrl(),
> clientId,
>
> PahoEndpoint.createMqttClientPersistence(getEndpoint().getConfiguration()));
> LOG.debug("Connecting client: {} to broker: {}", clientId,
> getEndpoint().getConfiguration().getBrokerUrl());
> client.connect(connectOptions);
> }
>
> // other code omitted for brevity
>
> client.subscribe(getEndpoint().getTopic(),
> getEndpoint().getConfiguration().getQos());{code}
>
> after that *doStop* is invoked but the *client* instance is not nullified,
> because it is not connected
>
> {code:java}
> @Override
> protected void doStop() throws Exception {
> super.doStop(); if (stopClient && client != null &&
> client.isConnected()) {
> String topic = getEndpoint().getTopic();
> // only unsubscribe if we are not durable
> if (getEndpoint().getConfiguration().isCleanSession()) {
> LOG.debug("Unsubscribing client: {} from topic: {}",
> clientId, topic);
> client.unsubscribe(topic);
> } else {
> LOG.debug("Client: {} is durable so will not unsubscribe from
> topic: {}", clientId, topic);
> }
> LOG.debug("Disconnecting client: {} from broker: {}", clientId,
> getEndpoint().getConfiguration().getBrokerUrl());
> client.disconnect();
> client = null;
> }
> }
> {code}
>
> when the supervisor tries to restart the route, *client* instance already
> exists, but the call to *client.subscribe* fails because the client is not
> connected.
> Perhaps always nullify *client* in *doStop* should resolve the issue; however
> I have no idea it this solution will impact in other ways.
> A better solution may be to handle automatic reconnect in the consumer, like
> *RabbitConsumer* does, for example.
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