Chapter 50. Slack
Both producer and consumer are supported
The Slack component allows you to connect to an instance of Slack and delivers a message contained in the message body via a pre established Slack incoming webhook.
Maven users will need to add the following dependency to their pom.xml for this component:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-slack</artifactId>
<version>{CamelSBVersion}</version>
<!-- use the same version as your Camel core version -->
</dependency>50.1. URI format
To send a message to a channel.
slack:#channel[?options]
To send a direct message to a slackuser.
slack:@userID[?options]
50.2. Configuring Options
Camel components are configured on two separate levels:
- component level
- endpoint level
50.2.1. Configuring Component Options
The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.
Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.
Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.
50.2.2. Configuring Endpoint Options
Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.
Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL as a type safe way of configuring endpoints.
A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.
The following two sections lists all the options, firstly for the component followed by the endpoint.
50.3. Component Options
The Slack component supports 5 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| bridgeErrorHandler (consumer) | Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. | false | boolean |
| lazyStartProducer (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean |
| autowiredEnabled (advanced) | Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. | true | boolean |
| token (token) | The token to use. | String | |
| webhookUrl (webhook) | The incoming webhook URL. | String |
50.4. Endpoint Options
The Slack endpoint is configured using URI syntax:
slack:channel
with the following path and query parameters:
50.4.1. Path Parameters (1 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| channel (common) | Required The channel name (syntax #name) or slackuser (syntax userName) to send a message directly to an user. | String |
50.4.2. Query Parameters (29 parameters)
| Name | Description | Default | Type |
|---|---|---|---|
| token (common) | The token to use. | String | |
| bridgeErrorHandler (consumer) | Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. | false | boolean |
| conversationType (consumer) | Type of conversation. Enum values:
| PUBLIC_CHANNEL | ConversationType |
| maxResults (consumer) | The Max Result for the poll. | 10 | String |
| naturalOrder (consumer) | Create exchanges in natural order (oldest to newest) or not. | false | boolean |
| sendEmptyMessageWhenIdle (consumer) | If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead. | false | boolean |
| serverUrl (consumer) | The Server URL of the Slack instance. | String | |
| exceptionHandler (consumer (advanced)) | To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. | ExceptionHandler | |
| exchangePattern (consumer (advanced)) | Sets the exchange pattern when the consumer creates an exchange. Enum values:
| ExchangePattern | |
| pollStrategy (consumer (advanced)) | A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel. | PollingConsumerPollStrategy | |
| iconEmoji (producer) | Deprecated Use a Slack emoji as an avatar. | String | |
| iconUrl (producer) | Deprecated The avatar that the component will use when sending message to a channel or user. | String | |
| lazyStartProducer (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean |
| username (producer) | Deprecated This is the username that the bot will have when sending messages to a channel or user. | String | |
| webhookUrl (producer) | The incoming webhook URL. | String | |
| backoffErrorThreshold (scheduler) | The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in. | int | |
| backoffIdleThreshold (scheduler) | The number of subsequent idle polls that should happen before the backoffMultipler should kick-in. | int | |
| backoffMultiplier (scheduler) | To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured. | int | |
| delay (scheduler) | Milliseconds before the next poll. | 500 | long |
| greedy (scheduler) | If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages. | false | boolean |
| initialDelay (scheduler) | Milliseconds before the first poll starts. | 1000 | long |
| repeatCount (scheduler) | Specifies a maximum limit of number of fires. So if you set it to 1, the scheduler will only fire once. If you set it to 5, it will only fire five times. A value of zero or negative means fire forever. | 0 | long |
| runLoggingLevel (scheduler) | The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that. Enum values:
| TRACE | LoggingLevel |
| scheduledExecutorService (scheduler) | Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool. | ScheduledExecutorService | |
| scheduler (scheduler) | To use a cron scheduler from either camel-spring or camel-quartz component. Use value spring or quartz for built in scheduler. | none | Object |
| schedulerProperties (scheduler) | To configure additional properties when using a custom scheduler or any of the Quartz, Spring based scheduler. | Map | |
| startScheduler (scheduler) | Whether the scheduler should be auto started. | true | boolean |
| timeUnit (scheduler) | Time unit for initialDelay and delay options. Enum values:
| MILLISECONDS | TimeUnit |
| useFixedDelay (scheduler) | Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details. | true | boolean |
50.5. Configuring in Sprint XML
The Slack component with XML must be configured as a Spring or Blueprint bean that contains the incoming webhook url or the app token for the integration as a parameter.
<bean id="slack" class="org.apache.camel.component.slack.SlackComponent">
<property name="webhookUrl" value="https://hooks.slack.com/services/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"/>
<property name="token" value="xoxb-12345678901-1234567890123-xxxxxxxxxxxxxxxxxxxxxxxx"/>
</bean>For Java you can configure this using Java code.
50.6. Example
A CamelContext with Blueprint could be as:
<?xml version="1.0" encoding="UTF-8"?>
<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" default-activation="lazy">
<bean id="slack" class="org.apache.camel.component.slack.SlackComponent">
<property name="webhookUrl" value="https://hooks.slack.com/services/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"/>
</bean>
<camelContext xmlns="http://camel.apache.org/schema/blueprint">
<route>
<from uri="direct:test"/>
<to uri="slack:#channel?iconEmoji=:camel:&username=CamelTest"/>
</route>
</camelContext>
</blueprint>50.7. Producer
You can now use a token to send a message instead of WebhookUrl.
from("direct:test")
.to("slack:#random?token=RAW(<YOUR_TOKEN>)");You can now use the Slack API model to create blocks. You can read more about it here https://api.slack.com/block-kit.
public void testSlackAPIModelMessage() {
Message message = new Message();
message.setBlocks(Collections.singletonList(SectionBlock
.builder()
.text(MarkdownTextObject
.builder()
.text("*Hello from Camel!*")
.build())
.build()));
template.sendBody(test, message);
}50.8. Consumer
You can use also a consumer for messages in channel.
from("slack://general?token=RAW(<YOUR_TOKEN>)&maxResults=1")
.to("mock:result");In this way you’ll get the last message from general channel. The consumer will take track of the timestamp of the last message consumed and in the next poll it will check from that timestamp.
You’ll need to create a Slack app and use it on your workspace.
Use the 'Bot User OAuth Access Token' as token for the consumer endpoint.
Add the corresponding history (channels:history or groups:history or mpim:history or im:history) and read (channels:read or groups:read or mpim:read or im:read) user token scope to your app to grant it permission to view messages in the corresponding channel. You will need to use the conversationType option to set it up too (PUBLIC_CHANNEL, PRIVATE_CHANNEL, MPIM, IM)
The naturalOrder option allows consuming messages from the oldest to the newest. Originally you would get the newest first and consume backward (message 3 ⇒ message 2 ⇒ message 1)
You can use the conversationType option to read history and messages from a channel that is not only public (PUBLIC_CHANNEL,PRIVATE_CHANNEL, MPIM, IM)
50.9. Spring Boot Auto-Configuration
When using slack with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency> <groupId>org.apache.camel.springboot</groupId> <artifactId>camel-slack-starter</artifactId> </dependency>
The component supports 6 options, which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| camel.component.slack.autowired-enabled | Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc. | true | Boolean |
| camel.component.slack.bridge-error-handler | Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. | false | Boolean |
| camel.component.slack.enabled | Whether to enable auto configuration of the slack component. This is enabled by default. | Boolean | |
| camel.component.slack.lazy-start-producer | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | Boolean |
| camel.component.slack.token | The token to use. | String | |
| camel.component.slack.webhook-url | The incoming webhook URL. | String |
