This page describes the usage of the Stream Reactor HTTP Sink Connector.
A Kafka Connect sink connector for writing records from Kafka to HTTP endpoints.
Support for Json/Avro/String/Protobuf messages via Kafka Connect (in conjunction with converters for Schema-Registry based data storage).
URL, header and content templating ability give you full control of the HTTP request.
Configurable batching of messages, even allowing you to combine them into a single request selecting which data to send with your HTTP request.
For more examples see the tutorials.
The Lenses HTTP sink comes with multiple options for content templating of the HTTP request.
If you do not wish any part of the key, value, headers or other data to form a part of the message, you can use static templating:
When you are confident you will be generating a single HTTP request per Kafka message, then you can use the simpler templating.
In your configuration, in the content property of your config, you can define template substitutions like the following example:
(please note the XML is only an example, your template can consist of any text format that can be submitted in a http request)
To collapse multiple messages into a single HTTP request you can use the multiple messaging template. This is automatic if the template has a messages tag. See the below example:
Again, this is an XML example but your message body can consist of anything including plain text, json or yaml.
Your connector configuration will look like this:
The final result will be HTTP requests with bodies like this:
When using simple and multiple message templating, the following are available:
URL including protocol (eg. http://lenses.io). Template variables can be used.
The URL is also a Content Template so can contain substitutions from the message key/value/headers etc. If you are batching multiple kafka messages into a single request, then the first message will be used for the substitution of the URL.
Currently, the HTTP Sink supports either no authentication, BASIC HTTP authentication and OAuth2 authentication.
By default, no authentication is set. This can be also done by providing a configuration like this:
BASIC auth can be configured by providing a configuration like this:
OAuth auth can be configured by providing a configuration like this:
To customise the headers sent with your HTTP request you can supply a Headers List.
Each header key and value is also a Content Template so can contain substitutions from the message key/value/headers etc. If you are batching multiple kafka messages into a single request, then the first message will be used for the substitution of the headers.
Example:
Enabling SSL connections between Kafka Connect and HTTP Endpoint ensures that the communication between these services is secure, protecting sensitive data from being intercepted or tampered with. SSL (or TLS) encrypts data in transit, verifying the identity of both parties and ensuring data integrity. Please check out SSL Configuration Properties section in order to set it up.
The connector offers three distinct flush options for data management:
Flush by Count - triggers a file flush after a specified number of records have been written to it.
Flush by Size - initiates a file flush once a predetermined size (in bytes) has been attained.
Flush by Interval - enforces a file flush after a defined time interval (in seconds).
It's worth noting that the interval flush is a continuous process that acts as a fail-safe mechanism, ensuring that files are periodically flushed, even if the other flush options are not configured or haven't reached their thresholds.
Consider a scenario where the flush size is set to 10MB, and only 9.8MB of data has been written to the file, with no new Kafka messages arriving for an extended period of 6 hours. To prevent undue delays, the interval flush guarantees that the file is flushed after the specified time interval has elapsed. This ensures the timely management of data even in situations where other flush conditions are not met.
The flush options are configured using the batchCount, batchSize and `timeInterval properties. The settings are optional and if not specified the defaults are:
Some configuration examples follow on how to apply this connector to different message types.
These include converters, which are required to instruct Kafka Connect on how to read the source content.
In this case the converters are irrelevant as we are not using the message content to populate our message template.
The HTTP request body contains the value of the message, which is retained as a string value via the StringConverter.
Specific fields from the JSON message are substituted into the HTTP request body alongside some static content.
The entirety of the message value is substituted into a placeholder in the message body. The message is treated as a string via the StringConverter.
Fields from the AVRO message are substituted into the message body in the following example:
Starting from version 8.1 as pilot release we give our customers ability to use functionality called Reporter which (if enabled) writes Success and Error processing reports to specified Kafka topic. Reports don't have key and you can find details about status in the message headers and value.
In order to enable this functionality we have to enable one (or both if we want full reporting) of the properties below:
Then we need to specify other connectivity properties just as we would when configuring Kafka Producer. Full configuration options can be found on Success Reporter Properties and Error Reporter Properties. Below you will be able to find two examples: one with local/plain configuration, other using SASL connection parameter.
This is most common scenario for on-premises Kafka Clusters used just for monitoring
This is more robust scenario when Connecting to external Kafka Cluster
This sink connector supports the following options as part of its configuration:
| Field | Usage Example |
|---|---|
| Field | Default |
|---|---|
| Field | Type | Required | Values (Default) |
|---|---|---|---|
Header
{{header.correlation-id}}
Value
{{value}}
{{value.product.id}}
Key
{{key}}
{{key.customer.number}}
Topic
{{topic}}
Partition
{{partition}}
Offset
{{offset}}
Timestamp
{{timestamp}}
batchCount
50_000 records
batchSize
500000000 (500MB)
timeInterval
3_600 seconds (1 hour)
connect.http.method
HttpMethod
Yes
POST, PUT, PATCH
connect.http.endpoint
String
Yes
connect.http.request.content
String
Yes
connect.http.authentication.type
Authentication
No
Authentication Options (none)
connect.http.request.headers
List[String]
No
connect.http.batch.count
Int
No
The number of records to batch before sending the request, see Batch Configuration
connect.http.batch.size
Int
No
The size of the batch in bytes before sending the request, see Batch Configuration
connect.http.time.interval
Int
No
The time interval in milliseconds to wait before sending the request
connect.http.upload.sync.period
Int
No
Upload Sync Period (100) - polling time period for uploads in milliseconds
connect.http.error.threshold
Int
No
The number of errors to tolerate before failing the sink (5)
connect.http.retries.on.status.codes
List[String]
No
The status codes to retry on (408,429,500,502,5003,504)
connect.http.retries.max.retries
Int
No
The maximum number of retries to attempt (5)
connect.http.retries.max.timeout.ms
Int
No
The maximum time in milliseconds to retry a request. Backoff is used to increase the time between retries, up to this maximum (30000)
connect.http.connection.timeout.ms
Int
No
The HTTP connection timeout in milliseconds (10000)
int
No
For each processed topic, the connector maintains an internal queue. This value specifies the maximum number of entries allowed in the queue before the enqueue operation blocks. The default is 100,000.
int
No
The maximum time window, specified in milliseconds, to wait for the internal queue to accept new records. The default is 2 minutes
Property Name
Description
ssl.truststore.location
Path to the truststore file containing the trusted CA certificates for verifying broker certificates.
ssl.truststore.password
Password for the truststore file to protect its integrity.
ssl.truststore.type
Type of the truststore (e.g., JKS, PKCS12). Default is JKS.
ssl.keystore.location
Path to the keystore file containing the client’s private key and certificate chain for client authentication.
ssl.keystore.password
Password for the keystore to protect the private key.
ssl.keystore.type
Type of the keystore (e.g., JKS, PKCS12). Default is JKS.
ssl.protocol
The SSL protocol used for secure connections (e.g., TLSv1.2, TLSv1.3). Default is TLSv1.3.
ssl.keymanager.algorithm
Algorithm used by the KeyManager to manage certificates. Default value is the key manager factory algorithm configured for the Java Virtual Machine.
ssl.trustmanager.algorithm
Algorithm used by the TrustManager to manage certificates. Default value is the key manager factory algorithm configured for the Java Virtual Machine.
Property Name
Description
connect.reporting.error.config.enabled
Specifies whether the reporter is enabled. false by default.
connect.reporting.error.config.bootstrap.servers
A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. Required if reporter is enabled.
connect.reporting.error.config.topic
Specifies the topic for Reporter to write to.
connect.reporting.error.config.location
SASL Mechanism used when connecting.
connect.reporting.error.config.sasl.jaas.config
JAAS login context parameters for SASL connections in the format used by JAAS configuration files.
connect.reporting.error.config.sasl.mechanism
SASL mechanism used for client connections. This may be any mechanism for which a security provider is available.
Property Name
Description
connect.reporting.success.config.enabled
Specifies whether the reporter is enabled. false by default.
connect.reporting.success.config.bootstrap.servers
A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. Required if reporter is enabled.
connect.reporting.success.config.topic
Specifies the topic for Reporter to write to.
connect.reporting.success.config.location
SASL Mechanism used when connecting.
connect.reporting.success.config.sasl.jaas.config
JAAS login context parameters for SASL connections in the format used by JAAS configuration files.
connect.reporting.success.config.sasl.mechanism
SASL mechanism used for client connections. This may be any mechanism for which a security provider is available.