HTTP Source connector

The HTTP Source connector is a Stateless NiFi dataflow developed by Cloudera that is running in the Kafka Connect framework. Learn about the connector, its properties, and configuration.

The HTTP Source connector listens on a port for HTTP POST requests and transfers the request body to a Kafka topic. The Kafka topic this connector transfers messages to is determined by the value of the topics property. The connector does not perform record processing, the messages are transferred to Kafka as they are received in the HTTP request. The connector uses HTTPS for secure communication. Optionally, client certificate authentication (mutual TLS) can also be configured.

Properties and configuration

Configuration is passed to the connector in a JSON file during creation. The properties of the connector can be categorized into three groups. These are as follows:

Common connector properties

These are the properties of the Kafka Connect framework that are accepted by all connectors. For a comprehensive list of these properties, see the Apache Kafka documentation.

Stateless NiFi Source properties

These are the properties that are specific to the Stateless NiFi Source connector. All Stateless NiFi Source connectors share and accept these properties. For a comprehensive list of these properties, see the Stateless NiFi Source property reference.

Connector/dataflow-specific properties

These properties are unique to this specific connector. Or to be more precise, unique to the dataflow running within the connector. These properties use the following prefix:

parameter.[***CONNECTOR NAME***] Parameters:

For a comprehensive list of these properties, see the HTTP Source properties referenceHTTP Source properties reference.

Notes and limitations

Required properties must be assigned a valid value even if they are not used in the particular configuration. If a required property is not used, either leave its default value, or completely remove the property from the configuration JSON.
If a property that has a default value is completely removed from the configuration JSON, the system uses the default value.
Properties not marked as required must be completely removed from the configuration JSON if not set.
The HTTP Source connector must use at least one-way SSL, it cannot be used without SSL.
The ListenHTTP processor in the NiFi flow keeps running when the connector is paused. Due to this, the connector accepts requests, but ultimately times out and sends an error response to the client.
The tasks.max property must be 1 to avoid port conflict due to executing multiple tasks on the same Kafka Connect node. Cloudera recommends that you use a load balancer to keep track of the actual node which runs the connector.

Configuration example

In this example, the connector accepts client requests sent to the connector’s URL. The connector's URL is based on the configuration of multiple properties. For example assume the following:

The connector is running on kc-host-1.
Listening Port is set to port 8080.
Base Path is set to data-ingest.

In a case like this, the connector's URL will be the following:

https://kc-host-1:8080/data-ingest

{
 "connector.class": "org.apache.nifi.kafka.connect.StatelessNiFiSourceConnector",
 "meta.smm.predefined.flow.name": "HTTP Source",
 "meta.smm.predefined.flow.version": "1.0.0",
 "key.converter": "org.apache.kafka.connect.storage.StringConverter",
 "value.converter": "org.apache.kafka.connect.converters.ByteArrayConverter",
 "tasks.max": "1",
 "nexus.url": "https://repository.cloudera.com/artifactory/repo",
 "extensions.directory": "/tmp/nifi-stateless-extensions",
 "working.directory": "/tmp/nifi-stateless-working",
 "topics": "[***KAFKA TOPIC NAME***]",
 "parameter.HTTP Source Parameters:Listening Port": "[***PORT***]",
 "parameter.HTTP Source Parameters:Base Path": "[***BASE PATH***]",
 "parameter.HTTP Source Parameters:Keystore Filename": "[***PATH TO KEYSTORE***]",
 "parameter.HTTP Source Parameters:Keystore Key Password": "[***KEYSTORE KEY PASSWORD***]",
 "parameter.HTTP Source Parameters:Keystore Password": "[***KEYSTORE PASSWORD***]",
 "parameter.HTTP Source Parameters:Keystore Type": "[***KEYSTORE TYPE***]"
}

The following list collects the properties from the configuration example that must be customized for this use case.

topics: The name of the Kafka topic that the connector sends messages to.
Listening Port: The port that the client needs to use in the URL.
Base Path: The path that the client needs to use in the URL.
Keystore *: The properties for accessing the keystore used for HTTPS.

Stateless NiFi Source properties reference

Review the following reference for a comprehensive list of the connector properties that are specific to the Stateless NiFi Source connector.

In addition to the properties listed here, Stateless NiFi connectors also accept the properties of the Kafka Connect framework. For a comprehensive list of these properties, see the Apache Kafka documentation.

dataflow.timeout

Description: Specifies the maximum amount of time to wait for the dataflow to complete. If the dataflow does not complete before this timeout, the thread is interrupted and the dataflow is considered as a failure. The session is rolled back and the connector retriggers the flow. Defaults to 60 seconds if not specified.
Default Value: 60 seconds
Accepted Values
Required: false

extensions.directory

Description: Specifies the directory that stores downloaded extensions. Extensions are the NAR (NiFi Archive) files containing the processors and controller services a flow might use. Since Stateless NiFi is only the NiFi engine, it does not contain any of the processors and controller services you might use in your flow. When deploying the connector with the custom flow, the system needs to download the specific extensions that your flow uses from Nexus (unless they are already present in this directory). These extensions are stored in this directory. Because the default directory might not be writable, and to aid in upgrade scenarios, Cloudera recommends that you always specify an extensions directory.
Default Value: /tmp/nifi-stateless-extensions
Accepted Values
Required: true

flow.snapshot

Description: Specifies the dataflow to run. When using Streams Messaging Manager to deploy a connector, the value you set in this property must be a JSON object. URLs, file paths, or escaped JSON strings are not supported when using Streams Messaging Manager. Alternatively, if using the Kafka Connect REST API to deploy a connector, this can be a file containing the dataflow, a URL that points to a dataflow, or a string containing the entire dataflow as an escaped JSON. Cloudera however, does not recommend using the Kafka Connect REST API to interact with this connector or Kafka Connect.
Default Value
Accepted Values
Required: true

header.attribute.regex

Description: A Java regular expression that is evaluated against all flowfile attribute names. Any attribute name matching the regular expression is converted into a Kafka message header. The name of the attribute is used as the header key, the value of the attribute is used as the header value. If not specified, headers are not added to the Kafka record.
Default Value
Accepted Values
Required: false

header.name.regex

Description: A Java regular expression that will be evaluated against all flowfile attribute names. For any attribute whose name matches the regular expression, the Kafka record will have a header whose name matches the attribute name and whose value matches the attribute value. If not specified, the Kafka record will have no headers added to it.
Default Value
Accepted Values
Required: false

key.attribute

Description: Specifies the name of a flowfile attribute that should be used to specify the key of the Kafka record. If not specified, the Kafka record will not have a key associated with it. If specified, but the attribute does not exist on a particular flowfile, it will also have no key associated with it.
Default Value
Accepted Values
Required: false

krb5.file

Description: Specifies the krb5.conf file to use if the dataflow interacts with any services that are secured using Kerberos. Defaults to /etc/krb5.conf if not specified.
Default Value: /etc/krb5.conf
Accepted Values
Required: false

name

Description: The name of the connector. On the Streams Messaging Manager UI, the connector names are specified using the Enter Name field. The name that you enter in the Enter Name field is automatically set as the value of the name property when the connector is deployed. Because of this, the name property is omitted from the configuration template provided in Streams Messaging Manager. If you manually add the name property to the configuration in Streams Messaging Manager, ensure that the value you set matches the connector name specified in the Enter Name field. Otherwise, the connector fails to deploy.
Default Value
Accepted Values
Required: True

nexus.url

Description: Specifies the Base URL of the Nexus instance to source extensions from. If configuring a Nexus instance that has multiple repositories, include the name of the repository in the URL. For example, https://nexus-private.myorganization.org/nexus/repository/my-repository/. If the property is not specified, the necessary extensions (the ones used by the flow) must be provided in the extensions directory before deploying the connector.
Default Value
Accepted Values
Required: true

output.port

Description: The name of the output port in the NiFi dataflow to pull data from. If the dataflow contains exactly one port, this property is optional and can be omitted. However, if the dataflow contains multiple ports (for example, a success and a failure port), this property must be specified. If any flowfile is sent to any port other than the specified port, it is considered as a failure. The session is rolled back and no data is collected.
Default Value
Accepted Values
Required: false

parameter.`[FLOW PARAMETER NAME]`

Description: Specifies a parameter to use in the dataflow. For example, assume that you have the following entry in your connector configuration "parameter.Directory": "/mydir". In a case like this, any parameter context in the dataflow that has a parameter named Directory gets the specified value (/mydir). If the dataflow has child process groups, and those child process groups have their own parameter contexts, the value is used for all parameter contexts that contain a parameter named Directory. Parameters can also be applied to specific Parameter Contexts only. This can be done by prefixing the parameter name (Directory) with the name of the parameter context followed by a colon. For example, parameter.My Context:Directory only applies the specified value for the Directory parameter in the parameter context named My Context.
Default Value
Accepted Values
Required: false

topic.name.attribute

Description: Specifies the name of a flowfile attribute to use for determining which Kafka topic a flowfile is sent to. Either the topics or topic.name.attribute property must be specified. If both are specified, topic.name.attribute takes precedence. However, if a flowfile does not have the specified attribute name, then the connector falls back to using the topics property.
Default Value
Accepted Values
Required: false

topics

Description: The name of the topic to deliver data to. All flowfiles are delivered to the topic specified here. However, it is also possible to determine the topic individually for each flowfile. To do this, ensure that the dataflow specifies the topic name in an attribute, and then use topic.name.attribute to specify the name of the attribute instead of topic name. For example, if you wanted a separate Kafka topic for each data source, you can omit the topics property and instead specify the attribute (for example, datasource.hostname) corresponding to the topic using the topic.name.attribute property.
Default Value
Accepted Values
Required: true

working.directory

Description: Specifies a directory on the Connect server that NiFi should use for unpacking extensions that it needs to perform the dataflow. The contents of extensions.directory are unpacked here. Defaults to /tmp/nifi-stateless-working if not specified.
Default Value: /tmp/nifi-stateless-working
Accepted Values
Required: false

HTTP Source properties reference

Review the following reference for a comprehensive list of the connector properties that are specific to the HTTP Source connector.

The properties listed in this reference must be added to the connector configuration with the following prefix:

parameter.[***CONNECTOR NAME***] Parameters:

In addition to the properties listed here, this connector also accepts certain properties of the Kafka Connect framework as well as the properties of the NiFi Stateless Source connector. When creating a new connector using the Streams Messaging Manager UI, all valid properties are presented in the default configuration template. You can view the configuration template to get a full list of valid properties. In addition, for more information regarding the accepted properties not listed here, you can review the Apache Kafka documentation and the Stateless NiFi Source property reference.

Authorized Issuer DN Pattern

Description: A regular expression to apply against the Issuer's Distinguished Name of incoming connections. You can use this property when the Client Authentication property is set to REQUIRED (mutual TLS).
Default Value: .*
Accepted Values
Required: false

Authorized Subject DN Patter

Description: A regular expression to apply against the Subject's Distinguished Name of incoming connections. You can use this property when the Client Authentication property is set to REQUIRED (mutual TLS).
Default Value: .*
Accepted Values
Required: false

Base Path

Description: The base path or context path of the URL.
Default Value: contentListener
Accepted Values
Required: true

Client Authentication

Description: The client authentication policy used for HTTPS.
Default Value: NONE
Accepted Values: NONE, REQUIRED
Required: true

Keystore Filename

Description: The fully-qualified filename of a keystore.
This keystore is used to establish a secure connection between this connector and its clients using HTTPS.
Default Value
Accepted Values
Required: true

Keystore Key Password

Description: The password used to access the key stored in the keystore file configured in the Keystore Filename property.
Default Value
Accepted Values
Required: true

Keystore Password

Description: The password used to access the contents of the keystore configured in the Keystore Filename property.
Default Value
Accepted Values
Required: true

Keystore Type

Description: The type of the keystore configured in the Keystore Filename property.
Default Value
Accepted Values: BCFKS, PKCS12, JKS
Required: true

Listening Port

Description: The port to listen on for communication.
Default Value
Accepted Values
Required: true

Truststore Filename

Description: The fully-qualified filename of a truststore.
When using one-way SSL (Client Authentication is set to NONE), this property must be completely removed from the configuration JSON.
Default Value
Accepted Values
Required: false

Truststore Password

Description: The password used to access the contents of the truststore configured in the Truststore Filename property.
When using one-way SSL (Client Authentication is set to NONE), this property must be completely removed from the configuration JSON.
Default Value
Accepted Values
Required: false

Truststore Type

Description: The type of the truststore configured in the Truststore Filename property.
When using one-way SSL (Client Authentication is set to NONE), this property must be completely removed from the configuration JSON.
Default Value
Accepted Values: BCFKS, PKCS12, JKS
Required: false