Syslog

The Syslog destination writes syslog messages to a Syslog server.

For example, you might have network devices that write log messages to flat files. You need to send these flat files to a centralized Syslog server, but the messages first must be converted to syslog messages. You design a pipeline that reads the flat files, performs some processing on the data, and then uses a Syslog destination that formats the data into syslog messages and writes the messages to the Syslog server.

When you configure the Syslog destination, you define the host name and port number of the Syslog server. You also define whether to use the UDP or TCP protocol to send messages to the server. If using the TCP protocol, you can optionally enable SSL or TLS for the destination.

You construct the syslog message content by specifying expressions that evaluate to the message values - such as the timestamp, facility code, severity level, message ID, and the log message itself.

You'll typically want to write the log message using the text data format. However, if needed, you can configure the Syslog destination to use a different data format for the log message.

Protocol

You configure the Syslog destination to use one of the following protocols to send messages to the Syslog server:

UDP protocol

When the destination uses the UDP protocol, you select the syslog message format that the destination uses. Choose one of the following formats:

TCP protocol

When the destination uses the TCP protocol, the destination uses the RFC 6587 message format.

When using the TCP protocol, you can also enable SSL/TLS for the destination.

Using SSL/TLS

You can configure the Syslog destination to use SSL, TLS, and mutual TLS encryption. By default, the destination does not use SSL or TLS.

SSL: To use SSL encryption, the Syslog destination requires configuring Java configuration options in the deployment in addition to configuring the destination to use SSL. For more information, see Enabling SSL.

TLS: You can configure the destination to use TLS by selecting the Enable TLS property. SSL must be enabled before you can enable TLS.

Mutual TLS: You can configure the destination to use mutual TLS encryption by selecting the Enable Mutual TLS property. SSL and TLS must be enabled before you can enable mutual TLS.

Enabling SSL

If you configure the Syslog destination to use the TCP protocol, you can enable the destination to use SSL to connect to the Syslog server.

In the Syslog Connection tab, select the Enable SSL property.
If the Syslog server certificate is signed by a private CA or not trusted by the default Java truststore, create a custom truststore file or modify a copy of the default Java truststore file to add the CA to the file. Then configure Data Collector to use the modified truststore file.

By default, Data Collector uses the Java truststore file located in $JAVA_HOME/jre/lib/security/cacerts. If your certificate is signed by a CA that is included in the default Java truststore file, you do not need to create a truststore file and can skip this step.

In these steps, we show how to modify the default truststore file to add an additional CA to the list of trusted CAs. If you prefer to create a custom truststore file, see the keytool documentation.
1. Use the following command to set the JAVA_HOME environment variable:
```
export JAVA_HOME=<Java home directory>
```
2. Use the following command to set the SDC_CONF environment variable:
```
export SDC_CONF=<Data Collector configuration directory>
```
  For example:
```
export SDC_CONF=/streamsets-datacollector-4.1.0/etc
```
3. Use the following command to copy the default Java truststore file to the Data Collector configuration directory:
```
cp "${JAVA_HOME}/jre/lib/security/cacerts" "${SDC_CONF}/truststore.jks"
```
4. Use the following keytool command to import the CA certificate into the truststore file:
```
keytool -import -file <Syslog certificate> -trustcacerts -noprompt -alias <Syslog alias> -storepass <password> -keystore "${SDC_CONF}/truststore.jks"
```
  For example:
```
keytool -import -file  mySyslogServer.pem -trustcacerts -noprompt -alias MySyslogServer -storepass changeit -keystore "${SDC_CONF}/truststore.jks"
```
5. In Control Hub, edit the deployment. In the Configure Engine section, click Advanced Configuration. Then, click Java Configuration. Define the following options in the Java Options property:
  - javax.net.ssl.trustStore - Path to the truststore file on the Data Collector machine.
  - javax.net.ssl.trustStorePassword - Truststore password.
  For example, define the options as follows:
```
-Djavax.net.ssl.trustStore=/streamsets-datacollector-4.1.0/etc/truststore.jks -Djavax.net.ssl.trustStorePassword=mypassword
```
6. Save the changes to the deployment and restart all engine instances.

Message Content

A syslog message includes fields such as a timestamp, facility code, severity level, message ID, and the log message itself. You construct the syslog message content by specifying the values for message fields on the Message tab. The content of the log message depends on how you configure the Data Format tab.

Use the Message tab to construct the syslog message properties by entering values or expressions for the message properties. In most cases, you'll want to define expressions to call fields in the record that contain the message values.

For example, the following image shows the timestamp and host name message properties defined with expressions and the severity level and syslog facility set to the default values of 6 and 1:

The content of the log message itself depends on the data format selected on the Data Format tab. For the Text data format, the destination writes data from a single text field in the record to the log message field. For the Binary data format, the destination writes data from a single field in the record to the log message field. For the remaining data formats, the destination writes data from all fields in the record to the log message field.

Data Formats

The Syslog destination writes data to the log message based on the data format that you select.

The destination can use the following data formats:

Avro

The stage writes records based on the Avro schema. You can use one of the following methods to specify the location of the Avro schema definition:

In Pipeline Configuration - Use the schema that you provide in the stage configuration.
In Record Header - Use the schema included in the avroSchema record header attribute.
Confluent Schema Registry - Retrieve the schema from Confluent Schema Registry. The Confluent Schema Registry is a distributed storage layer for Avro schemas. You can configure the destination to look up the schema in the Confluent Schema Registry by the schema ID or subject.
If using the Avro schema in the stage or in the record header attribute, you can optionally configure the stage to register the Avro schema with the Confluent Schema Registry. You can also optionally include the schema definition in the message. Omitting the schema definition can improve performance, but requires the appropriate schema management to avoid losing track of the schema associated with the data.

You can include the Avro schema in the output.

You can also compress data with an Avro-supported compression codec. When using Avro compression, avoid configuring any other compression properties in the stage.

Binary

The stage writes binary data to a single field in the record.

Delimited

The destination writes records as delimited data. When you use this data format, the root field must be list or list-map.

You can use the following delimited format types:

Default CSV - File that includes comma-separated values. Ignores empty lines in the file.
RFC4180 CSV - Comma-separated file that strictly follows RFC4180 guidelines.
MS Excel CSV - Microsoft Excel comma-separated file.
MySQL CSV - MySQL comma-separated file.
Tab-Separated Values - File that includes tab-separated values.
PostgreSQL CSV - PostgreSQL comma-separated file.
PostgreSQL Text - PostgreSQL text file.
Custom - File that uses user-defined delimiter, escape, and quote characters.
Multi Character Delimited - File that uses multiple user-defined characters to delimit fields and lines, and single user-defined escape and quote characters.

JSON

The destination writes records as JSON data. You can use one of the following formats:

Array - Each file includes a single array. In the array, each element is a JSON representation of each record.
Multiple objects - Each file includes multiple JSON objects. Each object is a JSON representation of a record.

Protobuf

Writes one record in a message. Uses the user-defined message type and the definition of the message type in the descriptor file to generate the message.

For information about generating the descriptor file, see Protobuf Data Format Prerequisites.

SDC Record

The destination writes records in the SDC Record data format.

Text

The destination writes data from a single text field to the destination system. When you configure the stage, you select the field to use.

You can configure the characters to use as record separators. By default, the destination uses a UNIX-style line ending (\n) to separate records.

When a record does not contain the selected text field, the destination can report the missing field as an error or to ignore the missing field. By default, the destination reports an error.

When configured to ignore a missing text field, the destination can discard the record or write the record separator characters to create an empty line for the record. By default, the destination discards the record.

XML

The destination creates a valid XML document for each record. The destination requires the record to have a single root field that contains the rest of the record data. For details and suggestions for how to accomplish this, see Record Structure Requirement.

The destination can include indentation to produce human-readable documents. It can also validate that the generated XML conforms to the specified schema definition. Records with invalid schemas are handled based on the error handling configured for the destination.

Configuring a Syslog Destination

Configure a Syslog destination to write syslog messages to a Syslog server.

In the Properties panel, on the General tab, configure the following properties:


General Property	Description
Name	Stage name.
Description	Optional description.
Required Fields	Fields that must include data for the record to be passed into the stage. Tip: You might include fields that the stage uses. Records that do not include all required fields are processed based on the error handling configured for the pipeline.
Preconditions	Conditions that must evaluate to TRUE to allow a record to enter the stage for processing. Click Add to create additional preconditions. Records that do not meet all preconditions are processed based on the error handling configured for the stage.
On Record Error	Error record handling for the stage: Discard - Discards the record. Send to Error - Sends the record to the pipeline for error handling. Stop Pipeline - Stops the pipeline.

On the Syslog Connection tab, configure the following properties:


Syslog Connection Property	Description
Protocol	Protocol to send messages to the Syslog server: UDP TCP
Syslog Host	Syslog server host name.
Syslog Port	Syslog server port number.
Message Format	For the UDP protocol, syslog message format to use: RFC 5424 RFC 3164 If using the TCP protocol, the destination uses the RFC 6587 message format.
Enable SSL	For the TCP protocol, enables SSL between Data Collector and the Syslog server. If the Syslog server certificate is signed by a private CA or not trusted by the default Java truststore, you also must define the truststore file and password in Java configuration options in the deployment, as described in Enabling SSL.
Enable TLS	For the TCP protocol, enables TLS between Data Collector and the Syslog server. Available if Enable SSL is active.
Enable Mutual TLS	For the TCP protocol, enables mutual TLS between Data Collector and the Syslog server. Available if Enable TLS is active.
TrustStore Path	If SSL is enabled, path to the TrustStore file. Enter an absolute path to the file or a path relative to the Data Collector resources directory: `$SDC_RESOURCES`.
TrustStore Password	Password to access the TrustStore file.
KeyStore Path	If mutual TLS is enabled, path to the KeyStore file. Enter an absolute path to the file or a path relative to the Data Collector resources directory: `$SDC_RESOURCES`.
KeyStore Password	Password to access the KeyStore file.
Socket Connection Timeout (ms)	For the TCP protocol, maximum time in milliseconds to wait for a socket connection.
TCP Connection Retries	For the TCP protocol, maximum number of times to retry a TCP connection.

On the Message tab, configure the following properties:


Message Property	Description
Timestamp	Timestamp for the syslog message. Default is the processing time, defined with the expression `${time:now()}`. To use a time associated with the record, use an expression that calls a field and resolves to a datetime value, such as `${record:value("/Timestamp")}`.
Hostname	Host name to use for the syslog message. Enter the host name or enter an expression that evaluates to the host name.
Severity Level	Numerical code from 0 through 7 representing the severity level for the syslog message. For a list of codes, see https://tools.ietf.org/html/rfc5424#section-6.2.1. Enter the numerical code or enter an expression that evaluates to the code.
Syslog Facility	Numerical code from 0 through 23 representing the facility for the syslog message. For a list of codes, see https://tools.ietf.org/html/rfc5424#section-6.2.1. Enter the numerical code or enter an expression that evaluates to the code.
Application Name	Application name to use for the syslog message. Enter the application name or enter an expression that evaluates to the name.
Message ID	Message ID to use for the syslog message. Enter the message ID or enter an expression that evaluates to the ID.
Process ID	Process ID to use for the syslog message. Enter the process ID or enter an expression that evaluates to the ID.

On the Data Format tab, configure the following property:


Data Format Property	Description
Data Format	Format of data to be written. Use one of the following options: Avro Binary Delimited JSON Protobuf SDC Record Text XML

For Avro data, on the Data Format tab, configure the following properties:


Avro Property	Description
Avro Schema Location	Location of the Avro schema definition to use when writing data: In Pipeline Configuration - Use the schema that you provide in the stage configuration. In Record Header - Use the schema in the avroSchema record header attribute. Use only when the avroSchema attribute is defined for all records. Confluent Schema Registry - Retrieve the schema from Confluent Schema Registry.
Avro Schema	Avro schema definition used to write the data. You can optionally use the `runtime:loadResource` function to load a schema definition stored in a runtime resource file.
Register Schema	Registers a new Avro schema with Confluent Schema Registry.
Schema Registry URLs	Confluent Schema Registry URLs used to look up the schema or to register a new schema. To add a URL, click Add and then enter the URL in the following format: `http://<host name>:<port number>`
Basic Auth User Info	User information needed to connect to Confluent Schema Registry when using basic authentication. Enter the key and secret from the `schema.registry.basic.auth.user.info` setting in Schema Registry using the following format: `<key>:<secret>` Tip: To secure sensitive information such as user names and passwords, you can use runtime resources or credential stores.
Look Up Schema By	Method used to look up the schema in Confluent Schema Registry: Subject - Look up the specified Avro schema subject. Schema ID - Look up the specified Avro schema ID.
Schema Subject	Avro schema subject to look up or to register in Confluent Schema Registry. If the specified subject to look up has multiple schema versions, the stage uses the latest schema version for that subject. To use an older version, find the corresponding schema ID, and then set the Look Up Schema By property to Schema ID.
Schema ID	Avro schema ID to look up in Confluent Schema Registry.
Include Schema	Includes the schema in each message. Note: Omitting the schema definition can improve performance, but requires the appropriate schema management to avoid losing track of the schema associated with the data.
Avro Compression Codec	The Avro compression type to use. When using Avro compression, do not enable other compression available in the destination.

For binary data, on the Data Format tab, configure the following property:


Binary Property	Description
Binary Field Path	Field that contains the binary data.

For delimited data, on the Data Format tab, configure the following properties:


Delimited Property	Description
Delimiter Format	Format for delimited data: Default CSV - File that includes comma-separated values. Ignores empty lines in the file. RFC4180 CSV - Comma-separated file that strictly follows RFC4180 guidelines. MS Excel CSV - Microsoft Excel comma-separated file. MySQL CSV - MySQL comma-separated file. Tab-Separated Values - File that includes tab-separated values. PostgreSQL CSV - PostgreSQL comma-separated file. PostgreSQL Text - PostgreSQL text file. Custom - File that uses user-defined delimiter, escape, and quote characters.
Header Line	Indicates whether to create a header line.
Delimiter Character	Delimiter character for a custom delimiter format. Select one of the available options or use Other to enter a custom character. You can enter a Unicode control character using the format \uNNNN, where N is a hexadecimal digit from the numbers 0-9 or the letters A-F. For example, enter \u0000 to use the null character as the delimiter or \u2028 to use a line separator as the delimiter. Default is the pipe character ( \| ).
Record Separator String	Characters to use to separate records. Use any valid Java string literal. For example, when writing to Windows, you might use `\r\n` to separate records. Available when using a custom delimiter format.
Escape Character	Escape character for a custom delimiter format. Select one of the available options or use Other to enter a custom character. Default is the backslash character ( \ ).
Quote Character	Quote character for a custom delimiter format. Select one of the available options or use Other to enter a custom character. Default is the quotation mark character ( " ).
Replace New Line Characters	Replaces new line characters with the configured string. Recommended when writing data as a single line of text.
New Line Character Replacement	String to replace each new line character. For example, enter a space to replace each new line character with a space. Leave empty to remove the new line characters.
Charset	Character set to use when writing data.

For JSON data, on the Data Format tab, configure the following properties:


JSON Property	Description
JSON Content	Method to write JSON data: JSON Array of Objects - Each file includes a single array. In the array, each element is a JSON representation of each record. Multiple JSON Objects - Each file includes multiple JSON objects. Each object is a JSON representation of a record.
Charset	Character set to use when writing data.

For protobuf data, on the Data Format tab, configure the following properties:


Protobuf Property	Description
Protobuf Descriptor File	Descriptor file (.desc) to use. The descriptor file must be in the Data Collector resources directory, `$SDC_RESOURCES`. For more information about environment variables, see Java and Security Configuration. For information about generating the descriptor file, see Protobuf Data Format Prerequisites.
Message Type	Fully-qualified name for the message type to use when writing data. Use the following format: `<package name>.<message type>`. Use a message type defined in the descriptor file.

For text data, on the Data Format tab, configure the following properties:


Text Property	Description
Text Field Path	Field that contains the text data to be written. All data must be incorporated into the specified field.
Record Separator	Characters to use to separate records. Use any valid Java string literal. For example, when writing to Windows, you might use `\r\n` to separate records. By default, the destination uses `\n`.
On Missing Field	When a record does not include the text field, determines whether the destination reports the missing field as an error or ignores the missing field.
Insert Record Separator if No Text	When configured to ignore a missing text field, inserts the configured record separator string to create an empty line. When not selected, discards records without the text field.
Charset	Character set to use when writing data.

For XML data, on the Data Format tab, configure the following properties:


XML Property	Description
Pretty Format	Adds indentation to make the resulting XML document easier to read. Increases the record size accordingly.
Validate Schema	Validates that the generated XML conforms to the specified schema definition. Records with invalid schemas are handled based on the error handling configured for the destination. Important: Regardless of whether you validate the XML schema, the destination requires the record in a specific format. For more information, see Record Structure Requirement.
XML Schema	The XML schema to use to validate records.