ClickHouseAppender

This is a custom Log4j 2 appender that sends LOGGER messages to a clickhouse database in a specified table in JSON format. Table must have 2 columns:

CREATE TABLE log_table (
	timestamp DateTime64 PRIMARY KEY,
	log String
	) Engine = MergeTree()

All messages are stored in the buffer. Log messages will be flushed straight to the ClickHouse DB after one of the conditions:

• timeout;
• buffer size limit exceeded;
• shutdown JVM (SHUTDOWN-THREAD)

For acquiring a connection to the ClickHouse DB used a JavaClient API (ClickHouse Java API).

Configuring example

        <ClickHouseAppender name="ClickHouseAppender" ignoreExceptions="false"
                            bufferSize="8192"
                            flushTimeoutSec="5"
                            tableName="log_table">

            <ConnectionSettings HOST=""
                                PORT=""
                                USERNAME=""
                                PASSWORD=""
                                DATABASE="log_db"
                                SSL="true" --> must be true for a ClickHouse Connection
                                SOCKET_TIMEOUT="300000"
            />