log4j2-hedera

Provides Log4j 2.x support for Hedera™ via an Appender that records logged events using the Hedera™ Consensus Service (HCS).

Install

Gradle

implementation 'com.hedera.hashgraph:log4j2:0.1.0'

Maven

<dependency>
    <groupId>com.hedera.hashgraph</groupId>
    <artifactId>log4j2</artifactId>
    <version>0.1.0</version>
</dependency>

Usage

• Create the directory src/main/resources in your project

• Add the file log4j2.xml to the resources directory you just made in your project. An example configuration file is in this repo.

• Add HederaAppender under Appenders in the log4j2.xml like this:

...
<Appenders>
    ...
    <HederaAppender name="HederaAppender" operator_id="0.0.555555" topic_id="0.0.555556" 
        operator_key="Ed25519PrivateKeyHere" network_name="testnet_or_mainnet" />
</Appenders>
<Loggers>
    <Root level="error">
        <AppenderRef ref="HederaAppender"/>
    </Root>
</Loggers>
...

• Import the log4j packages LogManager and Logger like this:

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

• Instantiate the logger like this:

final static Logger logger = LogManager.getLogger(App.class);

• Log things like this:

logger.debug("This is a debug log: " + message);
logger.info("This is an info log : " + message);
logger.warn("This is a warning log : " + message);
logger.error("This is an error log : " + message);
logger.fatal("This is a fatal log : " + message);

Configuration

All configuration for the Appender is done in log4j2.xml.

To log things under the level of error, make sure to change the line <Root level="error"> to <Root level="debug">,
<Root level="info">, or <Root level="warn">.

Make sure you remember to change the values for each of the <HederaAppender> attributes in your project! The ones provided in the example won't work as is!

Attributes

Note: All attribute values should be Strings.

Required:

name
The name of the appender

topicId
The ID of your topic in the form of shard.realm.num

operatorId
Your Hedera Account ID in the form of shard.realm.num

operatorKey
Your Hedera Account Ed25519 Private Key

networkName
The name of the network you wish to log to, either testnet or mainnet

Optional:

submitKey
If your HCS topic was created with a submit key, you must provide an Ed25519 Private Key
(your submit key) to sign each message with

Contributing to this Project

We welcome participation from all developers! For instructions on how to contribute to this repo, please review the Contributing Guide.

License

Licensed under Apache License, Version 2.0 – see LICENSE in this repo or apache.org/licenses/LICENSE-2.0