Pfthb

I have implemented the following plugin to create custom Json layout for log4j logs. I am not sure how I can implement the context lookup in the Plugin. For example, the application puts certain keys in MDC and with the below configuration in log4j.xml, it must be written in logs.

<KeyValuePair key="customerId" value="$$customerId" />. 

Plugin

@Plugin(name = "CustomJsonLayout", category = "Core", elementType = "layout", printObject = true)
public class CustomJsonLayout extends AbstractStringLayout 
private final ObjectMapper objectMapper;

CustomJsonLayout(Charset charset) 
 super(charset);
 SimpleModule module = new SimpleModule();
 module.addSerializer(LogEvent.class, new LogEventSerializer());
 module.addSerializer(ReadOnlyStringMap.class, new ContextDataSerializer() 
 );
 objectMapper = new ObjectMapper();
 objectMapper.registerModule(module);
 objectMapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);


@Override
public String toSerializable(LogEvent logEvent) 
 try 
 return objectMapper.writeValueAsString(logEvent);
 catch (JsonProcessingException e) 
 throw new IllegalStateException(e);
 


private static class LogEventSerializer extends StdSerializer<LogEvent> 
 LogEventSerializer() 
 super(LogEvent.class);
 

 @Override
 public void serialize(LogEvent value, JsonGenerator gen, SerializerProvider provider) throws IOException 
 String pattern = "yyyy-MM-dd HH:mm:ss.SSS";
 SimpleDateFormat simpleDateFormat = new SimpleDateFormat(pattern);
 String date = simpleDateFormat.format(new Date(value.getTimeMillis()));

 gen.writeStartObject();
 gen.writeStringField("timestamp", date);
 gen.writeStringField("component", MicroService.getAppName());
 gen.writeStringField("severity", value.getLevel().name());
 gen.writeObjectField("msg", value.getMessage().getFormattedMessage());
 gen.writeEndObject();
 gen.writeRaw("n");
 


@PluginBuilderFactory
public static <B extends Builder<B>> B newBuilder() 
 return new Builder<B>().asBuilder();


public static class Builder<B extends Builder<B>> extends org.apache.logging.log4j.core.layout.AbstractStringLayout.Builder<B> implements org.apache.logging.log4j.core.util.Builder<CustomJsonLayout> 
 Builder() 
 this.setCharset(StandardCharsets.UTF_8);
 

 public CustomJsonLayout build() 
 return new CustomJsonLayout(this.getCharset());