FluentD continuous_line_regexp parser is not working for given Regex

*same regex is not working for me in continuous_line_regexp *

I want to contact all multiline only starting.
In short : The most recent multiline will be read from the beginning of the file unitl it gets a next line as JSON.JSON always starts with {" togather. when we see lines begings with {" we will stop reading.Note next line may or may not be a json line.Its optional

I designed the regex to match the all multiline exception for fluentd parser in rubular format as below

(?<Exception_type>\A(?:SLF4J:|\w{3} \d{2}, \d{4} \d{1,2}:\d{2}:\d{2} \w{2}|Exception in thread|\w+(?:\.\w+)+).*(?:\R(?!(?:ANY:|\w+(?:\.\w+)+)|{).*)*$)

It matches nessary fields. but not working in fluentd plugin

Demo link
Your regex is available at: Rubular: (?<Exception_type>\A(?:SLF4J:|\w{3} \d{2}, \d{4} \d{1,2}:\d{2}:\d{2} \w{2}|Exception in thread|\w+(?:\.\w+)+).*(?:\R(?!(?:ANY:|\w+(?:\.\w+)+)|{).*)*$)

fluentd configuration

      <filter **>
        @type concat
        key log
        stream_identity_key pod_id
        multiline_start_regexp /^[a-zA-z_]*\.*\..*Exception|^[a-zA-z_]*\.*\..*|^\w{3} \d{2}, \d{4} \d{1,2}:\d{2}:\d{2} \w{2}|^SLF4J: Class path contains|^Exception in thread/
        continuous_line_regexp /(^(?:^\w{3} \d{2}, \d{4}|^Exception in thread|[a-zA-z_]*\.*\..*Exception).*(?:\R(?!(?:SLF4J:|\w+(?:\.\w+)+)|{).*)*)/
        separator ""
        flush_interval 3s
        # timeout_label @NORMAL
      </filter>

Input:

java.lang.InterruptedException: Timeout while waiting for epoch from quorum
        at org.apache.zookeeper.server.quorum.Leader.getEpochToPropose(Leader.java:1227)
        at org.apache.zookeeper.server.quorum.Leader.lead(Leader.java:482)
        at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:1284)
        ... 19 more
{"log_timestamp": "2021-02-18T11:33:23.114+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "QuorumPeer[myid=2](plain=/0.0.0.0:2181)(secure=disabled)", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "PeerState set to LOOKING"}
{"log_timestamp": "2021-02-18T11:33:23.115+0000", "log_level": "WARN", "process_id": "zookeeper#2", "process_name": "zookeeper", "thread_id": 1, "thread_name": "WorkerSender[myid=2]", "action_name": "org.apache.zookeeper.server.quorum.QuorumPeer", "log_message": "Failed to resolve address: zk-2.zk-headless.intam.svc.cluster.local"}
java.net.UnknownHostException: zk-2.zk-headless.intam.svc.cluster.local
        at java.net.InetAddress.getAllByName0(InetAddress.java:1281)
        at java.net.InetAddress.getAllByName(InetAddress.java:1193)
        at java.net.InetAddress.getAllByName(InetAddress.java:1127)
        at java.net.InetAddress.getByName(InetAddress.java:1077)
        at org.apache.zookeeper.server.quorum.QuorumPeer$QuorumServer.recreateSocketAddresses(QuorumPeer.java:194)
        at org.apache.zookeeper.server.quorum.QuorumPeer.recreateSocketAddresses(QuorumPeer.java:764)
        at org.apache.zookeeper.server.quorum.QuorumCnxManager.connectOne(QuorumCnxManager.java:699)
        at org.apache.zookeeper.server.quorum.QuorumCnxManager.toSend(QuorumCnxManager.java:618)
        at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.process(FastLeaderElection.java:477)
        at org.apache.zookeeper.server.quorum.FastLeaderElection$Messenger$WorkerSender.run(FastLeaderElection.java:456)
        at java.lang.Thread.run(Thread.java:748)

output expected

java.lang.InterruptedException: Timeout while waiting for epoch from quorum
        at org.apache.zookeeper.server.quorum.Leader.getEpochToPropose(Leader.java:1227)
        at org.apache.zookeeper.server.quorum.Leader.lead(Leader.java:482)
        at org.apache.zookeeper.server.quorum.QuorumPeer.run(QuorumPeer.java:1284)
        ... 19 more

It seems that continuous_line_regexp matches also start line, and multiline_end_regexp is missing.

ref. GitHub - fluent-plugins-nursery/fluent-plugin-concat: Fluentd Filter plugin to concatenate multiline log separated in multiple events.