decoder_utf8: do not read escaped newline (#615)

[meggarr]

In the UTF-8 decoder, it tries to read escaped char for general
purpose. Escaping a new-line is valid in JSON encoding, if it
lines a UTF-8 decoder and then a JSON decoder, the JSON decoder
will fail, as the escaped new-line is treated as a real newline
in the first UTF-8 decoder.

This fixes the issue in #615

Signed-off-by: Richard Meng mengangr@foxmail.com

[meggarr]

After the change, my config for K8s is like below,

  fluent-bit.conf: |
    [SERVICE]
        Flush         1
        Log_Level     info
        Daemon        off
        Parsers_File  parsers.conf
        HTTP_Server   On
        HTTP_Listen   0.0.0.0
        HTTP_Port     2020

    @INCLUDE input-kubernetes.conf
    @INCLUDE filter-kubernetes.conf
    @INCLUDE filter-fields.conf
    @INCLUDE output-elasticsearch.conf

  input-kubernetes.conf: |
    [FILTER]
        Name         modify
        Match        kube.*
        Rename       log log0

    [FILTER]
        Name         parser
        Match        kube.*
        Key_Name     log0
        Parser       escape_utf8_log
        Reserve_Data True

    [INPUT]
        Name              tail
        Tag               kube.*
        Path              /var/log/containers/*.log
        Parser            docker
        DB                /var/log/flb_kube.db
        Buffer_Chunk_Size 64KB
        Buffer_Max_Size   512KB
        Mem_Buf_Limit     16MB
        Skip_Long_Lines   On
        Refresh_Interval  10

  filter-kubernetes.conf: |
    [FILTER]
        Name                kubernetes
        Match               kube.*
        Kube_URL            https://kubernetes.kubernetes.rancher.internal:6443
        Annotations         Off
        Merge_Log           On
        K8S-Logging.Parser  On

  filter-fields.conf: |
    [FILTER]
        Name         record_modifier
        Match        kube.*
        Remove_key   time

    [FILTER]
        Name         modify
        Match        kube.*
        Rename       message message0

    [FILTER]
        Name         parser
        Match        kube.*
        Key_Name     message0
        Parser       escape_message
        Reserve_Data True

  output-elasticsearch.conf: |
    [OUTPUT]
        Name            es
        Match           *
        Host            ${ELASTICSEARCH_HOST}
        Port            ${ELASTICSEARCH_PORT}
        Logstash_Format On
        Logstash_Prefix cloud
        Retry_Limit     False


  parsers.conf: |
    [PARSER]
        Name   escape_message
        Format regex
        Regex  ^(?<message>.*)$
        # Command      | Decoder | Field | Optional Action
        # =============|=================|=================
        Decode_Field_As  escaped   message

    [PARSER]
        Name   json
        Format json
        Time_Key time
        Time_Format %d/%b/%Y:%H:%M:%S %z

    [PARSER]
        Name   escape_utf8_log
        Format regex
        Regex  ^(?<log>.*)$
        # Command      | Decoder     | Field | Optional Action
        # =============|=====================|=================
        Decode_Field_As  escaped_utf8  log

    [PARSER]
        Name        docker
        Format      json
        Time_Key    time
        Time_Format %Y-%m-%dT%H:%M:%S.%L
        Time_Keep   Off

It will handle the case blow,

{"log":"{\"timeMillis\":1532502611649,\"message\":\"Response \u003eGET /abc/xyz, 69ms, \u003e200 OK, \u003e{\\n  \\\"_id\\\" : \\\"50-CCBE59-261712046121\\\",\\n  \\\"manufacturer\\\" : \\\"BigBang\\\",\\n}\\n\",\"threadId\":64,\"threadPriority\":5}\r\n","stream":"stdout","time":"2018-07-25T07:10:11.650537766Z"}

[nikolay]

@edsiper Can you please merge this?

[edsiper]

thanks. Merged into 0.13 branch (I will port the change to 0.14)