Finding fields within square brackets

Freebird · January 23, 2019, 11:11pm

I'm brand new to this so please bear with me..

I have a log from an application that has inconsistent lines - as in the content of each line is different - so that might be a challenge in itself...but later.
For now I'm using stdin and stout to let me paste text into a command line and have logstash respond with the matches.
An example line of the log is:
2019-01-12 02:59:54.324 Trace [T24ServiceConnector] Sending OFS request [Tx be17fc06-f7c4-414c-b182-e5d41201fdeb]: ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,

So far, my conf file looks like this:
input { stdin { } }
filter
{
grok {
patterns_dir => ["C:\Logstash\patterns"]
match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{WORD:LogLevel}" }
}

  date {
    match => [ "timestamp" , "yyyy-MM-dd HH:mm:ss.SSS" ]
	timezone=> "Australia/Sydney"
    target => "@timestamp" } 
}

output
{
elasticsearch { hosts => ["localhost:9200"] }
stdout { codec => rubydebug }
}

This has mostly been through googling and trial and error. It took a while to get the timstamp bit to work.

The output so far is

{
"@timestamp" => 2019-01-11T15:59:54.324Z,
"@version" => "1",
"timestamp" => "2019-01-12 02:59:54.324",
"LogLevel" => "Trace",
"message" => "2019-01-12 02:59:54.324 Trace [T24ServiceConnector] Sending OFS request [Tx be17fc06-f7c4-414c-b182-e5d41201fdeb]: ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,\r",
"host" => "SYMV170150"
}

Now I'm trying to grab the next bit [T24ServiceConnector] but cannot work it out.

If I add another 'WORD'

input { stdin { } }
filter
{
grok {
patterns_dir => ["C:\Logstash\patterns"]
match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{WORD:LogLevel} %{WORD:LogSource}" }
}

date {
match => [ "timestamp" , "yyyy-MM-dd HH:mm:ss.SSS" ]
timezone=> "Australia/Sydney"
target => "@timestamp" }
}

output
{
elasticsearch { hosts => ["localhost:9200"] }
stdout { codec => rubydebug }
}

I just get a parse failure

{
"@version" => "1",
"message" => "2019-01-12 02:59:54.324 Trace [T24ServiceConnector] Sending OFS request [Tx be17fc06-f7c4-414c-b182-e5d41201fdeb]: ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,\r",
"host" => "SYMV170150",
"@timestamp" => 2019-01-23T22:57:14.953Z,
"tags" => [
[0] "_grokparsefailure"
]
}

I think I need to do some custom filter, Which is why I added the patterns.
Patterns file just contains
LOGSOURCE \W\b\w+\b\W
right now

and replacing WORD with LOGSOURCE for the third parameter gives a parse error also

{
"host" => "SYMV170150",
"@timestamp" => 2019-01-23T23:03:41.845Z,
"message" => "2019-01-12 02:59:54.324 Trace [T24ServiceConnector] Sending OFS request [Tx be17fc06-f7c4-414c-b182-e5d41201fdeb]: ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,\r",
"@version" => "1",
"tags" => [
[0] "_grokparsefailure"
]
}

So...I'm looking for pointers on how to grab the bits I want. Ultimately I need the logsource, the entry type, transaction ID and main body as separate entries. I'm hoping that once I get the initial pattern for the square bracket, I can butcher the rest together

Freebird · January 23, 2019, 11:44pm

I'm getting there
match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{WORD:LogLevel} \s*%{BRACKETEDWORD:LogSource}" }

Where
BRACKETEDWORD \[%{WORD}\]

So it looks like I have to delimit the brackets, but also specify the spaces exist

{
"@timestamp" => 2019-01-11T15:59:54.324Z,
"LogLevel" => "Trace",
"host" => "SYMV170150",
"message" => "2019-01-12 02:59:54.324 Trace [T24ServiceConnector] Sending OFS request [Tx be17fc06-f7c4-414c-b182-e5d41201fdeb]: ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,\r",
"LogSource" => "[T24ServiceConnector]",
"@version" => "1",
"timestamp" => "2019-01-12 02:59:54.324"
}

Badger · January 23, 2019, 11:52pm

I would dissect that rather than grok it.

dissect { mapping => { "message" => "%{ts} %{+ts} %{level} [%{source}] %{msg1} [Tx %{txId}]: %{msg2}" } }

If you are going to grok it. Then use two windows. In one run logstash with the -r flag so that it restarts every time you edit the config (this saves a huge amount of time). Instead of a stdin filter, put a couple of messages in a file and use a file input. That way it processes the same few messages every time you edit the filter.

input { file { path => "/home/user/foo.txt" sincedb_path => "/dev/null" start_position => "beginning" } }

In the other edit the config. For a small number of patterns it may be easier to use pattern_definitions

filter {
    grok {
        pattern_definitions => { "LOGSOURCE" => "\W\b\w+\b\W" }
        match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{WORD:LOGLEVEL} \[%{WORD:LOGSOURCE}\]" }
    }
}

Freebird · January 24, 2019, 12:27am

ooh! I didn't know you could use something else to carve up the line.

That's awesome Even better, it works on some of the other lines too

{
"@version" => "1",
"MainBody" => "ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,\r",
"LogSource" => "T24ServiceConnector",
"Description" => "Sending OFS request",
"message" => "2019-01-12 02:59:54.324 Trace [T24ServiceConnector] Sending OFS request [Tx be17fc06-f7c4-414c-b182-e5d41201fdeb]: ENQUIRY.SELECT,,SOMEUSER//AU0010001,RB.CARD.APP.HEARTBEAT,\r",
"timestamp" => "2019-01-12 02:59:54.324",
"txId" => "be17fc06-f7c4-414c-b182-e5d41201fdeb",
"@timestamp" => 2019-01-11T15:59:54.324Z,
"host" => "SYMV170150",
"LogLevel" => "Trace "
}

How would I trim the spaces out of the LogLevel entry?

Badger · January 24, 2019, 12:56am

If you are using dissect then the documentation covers how to handle visual alignment.

If you are using grok then typically you would replace ' ' with '%{SPACE}' in the pattern, so that it consumes one or more spaces.

Freebird · January 24, 2019, 1:18am

Not sure if I need to start a new thread or not but....

I'm using the dissect command as you suggested and it works well for most lines.
However, some lines lack the colon after the [Tx yyyyy], causing a _dissectfailure

If I remove the colon from the match, then those lines work and the other one fail. Evidently, I need a conditional entry. But I think I probably need the entire expression to be evaluated so it's kind of like;
if [entire dissect] is ok, then execute dissect, else execute the alternative dissect.

Is that possible? Or is there a way to do something like If exist ']:' then dissect 1, else dissect 2?

Badger · January 24, 2019, 2:00am

If the pattern is consistent, then dissect is fast and easy. If the pattern is variable then grok may be a better solution. If the colon after the transaction id then dissect is probably not a good fit.

You might want to post a new question showing the two different log lines you want to match (with either </> or ``` so that we can see them) and the grok pattern you are trying to use. Conditional pattern matching in grok is certainly a thing.

Freebird · January 24, 2019, 5:04am

Since I'm back to grok...

Is there a way to strip out the brackets?

ie,

BRACKETEDWORD \[%{WORD}\]

results in an output of:

"LogSource" => "[T24ServiceConnector]",

What I's like, is for it to say
"LogSource" => "T24ServiceConnector",

This will also apply to the Tx ID once I work out how to get passed the 'phrase' (other question). Since I'll want TxID to be cfbd08c6-9fea-4d88-b15b-6d0637418452, not [Tx cfbd08c6-9fea-4d88-b15b-6d0637418452] as I expect it will come out presently

Badger · January 24, 2019, 2:41pm

Note that you can use a combination of dissect and grok. Use dissect to chop up the consistently formatted part of the line, then grok the msg2.

dissect { mapping => { "message" => "%{ts} %{+ts} %{level} [%{source}] %{msg1} [Tx %{txId}]%{msg2}" } }

In grok, if you don't want to capture BRACKETEDWORD then why define a pattern for it? Just use

\[%{WORD:fieldname}\]

in your pattern.

Freebird · January 24, 2019, 10:06pm

Thanks!

I literally only got logstash running on Tuesday with the STDIN/Out so I could see what is happening, and I don't really understand how the matching etc works. I can't even figure out how to write the code across multiple lines so it is easier to read - everytime I try, I start getting errors.

Is "message" a keyword? I tried changing it yesterday to "OriginalMessage" and got errors so put it back.
If I wanted to feed msg2 from your dissect into grok, do I put "msg2" instead of "message" after the match? Is it saying feed this variable into the matching filter to the right?
Does that also mean I could grok twice?

your example for bracketedword works perfectly - I think I'm starting to see how it works

So now I've got

    grok { 
    patterns_dir => ["C:\Logstash\patterns"]
    match => { "message" => "%{TIMESTAMP_ISO8601:timestamp} %{WORD:LogLevel} \s*\[%{WORD:LogSource}\] %{DATA:Description} \[Tx %{TRANSACTIONID:TxID}\].? %{GREEDYDATA:BodyDetail}" }
  }

with only the TransactionID defined

TRANSACTIONID ([a-zA-Z0-9]{8}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{4}-[a-zA-Z0-9]{12})

and the output is what I want I just need to check it does work for all cases.

Then I need to work out how to get a beat to read the file and send it logstash, but that can be another thread, as too how to then graph the transaction duration which is why I started looking at this in the first place
Really appreciate your help and patience

Badger · January 24, 2019, 11:18pm

Yes, yes, and yes.

system · February 21, 2019, 11:18pm

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Finding fields within square brackets

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