Logstash Grok pattern to cut split a string and remove last part - logstash

Below is the field that is filebeat log path, that I need to split with delimiter '/' and remove the log file name in the text.
"source" : "/var/log/test/testapp/c.log"
I need only this part
"newfield" : "/var/log/test/testapp"

If you do a little of research you can find that this is a trivial question and it has not much complexity. You can use grok-patterns to match the interesting parts and differentiate the one you want to retrieve from the one you don't.
A pattern like this will match as you expected, having the newfield as you desire:
%{GREEDYDATA:newfield}(/%{DATA}.log)
Anyway, you can test your Grok patterns with this tool, and here you have some usefull grok-patterns. I recommend you to take a look to those resources.

Related

How to prevent "Timeout executing grok" and _groktimeout tag

I have a log entry whose last part keeps changing depending on few HTTPS conditions.
sample Logs:
INFO [2021-09-27 23:07:58,632] [dw-1001 - POST /abc/api/v3/pqr/options] [386512709095023:] [ESC[36mUnicornClientESC[0;39m]:
<"type": followed by 11000 characters including space words symbols <----- variable length.
grok pattern:
%{LOGLEVEL:loglevel}\s*\[%{TIMESTAMP_ISO8601:date}\]\s*\[%{GREEDYDATA:requestinfo}\]\s*\[%{GREEDYDATA:logging_id}\:%{GREEDYDATA:token}\]\s*\[(?<method>[^\]]+)\]\:\s*(?<messagebody>(.|\r|\n)*)
(.|\r|\n)*)
this works fine if the variable part of the log is small, but when a large log is encountered, it throws an exception:
[2021-09-27T17:24:40,867][WARN ][logstash.filters.grok ] Timeout executing grok '%{LOGLEVEL:loglevel}\s*\[%{TIMESTAMP_ISO8601:date}\]\s*\[%{GREEDYDATA:requestinfo}\]\s*\[%{GREEDYDATA:logging_id}\:%{GREEDYDATA:token}\]\s*\[(?<method>[^\]]+)\]\:\s*(?<messagebody>(.|\r|\n)*)' against field 'message' with value 'Value too large to output (178493 bytes)! First 255 chars are: INFO [2021-09-27 11:50:14,005] [dw-398 - POST /xxxxx/api/v3/xxxxx/options] [e3acfd76-28a6-0000-0946-0c335230a57e:]
and CPU starts choking and persistent queue increases and Lag in kibana. Any suggestions?
Performance problems in grok and timeouts are not usually a problem when the pattern matches the message, they are a problem when the pattern fails to match.
The first thing to do is anchor your patterns if possible. This blog post has performance data on how effective this is. In your case, when the pattern does not match, grok will start at the beginning of the line to see if LOGLEVEL matches. If it does NOT match, then it will start at the second character of the line and see if LOGLEVEL matches. If it keeps not matching it will have to make thousands of attempts to match the pattern, which is really expensive. If you change your pattern to start with ^%{LOGLEVEL:loglevel}\s*\[ then the ^ means that grok only has to evaluate the match against LOGLEVEL at the start of each line of [message]. If you change it to be "\A%{LOGLEVEL:loglevel}\s*\[ then it will only evaluate the match at the very beginning of the [message] field.
Secondly, if possible, avoid GREEDYDATA except at the end of the pattern. When matching a 10 KB string against a pattern that has multiple GREEDYDATAs, if the pattern does not match then each GREEDYDATA will be tried against thousands of different substrings, resulting in millions of attempts to do the match for each event (it's not quite this simple, but failing to match does get very expensive). Try changing GREEDYDATA to DATA and if it still works then keep it.
Thirdly, if possible, replace GREEDYDATA/DATA with a custom pattern. For example, it appears to me that \[%{GREEDYDATA:requestinfo}\] could be replaced with \[(?<requestinfo>[^\]]+) and I would expect that to be cheaper when the overall pattern does not match.
Fourthly, I would seriously consider using dissect rather than grok
dissect { mapping => { "message" => "%{loglevel->} [%{date}] [%{requestinfo}] [%{logging_id}:%{token}] [%{method}]: %{messagebody}" } }
However, there is a bug in the dissect filter where if "->" is used in the mapping then a single delimiter does not match, multiple delimiters are required. Thus that %{loglevel->} would match against INFO [2021, but not against ERROR [2021. I usually do
mutate { gsub => [ "message", "\s+", " " ] }
and remove the -> to workaround this. dissect is far less flexible and far less powerful than grok, which makes is much cheaper. Note that dissect will create empty fields, like grok with keep_empty_captures enabled, so you will get a [token] field that contains "" for that message.

Want to find all results containing specific pattern in Azure Search explorer

I want to find all records containing the pattern "170629-2" in Azure Search explorer, did try with
query string : customOfferId eq "170629-2*"
which only give one result back, which is the exactly match of "170629-2", but i do not get the records which have the patterns of "170629-20", "170629-21" or "170629-201".
Two things.
1-You can't use standard analyzer as it will break your "words" in two parts:
e.g. 170629-20 will be breaked as 170629 and another entry as 20.
2-You can use regex and specify the pattern you want:
170629-2+.*
https://learn.microsoft.com/en-us/azure/search/query-lucene-syntax#bkmk_regex
PS: use &queryType=full to allow regex

Grok parsing issue using parsing log containing text starting [date] [hostname]

I am trying to parse below log using grok
[2018-10-06 12:04:03:0227] [MYMACHINENAME]
and the grok expression which I used is
/[%{DATESTAMP:date}/] /[%{WORD:data}%/]
and this expression is not working. I tried to replace WORD with hostname even then it not working and if I try to either of the matchers alone then it works.
Can anyone provide me the better tutorial pages to learn grok expressions?
There are few errors in your pattern.
First off, you escape character using backslash / not forward slash \. Second, you don't need % to match ] in the end.
Third, DATESTAMP doesn't match your date pattern, you need TIMESTAMP_ISO8601.
Your final pattern should become,
\[%{TIMESTAMP_ISO8601}\] \[%{WORD}\]
Regex pattern DATESTAMP is not correct for your string. Try using TIMESTAMP_ISO8601.
Here you can see all grok regex patterns: grok-patterns.

logstash custom patterns not parsing

i am facing an issue in parsing the below pattern
the log file will have log importance in the form of == or <= or >= or << or >>
I am trying the below custom pattern. Some of the log msgs may not have this pattern, so I am using *
(?(=<>)*)
But the log mesages are not parsing and give 'grokparsefailure'
kindly check and suggest if the above pattern is wrong.. Thanks much
below pattern is working fine.
(?[=<>]*)
the one which I used earlier and was erroring is
(?(=<>)*)
One thing to note, there is a better way to handle the "some do, some don't" aspect of your log-data.
(?<Importance>(=<>)*)
That will match more than you want. To get the sense of 'sometimes':
((?<Importance>(=<>)*)|^)
This says, match these three characters and define the field Importance, or leave the field unset.
Second, you're matching specifically two characters, in combinations:
((?<Importance>(<|>|=){2})|^)
This should match two instances of any of the trio of characters you're looking for.

Paring a variable length dot separated string in grok

I am new with logstash and grok filters. I am trying to parse a string from an Apache Access Log, with a grok filter in logstash, where the username is part of the access log in the following format:
name1.name2.name3.namex.id
I want to build a new field called USERNAME where it is name1.name2.name3.namex with the id stripped off. I have it working, but the problem is that the number of names are variable. Sometimes there are 3 names (lastname.firstname.middlename) and sometimes there are 4 names (lastname.firstname.middlename.suffix - SMITH.GEORGE.ALLEN.JR
%{WORD:lastname}.%{WORD:firstname}.%{WORD:middle}.%{WORD:id}
When there are 4 names or more it does not parse correctly. I was hoping someone can help me out with the right grok filter. I know I am missing something probably pretty simple.
You could use two patterns, adding another one that matches when there are 4 fields:
%{WORD:lastname}.%{WORD:firstname}.%{WORD:middle}.%{WORD:suffix}.%{WORD:id}
But in this case, you're creating fields that it sounds like you don't even want.
How about a pattern that splits off the ID, leaving everything in front of it, perhaps:
%{DATA:name}.%{INT}

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