In Splunk Docs or presentations, Input and Indexing stages are often explained as a topic of Getting Data In. That’s all, for this post, we hope you understood how to configure Splunk to do an index time extraction on your data.When we think about log events life cycle in Splunk, we can think about how to collect data (Input stage), then processes to parse data and ingest them to Splunk Database (Indexing stage), then, how to keep data in database (hot->Warm->Cold->Freezing). The index file or the tsidx file holds all the metadata fields, so we should be able to query on our fields “operation” and “user” using the ‘tstats’ command. Step-7: Wait!! Let’s make sure that these fields got added to the index file ( tsidx file). Step-6:Let’s look for these extractions on the search head. This specifies the output field format, in this case whatever is captured by group 1(indicated by $1) is put under the field “operation”, and similarly anything captured by group2 is put under the field “user”. While for the later one you need to explicitly mention “_meta”įor the fields to get added to metadata. The former adds the extracted fields automatically to metadata NOTE: You can either use “WRITE_META = true” OR “DEST_KEY = _meta” This attribute in fact here tells Splunk to do index time processing for this transforms stanza, it is only valid for index-time field extractions. We have two capture groups in the regular expression.(highlighted in yellow in the screenshot below) WRITE_META = true May 28 16:04:10 server2 passwd: password for ‘avahi’ changed by ‘root’Īnd we wanted to extract the operation ( passwd) and the user name ( avahi) from all these events. You need to set your regular expression based on the incoming events to Splunk, above attribute sets the regular expression based on which the index time extraction(s) is going to take place a This stanza must be declared in the nf file. Step-5:Let’s create the nf (under, $SPLUNK_HOME/etc/system/local), here we are going to set the index time extraction rules. You can have multiple “transformation_name” in a comma separated fashion. In our case this “ transformation_name” is “ my_extraction”, which we are going to define in nf. The above attribute is required for doing index time operation(s), This attribute doesn’t let multiple lines form the logs to merge together into a single event. Step-4: We created a nf (under, $SPLUNK_HOME/etc/system/local), here we must put the entry of our nf stanza, basically, you need to declare the stanza(s) to be used in nf here. The above stanza tells the Splunk input processor to monitor a file “sample_logs.txt” located under the /tmp directory and the attributes “index” and “sourcetype” assign the values to the default fields “index” and “sourcetype” required by splunk. Step-3:We created an nf (under, $SPLUNK_HOME/etc/system/local) to monitor the “sample_logs.txt” file. Step-2 : We created a file named sample_logs.txt under /tmp directory, the contents of which you can see in the Screenshot below. You can simply create an index via Splunk GUI, in case you are on a non-clustered indexer. Step-1 : We created an index “test” to store the data that we are going to use for the testing purpose. To implement index-time extraction you can just follow the below tried and tested steps. To know more about “ index-time” and “ search-time” extraction, please click here. In this post we decided to cover a very common but little tricky Splunk configuration, implementing index time field extraction.Īlthough, it’s almost always better to prefer “ search-time extraction” over “ index-time extraction”. INDEX TIME FIELD EXTRACTION USING WRITE_META
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