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5. Honeytail + Custom Regex

Send Unstructured Logs with Honeytail + Custom Regex

Table of Contents

Use custom regular expressions and Honeytail, our lightweight tool to tail your existing log files, parse the content, and send it to Honeycomb.

Installation 

Download and install the latest honeytail by running:

wget -q https://honeycomb.io/download/honeytail/v1.10.0/honeytail_1.10.0_amd64.deb

echo '3db441215f97eaed068aa0531c986cf5405957e3e8e26b22c16b571091caf917  honeytail_1.10.0_amd64.deb' | sha256sum -c

sudo dpkg -i honeytail_1.10.0_amd64.deb

wget -q https://honeycomb.io/download/honeytail/v1.10.0/honeytail_1.10.0_arm64.deb

echo '4220756e5a941cde6a484cb4cfde184eb189aaf29170df301a874eb143e960ed  honeytail_1.10.0_arm64.deb' | sha256sum -c

sudo dpkg -i honeytail_1.10.0_arm64.deb

wget -q https://honeycomb.io/download/honeytail/v1.10.0/honeytail_1.10.0-1.x86_64.rpm

echo 'b23215a9301b20b2e2262a0823c9e761e8b57e1a62fd5cec35f697fce41fa863  honeytail_1.10.0-1.x86_64.rpm' | sha256sum -c

sudo rpm -i honeytail_1.10.0-1.x86_64.rpm

wget -q -O honeytail https://honeycomb.io/download/honeytail/v1.10.0/honeytail-linux-amd64

echo 'c9cc7dd1aa2b12afeb30b089061870f3407d2df0119e7c2807fec648b603e2d5  honeytail' | shasum -a 256 -c

chmod 755 ./honeytail

wget -q -O honeytail https://honeycomb.io/download/honeytail/v1.10.0/honeytail-linux-arm64

echo '1dd37227788548c4ed44592554e3c90e374c4d796c444dde9f372db8618bc7fa  honeytail' | shasum -a 256 -c

chmod 755 ./honeytail

wget -q -O honeytail https://honeycomb.io/download/honeytail/v1.10.0/honeytail-darwin-amd64

echo '9a3da0f48fe21b1e610ac6b63130dfb8118a9a0ec16abae13350edba02d85e4d  honeytail' | shasum -a 256 -c

chmod 755 ./honeytail

git clone https://github.com/honeycombio/honeytail

cd honeytail; go install

You should modify the config file and uncomment and set:

• WriteKey to your API key, available from the account page
• LogFiles to the path for the log file you want to ingest, or - for stdin
• Dataset to the name of the dataset you wish to create with this log file.
• ParserName to regex
• LineRegex to a regular expression with named capture groups.

Launch the Agent 

Start up a honeytail process using upstart or systemd or by launching the process by hand. This will tail the log file specified in the config and leave the process running as a daemon.

sudo initctl start honeytail

sudo systemctl start honeytail

honeytail -c /etc/honeytail/honeytail.conf

Backfilling Archived Logs 

To backfill existing data, run honeytail with --backfill the first time:

honeytail -c /etc/honeytail/honeytail.conf \
  --file /var/log/myapp/log12.log \
  --backfill

This command can also be used at any point to backfill from older, rotated log files. You can read more about our backfill behavior here.

Regexes 

We use golang’s regexp package, which uses RE2 syntax.

Specifying Regexes 

Command line: use the --regex.line_regex flag to tell honeytail how to extract data from a log line.

You must provide at least one regex. You may optionally specify multiple regexes. Lines will be parsed by the first regex to find a match. Precedence is based on the order you pass in line_regex, so specify your regexes from most-specific to least-specific.

On the command line, you will need to wrap the regex in quotes.

honeytail \
    --writekey YOUR_API_KEY \
    --file PATH/FILE.LOG \
    --parser regex \
    --dataset "MY_TEST_SET" \
    --backfill \
    --regex.line_regex="\[(?P<time>\d{2}:\d{2}:\d{2})\] (?P<message>\w+)" \
    --regex.line_regex="(?P<field1>\w+) (?P<field2>\w+)"

Equivalent configuration file specification. Note that you should not wrap the regex in quotes here.

[Regex Parser Options]
; a regular expression with named capture groups representing the fields you want parsed
LineRegex = \[(?P<time>\d{2}:\d{2}:\d{2})\] (?P<message>\w+)
LineRegex = (?P<field1>\w+) (?P<field2>\w+)

Regex Syntax 

Regexes must contain at least one named capture group. Use the (?P<name>re) syntax for named groups. Example:

Log file

[2017/11/07 22:59:46] 200 ...
[2017/11/07 22:59:48] 500 ...
[2017/11/07 23:01:02] 404 ...

with

--regex.line_regex="\[(?P<time>\d{4}/\d{2}/\d{2} \d{2}:\d{2}:\d{2})\] (?P<status>\d+)"

will yield rows like this:

{
  time: "2017/11/07 22:59:46",
  status: "200"
}

Nested Regex Grouping 

Nested groups are supported. For example:

--regex.line_regex="(?P<outer>[^ ]* (?P<inner1>[^ ]*) (?P<inner2>[^ ]*))"

will parse a log line “A B C” into { outer: "A B C", inner1: "B", inner2: "C" }.

Timestamp Parsing 

Honeycomb expects all events to contain a timestamp field; if one is not provided, the server will associate the current time of ingest with the given payload.

Use the --regex.timefield and --regex.time_format flags to help honeytail understand where and how to extract the event’s timestamp.

For example, given a log file like the following:

[08/Oct/2015:00:26:26 +0000] 200 174 0.099

A command to consume those log lines (retaining the "local_time" field as the event’s timestamp would look like:

honeytail \
    --parser=regex \
    --writekey=YOUR_API_KEY \
    --file=server.log  \
    --dataset='MY_DATASET' \
    --backfill \
    --regex.line_regex=SOME_REGEX \
    --regex.timefield="local_time" \
    --regex.time_format="%d/%b/%Y:%H:%M:%S %z"

The --regex.timefield="local_time" argument tells honeytail to consider the "local_time" value to be the canonical timestamp for the events in the specified file.

The --regex.time_format argument specifies the timestamp format to be used while parsing. (It understands common strftime formats.)

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