Cloudwatch to Elasticsearch parse/tokenize log event before push to ES - elasticsearch

Question

Appreciate your help in advance.
In my scenario - Cloudwatch multiline logs needs to be shipped to elasticsearch service.
ECS--awslog->Cloudwatch---using lambda--> ES Domain
(Basic flow though very open to change how data is shipped from CW to ES )
I was able to solve multi-line issue using multi_line_start_pattern BUT
The main issue I am experiencing now - is my logs have ODL format (following format)
[yyyy-mm-ddThh:mm:ss.SSS-Z][ProductName-Version][Log Level]
[Message ID][LoggerName][Key Value Pairs][[
Message]]
AND I will like to parse and tokenize log events before storing in ES (vs the complete log line ).
For example:
[2018-05-31T11:08:49.148-0400] [glassfish 4.1] [INFO] [] [] [tid: _ThreadID=43 _ThreadName=Thread-8] [timeMillis: 1527692929148] [levelValue: 800] [[
[] INFO : (DummyApplicationFunctionJPADAO) EntityManagerFactory located under resource lookup name [null], resource name=AuthorizationPU]]
Needs to be parsed and tokenize using format
timestamp 2018-05-31T11:08:49.148-0400
ProductName-Version glassfish 4.1
LogLevel INFO
MessageID
LoggerName
KeyValuePairs tid: _ThreadID=43 _ThreadName=Thread-8
Message [] INFO : (DummyApplicationFunctionJPADAO)
EntityManagerFactorylocated under resource lookup name
[null], resource name=AuthorizationPU
In above Key Value pairs repeat and are variable - for simplicity I can store all as one long string.
As far as what I gathered about Cloudwatch - It seems Subscription Filter Pattern reg ex support is very limited really not sure how to fit the above pattern. For lambda function that pushes the data to ES have not seen AWS doc or examples that support lambda as means to parse and push for ES.
Will appreciate if someone can please guide what/where will be best option to parse CW logs before it gets into ES => Subscription Filter -Pattern vs in lambda function or any other way.
Thank you .

Answer 1

From what I can see your best bet is what you're suggesting, a CloudWatch log triggered lambda that reformats the logged data into your ES prefered format and then posts it into ES.
You'll need to subscribe this lambda to your CloudWatch logs. You can do this on the lambda console, or the cloudwatch console (https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/Subscriptions.html).
The lambda's event payload will be: { "awslogs": { "data": "encoded-logs" } }. Where encoded-logs is a Base64 encoding of a gzipped JSON.
For example, the sample event (https://docs.aws.amazon.com/lambda/latest/dg/eventsources.html#eventsources-cloudwatch-logs) can be decoded in node, for example, using:
const zlib = require('zlib');
const data = event.awslogs.data;
const gzipped = Buffer.from(data, 'base64');
const json = zlib.gunzipSync(gzipped);
const logs = JSON.parse(json);
console.log(logs);
/*
{ messageType: 'DATA_MESSAGE',
owner: '123456789123',
logGroup: 'testLogGroup',
logStream: 'testLogStream',
subscriptionFilters: [ 'testFilter' ],
logEvents:
[ { id: 'eventId1',
timestamp: 1440442987000,
message: '[ERROR] First test message' },
{ id: 'eventId2',
timestamp: 1440442987001,
message: '[ERROR] Second test message' } ] }
*/
From what you've outlined, you'll want to extract the logEvents array, and parse this into an array of strings. I'm happy to give some help on this too if you need it (but I'll need to know what language you're writing your lambda in- there are libraries for tokenizing ODL- so hopefully it's not too hard).
At this point you can then POST these new records directly into your AWS ES Domain. Somewhat crypitcally the S3-to-ES guide gives a good outline of how to do this in python: https://docs.aws.amazon.com/elasticsearch-service/latest/developerguide/es-aws-integrations.html#es-aws-integrations-s3-lambda-es
You can find a full example for a lambda that does all this (by someone else) here: https://github.com/blueimp/aws-lambda/tree/master/cloudwatch-logs-to-elastic-cloud