Analysing JSON logs with OpenObserve

Level up your JSON log analysis with OpenObserve.

Analysing JSON logs with OpenObserve

In years past, when I wanted to analyse a bunch of JSON logs, I would use jq. jq is an amazing tool, but suffers from some pretty massive drawbacks for large log analysis:

  • jq is slow. It is single threaded. Parsing a several GB file will take minutes
  • If you want to run multiple different reports, then you need jq to parse it all again. So the first point becomes even more painful

Enter OpenObserve (O2). O2 is an awesome, open source (GPLv3), all in one application that is able to ingest vast quantities of logs (and other things) and be able to query them extremely quickly, and even draw visualisations and dashboards.

Think of O2 like an extremely lightweight ElasticSearch.

In my particular case, I often need to visualise JSON logs that come from Fastly. These logs are vast in nature, and being able to analyse millions of logs quickly is key.

Example screenshot of the logs feature of O2

The best thing (IMO) is that you can run it all locally, with a single container, and your computer will not grind to a halt in the process.

Here is a docker-compose file to get you up and running:

    restart: unless-stopped
      ZO_ROOT_USER_PASSWORD: "password"
      ZO_PAYLOAD_LIMIT: "2000000000"
      ZO_JSON_LIMIT: "2000000000"
      - "5080:5080"
      - data:/data
docker-compose.yml example

I had to tweak a few settings (all through environment variables) to allow me to ingest hundreds of MBs in a single payload, and also allow me to ingest data up to 2 days old.

In order to get my JSON logs into a format that O2 would like, I needed to massage them a little.

O2 will automatically parse timestamps that have the name @timestamp, in my case, the field was just called timestamp. So a little sed to the rescue:

sed -i -e 's/"timestamp/"@timestamp/g' $FILE
Ensure the timestamp field has a @ prefixing it

I then needed to format the JSON lines into a giant JSON array, luckily someone on stackoverflow sorted this:

sed -i -e '1s/^/[/; $!s/$/,/; $s/$/]/' $FILE
Convert a JSON entry per line, into a giant JSON array using sed

Finally, you need to send the formatted JSON array into O2

curl -u -k --data-binary "@$FILE"
Ingest the JSON array into a local O2 container

If it all goes well, then you should see something like:

Example command line output from O2 after curl import of JSON

You can now view the UI at http://localhost:5080/ and start to use the power of O2.

Example dashboard showing off 2 visualisations

Happy graphing and log visualising.