Aug 31, 2017

What's coming in Cistern v0.2.0

Those who saw my tweets from last night know that I’m really exciting about what I’ve been implementing in Cistern for the next release.

In the v0.1.0 release post from about a month ago I mentioned that the next release will focus on generic JSON log messages. That’s still really important for me, but there are a couple of even more exciting things too.

Query language

Cistern’s storage and querying code came from Epsilon which didn’t have a query language. It only had a JSON REST API, and queries had to be described with a JSON object that sort-of resembled a SQL query. Not user-friendly at all! It was a pain to keep writing that stuff by hand.

Cistern v0.1.0 introduced a pseudo query language in the CLI which uses flags and looks like this:

  -columns 'sum(bytes), count(_id), max(packets), max(bytes)' \
  -group 'source_address, dest_address' \
  -order-by 'sum(bytes)' \
  -limit 3 \

But that’s still not very neat.

Cistern v0.2.0 will come with an actual query language with a well-defined grammar that looks a lot like SQL. The parser translates a SQL-like string into the JSON query object I described before.

So this

SELECT sum(bytes) GROUP BY dest_address ORDER BY sum(bytes) desc limit 100 POINT SIZE 3h

actually works! It’s converted into a JSON query object which is now used internally. I’m planning on writing up another post explaining how that works.


Having a SQL-like query language makes the CLI just barely better than curl. My D3.js and Mithril.js experiments from another project have been going so well that I decided to borrow that code to make a UI for Cistern.

It only took me a few hours to come up with this:

Here’s another screenshot:

I copied the layout from Honeycomb.io. It works really well.

Generic JSON log messages

Of course, generic JSON messages will make it into v0.2.0.

Release schedule

I hope to release v0.2.0 within a week, and then have a regular release once a month or so. There probably won’t be any huge changes after this. Just a lot of testing and refinement.

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