What is this?

It's a output plugin for Fluentd, that sends data into Yandex ClickHouse database. By now it supports buffered output (I still don't know how) and handling few exceptions.

How to use it?

I'm not a ruby programmer who knows how to write gems, so just put out_clickhouse.rb to /etc/td-agent/plugin.
There's example td-agent.conf:

<source>
    @type http
    port 8888
</source>
<match inp>
    @type clickhouse
    host 127.0.0.1
    port 8123
    table FLUENT
    datetime_name DateTime # name for internal fluentd datetime field
    fields DateTime,tag,Num # in this order values will be inserted in CH
</match>

Before launching td-agent, create table into ClickHouse:
CREATE TABLE FLUENT ( Date Date MATERIALIZED toDate(DateTime), DateTime DateTime, Str String, Num Int32) ENGINE = MergeTree(Date, Date, DateTime, 8192)
Start td-agent and send a few events to fluentd:

curl -X POST -d 'json={"Num":1}' http://localhost:8888/inp
curl -X POST -d 'json={"Num":2}' http://localhost:8888/inp
curl -X POST -d 'json={"Num":3}' http://localhost:8888/inp

After a few seconds, when buffer flushes, in ClickHouse you could see this:

┌───────Date─┬────────────DateTime─┬─Str─┬─Num─┐  
│ 2017-11-06 │ 2017-11-06 14:42:03 │ inp │   1 │  
│ 2017-11-06 │ 2017-11-06 14:42:06 │ inp │   2 │  
│ 2017-11-06 │ 2017-11-06 14:42:09 │ inp │   3 │  
└────────────┴─────────────────────┴─────┴─────┘  

Wow, it doesn't even support HTTP auth

Yes, and besides auth, there's still a work to do:

• SSL
• Timezones that doesn't suck
• GZIP. ClickHouse supports compressing, so why not?
• and more