Running Highly available Postgres databases in Containers - Cattle and Pets

EDB Postgres Container Platform Webinar  Notes 

I attended a good high-level webinar hosted by EDB Postgres. It was 45 mins long , which is a reasonable time slot. There was the obligatory overview of EDB Postgres, personnel - which is useful if you haven't seen it before. 

These are some notes on the main points. There was also a demo of setting up Postgres HA within a Kubernetes Orchestration system.

>>Best Practises are emerging , and the conversation should focus on Databases and Containers , think of large scalable databases and how does this feed into working with Containers ?

In Containers  numbers can fluctuate , so think about the management  tools , how you are managing inventory control, monitoring and other management issues that reflect the current  state?

Important to think about how would you not only build new Containers bit also how would you migrate  existing applications into Containers 

Cattle versus Pets 

Containers support an ephemeral and fungible model  -     Need more? Make more!

Applications are fungible , like cattle

Databases are persistent , take a long time to warm up - cache loading , app impact , recovery\rollback 

Treat databases lovingly just like pets 

HA for databases

    - streaming replication with query routing ?

    -  read scaling?

    -  synchronous or asynchronous replication?

    -  Double check the db containers is really down

    -  Promote carefully and make 100% sure that no applications remains connected

  How do you avoid split brain ?

Options

Custom scripting 

Stolon  https://github.com/sorintlab/stolon

Patroni - https://github.com/zalando/patroni

EDB failover manager 

Demo by EDB