This blog was running on WordPress on a dedicated Ubuntu 14.04 VM host. When I tried to update the host to Ubuntu 16.04, I broke WordPress. Rather than trying to figure out what went wrong, I decided to just run a new WordPress instance under Docker and move the blog to that. The transition wasn’t quite as easy as I’d hoped, so here are the steps (and missteps) I followed to finally get it to work. I first created a directory “blog” and two subdirectories “wp-content” and “db” on a docker host (an Ubuntu 16.04 VM) and brought up a new instance of the WordPress image from the official Docker repository (https://hub.docker.com/_/wordpress/) with the following docker-compose.yml file: I brought it[…]

Postgres-BDR +  To achieve fault tolerance, you need redundant systems. There are two basic approaches to redundancy, active-standby or active-active. Active-standby Active-standby means that in the event of failure of the active node, a failover to a standby node is carried out. Active-active Active-active means that all nodes are continuously active. In the event of failure of a node, that node simply stops being used and the other nodes assume the full load. The problem with active-standby Active-standby has a huge problem in the real world – at the time when a node fails, the chances of failover occurring smoothly are hugely reduced since that the problem that caused the failure is quite likely to affect the system’s ability to failover smoothly – in other words, when things are[…]