alt Hacker NewsFor something like a database, what is the added advantage to using Kubernetes as opposed to something simple like Docker Compose?
Replies
Docker Compose (ignoring Swarm which seems to be obsolete) manages containers on a single machine. With Kubernetes, the pod that hosts the database is a pod like any other (I assume). It gets moved to a healthy machine when node goes bad, respects CPU/mem limits, works with generic monitoring tools, can be deployed from GitOps tools etc. All the k8s goodies apply.
The assumption is that you’re already using Kubernetes, sorry.
Docker compose has always been great for running some containers on a local machine, but I’ve never found it to be great for deployments with lots of physical nodes. k8s is certainly complex, but the complexity really pays off for larger deployments IMO.
I hate that this is starting to sound like a bot Q&A, but the primary advantages is that it provides secure remote configuration and it's that it's platform agnostic, multi-node orchestration, built in load balancing and services framework, way more networking control than docker, better security, self healing and the list goes on, you have to read more about it to really understand the advantages over docker.
In this case the advantage are operators for running postgres.
With Docker Compose, the abstraction level you're dealing with is containers, which means in this case you're saying "run the postgres image and mount the given config and the given data directory". When running the service, you need to know how to operate the software within the container.
Kubernetes at its heart is an extensible API Server, which allows so called "operators" to create custom resources and react to them. In the given case, this means that a postgres operator defines for example a PostgresDatabaseCluster resource, and then contains control loops to turn these resources into actual running containers. That way, you don't necessarily need to know how postgres is configured and that it requires a data directory mount. Instead, you create a resource that says "give me a postgres 15 database with two instances for HA fail-over", and the operator then goes to work and manages the underlying containers and volumes.
Essentially operators in kubernetes allow you to manage these services at a much higher level.