● Compose is a tool for defining and running multi-container Docker applications. ● Services and dependencies are defined in YAML file to configure application. ● Using single command, you create and start all the services from your configuration. ● Also works with swarm. ● Tool for developers. https://docs.docker.com/compose/ Diagram Credit : cloudacademy
● Provides the flexibility to use a project name to isolate the environments from each other ● Compose preserves all volumes used by the services defined in the compose file, thus no data is lost when the containers are recreated ● Containers which have changed are recreated, the containers whose state did not change remain untouched ● Support for variables in the compose file, we can define variables in a .env file and use them in the docker-compose file https://docs.docker.com/compose/
● The Kubernetes API is amazingly general purpose – it exposes low-level primitives for building the full range of distributed systems. ● ● There are more than 50 first-class objects in the latest release, from Pods and Deployments to ValidatingWebhookConfiguration and ResourceQuota etc ● ● This can lead to a verbosity in configuration, which then needs to be managed by you, the developer. kubernetes APIs Compose on Kubernetes ● Compose meanwhile isn’t an API but a high-level tool focused on developer productivity ● For the common case of a set of interconnected web services, Compose provides an abstraction that simplifies Kubernetes configuration ● For everything else you can still drop down to the raw Kubernetes API primitives
- Adds ‘stack’ object by extending kubernetes using API Aggregation. - As ‘stack’ object is native, can be integrated with other k8s tools like skaffold.
$ git clone https://github.com/microservices-demo/microservices-demo.git $ cd deployment/kubernetes/manifests $ (Get-ChildItem -Recurse -File | Get-Content | Measure-Object -line).Lines 908 $ cd ../../docker-compose $ (Get-Content docker-compose.yml | Measure-Object -line).Lines 174 More than 5x code is reduced in compose as compared to raw k8s object description