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An application running as a container bascially carries the same configuration as one running without the container bits would. That may include things like endpoint addresses, certificates, secrets, but can also be things like feature flags, authorizations, API tokens. Basically anything that's not compiled in is configuration. The deployment side also carries configuration, including things like desired amount of instances, request routing and filtering, log destinations, log retention, persistent volume sizes and location, backup rules, metrics and monitoring rules etc. If anything, application deployments today carry more configuration, not less. Fifteen years ago, half of the above didn't even exist. Perhaps you pointed you application to a syslog server and that was it. All of this configuration exists in disparate tools (JSON files, YAML files, firewalls, metrics dashboards, cloud providers proprietary APIs) and will over time slowly turn into a sprawling mess. Bringing control over this into a central repository is a good thing. Not sure about expensive, as the aim is maintainability and reduced complexity, but these tools do tend to get cumbersome. After all, they want to do everything. It's a fundamental problem. It's not surprising that has led to a surge in less capable tools. |
But Kubernetes solves most of this problem in an easier way with Pods, ConfigMaps, Secrets, Services and Endpoints.