RFC.

What this does

Adds a newruntimeconfig package for managing all runtime related configuration. The goal of this package is to create a consistent method for CRUD on runtime configuration (as opposed to startup values).

The motivation and driver is mutli-org. Multi org settings must be configured at runtime. Instead of creating ad-hoc CRUD operations to a key/val store, this package creates a single code path for all settings.

Design

The design uses aManager singleton that producesResolvers to enable a cache layer in the future. A pure singleton cannot be used as theResolver requires adatabase.Store, which could be atx. So the user of the package must create theResolver on demand with their local instance of thedb.

Usage

The design is intentionally created so that we can deprecate startup values in favor of runtime in the future. TheDeploymentEntry type specifically uses startup values as a fallback.

This will allow us to move some startup values into runtime, which has been a sticky point for configuring aspects of coder for awhile now.

Future work

Caching layer ::#14586

A follow up to this PR will be a caching layer that uses pubsub to update it's cached values. Adding a cache layer will make all settings essentially free to read, allowing use in hot paths such ashttpmw (as we currently do for startup values).

RBAC layer ::coder/internal#154

When caching is implemented,dbauthz will not be called for cache hits. So this layer, or some layer above, needs to be RBAC aware.

Maybe in theinitialize? theNew? The field could know it's own RBAC properties??

Remove old runtime settings in favor of this

Pretty much all these sql queries:https://github.com/coder/coder/blob/e461d2773b5a2f1bd04ff899a922032b373e187f/coderd/database/queries/siteconfig.sql

Upside is we will remove a lot of database.Store queries (always nice to trim)