[kamal-proxy](https://github.com/basecamp/kamal-proxy) is a custom
minimal proxy designed specifically for Kamal.
It has some advantages over Traefik:
1. Imperative deployments - we tell it to switch from container A to
container B, and it waits for container B to start then switches. No
need to poll for health checks ourselves or mess around with forcing
health checks to fail.
2. Support for multiple apps - as much as possible, configuration is
supplied at runtime by the deploy command, allowing us to have
multiple apps share a proxy without conflicting config.
3. First class support for Kamal operations - rather than trying to
work out how to make Traefik do what we want, we can build features
directly into the proxy, making configuration simpler and avoiding
obscure errors
Useful for checking the status of CI before deploying. Doing this at
this point in the deployment maximises the parallelisation of building
and running CI.
These replace the custom audit_broadcast_cmd code. An additional env
variable MRSK_RUNTIME is passed to them.
The audit broadcast after booting an accessory has been removed.
Adds hooks to MRSK. Currently just two hooks, pre-build and post-push.
We could break the build and push into two separate commands if we
found the need for post-build and/or pre-push hooks.
Hooks are stored in `.mrsk/hooks`. Running `mrsk init` will now create
that folder and add sample hook scripts.
Hooks returning non-zero exit codes will abort the current command.
Further potential work here:
- We could replace the audit broadcast command with a
post-deploy/post-rollback hook or similar
- Maybe provide pre-command/post-command hooks that run after every
mrsk invocation
- Also look for hooks in `~/.mrsk/hooks`
Audit details
* Audit logs and broadcasts accept `details` whose values are included as log tags and MRSK_* env vars passed to the broadcast command
* Commands may return execution options to the CLI in their args list
* Introduce `mrsk broadcast` helper for sending audit broadcasts
* Report UTC time, not local time, in audit logs. Standardize on ISO 8601 format
* main:
Simplify domain language to just "boot" and unscoped config keys
Retain a fixed number of containers when pruning
Don't assume rolling back in message
Check all hosts before rolling back
Ensure Traefik service name is consistent
Extend traefik delay by 1 second
Include traefik access logs
Check if we are still getting a 404
Also dump load balancer logs
Dump traefik logs when app not booted
Fix missing for apt-get
Report on container health after failure
Fix the integration test healthcheck
Allow percentage-based rolling deployments
Move `group_limit` & `group_wait` under `boot`
Limit rolling deployment to boot operation
Allow performing boot & start operations in groups
