The `app exec` and `accessory exec` commands will run `docker run` if
they are not set to reuse existing containers. This might need to pull
an image so let's make sure we are logged in before running the command.
Fixes: https://github.com/basecamp/kamal/issues/1163
We hook into the SSHKit `on` method to run the pre-connect hook before
the first SSH command. This doesn't work for interactive exec commands
where ssh is called directly.
Fixes: https://github.com/basecamp/kamal/issues/1157
Adds support for maintenance mode to Kamal.
There are two new commands:
- `kamal app maintenance` - puts the app in maintenance mode
- `kamal app live` - puts the app back in live mode
In maintenance mode, the kamal proxy will respond to requests with a
503 status code. It will use an error page built into kamal proxy.
You can use your own error page by setting `error_pages_path` in the
configuration. This will copy any 4xx.html or 5xx.html files from that
page to a volume mounted into the proxy container.
Add two new hooks pre-app-boot and post-app-boot. They are analagous
to the pre/post proxy reboot hooks.
If the boot strategy deploys in groups, then the hooks are called once
per group of hosts and `KAMAL_HOSTS` contains a comma delimited list of
the hosts in that group.
If all hosts are deployed to at once, then they are called once with
`KAMAL_HOSTS` containing all the hosts.
It is possible to have pauses between groups of hosts in the boot config,
where this is the case the pause happens after the post-app-boot hook is
called.
We only loaded the configuration once, which meant that aliases always
used the initial configuration file and destination.
We don't want to load the configuration in subcommands as it is not
passed all the options we need. But just checking if we are in a
subcommand is enough - the alias reloads and the subcommand does not.
One thing to note is that anything passed on the command line overrides
what is in the alias, so if an alias says
`other_config: config -c config/deploy2.yml` and you run
`kamal other_config -c config/deploy.yml`, it won't switch.
this is useful for long running rake tasks or scripts
that can be run without having to keep open connection to the server.
Example:
```
kamal app exec 'bin/rails db:backfill_task' --detach
```
By default only the primary role runs the proxy. To disable the proxy
for that role, you can set `proxy: false` under it.
For other roles they default to not running the proxy, but you can
enable it by setting `proxy: true` for the role, or alternatively
setting a proxy configuration.
The proxy configuration will be merged into the root proxy configuration.
Remove `stop_wait_time` and `readiness_timeout` from the root config
and remove `deploy_timeout` and `drain_timeout` from the proxy config.
Instead we'll just have `deploy_timeout` and `drain_timeout` in the
root config.
For roles that run the proxy, they are passed to the kamal-proxy deploy
command. Once that returns we can assume the container is ready to
shut down.
For other roles, we'll use the `deploy_timeout` when polling the
container to see if it is ready and the `drain_timeout` when stopping
the container.
The proxy can be enabled via the config:
```
proxy:
enabled: true
hosts:
- 10.0.0.1
- 10.0.0.2
```
This will enable the proxy and cause it to be run on the hosts listed
under `hosts`, after running `kamal proxy reboot`.
Enabling the proxy disables `kamal traefik` commands and replaces them
with `kamal proxy` ones. However only the marked hosts will run the
kamal-proxy container, the rest will run Traefik as before.
When overriding the command, docker will still run the entrypoint. We
want to avoid that here - we just want to get the assets out as quickly
as possible. Otherwise maybe something important is going on when we
stop the container.
Add env files back in for secrets - hides them from process lists and
allows you to pick up the latest env file when running
`kamal app exec` without reusing.
If you can have an alias like:
```
aliases:
rails: app exec -p rails
```
Then `kamal rails db:migrate:status` will execute
`kamal app exec -p rails db:migrate:status`.
So this works, we'll allow multiple arguments `app exec` and
`server exec` to accept multiple arguments.
The arguments are combined by simply joining them with a space. This
means that these are equivalent:
```
kamal app exec -p rails db:migrate:status
kamal app exec -p "rails db:migrate:status"
```
If you want to pass an argument with spaces, you'll need to quote it:
```
kamal app exec -p "git commit -am \"My comment\""
kamal app exec -p git commit -am "\"My comment\""
```
If a primary role container is unhealthy, we might take a while to
timeout the health check poller. In the meantime if we have started the
other roles, they'll be running tow containers.
This could be a problem, especially if they read run jobs as that
doubles the worker capacity which could cause exessive load.
We'll wait for the first primary role container to boot successfully
before starting the other containers from other roles.
To speed up deployments, we'll remove the healthcheck step.
This adds some risk to deployments for non-web roles - if they don't
have a Docker healthcheck configured then the only check we do is if
the container is running.
If there is a bad image we might see the container running before it
exits and deploy it. Previously the healthcheck step would have avoided
this by ensuring a web container could boot and serve traffic first.
To mitigate this, we'll add a deployment barrier. Until one of the
primary role containers passes its healthcheck, we'll keep the barrier
up and avoid stopping the containers on the non-primary roles.
It the primary role container fails its healthcheck, we'll close the
barrier and shut down the new containers on the waiting roles.
We also have a new integration test to check we correctly handle a
a broken image. This highlighted that SSHKit's default runner will
stop at the first error it encounters. We'll now have a custom runner
that waits for all threads to finish allowing them to clean up.
