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.
Allow hosts to be tagged so we can have host specific env variables.
We might want host specific env variables for things like datacenter
specific tags or testing GC settings on a specific host.
Right now you either need to set up a separate role, or have the app
be host aware.
Now you can define tag env variables and assign those to hosts.
For example:
```
servers:
- 1.1.1.1
- 1.1.1.2: tag1
- 1.1.1.2: tag2
- 1.1.1.3: [ tag1, tag2 ]
env_tags:
tag1:
ENV1: value1
tag2:
ENV2: value2
```
The tag env supports the full env format, allowing you to set secret and
clear values.
Currently the latest container is the one that was created last. But if
we have had a failed deployment that left two containers running that
would not be the one we want. The second container could be in a
restart loop for example.
Instead we want the container that is running the image tagged as
latest. As we now tag as latest after a successful deployment we can
trust that that is a healthy container.
In the case that there is no container running the latest image tag,
we'll fall back to the latest container.
This could happen if the deploy was halted in between the old container
being stopped and the image being tagged as latest.
When calling `kamal app exec` for new non interactive containers, run
the command per role on each server and include the role config
including the environment.
Fixes: https://github.com/basecamp/kamal/issues/492
Adding -T to the copy command ensures that the files are copied at the
same level into the target directory whether it exists or not.
That allows us to drop the `/*` which was not picking up hidden files.
Fixes: https://github.com/basecamp/kamal/issues/465
