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.
By default look for the env file in .kamal/env to avoid clashes with
other tools using .env.
For now we'll still load .env and issue a deprecation warning, but in
future we'll stop reading those.
1. Add driver as an option, defaulting to `docker-container`. For a
"native" build you can set it to `docker`
2. Set arch as a array of architectures to build for, defaulting to
`[ "amd64", "arm64" ]` unless you are using the docker driver in
which case we default to not setting a platform
3. Remote is now just a connection string for the remote builder
4. If remote is set, we only use it for non-local arches, if we are
only building for the local arch, we'll ignore it.
Examples:
On arm64, build for arm64 locally, amd64 remotely or
On amd64, build for amd64 locally, arm64 remotely:
```yaml
builder:
remote: ssh://docker@docker-builder
```
On arm64, build amd64 on remote,
On amd64 build locally:
```yaml
builder:
arch:
- amd64
remote:
host: ssh://docker@docker-builder
```
Build amd64 on local:
```yaml
builder:
arch:
- amd64
```
Use docker driver, building for local arch:
```yaml
builder:
driver: docker
```
Include the host name in the builder name, so we can have one builder
per host/arch across all kamal projects.
Inherit from the remote builder. The difference in the hybrid builder
is that we create a local buildx instance and append the remote context
to it.
It's just a remote builder, that will build whichever platform is asked
for, so let's remove the "native" part.
We'll also remove the service name from the builder name, so multiple
services can share the same builder.
Combine the two builders, as they are almost identical. The only
difference was whether the platforms were set.
The native cached builder wasn't using the context it created, so now
we do.
We'll set the driver to `docker-container` - it seems to be the default
but the Docker docs claim it is `docker`.
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\""
```
