Adds:
- `kamal upgrade` to upgrade all app hosts and accessory hosts
- `kamal proxy upgrade` to upgrade the proxy on all hosts
- `kamal accessory upgrade [name]` to upgrade accessories on all hosts
Upgrade takes rolling and confirmed options and calls `proxy upgrade`
and `accessory upgrade` in turn.
To just upgrade a single host add -h [host] to the command. But the
upgrade should run on all hosts, not just those running the proxy.
Calling upgrade on a host that has already been upgraded should work ok.
Upgrading hosts causes downtime but you can avoid if you run multiple
hosts by:
1. Implementing the pre-proxy-reboot and post-proxy-reboot hooks to
remove the host from external load balancers
2. Running the upgrade with the --rolling option
**kamal proxy upgrade**
1. Creates a `kamal` network if required
2. Stops and removes the old proxy (whether Traefik or kamal-proxy)
3. Starts a kamal-proxy container in the `kamal` network
4. Reboots the app containers in the `kamal` network
**kamal accessory upgrade [name]**
1. Creates a `kamal` network if required
2. Reboots the accessory containers in the `kamal` network
A matching `downgrade` command will be added to Kamal 1.9.
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.
Secret and clear env variables have different lifecycles. The clear ones
are part of the repo, so it makes sense to always deploy them with the
rest of the repo.
The secret ones are external so we can't be sure that they are up to
date, therefore they require an explicit push via `envify` or `env push`.
We'll keep the env file, but now it just contains secrets. The clear
values are passed directly to `docker run`.
Setting env variables in the docker arguments requires having them on
the deploy host.
Instead we'll add two new commands `kamal env push` and
`kamal env delete` which will manage copying the environment as .env
files to the remote host.
Docker will pick up the file with `--env-file <path-to-file>`. Env files
will be stored under `<kamal run directory>/env`.
Running `kamal env push` will create env files for each role and
accessory, and traefik if required.
`kamal envify` has been updated to also push the env files.
By avoiding using `kamal envify` and creating the local and remote
secrets manually, you can now avoid accessing secrets needed
for the docker runtime environment locally. You will still need build
secrets.
One thing to note - the Docker doesn't parse the environment variables
in the env file, one result of this is that you can't specify multi-line
values - see https://github.com/moby/moby/issues/12997.
We maybe need to look docker config or docker secrets longer term to get
around this.
Hattip to @kevinmcconnell - this was all his idea.
Allow the hosts for accessories to be specified by host or role, or on
all app hosts by setting `daemon: true`.
```
# Single host
mysql:
host: 1.1.1.1
# Multiple hosts
redis:
hosts:
- 1.1.1.1
- 1.1.1.2
# By role
monitoring:
roles:
- web
- jobs
```
