There's a usecase for running workers at a different machine than
the composer. For example when there's need for making images for
architecture different then the composer is running at. Although osbuild has
some kind of support for cross-architecture builds, we still consider it
as experimental, not-yet-production-ready feature.
This commit adds a support to composer and worker to communicate using TCP.
To ensure safe communication through the wild worlds of Internet, TLS is not
only supported but even required when using TCP. Both server and client
TLS authentication are required. This means both sides must have their own
private key/certificate pair and both certificates must be signed using one
certificate authority. Examples how to generate all this fancy crypto stuff
can be found in Makefile.
Changes on the composer side:
When osbuild-remote-worker.socket is started before osbuild-composer.service,
osbuild-composer also serves jobqueue API on this socket. The unix domain
socket is not affected by this changes - it is enabled at all times
independently on the remote one. The osbuild-remote-worker.socket listens
by default on TCP port 8700.
When running the composer with remote worker socket enabled, the following
files are required:
- /etc/osbuild-composer/ca-crt.pem (CA certificate)
- /etc/osbuild-composer/composer-key.pem (composer private key)
- /etc/osbuild-composer/composer-crt.pem (composer certificate)
Changes on the worker side:
osbuild-worker has now --remote argument taking the address to a composer
instance. When present, the worker will try to establish TLS secured TCP
connection with the composer. When not present, the worker will use
the unix domain socket method. The unit template file osbuild-remote-worker
was added to simplify the spawning of workers. For example
systemctl start osbuild-remote-worker@example.com
starts a worker which will attempt to connect to the composer instance
running on the address example.com.
When running the worker with --remote argument, the following files are
required:
- /etc/osbuild-composer/ca-crt.pem (CA certificate)
- /etc/osbuild-composer/worker-key.pem (worker private key)
- /etc/osbuild-composer/worker-crt.pem (worker certificate)
By default osbuild-composer.service will always spawn one local worker.
If you don't want it you need to mask the default worker unit by:
systemctl mask osbuild-worker@1.service
Closing remarks:
Remember that both composer and worker certificate must be signed by
the same CA!
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