[bug#66160] [PATCH] gnu: Add oci-container-service-type.

[Ludovic Courtès]

Hi,

Giacomo Leidi <goodoldpaul@autistici.org> skribis:

> * gnu/services/docker.scm (oci-container-configuration): New variable;
> (oci-container-shepherd-service): new variable;
> (oci-container-service-type): new variable.
> * doc/guix.texi: Document it.

Neat!

> +@cindex OCI-backed, Shepherd services
> +@subsubheading OCI backed services
> +
> +Should you wish to manage your Docker containers with the same consistent
> +interface you use for your other Shepherd services,
> +@var{oci-container-service-type} is the tool to use.

Perhaps expound a bit, like:

  … is the tool to use: given an @acronym{Open Container Initiative,
  OCI} container image, it will run it in a Shepherd service.  One
  example where this is useful: it lets you run services that are
  available as Docker/OCI images but not yet packaged for Guix.

> +@defvar oci-container-service-type
> +
> +This is a thin wrapper around Docker's CLI that wraps OCI images backed
> +processes as Shepherd Services.
> +
> +@lisp
> +(simple-service 'oci-grafana-service
> +                (list
> +                 (oci-container-configuration

The second argument to ‘simple-service’ is missing.

> +                  (image "prom/prometheus")
> +                  (network "host")
> +                  (ports
> +                    '(("9000" . "9000")
> +                      ("9090" . "9090"))))))
> +                 (oci-container-configuration
> +                  (image "grafana/grafana:10.0.1")
> +                  (network "host")
> +                  (volumes
> +                    '("/var/lib/grafana:/var/lib/grafana"))))))
> +@end lisp

Please explain the example in one or two sentences.

Personally, I’d like to know how the image names are resolved; would be
nice to mention it in the doc.

> +@table @asis
> +@item @code{command} (default: @code{()}) (type: list-of-strings)
> +Overwrite the default CMD of the image.

“… the default command (@code{CMD}) of the image.”

> +@item @code{entrypoint} (default: @code{""}) (type: string)
> +Overwrite the default ENTRYPOINT of the image.

Likewise.

> +@item @code{environment} (default: @code{()}) (type: list)
> +Set environment variables. This can be a list of pairs or strings, even 
> mixed:
> +
> +@lisp
> +(list '("LANGUAGE" . "eo:ca:eu")
> +      "JAVA_HOME=/opt/java")

I would choose one or the other, but not both.

> +@item @code{ports} (default: @code{()}) (type: list)
> +Set the port or port ranges to expose from the spawned container. This can 
> be a
> +list of pairs or strings, even mixed:
> +
> +@lisp
> +(list '("8080" . "80")
> +      "10443:443")

Likewise.

> +(define (oci-sanitize-pair pair delimiter)
> +  (cond ((file-like? (car pair))
> +         (file-append (car pair) delimiter (cdr pair)))

Please use ‘match’ instead of car/cdr (info "(guix) Data Types and
Pattern Matching").

> +         (error
> +          (format #f "pair members must only contain gexps, file-like 
> objects and strings but ~a was found" (car pair))))))

Should be (raise (formatted-message (G_ …))).  That way we get i18n
support and the message is presented like other error messages.

> +            (error
> +             (format #f "~a members must be either a string or a pair but ~a 
> was found!" name el)))))

Ditto.

> +    (shepherd-service (provision `(,(string->symbol name)))
> +                      (requirement '(dockerd))

Actually: (requirement '(dockerd user-processes)).

> +                (description
> +                 "This service provides allows the management of Docker
> +containers as Shepherd services.")))

“Docker and OCI containers”

Could you send an updated patch?

Thanks,
Ludo’.