[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Expanding service procedure to accept additional arguments
From: |
mirai |
Subject: |
Expanding service procedure to accept additional arguments |
Date: |
Wed, 28 Dec 2022 16:46:32 +0000 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 |
It is occasionally desired to have a service depend on additional shepherd
services
than the defaults listed in their definition.
Examples where this can be seen is the shepherd-requirement field provided by
nginx-configuration and opensmtpd-configuration, but these fields are
record-type
specific and not available for the other service types (unless patched in).
An alternative to patching the original record-type is to define a custom
service-type
record-type and inheriting it which is somewhat clunky for what amounts to a
setup-specific
single line change:
--8<---------------cut here---------------start------------->8---
(shepherd-service
...
- (requirement `(...))
+ (requirement `(... ,@shepherd-requirement))
--8<---------------cut here---------------end--------------->8---
Another type of extensibility that should be considered is the capability to
add extra
service-extensions to existing service-type records.
These can be useful for setup-specific (i.e. not applicable in general to be
included with Guix) scenarios,
for example, to add an extra activation-service-type extension or have a
special-files-service-type
extension that the service-type usually does not have.
The current approach that I'm aware of to achieve something similar is through
simple-service, drawbacks being extra boilerplate code and a "disjoint" service
whose connection to the "parent service" is not immediately apparent.
--8<---------------cut here---------------start------------->8---
;; Ideally this should go in radicale-service-type
(simple-service 'chmod-radicale shepherd-root-service-type
(list (shepherd-service (requirement '(user-homes))
(provision '(radicale-home))
(documentation "chmod g+rwx
to user 'radicale' home.")
(one-shot? #t)
(start #~(lambda _
(chmod (passwd:dir
(getpw "radicale")) #o770)
#t)))))
--8<---------------cut here---------------end--------------->8---
Instead, what if the service procedure could be changed to accept optional
keyword arguments?
Then one could express the extensions and dependencies as:
--8<---------------cut here---------------start------------->8---
(services
(service foo-service-type
#:requirements '(networking nscd smtpd)
#:extensions (list (service-extension bar-service-type (lambda _
...))
(service-extension activation-service-type
(lambda _ ...))))
--8<---------------cut here---------------end--------------->8---
Thoughts?
Regards,
Bruno
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- Expanding service procedure to accept additional arguments,
mirai <=