tags 801065 + patch tags 801065 - moreinfo thanks hi Holger, thanks for the feedback.
On Mon Jun 1, 2026 at 9:08 PM CEST, Holger Levsen wrote: > On Fri, May 29, 2026 at 10:50:10PM +0200, Serafeim (Serafi) Zanikolas wrote: [..] >> fwiw I wonder whether this would be of much use. "typical Debian setups" is >> ambiguous. verifying whether a remote service is unreachable is not always >> straightforward. "backwards incompatible" is not always black and white. > > I think this is still useful, despite its not all black and white, maybe > especially because its not black and white. please find a lightly edited version attached as a patch. thanks, serafi
From 18b25192ea75abe9a912de97846e8ceaabcc66e6 Mon Sep 17 00:00:00 2001 From: "Serafeim (Serafi) Zanikolas" <[email protected]> Date: Mon, 1 Jun 2026 22:39:43 +0200 Subject: [PATCH] best-pkging-practices: when failing postinst might be appropriate. Closes #801065. --- source/best-pkging-practices.rst | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/source/best-pkging-practices.rst b/source/best-pkging-practices.rst index 3dea1c4..fc570c7 100644 --- a/source/best-pkging-practices.rst +++ b/source/best-pkging-practices.rst @@ -574,6 +574,9 @@ that isn't handled merely by the creation or removal of files and directories. The following instructions supplement the `Debian Policy <https://www.debian.org/doc/debian-policy/>`__. +Generic guidelines +-------------------------------------------------------------------------------------------------------------------------------- + Maintainer scripts must be idempotent. That means that you need to make sure nothing bad will happen if the script is called twice where it would usually be called once. @@ -612,6 +615,33 @@ shell-builtin for many shells and is defined in POSIX. Using ``which`` is an acceptable alternative, since it is from the required ``debianutils`` package. +Expected behavior of complex postinst scripts +-------------------------------------------------------------------------------------------------------------------------------- + +Failing from a ``postinst`` script is very disruptive and should not be taken +lightly: + +- A service failing to start upon a fresh install should, in general, + fail ``postinst``, if + + - the service configuration is straightforward and can be reasonably + expected to work as-is in typical Debian setups + + - the service has no external dependencies (e.g. a database which may not + yet be configured, or unreachable at install time) + +- A service failing to restart upon an upgrade should, in general, fail + ``postinst`` if + + - ``postinst`` can verify with high confidence (which may not always be + feasible) that the service was running prior to the restart + + - the service has no external dependencies or ``postinst`` can verify that + they are functional + + - the service configuration has not changed in backwards incompatible ways + between the old and new package versions + .. _bpp-config-mgmt: Configuration management with ``debconf`` -- 2.47.3
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