A suggestion: implement namespaces to isolate package sets

[Arto Pekkanen]

I just joined the mailing lists, so I haven't been able to reply to the 
earlier threads.

In 
https://lists.freebsd.org/pipermail/freebsd-pkgbase/2016-March/000032.html 
it was mentioned
> 2) At present, running 'pkg delete -a' will implicitly remove the
>   'FreeBSD-*' packages, leaving the system in an unusable state.  There
>   are valid use cases for removing all packages, such as test chroot(8)
>   or jail(8) environments, so a solution to avoid accidental foot
>   shooting is still being investigated

The easiest way to prevent accidents is to implement a namespacing 
scheme. That is, each package can define a namespace in which it 
resides. Package would only be acted upon if, and only if, both it's 
name and namespace match the package selection criteria of the 
operation.

If a package would not define a namespace, it would be considered part 
of the "default" or "undefined" namespace. This "default" namespace 
would, by default, mostly consist of packages built from /usr/ports and 
installed in /usr/local prefix.

When invoking the pkg tools, the namespace would have to be explicitly 
declared in each context. My suggestion on how to do this is to declare 
namespaces in the form of //<namespace>. A package glob within a 
namespace would be declared in the form of //<namespace>/<glob>. NOTE: I 
think there is no need to panic about this namespacing scheme getting 
mixed up with filenames, because pkg utilities either handle name globs 
for packages from repository (install, remove, query, rquery) or 
filenames (add), not both at the same time.

IF a namespace is declared without a glob, then "*" is assumed. Thus 
//foo/* would equal //foo

IF namespaces are NOT declared for package globs during the invocation 
of the pkg utilities, the "default" namespaces would be implicitly 
assumed.

Like this:

# install zfs stuff from org.freebsd namespace
pkg install -r FreeBSD-base //org.freebsd/zfs

# remove all packages matching *ssl* from org.freebsd namespace
# note: quoted to prevent shell globbing ... you'd do that normally 
anyway
pkg remove "//org.freebsd/*ssl*"

# install bash without specifying a namespace
# that is, bash would be installed from a repository in which it's 
namespace is default (or undefined)
pkg install bash

# this would return error, since no repository has package bash with 
namespace org.freebsd
pkg install //org.freebsd/bash

# remove all packages from "default" namespace.
# NOTE: this will NOT touch ANY packages from any other namespace, 
including org.freebsd
pkg remove -a

# remove all *ssl* packages from "default" namespace
# NOTE: does NOT remove, say, base system libssl
pkg remove *ssl*

# would list all installed packages from "default" namespace
pkg info

# would list all installed packages from org.freebsd namespaces, ie. the 
base system packages
pkg info //org.freebsd

In the examples it is assumed that base system is in repository 
FreeBSD-base, and that all the base system packages have the org.freebsd 
namespace. Yeah, I would use reverse domain names as namespaces, that is 
just the rational thing to do, all things considered.

If no namespacing scheme is implemented, then the other options to 
prevent scenarions like "I accidentally the whole base system" I can 
think of are ugly kludges; kludges like "protected" or "hidden" package 
flags. I think in the end we want beautiful solutions, and namespacing 
gives just that.

Besides, no other packaging system I know uses namespaces. Having the 
namespace option in FreeBSD, even if just for base system packages, 
would make pkg really cool and different. Also, I am kinda sure there 
are plenty other applications for having a namespaced package 
management.

PS. typing this from webmail, next messages include my public key, but I 
haven't got it in this mail yet.

-- 
Arto Pekkanen