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Although several thousand Emacs Lisp libraries exist, GNU Emacs, until version 24.1 did not have an (internal) package manager.
I guess that most users would agree that it is currently rather inconvenient to find, install and especially keep up-to-date Emacs Lisp libraries.
Pages that make life a bit easier
For versions of Emacs older than 24.1:
Emacs Lisp List - Problem: I see dead people (links).
Emacswiki - Problem: May contain traces of nuts (malicious code).
Emacsmirror - The package repository I am working on. Problem: No package manager supports it natively yet.
Some package managers
It's not that nobody has tried yet. (Some of these did not exist when this question was asked.)
auto-install
borg.el - Assimilate Emacs packages using Git submodules.
el-get.el - Supports many sources.
elinstall.el
epackage aka DELPS - Debian packaging concepts applied to Emacs Lisp packages.
epkg.el - This is now just a tool for browsing the Emacsmirror.
install.el
install-elisp.el
jem-pkg.el
package.el - ELPA. Seems like it will be included in Emacs 24.
UPDATE -- package.el is included in GNU Emacs, starting with version 24.1
pases.el
pelm - Command line installer; using php.
plugin.el
straight.el - Recent and experimental, has not reached 1.0 release yet.
use-package.el
XEmacs package manager
package has been included in the Emacs trunk. epkg is not ready yet and also currently not available. At least install-elisp, plugin and use-package do not seem to be actively maintained anymore.
I have created a git repository containing all these package managers as submodules.
Some utilities that might be useful
Package managers could use these utilities and/or they could be used to maintain a mirror of packages.
date-calc.el - Date calculation and parsing routines.
ell.el - Browse the Emacs Lisp List.
elm.el, elx.el, xpkg.el - Used to maintain the Emacsmirror.
genauto.el - Helps generate autoloads for your elisp packages.
inversion.el - Require specific package versions.
loadhist.el, lib-requires.el, elisp-depend.el - Commands to list Emacs Lisp library dependencies.
project-root.el - Define a project root and take actions based upon it.
strptime.el - Partial implementation of POSIX date and time parsing.
wikirel.el - Visit relevant pages on the Emacs Wiki.
Discussions about the subject at hand
emacs-devel 20080801
comp.emacs 20021121
RationalElispPackaging
The question (finally)
So - I would like to know from you what you consider important/unimportant/supplementary etc. in a package manager for Emacs.
Some ideas
Many packages (the Emacsmirror provides that largest available collection of packages, but there is no explicit support in any package manager yet).
Only packages that have been tested.
Support for more than one package archive (so people can choose between many/tested packages).
Dependency calculated based on required features only.
Dependencies take particular versions into account.
Only use versions that have been released upstream.
Use versions from version control systems if available.
Packages are categorized.
Packages can be uninstalled and updated not only installed.
Support creating fork of upstream version of packages.
Support publishing these forks.
Support choosing a fork.
After installation packages are activated.
Generate autoload files.
Integration with Emacswiki (see wikirel.el).
Users can tag, comment etc. packages and share that information.
Only FSF-assigned/GPL/FOSS software or don't care about license.
Package manager should be integrated be distributed with Emacs.
Support for easily contacting author.
Lots of metadata.
Suggest alternatives before installing a particular package.
I am hoping for these kinds of answers
Pointers to more implementations, discussions etc.
Lengthy descriptions of a set of features that make up your ideal package manager.
Descriptions of one particular desired/undesired feature. Feel free to elaborate on my ideas from above.
Surprise me.
I'm still learning Emacs, so I haven't had a chance to look into package managers, but a great feature would be to inform the user that the package is available if they try to use it but it's not on their system. For example, I wanted to edit a PHP file on a server once, and I tried
M-x php-mode
and Emacs was all like
M-x php-mode [no match]
when it should have been like
php-mode available from ftp.gnu.org. install? (y/n)
and then it would have installed and loaded up php-mode for me. That would have made my day right there.
Automatic publishing from version control
I'd love to see a standard, central, and single Emacs package manager. Right now, I'd put my money on ELPA, but there is still a long way to go.
The biggest thing that would help an Emacs package manager would be to make it super trivial to publish packages. In my opinion, I'd like to see this happen in combination with a version control system like git on a central hosted platform like GitHub -- something that would make it easy for authors to publish their packages and would make it easy for others to contribute back.
Similar to how GitHub (used to) make it easy to publish RubyGems, I'd like to see something similar in an Emacs package manager. For example, tag your repository with "vX.Y.Z" and have your elisp goodness automatically available to all.
The added benefit of using a popular backend like GitHub is that you'd immediately get a lot of exposure which should help drive its success.
What I expect most is that everything useful is on it, and works well. This requires you (or a team of maintainers) to aggressively pursue packaging everything for it, and doing whatever that involves — emailing every author of a useful package, and so on.
For instance, the reason Debian (and its derivatives: Ubuntu etc.) is so good is that you can happily use your system without ever having to install something outside the repositories, and that everything on it is thoroughly tested. The actual features of the package manager are important, but secondary to the managed packages themselves.
Easy configuration synchronization: I, like many people, use Emacs on many different computers and servers, some of them my own and some not. It would be amazing if the package manager had some sort of file which I could transfer from one computer to another; then, on the latter computer, the package manager would bring my Emacs into the state I like it in -- all the packages installed and configurations set. Combined with the ability to be able to easily install either site-wide (if one has root permissions) or as a single user, I could synchronize all of Emacsen everywhere.
I'm nearly positive that the best solution involves submitting more packages to ELPA and adding multi-source support to package.el. The Emacs maintainers have said that they would consider including package.el in version 24 as long as it pointed to an FSF repository by default.
Of course, submission also needs to be an automated process too; the current method of mailing the ELPA maintainer only works on a small scale.
No matter how this is done, the most important thing in my opinion is that it should be trivial to submit packages to the repository. At the same time, we do not want those packages to be instantly available, to guard against malicious code(and due to licensing issues). Unless there is a "trust" system in place, based on crypto signatures.
Also useful:
"metapackages", to install several packages at once.
In the same way, we should be able to install a set of elisp files, for maintainability
"Broken" packages should not be allowed to disrupt Emacs startup. This is easy and I have it implemented in my own .emacs
Ability to install files other than scripts. This is often overlooked, but very useful. You'd be able to, for instance, ship images, for icons, toolbars, etc.
Versioning:package X requires package Y > 1.0
Testing: perform basic sanity checks, testing for conflicts (keybindings, function redefinitions, functions that are expected to be present but aren't, etc).
BUG TRACKING: I can't stress the importance of this enough. Having a centralized place to report package bugs (and being able to track them) is extremely important to assure the quality of the packages.
Some sort of compressed archive seems to be best to do some of the above.
So far, a much improved ELPA seems the way to go.
I once spent some time writing a small package manager for Emacs.
http://gmarceau.qc.ca/plugin.el
I wrote:
Plugin is my attempt at creating a
package manager for Emacs. Plugin
will automatically downloads Emacs
extensions, unpacks them in a
directory, adds that directory to the
load-path, generates auto-load
annotations, and modify your dot-emacs
file. The auto-load annotations are a
little-known feature of Emacs. Once
they are generated, Emacs extensions
load quickly and incrementally, which
is really nice if you have as many
extensions installed as I do.
You will need two library files to get it to run, loop-constructs.el and record.el
I think the hackers for the iPhone got quite close to what I want, as does Ubuntu's "apt".
I like to be able to:
add
remove (package only)
remove user settings
view documentation
upgrade ( after reading the change log)
add new archive ( aka add repository )
see dependencies
see version
search for name, keyword
browse by (date added, date modified, name)
save all installed packages & settings
load set of packages & settings
I would like a main set of things that all work nicely and are the recommended way of doing whatever. Then a global set where everything working gets in. Then the ability for anyone to host their own archive.
It would be nice if this was all tied into git/svn/whatever so that you could install old versions. Make your own patches by forking off etc etc etc....
Besides the mentioned above, i expect something like debian, and other repositories - set of the stable, experemental, untested packages. Ability to add my own repositories - i use lot of the packages directly from VCS, so it could be useful to create my own packages
I think that the package manager should take a lot of inspiration from Rubygems. I also think that it should have a site like Gemcutter.
A central repository could also be nice (like Emacsmirror). This however may not be necessary if a site like Gemcutter exists that collects all packages.
I think these things are important for this to work.
Central location of some kind that collects all packages
Easy to add packages
Easy to maintain packages
Easy to contribute to other packages
Easy to install, uninstall and update packages
Possibility to add package dependencies
Common structure for all packages
So a package manager like Rubygems with a site like Gemcutter and a central repository like Emacsmirror (preferably on Github because of it's social coding) would do Emacs really good.
All in all I think that much inspiration should be taken from Rails and how Rails handles Gems.
I don't know how fresh this question is...
but the model I would like to see is CPAN. I also don't know Rubygems but it sounds similar to CPAN.
CPAN is a perl archive + library management system. When I need to write a perl program that requires... FTP or SOAP or JSON or XML or ZIP, or...etc, I can run the CPAN package manager, select the requisite package for download, view and verify the dependencies, then install everything. CPAN is mirrored .."everywhere".
CPAN works wonderfully for my purposes, and something similar for emacs would be nice to have. It also supports building C/C++ code on demand.
That's what I would like to see in emacs.
Some further comment on requirements.
explicit download of packages. No auto install. No invisible downloads. I want to ask for new libraries or new function.
I should be able to list the name/version/timestamp of installed packages.
If my friend gives me his list, I should be able to diff his emacs state against mine.
check-for-updates function. What updates are available? What do they fix?
depedency checking, verification, and download. If I install csharp-mode and it requires v5.0.28 of cc-mode, then it should confirm with me, that I must also download cc-mode.
there should be some sort of community ranking of these packages, like ranking torrents on isohunt. I want to see if a package has 3 upvotes or 3000.
"transactional" behavior. If an install goes boom, it must unwind to a last-known-good state.
failsafes. If I've put custom mods in linum.el, it should refuse to install a new version over my changes, unless I explicitly allow it. It should warn me before even starting. Do this with checksums/md5's over the existing install.
have the option of running some packages from compressed archives, like zip files. So I never have any doubt that I have not updated any of the embbedded elisp.
ability to use mirrored hosts for package distribution.
all this function should be accessible through M-x library-manageemnt or something.
Finally, it would be nice to have a way to segregate or organize libraries of functions. Hierarchical namespaces. Emacs' flat namespace is very dated. This is sort of independent but complementary to the core function of package management. I'm not a lisp guru so I don't know how hard this would be; maybe there is already a way to do it.
Package managers don't offer anything I value w.r.t. single-file elisp packages with simple dependencies: adding and deleting from site-lisp has never caused problems. It's packages that depend on external programs (e.g., ispell), multi-file packages (e.g., auctex, org-mode) that can be tricky. Can't think of any single-file elisp package with nontrivial dependencies, offhand.
For these, short of a package manager, I'd like emacs' elisp-packages to acquire test suites which can be run en masse, and which provide useful information in the event of dependency failures.
Related
Many languages' package management systems install third-party packages in a subfolder of a given project's root repository. (E.g. node_modules/, deps/, etc.) This is nice as it allows multiple versions of a single package to coexist nicely, as each is isolated to the project that depends on it.
raco by default installs packages system-wide it seems. Is there a way to tell raco it should install packages in a particular folder?
The comment is right to point you to package scopes: using a directory package scope is the most fine-grained level of control available at the level of the package manager. However, as the docs say,
Conflict checking disallows installation of the same or conflicting
package in different scopes …
It is a design decision in the Racket package system not to allow multiple versions of the same package to coexist in the same installation. The idea is that a package shouldn't make breaking changes while using the same name. One inspiration that's been mentioned is OS level package systems like Debian's, where gcc-4.7 and gcc-4.8 are different packages that install different binaries. This is very different than the practice of some other language package systems (e.g. npm), but it works out well in practice because the Racket community takes backwards-compatibility quite seriously.
This is actually Racket's second package system. The old system, PLaneT, tried to be much more opinionated, including built-in notions of versioning. The new/current system consciously removed some of those elements to create a more minimal and focused package system, which means that a great deal of what formerly had to be "built in" to Racket can now be just another package. You may be interested in a talk about the design of the package system. There was also a fair amount of discussion at the time on the mailing list, which is archived here.
If you do find you need different package versions to an extent that can't be supported by existing mechanisms, you could use a stand-alone Racket installation (rather than a system-wide one) to get a completely isolated environment. I'm sure the Racket community would also be interested in hearing about any issues you have in practice.
I maintain a fairly well-used emacs package (ido-ubiquitous), and in the next version I plan to drop support for Emacs 23 and below. People who use Emacs 23 and below will be able to continue using the current version of my package.
However, I don't want to have Emacs 23 users upgrading via ELPA or git or something else and ending up with the new version that isn't compatible with their emacs. Is there a generally accepted way of handling this gracefully? Do I have any choice short of renaming the new version to "ido-ubiquitous-ng" or something?
ELPA/package.el
To prevent updates via package.el, add the special dependency (emacs "24.1") to the Package-Requires list. See Library Headers in the Emacs Lisp Manual, in the description of the Package-Requires: header:
[…] The package code automatically defines a package named ‘emacs’ with the version number of the currently running Emacs. This can be used to require a minimal version of Emacs for a package.
The package.el which is distributed independently for Emacs 23 and below does not provide this special package. Thus, any attempt to install your package on Emacs 23 will fail with a message complaining about “emacs” being unavailable for installation, leaving the old, compatible version in place.
However, when using this, be prepared to handle complaints from users of Emacs 24. Many users apparently do not delete their old package.el when upgrading to Emacs 24. Thus the old package.el overrides the new built-in one, leading to spurious errors on installation.
ELGet
I do not know Elget. Probably ask its author for help in this matter.
Git submodules, Tarballs and other legacy methods
I do not think, that you can really prevent updates, if users install your package in a legacy way (e.g. Git submodules, distribution packages, etc.). You can only complain after your package was updated, which is arguably too late, because the incompatible code is now already there.
You may choose to add an explicit version check, with a detailed error. I consider this superfluous, though. If you really go for Emacs 24, you will be using incompatible functions, so your package won't load successfully, whether you explicitly prevent it or not. So save yourself of superfluous code :)
TL;DR (+ personal experience)
First of all, please do not rename your package. Few users can follow the news on each and every installed package. Thus many users will not immediately realize that the package was renamed, and continue to use an outdated version without notice or warning. Effectively, you would sort of punish Emacs 24 users of your package.
Add the special dependency to prevent accidental updates via package.el. Add prominent documentation, that your package requires Emacs 24, like in the first section of your Github Readme. Then, let the matter rest. Anything else is likely more hassle that it is worth.
In my personal experience, Emacs users are not stupid (well, at least the majority isn't). They read documentation. They understand documentation.
Users of Emacs 23 know that their Emacs is outdated. Many of them expect incompatibilities and breakage. If the package suddenly breaks for them, they will seek advice on Github, realize that the package is not available for Emacs 23 anymore, and either go back to the last working release, or (hopefully) upgrade their Emacs.
I have several applications that I wish to deploy using rpm. Some of the files in my application deployments override files from other deployed packages. Simply including the new files in the deployment package will cause rpm conflicts.
I am looking for the proper way to use rpm to update/replace already installed files.
I have already come up with a few solutions but nothing seems quite right.
Maintain custom versions of the rpms containing the original files.
This seems like a large amount of work for a relatively small reward even though it feels less like a hack than some of the other possible solutions.
Include the files in the rpm with another name and copy them over in the post section.
This would work but will mean littering the system with multiple copies of the files. Also it means additional maintenance in the rpm build spec for each file.
Use wget in the post section to replace the original files from some known server.
This is similar to the copy technique but the files wouldn't even live in the rpm. This might act like a nice central configuration authority though.
Deploy the files as new files, then use symlinks to override the originals.
This is also similar to the copy technique but with less clutter. The problem here is that some files don't behave well as symlinks.
To the best of my knowledge, RPM is not designed to permit updating / replacing existing files, so anything that you do is going to be a hack.
Of the options you list, I'd choose #1 as the least bad hack if the target systems are systems that I admin (as you say, it's more work but is the cleanest solution) and a combination of #2 and #4 (symlinks where possible, copies where not) if I'm creating the RPMs for others' systems (to avoid having to distribute a bunch of RPMs, but I'd make it very clear in the docs what I'm doing).
You haven't described which files need to be updated or replaced and how they need to be updated. Depending on the answers to those questions, you may have a couple of other options:
Many programs are designed to use a single default configuration file and also to grab configuration files from a .d subdirectory. For example, Apache uses /etc/httpd/conf/httpd.conf and /etc/httpd/conf.d/*.conf, so your RPMs could drop files under /etc/httpd/conf.d instead of modifying /etc/httpd/conf/httpd.conf. And if the files that you need to modify are config files that don't follow this pattern but could be made to, you can suggest to the package maintainers that they add this capability; this wouldn't help you immediately but would make future releases easier.
For command-line utilities like sendmail and lpr that can be provided by multiple packages, the alternatives system (see man alternatives) permits more than 1 RPM that provides these utilities to be installed side by side. Again, if the files that you need to modify are command-line utilities that don't follow this pattern but could be made to, you can suggest to the package maintainers that they add this capability.
Config file changes on systems that you administer are better managed through a tool like Cfengine or Puppet rather than through custom RPMs. I think that Red Hat favors Puppet.
If I were creating the RPMs for systems I don't administer, I'd consider using a third-party tool like Bitrock and dumping all of my stuff under /opt just so I wouldn't have to stomp on files installed by other admins' RPMs.
Edit (2019): Nowadays, Software Collections offers a useful alternative. You can create packages that install somewhere under /opt, and the Software Collections tools offer a standardized way for users to opt in to using those instead of whatever's normally installed under /usr. Red Hat uses this to distribute newer versions of tools for their otherwise stable and long-lived (i.e., older) Red Hat Enterprise Linux distributions.
You can also execute rpm -U --replacefiles --replacepkgs ..., which will give you what you want.
See here for more info on RPM %files directives:
http://www.rpm.org/max-rpm/s1-rpm-inside-files-list-directives.html
You can use the arguments from the %post and %pre sections in the RPM scriptlets to determine if you are installing, upgrading or removing packages.
If $1 is 0 - then we're removing old stuff. Targeting 0 packages installed.
If $1 is 1 - then we're installing new stuff. Targeting a total of 1 package to be installed.
If $1 is 2 or more - then we're upgrading this package and $1 represents the number of packages already installed.
These sections help with managing files among the versions.
Keep track of what you're doing between versions and consider what one might do if they were to skip a version or two.
Have consideration for these things and you should be good to go!
I'm tasked with replicating a production environment to create many test/sit environments.
One of the things I need to do is build up Perl, with all the modules which have been installed (including internal and external modules) over the years. I could just use CPAN.pm autobundle, but this will result in the test environment having much newer versions of the external modules that production has.
What is the easiest/best way to get and install (a lot of) version specific Perl modules.
bdfoy has the best large scale solution, but if you just want to install a few modules you can ask the CPAN shell to install a specific distribution by referencing a path to a tarball (relative to the top of the CPAN tree).
cpan> install MSCHWERN/Test-Simple-0.62.tar.gz
Throw a URL to BackPAN into your URL list and you can install any older version.
cpan> o conf urllist push http://backpan.perl.org/
This is in the CPAN.pm FAQ under "how do I install a 'DEVELOPER RELEASE' of a module?"
cpan install App::cpanminus
cpanm Your::Module#1.23
(Carton, as referenced in other answers, uses cpanm underneath to resolve explicit version requirements.)
Make your own CPAN mirror with exactly what you want. Stratopan.com, a service, and Pinto, tools that's built on top of, can help you do that.
The CPAN tools only install the latest version of any distribution because PAUSE only indexes the latest version. However, you can create your own, private CPAN that has exactly the distributions that you want. Once you have your own CPAN mirror with only what you want, you point your CPAN tools at only that mirror so it only installs those versions. More on that in a minute.
Now, you want to have several versions of that. You can create as many mirrors as you like, and you can also put the mirrors in source control so you can check out any version of the mirror that you like.
Tools such as CPAN::Mini::Inject can help you set up your own CPAN. Check out my talks on Slideshare for the basic examples, and some of my videos on Vimeo for some of the demonstrations. Look at anything that has "CPAN" or "BackPAN" in the title. I think I might have some stuff about it in The Perl Review too, or should by the next issue. :)
Lately, I've been working on a program called dpan (for DarkPAN) that can look at random directories, find Perl distributions in them, and create the structure and index files that you need. You run dpan, you get a URL to point your CPAN client toward, and off you go. It's part of my MyCPAN-Indexer project, which is in Github. It's not quite ready for unsupervised public use because I mostly work with corporate clients to customize their setup. If you're interested in that, feel free to ask me questions though.
Also, I recently released CPAN::PackageDetails that can help you build the right index file. It's still a bit young too, but again, if you need something special, just ask.
[It's almost five years on and this is a well-asked and well-answered question that has had a lot of views. Since this page must still come up in Google searches, an update can't hurt.]
Carton is worth mentioning here. Carton is a relatively recent tool in the same style as App::cpanminus, App::cpanoutdated, perlbrew, et. al. The author (Miyagawa) calls it "alpha" quality, but even in its current state carton helps simplify the maintenance of multiple environments of version tuned modules across machines.
Pinto too is another recent tool relevant to some of the responses (in fact one of the respondents is a contributor).
Stratopan.com is another alternative. Stratopan provides private CPANs in the cloud. You can fill your Stratopan repository with specific versions of modules (and their dependencies) and then install them using the standard Perl tool chain. The repository changes only when you decide to change it, so you'll get always get the versions of the modules that you want.
Disclaimer: I operate Stratopan.
It seems that creating a cpanfile listing all your modules and desired versions (using the == <version> syntax to lock it to a specific release) could serve well here, too. That would mean using Carton or cpanm for installing the modules.
Doing this would have the benefit of being able to quickly/easily tweak the file to test upgrading specific modules in a dev or staging environment - something that a private CPAN mirror wouldn't let you do (without creating multiple mirrors).
It seems that most of the installers for Perl are centered around installing Perl modules, not applications. Things like ExtUtils::MakeMaker and Module::Build are very well suited for modules, but require some additional work for Web Apps.
Ideally it would be nice to be able to do the following after checking out the source from the repository:
Have missing dependencies detected
Download and install dependencies from CPAN
Run a command to "Build" the source into a final state (perform any source parsing or configuration necessary for the local environment).
Run a command to install the built files into the appropriate locations. Not only the perl modules, but also things like template (.tt) files, and CGI scripts, JS and image files that should be web-accessible.
Make sure proper permissions are set on installed files (and SELinux context if necessary).
Right now we have a system based on Module::Build that does most of this. The work was done by done by my co-worker who was learning to use Module::Build at the time, and we'd like some advice on generalizing our solution, since it's fairly app-specific right now. In particular, our system requires us to install dependencies by hand (although it does detect them).
Is there any particular system you've used that's been particularly successful? Do you have to write an installer based on Module::Build or ExtUtils::MakeMaker that's particular to your application, or is something more general available?
EDIT: To answer brian's questions below:
We can log into the machines
We do not have root access to the machines
The machines are all (ostensibly) identical builds of RHEL5 with SELinux enabled
Currently, the people installing the machines are only programmers from our group, and our source is not available to the general public. However, it's conceivable our source could eventually be installed on someone else's machines in our organization, to be installed by their programmers or systems people.
We install by checking out from the repository, though we'd like to have the option of using a distributed archive (see above).
The answer suggesting RPM is definitely a good one. Using your system's package manager can definitely make your life easier. However, it might mean you also need to package up a bunch of other Perl modules.
You might also take a look at Shipwright. This is a Perl-based tool for packaging up an app and all its Perl module dependencies. It's early days yet, but it looks promising.
As far as installing dependencies, it wouldn't be hard to simply package up a bunch of tarballs and then have you Module::Build-based solution install them. You should take a look at pip, which makes installing a module from a tarball quite trivial. You could package this with your code base and simply call it from your own installer to handle the deps.
I question whether relying on CPAN is a good idea. The CPAN shell always fetches the latest version of a distro, rather than a specific version. If you're interested in ensuring repeatable installs, it's not the right tool.
What are your limitations for installing web apps? Can you log into the machine? Are all of the machines running the same thing? Are the people installing the web apps co-workers or random people from the general public? Are the people installing this sysadmins, programmers, web managers, or something else? Do you install by distributed an archive or checking out from source control?
For most of my stuff, which involves sysadmins familiar with Perl installing in control environments, I just use MakeMaker. It's easy to get it to do all the things you listed if you know a little about MakeMaker. If you want to know more about that, ask a another question. ;) Module::Build is just as easy, though, and the way to go if you don't already like using MakeMaker.
Module::Build would be a good way to go to handle lots of different situations if the people are moderately clueful about the command line and installing software. You'll have a lot of flexibility with Module::Build, but also a bit more work. And, the cpan tool (which comes with Perl), can install from the current directory and handle dependencies for you. Just tell it to install the current directory:
$ cpan .
If you only have to install on a single platorm, you'll probably have an easier time making a package in the native format. You could even have Module::Build make that package for you so the developers have the flexibility of Module::Build, but the installers have the ease of the native process. Sticking with Module::Build also means that you could create different packages for different platforms from a single build tool.
If the people installing the web application really have no idea about command lines, CPAN, and other things, you'll probably want to use a packager and installer that doesn't scare them or make them think about what is going on, and can accurately report problems to you automatically.
As Dave points out, using a real CPAN mirror always gets you the latest version of a module, but you can also make your own "fake" CPAN mirror with exactly the distributions you want and have the normal CPAN tools install from that. For our customers, we make "CPAN on a CD" (although thumb drives are good now too). With a simple "run me" script everything gets installed in exactly the versions they need. See, for instance, my Making my own CPAN talk if you're interested in that. Again, consider the audience when you think about that. It's not something you'd hand to the general public.
Good luck, :)
I'd recommend seriously considering a package system such as RPM to do this. Even if you're running on Windows I'd consider RPM and cygwin to do the installation. You could even set up a yum or apt repository to deliver the packages to remote systems.
If you're looking for a general installer for customers running any number of OSes and distros, then the problem becomes much harder.
Take a look at PAR.
Jonathan Rockway as a small section on using this with Catalyst in his book.