What's wrong with running a live site from a DVCS clone? - deployment

I see insinuations here and there that it's bad to run a live deployment directly off a DVCS clone, and better to export a clean tree or tarball and deploy that. It seems to me that running directly from a DVCS clone has several advantages:
No need to transport the entire codebase on every deployment.
Trivial to update code to any desired version.
Trivial to rollback to previous version if deployment goes badly.
And I can't really see any disadvantages. The presence of the repo files (in my case, a single .hg/ directory) causes no problems.
Is there really any good reason not to run a live deployment off a DVCS clone?

This is what I do. The only "disadvantage" is you can't really version-control the databases or site-generated content (user uploads). It's not a disadvantage at all though because there's no alternative. Just as usual, you need a backup script to copy all that content out.
This isn't an answer but rather an explanation of modern webapp directory layouts. A very simple Python webapp might look something like this:
webapp/
.hg/
webroot/
handler.py
You would set it up so that the webserver only serves static content from webroot/ and if the path doesn't exist in there it asks python (in this case) for that page.
Since none of the server-side source-code is within webroot/, it cannot be served (unless you have a python directive ordering it to serve source code). The same applies to the .hg/ directory.
Note: SVN (< 1.7) and CVS are exceptions as they spray their .svn directories over every subdirectory. In this case that would include webroot/ so, yes, you'd need to make sure you weren't serving hidden files but this is commonly the case anyway.

Well, I know of one.
If someone can gain access to your .hg directory, they could potentially view your source code. But really, access to this directory should be disallowed by the server or by .htaccess files.

Related

Zend framework 2 configuration uses

I would like know what's the difference between the uses of global.php and local.php files.
In the Zend documentation, these files only register the database configuration, but I don't understand because the credentials are in a separated file (local.php).
Zend documentation talks about a version control system (VCS), but I don't understand because if these files are in a same directory, they don't have the same visibility inside VCS.
Thanks in advance.
The idea they work with, is (in git terms) an ignore. If you watch the git repository for the Skeleton Application, you see there is a .gitignore file in that directory.
This means, if you use git as a VCS, all files except any file matching local.php or *.local.php will be commited into the VCS. Therefore, the local.php but also the my-foo.local.php files will be kept outside the VCS.
This is very useful for local configuration (e.g. you want to turn the cache off on your development machine) or credentials (database, email or api keys for 3rd party services). The content of the local config files can be stored or communicated via other means.
To answer your question: yes, they are in the same directory, but they are ignored for the VCS. If you work with svn, there is also a term called svn:ignore and other VCSes have similar features.

How to force a directory to stay in exact sync with subversion server

I have a directory structure containing a bunch of config files for an application. The structure is maintained in Subversion, and then a few systems have that directory struture checked out. Developers make changes to the struture in the repository, and a script on the servers just runs an "svn update" periodically.
However, sometimes we have people who will inadvertently remove a .svn directory under one of the directories, or stick a file in that doesn't belong. I do what I can to cut off the hands of the procedural unfaithful, but I'd still prefer for my update script to be able to gracefully (well, automatically) handle these changes.
So, what I need is a way to delete files which are not in subversion, and a way to go ahead and stomp on a local directory which is in the way of something in the repository. So, warnings like
Fetching external item into '/path/to/a/dir'
svn: warning: '/path/to/a/dir' is not a working copy
and
Fetching external item into '/path/to/another/dir'
svn: warning: Failed to add directory '/path/to/another/dir': an unversioned directory of the same name already exists
should be automatically resolved.
I'm concerned that I'll have to either parse the svn status output in a script, or use the svn C API and write my own "cleanup" program to make this work (and yes, it has to work this way; rsync / tar+scp, and whatever else aren't options for a variety of reasons). But if anyone has a solution (or partial solution) which takes care of the issue, I'd appreciate hearing about it. :)
How about
rm -rf $project
svn checkout svn+ssh://server/usr/local/svn/repos/$project
I wrote a perl script to first run svn cleanup to handle any locks, and then parse the --xml output of svn status, removing anything which has a bad status (except for externals, which are a little more complicated)
Then I found this:
http://svn.apache.org/repos/asf/subversion/trunk/contrib/client-side/svn-clean
Even though this doesn't do everything I want, I'll probably discard the bulk of my code and just enhance this a little. My XML parsing is not as pretty as it could be, and I'm sure this is somewhat faster than launching a system command (which matters on a very large repository and a command which is run every five minutes).
I ultimately found that script in the answer to this question - Automatically remove Subversion unversioned files - hidden among all the suggestions to use Tortoise SVN.

Using version control with non-hierarchical code?

I am looking at putting a code base that runs several website into version control. There are several instance of this code base running websites on different virtual servers.
The problem I'm grappling with is that each of these separate instances of more or less the same code have sub-directories with site-specific functions. But it seems that version control systems want to control the entire directory hierarchy.
For instance, each instance has the directory
/www/smarty/libs/plugins/
Where you'll find site-specific functions for smarty. When we are ready to put it into version control, the folder /www would be the root.
So one option is to have all the site-specific functions going out to all sites. I don't see a problem in and of itself, but it seems somehow architecturally 'wrong'. There would be a bunch of files that only belong to one deployment.
Another option is to have a separate repository for each site's specific files within the code base. But that sounds like it could quickly become a nightmare when trying to get new sites deployed properly.
What's the best way to do this? The version control system we're looking at is subversion.
Generally, source control systems should be used to control source. They are not at their best completely controlling file hierarchies, permissions, and other related things. These are best left to deployment configuration.
How about having each of the projects and directories you need represented once in the version control system. Then, in a separate directory (perhaps called /build/), have the various configuration layouts. You might have an ant file that builds each site, or maven. Or you can use tools like Capistrano or Fabric to have more control over each deployment.
The tools are made to be flexible (generally), so here are some suggestions:
Most VCS' allow you to ignore files and directories through some mechanism (e.g. Mercurial .hg ignore file), so you should be able to target what you want/should control versus what shouldn't be.
Separate the files/directories into common resource project and site-specific projects and then use a build system to integrate them to create a deployable package. The build system can be as simple as a shell script or a more sophisticated framework. If its a really simple integration, the VCS may have some basic features for merging bases (e.g. Mercurial subrespositories).
With subversion, you could have a bunch of repositories:
www be in a general repository
plugins each be in a site-specific repository
Then have nested working copies:
svn co http://www_repo www
cd www/smarty/libs
svn co http://foo_plugins_repo plugins
Tip: add plugins to svn:ignore property of www/smarty/libs
svn propset svn:ignore "plugins" www/smarty/libs
You could certainly do that with git too (through .gitignore), and probably with other version control systems but I don't know them.
(Alternatively you could skip the nested working copy part (which can freak some people out) and check out stuff side by side, but use a symlink in lieu of smarty/libs/plugins, while ignore still pertains)
You're missing a "build" step, which whould take the source in source control and create the deployment bundles for the different sites. Only one source package is needed, different build configurations create the different deployment packages. Don't try to directly put the deplyoment set into source control, it is not the source!
I believe the best thing to do would be to create a top level directory in your repository for each site (Site-01, Site-02, etc) and inside those directories put the source tree. Then you can checkout the projects separately. I think it's acceptable and somewhat standard to use the same repository for all the projects your company is involved with.
My terminology might be off kilter, but the fundamental idea is sound, I believe.

Emulating symlink-like behaviour in a source control repository

Suppose I have the following (desired) folder structure:
*CommonProject
*Project#1
----> CommonProject(link)
*Project#2
----> CommonProject(link)
Where the CommonProject is the location of the source belonging to that project, and CommonProject(link) is merely a soft link to the main location. If we imagine this as a tree-view in a visual client, if I expand Project#1 I will see CommonProject there as a subdirectory, even though the files are not actually stored there.
The purpose of this is to enable the following behaviour:
When I check out Project#1 I get the files associated with that project as well as a subfolder CommonProject containing all of its files (as if Project#1 contained the copy of the files in the Version Control repository). Now if I were to modify CommonProject's files inside of Project#1 and was to submit my changes to the repository, the changes would go into the CommonProject location (no file is actually stored locally under Project#1 in the repository). Now if I was to sync Project#2, as it also contains symlink to CommonProject, it will now get my updates.
Essentially the duplication of files only exists on my machine, but in the repository there is only one version of CommonProject.
I know Perforce can’t do this, without juggling 3 specs. This is very complicated and error prone, especially when a lot of people do it. Is there a source control repository out there that can do this? (a pointer to some docs on how it can be done is a plus)
Thank you.
Subversion can directly store symlinks in the repository. This only works for operating systems that support symlinks though, as svn just stores the symlink the same way it would with any other file.
I think what you really want is to link to separate projects though. Subversion supports this through externals and git through submodules. Another alternative is to manage this sort of thing with in your build process, so that some static resources are gathered when you initialize the build. Generally, updating a utilities library that changes often is going to cause stability problems, so you can do this manually (or with clever scripts) when you need to
You'd probably be much better off just storing the projects in a flat directory (1 directory per project, all at the same level), and using whatever you build system or IDE is to link all the stuff together.

How to actually use a source control system?

So I get that most of you are frowning at me for not currently using any source control. I want to, I really do, now that I've spent some time reading the questions / answers here. I am a hobby programmer and really don't do much more than tinker, but I've been bitten a couple of times now not having the 'time machine' handy...
I still have to decide which product I'll go with, but that's not relevant to this question.
I'm really struggling with the flow of files under source control, so much so I'm not even sure how to pose the question sensibly.
Currently I have a directory hierarchy where all my PHP files live in a Linux Environment. I edit them there and can hit refresh on my browser to see what happens.
As I understand it, my files now live in a different place. When I want to edit, I check it out and edit away. But what is my substitute for F5? How do I test it? Do I have to check it back in, then hit F5? I admit to a good bit of trial and error in my work. I suspect I'm going to get tired of checking in and out real quick for the frequent small changes I tend to make. I have to be missing something, right?
Can anyone step me through where everything lives and how I test along the way, while keeping true to the goal of having a 'time machine' handy?
Eric Sink has a great series of posts on source control basics. His company (Sourcegear) makes a source control tool called Vault, but the how-to is generally pretty system agnostic.
Don't edit your code on production.
Create a development environment, with the appropriate services (apache w/mod_php).
The application directory within your dev environment is where you do your work.
Put your current production app in there.
Commit this directory to the source control tool. (now you have populated source control with your application)
Make changes in your new development environment, hitting F5 when you want to see/test what you've changed.
Merge/Commit your changes to source control.
Actually, your files, while stored in a source repository (big word for another place on your hard drive, or a hard drive somewhere else), can also exist on your local machine, too, just where they exist now.
So, all files that aren't checked out would be marked as "read only", if you are using VSS (not sure about SVN, CVS, etc). So, you could still run your website by hitting "F5" and it will reload the files where they currently are. If you check one out and are editing it, it becomes NOT read only, and you can change it.
Regardless, the web server that you are running will load readonly/writable files with the same effect.
You still have all the files on your hard drive, ready for F5!
The difference is that you can "checkpoint" your files into the repository. Your daily life doesn't have to change at all.
You can do a "checkout" to the same directory where you currently work so that doesn't have to change. Basically your working directory doesn't need to change.
This is a wildly open ended question because how you use a SCM depends heavily on which SCM you choose. A distributed SCM like git works very differently from a centralized one like Subversion.
svn is way easier to digest for the "new user", but git can be a little more powerful and improve your workflow. Subversion also has really great docs and tool support (like trac), and an online book that you should read:
http://svnbook.red-bean.com/
It will cover the basics of source control management which will help you in some way no matter which SCM you ultimately choose, so I recommend skimming the first few chapters.
edit: Let me point out why people are frowning on you, by the way: SCM is more than simply a "backup of your code". Having "timemachine" is nothing like an SCM. With an SCM you can go back in your change history and see what you actually changed and when which is something you'll never get with blobs of code. I'm sure you've asked yourself on more than one occasion: "how did this code get here?" or "I thought I fixed that bug"-- if you did, thats why you need SCM.
You don't "have" to change your workflow in a drastic way. You could, and in some cases you should, but that's not something version control dictates.
You just use the files as you would normally. Only under version control, once you reach a certain state of "finished" or at least "working" (solved an issue in your issue tracker, finished a certain method, tweaked something, etc), you check it in.
If you have more than one developer working on your codebase, be sure to update regularly, so you're always working against a recent (merged) version of the code.
Here is the general workflow that you'd use with a non-centralized source control system like CVS or Subversion: At first you import your current project into the so-called repository, a versioned storage of all your files. Take care only to import hand-generated files (source, data files, makefiles, project files). Generated files (object files, executables, generated documentation) should not be put into the repository.
Then you have to check out your working copy. As the name implies, this is where you will do all your local edits, where you will compile and where you will point your test server at. It's basically the replacement to where you worked at before. You only need to do these steps once per project (although you could check out multiple working copies, of course.)
This is the basic work cycle: At first you check out all changes made in the repository into your local working copy. When working in a team, this would bring in any changes other team members made since your last check out. Then you do your work. When you've finished with a set of work, you should check out the current version again and resolve possible conflicts due to changes by other team members. (In a disciplined team, this is usually not a problem.) Test, and when everything works as expected you commit (check in) your changes. Then you can continue working, and once you've finished again, check out, resolve conflicts, and check in again. Please note that you should only commit changes that were tested and work. How often you check in is a matter of taste, but a general rule says that you should commit your changes at least once at the end of your day. Personally, I commit my changes much more often than that, basically whenever I made a set of related changes that pass all tests.
Great question. With source control you can still do your "F5" refresh process. But after each edit (or a few minor edits) you want to check your code in so you have a copy backed up.
Depending on the source control system, you don't have to explicitly check out the file each time. Just editing the file will check it out. I've written a visual guide to source control that many people have found useful when grokking the basics.
I would recommend a distributed version control system (mercurial, git, bazaar, darcs) rather than a centralized version control system (cvs, svn). They're much easier to setup and work with.
Try mercurial (which is the VCS that I used to understand how version control works) and then if you like you can even move to git.
There's a really nice introductory tutorial on Mercurial's homepage: Understanding Mercurial. That will introduce you to the basic concepts on VCS and how things work. It's really great. After that I suggest you move on to the Mercurial tutorials: Mercurial tutorial page, which will teach you how to actually use Mercurial. Finally, you have a free ebook that is a really great reference on how to use Mercurial: Distributed Revision Control with Mercurial
If you're feeling more adventurous and want to start off with Git straight away, then this free ebook is a great place to start: Git Magic (Very easy read)
In the end, no matter what VCS tool you choose, what you'll end up doing is the following:
Have a repository that you don't manually edit, it only for the VCS
Have a working directory, where you make your changes as usual.
Change what you like, press F5 as many times as you wish. When you like what you've done and think you would like to save the project the way it is at that very moment (much like you would do when you're, for example, writing something in Word) you can then commit your changes to the repository.
If you ever need to go back to a certain state in your project you now have the power to do so.
And that's pretty much it.
If you are using Subversion, you check out your files once . Then, whenever you have made big changes (or are going to lunch or whatever), you commit them to the server. That way you can keep your old work flow by pressing F5, but every time you commit you save a copy of all the files in their current state in your SVN-repository.
Depends on the source control system you use. For example, for subversion and cvs your files can reside in a remote location, but you always check out your own copy of them locally. This local copy (often referred to as the working copy) are just regular files on the filesystem with some meta-data to let you upload your changes back to the server.
If you are using Subversion here's a good tutorial.
Depending on the source control system, 'checkout' may mean different things. In the SVN world, it just means retrieving (could be an update, could be a new file) the latest copy from the repository. In the source-safe world, that generally means updating the existing file and locking it. The text below uses the SVN meaning:
Using PHP, what you want to do is checkout your entire project/site to a working folder on a test apache site. You should have the repository set up so this can happen with a single checkout, including any necessary sub folders. You checkout your project to set this up one time.
Now you can make your changes and hit F5 to refresh as normal. When you're happy with a set of changes to support a particular fix or feature, you can commit in as a unit (with appropriate comments, of course). This puts the latest version in the repository.
Checking out/committing one file at a time would be a hassle.
A source control system is generally a storage place for your files and their history and usually separate from the files you're currently working on. It depends a bit on the type of version control system but suppose you're using something CVS-like (like subversion), then all your files will live in two (or more) places. You have the files in your local directory, the so called "working copy" and one in the repository, which can be located in another local folder, or on another machine, usually accessed over the network. Usually, after the first import of your files into the repository you check them out under a working folder where you continue working on them. I assume that would be the folder where your PHP files now live.
Now what happens when you've checked out a copy and you made some non-trivial changes that you want to "save"? You simply commit those changes in your working copy to the version control system. Now you have a history of your changes. Should you at any point wish to go back to the version at which you committed those changes, then you can simply revert your working copy to an older revision (the name given to the set of changes that you commit at once).
Note that this is all very CVS/SVN-specific, as GIT would work slightly different. I'd recommend starting with subversion and reading the first few chapters of the very excellent SVN Book to get you started.
This is all very subjective depending on the the source control solution that you decide to use. One that you will definitely want to look into is Subversion.
You mentioned that you're doing PHP, but are you doing it in a Linux environment or Windows? It's not really important, but what I typically did when I worked in a PHP environment was to have a production branch and a development branch. This allowed me to configure a cron job (a scheduled task in Windows) for automatically pulling from the production-ready branch for the production server, while pulling from the development branch for my dev server.
Once you decide on a tool, you should really spend some time learning how it works. The concepts of checking in and checking out don't apply to all source control solutions, for example. Either way, I'd highly recommend that you pick one that permits branching. This article goes over a great (in my opinion) source control model to follow in a production environment.
Of course, I state all this having not "tinkered" in years. I've been doing professional development for some time and my techniques might be overkill for somebody in your position. Not to say that there's anything wrong with that, however.
I just want to add that the system that I think was easiest to set up and work with was Mercurial. If you work alone and not in a team you just initialize it in your normal work folder and then go on from there. The normal flow is to edit any file using your favourite editor and then to a checkin (commit).
I havn't tried GIT but I assume it is very similar. Monotone was a little bit harder to get started with. These are all distributed source control systems.
It sounds like you're asking about how to use source control to manage releases.
Here's some general guidance that's not specific to websites:
Use a local copy for developing changes
Compile (if applicable) and test your changes before checking in
Run automated builds and tests as often as possible (at least daily)
Version your daily builds (have some way of specifying the exact bits of code corresponding to a particular build and test run)
If possible, use separate branches for major releases (or have a development and a release branch)
When necessary, stabilize your code base (define a set of tests such that passing all of those tests means you are confident enough in the quality of your product to release it, then drive toward 0 test failures, i.e. ban any checkins to the release branch other than fixes for the outstanding issues)
When you have a build which has the features you want and has passed all of the necessary tests, deploy it.
If you have a small team, a stable product, a fast build, and efficient, high-quality tests then this entire process might be 100% automated and could take place in minutes.
I recommend Subversion. Setting up a repository and using it is actually fairly trivial, even from the command line. Here's how it would go:
if you haven't setup your repo (repository)
1) Make sure you've got Subversion installed on your server
$ which svn
/usr/bin/svn
which is a tool that tells you the path to another tool. if it returns nothing that tool is not installed on your system
1b) If not, get it
$ apt-get install subversion
apt-get is a tool that installs other tools onto your system
If that's not the right name for subversion in apt, try this
$ apt-cache search subversion
or this
$ apt-cache search svn
Find the right package name and install it using apt-get install packagename
2) Create a new repository on your server
$ cd /path/to/directory/of/repositories
$ svnadmin create my_repository
svnadmin create reponame creates a new repository in the present working directory (pwd) with the name reponame
You are officially done creating your repository
if you have an existing repo, or have finished setting it up
1) Make sure you've got Subversion installed on your local machine per the instructions above
2) Check out the repository to your local machine
$ cd /repos/on/your/local/machine
$ svn co svn+ssh://www.myserver.com/path/to/directory/of/repositories/my_repository
svn co is the command you use to check out a repository
3) Create your initial directory structure (optional)
$ cd /repos/on/your/local/machine
$ cd my_repository
$ svn mkdir branches
$ svn mkdir tags
$ svn mkdir trunk
$ svn commit -m "Initial structure"
svn mkdir runs a regular mkdir and creates a directory in the present working directory with the name you supply after typing svn mkdir and then adds it to the repository.
svn commit -m "" sends your changes to the repository and updates it. Whatever you place in the quotes after -m is the comment for this commit (make it count!).
The "working copy" of your code would go in the trunk directory. branches is used for working on individual projects outside of trunk; each directory in branches is a copy of trunk for a different sub project. tags is used more releases. I suggest just focusing on trunk for a while and getting used to Subversion.
working with your repo
1) Add code to your repository
$ cd /repos/on/your/local/machine
$ svn add my_new_file.ext
$ svn add some/new/directory
$ svn add some/directory/*
$ svn add some/directory/*.ext
The second to last line adds every file in that directory. The last line adds every file with the extension .ext.
2) Check the status of your repository
$ cd /repos/on/your/local/machine
$ svn status
That will tell you if there are any new files, and updated files, and files with conflicts (differences between your local version and the version on the server), etc.
3) Update your local copy of your repository
$ cd /repos/on/your/local/machine
$ svn up
Updating pulls any new changes from the server you don't already have
svn up does care what directory you're in. If you want to update your entire repository, makre sure you're in the root directory of the repository (above trunk)
That's all you really need to know to get started. For more information I recommend you check out the Subversion Book.