Practical SVN for PHP Developers
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Practical SVN for PHP Developers

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Practical SVN for PHP Developers Practical SVN for PHP Developers Presentation Transcript

  • Practical SVN for PHP Developers Matthew Weier O'Phinney Project Lead Zend Framework Lorna Jane Mitchell Software Engineer Ibuildings
  • What is Version Control?
    • What did you change from the previous revision?
    • What changes have others recorded since your last local update?
    Change Management
  • Types of Version Control
    • Each checkout is a fully functional repository
    • Anybody may accept patches from anyone else
    • Anybody may send patches to anyone else
    • Ideal for projects with parallel feature developement
    Distributed
    • One canonical repository
    • All changes are submitted to the repository
    • All changes are retrieved from the repository
    • Ideal when:
      • a canonical version is required,
      • access to the repository should be controlled
    Non-Distributed
  • What is Subversion?
    • Non-Distributed Version Control System
    • Successor to CVS
    • Stores and versions:
      • source code
      • documentation
      • anything, really
    Subversion is...
  • Installing Subversion
  • Choose a Protocol
    • give repo access to local users
    • give users and/or groups read/write on the repo to grant access
    • file:///home/lorna/svn-repos/main/trunk/
    Local filesystem
    • give repo access to users with ssh credentials
    • give users and/or groups read/write on the repo to grant access
    • svn+ssh svn://rivendell/home/lorna/svn-repos/main/trunk
    svn+ssh
    • make repo web-browseable and have apache handle credentials
    • basic or digest HTTP authentication (e.g., .htpasswd)
    • mod_authz_svn - an Apache module to give finer access control
    • http://svn.example.com/main/trunk
    WebDAV via HTTP/S
  • Installing on Linux
    • Debian/Ubuntu: aptitude install subversion
    • Fedora/RedHat: yum install subversion
    Distribution packages
    • download from http://subversion.tigris.org
    • check dependencies (install apache, mod_dav, etc., first)
    • compile
    From source
  • Setting up a repository
  • What is a repository ?
    • The place all changesets are stored
    • A black box; you may only interact with it using svn tools
    A repository is...
  • Creating the repository
  • Use “svnadmin create”
  • Create initial content
  • Commit initial structure
  • Alternate way: import into the repo
  • About repository structure
    • Trunk – the main code version
    • Branches – copies of code which can be modified
    • Tags – copies of code which are never changed
    • All are “cheap” copies
    Repository Structure
  • Using Subversion
  • Checkout: svn checkout (co)
  • .svn directory
  • Status: svn status (st)
    • ' ' no modifications
    • 'A' Added
    • 'C' Conflicted
    • 'D' Deleted
    • 'M' Modified
    • '?' item is not under version control
    • '!' item is missing (removed by non-svn command) or incomplete
    • 'X' external resource managed by svn (svn:externals)
    Common status codes
  • Add to repo: svn add
  • Commit to repo: svn commit (ci)
  • Changelog: svn log
  • Dealing with missing files
    • “ !” in the status listing
    • Usually because something was moved or deleted without using the svn tools
    • Always use svn rm and svn mv
    • To fix: update (svn up) and try again
    Missing files - ! in the status
  • What and When to commit
    • hourly, semi-daily, daily checkins
    • code only, tests only, docs only
    Bad practices
  • Each commit should include all code, tests, and docs related to a discrete behavior or set of functionality. The Best Practice:
    • Easy to “cherry-pick” changesets between branches
    • Trivial to identify changesets to rollback
    Why?
  • Examples
  • Examples
    • PLAN your project; break it into distinct units of functionality
    • Use an issue tracker; issues should include expectations, actual results, and reproduce code (these become your tests!)
    • No unit of functionality should take more than 3-4 hours to implement; longer, and it likely should be broken into sub-tasks.
    How?
  • Conflicts
    • svn blame / annotate / praise
    • shows who last edited which line
    svn blame
  • Example
    • Two people change same line of same file
    • svn will ask user to choose
    Conflicts
    • index.php.r4 version from before either your changes or the commit that has conflicted
    • index.php.r6 current repo version
    • index.php.mine working copy before server showed conflict
    • index.php whole file with some markup to show just the conflict(s) in place
    Example: conflict adds files
    • edit index.php until correct
    • may copy one of the "extra" files into place of this one
    • let SVN know you're all sorted
    svn resolved
    • Good team communication
    • Update often
    • Commit first!
    Avoiding Conflicts
  • Branching and Tagging
  • Patterns
  • Feature Branches Graph by Eli White
    • Pros:
      • Features may be developed in isolation
      • Trunk always contains “finished” features
    • Cons:
      • Features may be developed in isolation
      • Hard to cleanly merge at times if multiple features touch the same areas of code
      • Harder to rollback (trunk doesn't always have discrete featuresets)
    Feature Branches
  • Long-lived Branches Graph by Eli White
    • Pros:
      • Production is always stable
      • Rollback by pointing to production tags
    • Cons:
      • Long-lived feature development often lags trunk features
        • Difficult to determine what to merge
      • Difficult to do parallel feature development
      • More difficult to rollback specific features
    Long-lived Branches
  • Release Branches Graph by Eli White
    • Pros:
      • Easy to isolate features by version (parallel development)
      • Possibility of keeping multiple active versions of a project
    • Cons:
      • Harder to merge patches between branches (files may differ widely)
    Release Branches
  • Merging
    • Moving changes between branches (including trunk)
    • Merge single changes
    • Merging as part of a branch lifecycle
    Merging
    • Check out the target branch
    • From the target directory, run svn diff until the output illustrates the operation you wanted
    • Replace "diff" with "merge"
    • Review changes to working copy and/or test
    How to merge
    • Use “svn log” to identify discrete changesets you want to merge.
    • Use the “cherry-pick” flag of “svn merge” (-c) to merge that single changeset.
    • Works well if you're following the best practices outlined earlier!
    How to merge: the easy way
  • Administering Repositories
  • Backing up your Repository
    • Copying files directly can lead to corruption in the copy
    • Use “svnadmin hotcopy” or “svnadmin dump”
    svnadmin hotcopy
  • Authentication
    • Dependent on how the OS does authentication:
      • Local accounts
      • “ Virtual” accounts
      • etc.
    • SSH public keys are a common solution
    svnserve or svn+ssh
    • Typically HTTP basic or digest authentication
      • Use htpasswd to generate user/pass pairs
      • Can still allow anonymous access
      • Configure your server to require it
    WebDAV (http/https)
  • Example HTTP Auth configuration
  • Authorization
    • Typically conf/authz in your repo, or “access.conf” accessible to web server
    • INI-style file with [sections]
      • [groups] section to define users and groups
      • [/path] specifies path on repo
      • [repo:/path] specifies path on specific repo (if more than one repo defined)
    ACL File
    • ACLs:
      • [user|group] = [r|rw]
      • “ *” as group/user means any user
      • Groups are prefixed with “@”
    ACL File
  • ACL File: example
    • Svnserve, file access, or svn+ssh: conf/authz in your repository
    • WebDAV: anywhere.
      • Tell your vhost where to find it
      • Must setup authorization prior to authentication
    ACL File: placement
  • ACL File in WebDAV: vhost setup
  • Hooks
    • Allow extending SVN's capabilities via userland scripts
    • “ Hook” into specific processes:
      • pre/post-commit, start-commit
      • pre/post-revprop-change
      • pre/post-lock
      • pre/post-unlock
    What are hooks?
  • Running a linter REPOS = "$1" TXN = "$2" PHP = "/path/to/php" SVNLOOK = "/path/to/svnlook" AWK = "/path/to/awk" GREP = "/path/to/egrep" SED = "/path/to/sed" CHANGED = `$SVNLOOK changed -t "$TXN" "$REPOS" | $AWK '{print $2}' | $GREP php$` for FILE in $CHANGED do MESSAGE = `$SVNLOOK cat -t "$TXN" "$REPOS" "$FILE" | $PHP -l` if [ $? - ne 0 ] then echo 1 >& 2 echo "***********************************" 1 >& 2 echo "PHP error in: $FILE:" 1 >& 2 echo `echo "$MESSAGE" | $SED "s| -| $FILE|g"` 1 >& 2 echo "***********************************" 1 >& 2 exit 1 fi done
  • *********************************** PHP error in: test.php echo $foobar *********************************** Sample linter output
    • Run post-commit – prevents blocking issues
    • Send email notification when tests fail
    • Two approaches:
      • Run entire suite
      • Grep committed files for classes, and test just those classes
    • Typically best to do this from a Continuous Integration server, and not via subversion hooks
    Running unit tests
    • Email, Nabaztag, TwitterSVN
    • Email notifications post-commit
    • SVN::Notify:
      • http://search.cpan.org/~dwheeler/SVN-Notify-2.79/lib/SVN/Notify.pm
      • Can selectively determine which people/lists get notifications based on commit path
      • Plain text and/or HTML emails
    Sending notifications
  • Example notification:
    • svn2feed.py: http://svn.collab.net/repos/svn/trunk/tools/hook-scripts/svn2feed.py
    • Add svn2feed.py to your hooks/ directory
    Publishing RSS Feeds
  • Adding svn2feed.py to your post-commit hook: path / to / python path / to / hooks / svn2feed.py -- svn - path / usr / bin / -- max - items = 100 -- format = atom -- revision "$REV" – item - url "http://localhost/svn/" -- feed - url = "http://localhost/rss/svn.rss" -- feed - file "path/to/rss/svn.rss" "$REPOS" &
    • Trigger docbook build process, or PhpDocumentor
    • Run post-commit, so as not to block
    • Typically best done from a CI server, and not subversion hooks
    Generating documentation
    • PHP_CodeSniffer includes a script, bin/scripts/phpcs-svn-pre-commit
      • Edit the script to provide the path to svnlook:
      • define('PHP_CODESNIFFER_SVNLOOK', '/usr/bin/svnlook');
    • Edit the pre-commit hook script to invoke the script:
      • /path/to/bin/scripts/phpcs-svn-pre-commit "$REPOS" -t "$TXN" >&2 || exit 1
    Running PHP_CodeSniffer
        • Transmitting file data .svn: Commit failed (details follow):
        • svn: 'pre-commit' hook failed with error output:
        • FILE: temp.php
        • ---------------------------------------------------------------
        • FOUND 1 ERROR(S) AND 0 WARNING(S) AFFECTING 1 LINE(S)
        • ---------------------------------------------------------------
        • 2 | ERROR | Missing file doc comment
        • --------------------------------------------------------------
    PHP_CodeSniffer hook output
        • http://pear.php.net/manual/en/package.php.php-codesniffer.svn-pre-commit.php
    For more info on PHP_CodeSniffer:
  • Deploying from SVN
    • What else needs to happen at deploy time?
    • Preserve uploads
    • Set permissions
    • Database patches
    Deployment Considerations
    • Checkout retains link to repo
    • Meta data present on server
    • Inconsistent state during update
    • Export is clean copy, no dependencies
    • Other ways to keep track of version
    Checkout or Export
    • Tag and export from svn – include some tag info
    • Use symlinks to enable seamless switching
    • Wrap in a script
    • Have a rollback plan/script
    • Consider database strategies
    Best Practices
  • Thank you.