Building GitHub projects on Jenkins slaves on OpenShift

This post showed how to build GitHub projects with Jenkins, Maven and SonarQube 4 on OpenShift. For starters, it used the Jenkins master node for running build jobs. However, when running on a small gear, the master node might run out of memory pretty fast, resulting in a reboot of the node during builds.

In order to resolve this issue, there are two options:

  • limitting the memory of the build or
  • running the build on a slave node.

As spawning additional nodes is easy in a PaaS context such as OpenShift and provides a better performance than running builds with small memory, the slave solution seems to be the better approach.

This post shows how.

  1. Create new DYI app as a slave node (a how-to can be found here), name the node e.g. slave
  2. Create node in Jenkins
    1. Go to Jenkins web UI and create new node:
      https://jenkins-<yourAccount>.rhcloud.com/computer/new
    2. Set the following values:
      Remote FS root:/app-root/data folder on slave. Typically this is /var/lib/openshift/<slave's UID>/app-root/data/jenkins, you can find out by SSHing to the slave node and calling

      echo $OPENSHIFT_DATA_DIR/app-root/data/jenkins

      Labels: Some label to use within builds to refer the node, e.g. OS Slave #1
      Host: the slave’s hostname, e.g. slave-<youraccount>.rhcloud.com

    3. Add Credentials
      username: <slave's UID>
      Private Key File:Path to a private key file that is authorized for your OpenShift account. In the first post this path was used: /var/lib/openshift/<UID of your jenkins>/app-root/data/git-ssh/id_rsa. Note: $OPENSHIFT_DATA_DIR seems not to work here.
      BTW: You can change the credentials any time later via this URL

      https://jenkins-<yourAccount>.rhcloud.com/credentials/
  3. Prepare slave node: Create same environment as on master in the first post
    1. Create folder structure
      mkdir $OPENSHIFT_DATA_DIR/jenkins
      mkdir $OPENSHIFT_DATA_DIR/.m2
      echo -e "&lt;settings&gt;&lt;localRepository&gt;$OPENSHIFT_DATA_DIR/.m2&lt;/localRepository&gt;&lt;/settings&gt;" &gt; $OPENSHIFT_DATA_DIR/.m2/settings.xml
      
    2. Copy SSH directory from master to same directory on slave, e.g.
      scp -rp -i $OPENSHIFT_DATA_DIR/.ssh $OPENSHIFT_DATA_DIR/.ssh &lt;slave's UID&gt;@slave-&lt;your account&gt;.rhcloud.com:app-root/data/.ssh
    3. As the different cartridges (jenkins and DIY) have different environment variables for their local IP addresses ($OPENSHIFT_JENKINS_IP vs $OPENSHIFT_DIY_IP) we’ll have to improvise at this point. There are two options: Either
      1. Replace all occurrences of $OPENSHIFT_JENKINS_IP
        In all builds and in

        https://jenkins-<yourAccount>.rhcloud.com/configure

        Sonar | Sonar installations
        Database URL: jdbc:postgresql://$OPENSHIFT_DIY_IP:15555/sonarqube
        or

      2. Create an $OPENSHIFT_JENKINS_IP environment variable on your slave machine
        rhc env set OPENSHIFT_JENKINS_IP=&lt;value of  $OPENSHIFT_DIY_IP&gt; -a slave

        You can find out the value of $OPENSHIFT_DIY_IP by SSHing to the slave and execute

        echo $OPENSHIFT_DIY_IP 
      3. I’d love to hear suggesstions that do better 😉
  4. Adapt Build
    Easiest way is to not use the master at all.
    To do so, go to

    https://jenkins-<yourAccount>.rhcloud.com/configure

    and set # of executors to 0.
    Hit Apply

  5. Limit memory usage.
    Make sure the slave does not run out of memory (which leads to a restart of the node):
    Global properties | Environment variables
    name: MAVEN_OPTS
    value: -Xmx512m
    Hit Save.
  6. Now run a build. It should run on the slave and hopefully succeed 🙂

See also Libor Krzyzanek’s Blog: Jenkins on Openshift wi… | JBoss Developer

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Modernizing android UIs part 2: design support library, switches, action buttons

After finishing the migration from Actionbarsherlock to appcompat described in the first Post on modernizing android UIs, it turns out there are even more things to modernize in terms of android UIs.

Tabs and design support library

If you used Tabs within the ActionBar, after migrating to appcompat-v7 API 22 you might recognize a warning, that tells you that they are now deprecated.

In order to modernize those, you should use the design support library that was added to the Android SDK with API level 22. Similar to the appcompat -v7, the design support library provides backports of material design components of Android lollipop (5.x) for older versions of Android.

Here’s the steps that rid you of the deprecation warning

  • Add the design library to your eclipse workspace and link it with your project in pretty much the same way as appcompat described in the first Post. The library can be found on the following path: <sdkdir>/extras/android/support/design.
    Import it into eclipse as Existing Android Code Into Workspace, change the build target to level 22, and link the appcompat project with it.
  • Add the following to maven
    <dependency>
    <groupId>com.android.support</groupId>
    <artifactId>design</artifactId>
    <version>${android.compatibility.version}</version>
    <type>aar</type>
    </dependency>
    
  • Change your code to use the new TabLayout as described here. A complete example is the cheesesquare app: activity_main.xml, include_list_viewpager.xml, MainActivity.java
  • Once you’re done with this and have the design support library up an running, you could modernize your app by using more of the library’s features like navigation drawers, floating labels and buttons, snackbars, collapsing toolsbars, etc. See this blog post for more features.

The screenshots bellow show a before-after comparison – deprecated tabs vs material design tabs.

Tabs: design support library, API-22

Tabs: design support library, API-22

Tabs: AppCompat-v7, API-22, deprecated

Tabs: AppCompat-v7, API-22, deprecated

 

Checkboxes to switches

Android API level 14 introduces the switch component, that according to google should be used when only one option is available. For API levels < 14  there’s no such thing as switches. So we’ll have to rely on checkboxes there. Here’s how to replace checkbox preferences by switches for devices running API level 14 and above

  • In a preference XML, replace CheckBoxPreference by SwitchPreference (see commit ab16eb1997dfba743abcd488b6b20de71b5c3ff0 for an example).
  • However, If you want to keep compatibility with API levels < 14, you’re only choice is to keep redundant copies of the same preferences.xml in

    • res/xml/ that contains the preferences with CheckBoxPreferences and
    • res/xml-v14/ that contains the same file with SwitchPreferences.

Another before-after comparison is shown bellow – checkboxes vs switches.

AppCompat-v7, API-22 with checkboxes

Preferences: AppCompat-v7, with checkboxes

AppCompat-v7, API-22 with switches

AppCompat-v7, API-22 with switches

Using Action Buttons

Action Buttons are icons that realize the most important actions on the actionBar if there is enough room to display them. These could have been used in Actionbarsherlock already, but if you still didn’t modernized them then it’s about time 🙂

One reason for not using action buttons might be that you don’t have suitable icons. Here’s the solution: Google provides a huge amount of material design icons under open source (CC-BY) license. They can be found on this site, or you can just clone their git repository.

So it’s as easy as that

  • Choose proper icons for your actions and copy them to your res/drawable-xyz folders
  • Add icon tags to your menu.xml like so
        <item
            android:id="@+id/action_refresh"
            android:icon="@drawable/ic_refresh_white_24dp"
            android:title="@string/action_refresh"
            app:showAsAction="ifRoom"/>

And that’s it. See bellow for an example. For an example see the commit that realized this change.

AppCompat-v7, API-22, ActionBar with menu

AppCompat-v7, API-22, ActionBar with menu

AppCompat-v7, API-22, ActionBar with action buttons

AppCompat-v7, API-22, ActionBar with action buttons

Modernizing android UIs part 1: Migrating from Actionbarsherlock to Material Design

This post shows by example the steps that are necessary for migrating an android application from Actionbarsherlock to Material Design (introduced in android KitKat/Version 5.x/API level 21/22), while keeping compatibility with at least android Gingerbread/Version 2.3 /API level 9). It uses the appcompat-v7 library on API level 22. The app that was migrated (nusic) in this example is developed using Eclipse, Maven and RoboGuice.

Before-after comparison

Let’s begin with some before-after screenshots:

ActionBarSherlock

ActionBarSherlock

AppCompat-v7, API-22

AppCompat-v7, API-22

02-nusic-abs-prefs

Preferences: ActionBarSherlock

Preferences: AppCompat-v7, API-22

Preferences: AppCompat-v7, API-22

Basic migration (appcompat-v7)

The following lists the steps that were implemented in order to change the app as depicted in the screenshots above.

  • Update Android SDK Tools
  • Eclipse
    • Setup Eclipse project for appcompat described here.
    • Link your project with it. Right click on your project | Properties | Android | Library | Add
      eclipse-choose-appcompat
    • Remove action bar sherlock. Same menu as above.
  • Set Up Maven Build
    • <repositories>
      <repository>
      <id>android</id>
      <url>file://${env.ANDROID_HOME}/extras/android/m2repository</url>
      </repository>
      </repositories>
      
    • <dependency>
      <groupId>com.android.support</groupId>
      <artifactId>appcompat-v7</artifactId>
      <version>${android.compatibility-v7.version}</version>
      <type>aar</type>
      </dependency>
      
  • Migrate from Actionbarsherlock to appcompat
    • styles.xml

      <!-- <style name="AppBaseTheme" parent="@style/Theme.Sherlock"> -->
       <style name="AppBaseTheme" parent="@style/Theme.AppCompat">
      
    • Replacing classes
      • RoboSherlockFragment -> RoboFragment
      • RoboSherlockFragmentActivity -> RoboActionBarActivity
      • RoboSherlockPreferenceActivity -> Write your own RoboAppCompatPreferenceActivity that looks like this (or as described here) but is derived from RoboPreferenceActivity (see here for the class that was used in the example).
        Then derive your class from it as before with RoboSherlockPreferenceActivity.
    • Replacing methods
      • getSherlockActivity() -> getActivity()
      • getSupportMenuInflater() -> getMenuInflater()
    • Fixing imports
      • android.view.Menu
      • android.support.v7.app.ActionBar
    • Updating proguard.cfg
      • Remove actionbarsherlock
      • Add
        # support4, appcompat-v7, design support
        -dontwarn android.support.**
        -keep class android.support.** { *; }
        -keep interface android.support.** { *; }
        

For further info please see

iTunes: Exporting playlists with relative paths

TL;DR; A way of exporting iTunes playlists with relative paths is described here.

iTunes Export

Once upon a time I wrote a little tool for exporting playlists from Songbird/Nightinale. After migrating to iTunes, I was looking for a tool that provides the same functionality for iTunes. Fortunately, there already is one: iTunes Export. It’s twofold – you can either use a UI or a console version. I’m more the console type of guy, so my choice is clear. The latest release, version 2.2.2, was released in 2010, almost 5 years ago… and it still works with iTunes 12.1.2 – it’s a miracle! And it’s fast – my approximately 100 playlists are exported in less than 2 minutes.

Relative Playlist workaround

Among all those parameters of iTunes export, there is none for creating relative playlists, though. However, we can use a workaround for achieving this, by combining the musicPath and musicPathOld parameters. Here’s what the doc says:

  • musicPath
    iTunes Export will use the absolute location of your music files in the playlist. iTunes Export accepts a command line parameter that will override this default. Example:

    java -jar itunesexport.jar -musicPath="c:\My Music Directory"
  • musicPathOld
    Tunes Export will only apply the prefix to tracks stored in the directory configured in iTunes as the iTunes Music Folder location. Files stored in a different directory will not have the prefix applied.If you only wish to override a portion of the music path you can specifi the musicPathOld parameter. iTunes Export will replace this path with the musicPath parameter instead of replacing the default music path.

    java -jar itunesexport.jar -musicPathOld="c:\My Old Path"

A bit complicated, eh?!

Exporting playlists with relative paths by example

I’ll point out how we can use those parameters by a small example. Imagine the following folder structure

D:\Music\
  Playlists\
  Artist1\ 
    Song1.ext
  Artist2\
    Album\
      Song2.ext
  iTunes
    iTunes Library.xml

If we had a playlist call playlistX that contained Song1 and Song2 (anyone remember a band called Blur? 🙂 ) and we would export it without further parameters to the Playlists folder, it would look like this:

D:\Music\Artist1\Song1.ext
D:\Music\Artist2\Album\Song2.ext

What we’re going to do is replace the absolute part with a relative one (in respect to the destination folder for playlists). In our example: Replace “D:\Music” by “..” because it’s the parent folder of “D:\Music\Playlists“. That’s exactly what the parameters mentioned above are for! musicPathOld is the the part that is going to be replaced by musicPath. Speaking of which, our call to iTunesExport looks like this:

java -jar itunesexport.jar -library="D:\Music\iTunes\iTunes Library.xml" -outputDir="D:\Music\Playlists" -musicPath=".." -musicPathOld="D:\Music"

and results in the file D:\Music\Playlists\playlistX.m3u

..\Artist1\Song1.ext
..\Artist2\Album\Song2.ext

Migrating from Songbird/Nightingale to iTunes

TL;DR; If you still use Songbird or Nightingale and want to migrate your music database to iTunes, start reading here.

Bye-bye Songbird, bye-bye Nightingale

Is anyone out there still using Nightingale or even Songbird? I started using Songbird in 2009 (or even earlier) and switched to Nightingale in 2013. All that time I loved the open source approach of both applications and even contrtibuted a bit myself. However, there also were a lot of drawbacks like performance, incompatibilities of addons after each new version, etc. Speaking of addons – the idea of a modular media player that is extensible just like Firefox or Thunderbird is wonderful. However, it seems to me there’s not much of a community left that releases addons for Nightingale. One of my favorites used to be MLyrics, which was last released in 2013 and doesn’t work properly anymore in the current version of Nightingale (at least for me). Still, there seems to be some development going on. Same goes for the core media player software itself: We all know that Songbird was discontinued in 2013 and the last release of Nightingale was published in January, 2014. Even though there also seems to be some development going on, I lost hope that there will be better usability at some point. So I finally decided with a heavy heart to move on. Nevertheless, I’d like to say thank you to all the Nightingale developers for their strong efforts to keep the dream of a real open source alternative for iTunes alive.

Is there a better alternative to Nightingale? That question I cannot answer properly. My reasons for migrating to iTunes are that it has been maintained by a huge company for years and it’s one of the most popular media players around. So hopefully, it might get along better with my rather huge media library in terms of performance. Plus it is the only tool that is capable of feeding my iPod Nano 6 :-/

Technical approaches of migrating to iTunes

Leaving sentimentality behind – how to migrate from Songbird/Nightingale to iTunes?

One of the nice things about Songbird/Nightingale is their SQLite database. I already worked with it before when creating a playlist exporter for Songbird using the java programming language. It’s always a good idea not to reinvent the wheel. So after extracting the database wrapper into a separate project – songbirdDbApi4j (right now, I really wonder why I named it like this 😮 ) – we’re halfway done with the Songbird to iTunes migration. Almost.

The other half – importing to iTunes was a bit more challenging. iTunes stores its database in an XML file. So one approach is to access this XML directly, just like tools such as iTunesExport. However, this file is generated by iTunes merely for the purpose of exporting, the actual database is stored in the ITL file. It would be possible to recreate the ITL from the XML, but this approach is not very convenient. So a different approach might be more suitable here: on Windows, iTunes offers a COM Interface. It’s poorly documented but fortunately, the developers of COM4j implemented it as one of their sample projects. In order to ease the use of this API, I create a very basic Java wrapper for iTunes’ COM API (itunes4j).

Almost done! What’s missing is a bit of glue logic that reads all files, some of their attributes and all playlists from songbird using songbirdDbApi4j and adds them to iTunes via iTunes4j.

Migrating to iTunes

After a lot of empirical studies and nightly test migrations, I’m proud to present a tool for migrating from songbird to iTunes: songbird2itunes. In case there happen to be any other Nightingale survivors out there that run on Windows and would like to migrate their music database to iTunes, you might just give it a go!

I did my best to make it a resilient migration tool. Still, there might be errors. So:

  1. Double check if you really want to leave Nightingale behind
  2. Make sure to read the wiki first. If you’re sure you want to do this, start the migration as described there.
  3. When the migration is done, check if the statistics show any warnings.
  4. If so, look for WARN in the songbird2itunes.log and see if those are not critical for you.
  5. In case of error, please fix it and contribute 🙂
  6. Manually check your new iTunes library, making sure everything is as expected

Building GitHub projects with Jenkins, Maven and SonarQube 4.1.1 on OpenShift

Basic installation SonarQube

There are different community-driven sonar cartridges around. There is

  • this one that bases on a Tomcat cartridges and provides SonarQube 3.x and
  • that one that comes with SonarQube 4.0.
  • The most uptodate and flexible one is this, though. It downloads a specific version of SonarQube with each build. At the moment it works with version 4.1.1. I’m still working on getting SonarQube 5 to run on openshift, but haven’t succeeded, yet.

There also is a tutorial that shows how to install SonarQube 3.1.1. It also contains general thoughts on how to bypass OpenShift’s restrictions.

Anyway, to install SonarQube 4.1.1 execute the following steps on your machine:

    1. rhc app create sonar diy-0.1 postgresql-9.2

Make sure to remember the login and passwords!

  1. git rm -r diy .openshift misc README.md
    git remote add upstream -m master https://github.com/worldline/openshift-sonarqube.git
    git pull -s recursive -X theirs upstream master
    git push
    
  2. Login to your SonarQube instance at
    http://sonar-<yourAccount>.rhcloud.com/

    The default login and passwords are admin / admin.
    You might want to change the password right away!

Basic installation Jenkins

A lot of information within this paragraph was taken from here.

  1. Create Jenkins gear with Git-SSH
    rhc create-app jenkins  jenkins-1  "https://cartreflect-claytondev.rhcloud.com/reflect?github=majecek/openshift-community-git-ssh"
  2. Authorize your Jenkins node to communicate with other gears (and with you Git Repository)
    Generate SSH key for your Jenkins node
    SSH to the jenkins node

    ssh-keygen -t rsa -b 4096 -f $OPENSHIFT_DATA_DIR/git-ssh
  3. Add the key to your OpenShift, either
    • via web console
      In SSH console

      cat id_rsa.pub

      then copy and paste the output into web console
      or

    • via rhc
      Download the public key (id_rsa.pub) to your host (e.g. by SFTP) and use the

      rhc sshkey add

      command to authorize the public keys for your OpenShift account.
      If you plan on accessing a private repo or want to allow jenkins committing to your repo (e.g. for generate releases with the maven release plugin) you should also add the key to your repo account. See GitHub Help.

  4. Install Plugins
    Browse to Update Center

    https://jenkins-<yourAccount>.rhcloud.com/pluginManager/advanced

    and hit Check Now (as described here).
    Then go to the Available tab and install

    1. Sonar Plugin,
    2. GitHub plugin,
    3. embeddable-build-status (if you’d like to include those nifty build badges in you README.md).

    While you’re at it, you might as well update the already installed plugins in the Updates tab.
    Then hit Install without restart or Download and install after restart. If necessary, you can restart your app like so

    rhc app restart -a jenkins
  5. Set up maven settings.xml to a writable location.
    • SSH to Jenkins
      mkdir $OPENSHIFT_DATA_DIR/.m2
      echo -e "<settings><localRepository>$OPENSHIFT_DATA_DIR/.m2</localRepository></settings>" > $OPENSHIFT_DATA_DIR/.m2/settings.xml
      
    • Browse to Configure System
      https://jenkins-<yourAccount>.rhcloud.com/configure

      Default settings provider: Settings file in file system
      File path=$OPENSHIFT_DATA_DIR/.m2/settings.xml

  6. Set up main Jenkins node as slave (easy to set up and doesn’t need extra gears).
    Go to Configure System

    https://jenkins-<yourAccount>.rhcloud.com/configure

    and set
    # of executors: 1
    As an alternative, you could also use another gear as dedicated Jenkins slave. To do so, follow the steps described here.

    [EDIT 2015-08-09: As it turned out, memory is too low to run the jenkins master and builds on one node. See my second post on how to introduce a dedicated slave node to this setup]

  7. Setup sonar plugin
    On the Jenkins frontend, go to Configure System

    https://jenkins-<yourAccount>.rhcloud.com/configure
    • Global properties,
      tick Environment variables
      Click Add
      name=SONAR_USER_HOME
      value=$OPENSHIFT_DATA_DIR
      See here for more information.
    • Then set up the plugin itself
      Navigate to Sonar, Sonar installations and set the following
      Name=<be creative>
      Server URL:

      http://sonar-<yourAccount>.rhcloud.com/

      Sonar account login: admin
      Sonar account password: <your pw>, default: admin
      Database URL: jdbc:postgresql://$OPENSHIFT_JENKINS_IP:15555/sonar
      Database login: The admin account that was returned when you first created the sonar application
      Database password: The password that was returned when you first created the sonar application

    • Hit Save

Configure build for a repository

Now lets set up our first build.

  1. Go to
    https://jenkins-<yourAccount>.rhcloud.com/view/All/newJob

    Item name: <your Project name>
    Build a free-style software project (Unfortunately, Maven projects do not work due to OpenShift’s restrictions.)
    Hit OK

  2. On the next Screen
    GitHub project:

    https://github.com/<your user>/<your repo>/

    Source Code Management:

    https://github.com/<your user>/<your repo>.git

    Branch Specifier (blank for ‘any’): origin/master
    Build Triggers: Tick: Build when a change is pushed to GitHub
    Build | Execute Shell

    cd $WORKSPACE
    # Start the actual build
    mvn clean compile test package
    

    Post-build Actions | Add post-build action | Sonar

  3. I’d also recommend the following actions
    Post-build Actions | Add post-build action | Publish JUnit test result report
    Test report XMLs=target/surefire-reports/TEST-.xml*
    Post-build Actions | Add post-build action | E-mail Notification
    Recipients=<your email address>
  4. Hit Apply.
  5. That’s it for the basic build set up. Now for the fun part: We need to find a way for Jenkins to reach sonar’s database.
    We’ll use an SSH tunnel for that.
    Build | Add build step | Execute Shell
    Now enter the following:

    # Make sure Tunnel for Sonar is open
    # Find out IP and port of DB
    OPENSHIFT_POSTGRESQL_DB_HOST_N_PORT=$(ssh -i $OPENSHIFT_DATA_DIR/git-ssh/id_rsa -o "UserKnownHostsFile=$OPENSHIFT_DATA_DIR/git-ssh/known_hosts" <UID>@sonar<yourAccount>.rhcloud.com  '(echo `printenv OPENSHIFT_POSTGRESQL_DB_HOST`:`printenv OPENSHIFT_POSTGRESQL_DB_PORT`)')
    # Open tunnel to DB
    BUILD_ID=dontKillMe nohup ssh -i $OPENSHIFT_DATA_DIR/git-ssh/id_rsa -o "UserKnownHostsFile=$OPENSHIFT_DATA_DIR/git-ssh/known_hosts" -L $OPENSHIFT_JENKINS_IP:15555:$OPENSHIFT_POSTGRESQL_DB_HOST_N_PORT -N <UID>@sonar<yourAccount>.rhcloud.com &
    

    This will tunnel requests from your Jenkins’ local Port 15555 via SSH to your sonar gear, which will forward it to its local PostgreSQL database.
    What is missing is script that explicitly closes the tunnel. But for now I’m just happy that everything is up and running. The tunnel will eventually be closed after a timeout. Let me know if you have any ideas how to improve the tunnel handling.

  6. Finally, press Save and you’re almost good to go.
  7. Before running your first build you should SSH to your Jenkins once more and
    ssh -i $OPENSHIFT_DATA_DIR/git-ssh/id_rsa -o "UserKnownHostsFile=$OPENSHIFT_DATA_DIR/git-ssh/known_hosts" <UID>@sonar<yourAccount>.rhcloud.com

    so the sonar node is added to the list of know hosts.

Moving from Google Code to GitHub: Migrating the wiki

When moving your project repositories from Google Code to GitHub, the migration from SVN to Git is supported by a a rich toolset.

 

But what about the project wikis?

There’s this tutorial, that also contains a python tool to convert the syntax. I somehow didn’t manage to get it to work.

As I had only few pages to migrate, I pragmatically decided to do it manually.

Here are the steps that were performed

  1. On your github repo, create the first wiki page (which creates the wiki, effectively).
  2. Clone the wiki via git (it’s much more comfortable to work on a local copy):
    git clone https://github.com/<user>/<repo>.wiki.git
    
  3. Copy the Google Code wiki files into your local clone.
  4. Replace the file endings to .md
  5. If your Google Code wiki featured a sidebar, rename your sidebar file to _Sidebar.md. The links are converted later on.
  6. For each wiki page do the following steps
    1.  Convert bold words, replace the regex
      \*(.*)\*
      by
      **\1**
    2.  Convert italic words, replace
      _word_
      by
      *word*
    3. Replace headings for all levels
      1. = Heading1 = to * Heading1
      2. == Heading2 == to ** Heading2
      3.  And so on
    4. Convert links, by replacing the  regex
      \[([^\s]*) (.*?)]
      by
      [[\2|\1]]
      For anchors (starting with #) make all characters lowercase and replace underscores (_) by minus (-).
    5. Replace
      <code> or {{{
      by
      ``` java
      (replace java by any other available highlighter).
    6. Replace
      </code> or }}}
      by
      ```
      (make sure to always have the ``` in a new line).
    7. Remove #summary. Leave the text after it as is.
    8. Remove the line that starts with #sidebar on each page.
    9. Convert ordered lists: replace the remaining
      #
      by
      1.
    10. Convert unordered lists: Replace
      -
      by
      *
  7. Push the changes upstream.
  8. Manually compare each page of the old version with the new version.
  9. You might have to adjust the layout of the sidebar a bit.
  10. Delete the google code wiki from your source code repository

Note that these steps were sufficient for the paricular repo I moved over. Thus, this list is definitely not complete. You might recognize that more transformations might be necessary for you. That’s why step 7 is extra important!

Please comment on any rules I left out.