Saturday, August 23, 2014

How to render image serverside using OpenShift Node.js?

Hey everyone,

Leaving a developer world in favor of non-coding job has certain advantages.
And one big disadvantage - no more coding. That is a big problem and I lasted about 6 months before I started created something after hours - just for my pleasure.

Things have changed significantly since I was studying. Back then it was a big problem (especially for a poor student) to rent a server and static IP address. And today, with the presence of Weebly and Openshift (a really great Platform As A Service) you can get up your small portal (like mine) in less than a couple of hourse and 100$.

Openshift provides a great array of technologies - I have chosen Node.js + MongoDB as it offers the quickest route to a working app.

One big problem I had was that I wanted to render images server side. This is not trivial as there is no javascript libraries that could do that. One can rely only on native software, but if you consider semi-automated PaaS and customer server-side solution, you will feel the pain.

So I'm sharing with you my setup, as I got it working - it renders images using node.js canvas module, that uses underlying Cairo library.

Installing Cairo on OpenShift gear is not so simple - it is necessary to build cairo manually:

export PATH=/sbin:$PATH
export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/usr/local/lib:/opt/rh/nodejs010/root/usr/lib64:$LD_LIBRARY_PATH
export PKG_CONFIG_PATH=$OPENSHIFT_DATA_DIR/usr/local/lib/pkgconfig

curl -L -o libpng.tar.xz
tar -Jxf libpng.tar.xz && cd libpng-1.5.18/
./configure --prefix=$OPENSHIFT_DATA_DIR/usr/local
make install

curl -o jpegsrc.tar.gz
tar -zxf jpegsrc.tar.gz && cd jpeg-8d/
./configure --disable-dependency-tracking --prefix=$OPENSHIFT_DATA_DIR/usr/local  
make install

curl -o pixman.tar.gz  
tar -zxf pixman.tar.gz && cd pixman-0.28.2/  
./configure --prefix=$OPENSHIFT_DATA_DIR/usr/local   
make install

curl -o freetype.tar.gz
tar -zxf freetype.tar.gz && cd freetype-2.4.11/  
./configure --prefix=$OPENSHIFT_DATA_DIR/usr/local   
make install 

curl -o cairo.tar.xz  
tar -xJf cairo.tar.xz && cd cairo-1.12.14/  
./configure --disable-dependency-tracking --without-x --prefix=$OPENSHIFT_DATA_DIR/usr/local 
make install

After that it is necessary to hack package.json file - it cannot contain canvas in it, as paths are wrong, and canvas will never discover cairo in non-standard location. Canvas has to be installed using build hook:

export PATH=/sbin:$PATH
export LD_LIBRARY_PATH=$OPENSHIFT_DATA_DIR/usr/local/lib:/opt/rh/nodejs010/root/usr/lib64:$LD_LIBRARY_PATH
export PKG_CONFIG_PATH=$OPENSHIFT_DATA_DIR/usr/local/lib/pkgconfig

scl enable nodejs010 v8314 'npm install canvas'    

And a really dirty hack. OpenShift tends to cache installed modules, which is a bit of a problem, because when scripts are restored, they know nothing about where the cairo is installed. This simple pre_build hook is reverse engineered from the OpenShift code - I remove cached modules, and therefore force canvas installation by my script.

rm -rf "${OPENSHIFT_NODEJS_DIR}/tmp/saved.node_modules"

I hope this will help someone trying to run canvas module in OpenShift - it took a couple of long hours to figure out what is going on.

Wednesday, December 18, 2013

P2 - retrospection

My work towards getting P2-RPM integration is leaning towards an end.  Patches are in gerrit, here and here. While Eclipse with the patches is being built, I have plenty of time to think.

I've been with P2 since it was announced at EclipseCon 2008 in Santa Clara. It's hard to remember how crowded was the room, but I remember my sheer enthusiasm to the idea of solving the satisfiability problem, and runnig the optimal set of bundles.

Little had I know how much influence it will have on me. But P2, and especially dropins, were supposed to be my daily bread for the next couple of years.

Then I changed the job, hoping for something new, but P2 did not let me to forget. Fedora turned out to rely on dropins (because there was *no* alternative). I tried to change Fedora, but was confronted with 20+ years of Linux releng, and got really convinced that P2 could have been quite different.

So, how the P2 could have look like now?
The core P2 functionality, responsible for installing things, should *not* be running in JVM. Java itself is not granted on every computer, and it has plenty of dependencies (at least on Linux), which makes it very unwanted member of the installer stack. Not to mention that it adds size to the installer, which is really important in the case of corporate setups and people using modems. Another problem is that P2 running in JVM cannot update that JVM because of locking. Not to mention the lack of elevated privileges support.

I can easily imagine P2 being a native, embeddable processing library that would rather work take the state of a system, the request, and respond with steps leading to another state, but without really touching anything, but just letting the installer to deal with file operations.

I'd be the first to work on it to integrate it fully into RPM and make it responsible for the whole Linux installation - not just Eclipse.

Disclaimer: Don't be afraid. Those are only my thougths, which (un)luckily I'm not able to materialize without making many people upset.

Friday, October 25, 2013

Google Talk plugin presence breaks Eclipse in Fedora 20.

This is the kind of news I really hate to announce, and at the same time, this is the reason why I'm addicted to open source. With open-source I could report it. Investigate it, or even workaround it. But the only thing I can do with a binary plugin is to remove it.

Eclipse 4.3.1 in Fedora 20 crashes shortly after content assist or javadoc is shown. ABRT discovers a crash.

Both content assist and javadoc are browser-based. Google Talk plugin interferes with webkit/SWT, and in the end JVM crashes.

Remove Google Talk plugin.
yum -y remove google-talkplugin 

Thursday, October 24, 2013

Enabling Tycho tests for P2 - lessons learned

Today's morning, after turning on Eclipse, I got this notification:

I find it to be a big step forward (at least to me), because from now on, all P2 patches pushed to gerrit will be automatically verified in a quite reasonable time - more or less 2 hours - yes, that's the time that is necessary to run the build and execute all P2 tests.

However, the road to the green build was a rather bumpy one - here is the list of issues that may impact more people doing the migration:

Issue #1 - Error code 23.

First reported as Bug 415489 - tycho-surefire occasionally fails with unexpected return code 23. Then after investigation - duplicate opened by me:
Bug 417430 - tycho-eclipserun may interfere with tycho-surefire OSGi runtime.

Tycho builds stops with an unexpected error code 23. The build is not failed, it just exits.

Tycho occasionally assembles and spins Equinox instances, if it is necessary to run OSGi-based tooling during the build. But in one place, Equinox was refusing to start, and was returning error code 23, demanding to be restarted. The sequence that lead to this was pretty simple:
  • Tycho assembled and run Equinox instance based on Kepler versions to generate API description
  • a bit later, tycho assembled and run another Equinox instance based on Luna-Nightly to run tests, but the configuration directory was not cleaned, so Equinox thought an update was happening, and demanded a restart.
  • Update to Tycho 0.19.0 - the issue has been fixed there
  • Change tycho surefire configuration area to avoid collision with api builder:

Issue #2 - Different naming schemas.

One of the tests was failing all the time, returning doubled number of artifacts in a generated P2 repository (expected:3, was:6). What happened was that P2 was copying bundles from a running application, and this Surefire application was using different naming scheme: Regular Eclipse apps use following convention: bundleId_version.qualifier.jar, but Tycho Surefire uses bundleId-version.qualifier.jar. Of course, P2 processed those files properly, and generated valid repo, just the test input was wrong.

Issue #3 - Circular dependencies.

P2 Tests, to run properly, require platform specific filesystem bundles. The only way to add those bundles to Surefire is to add parent feature - and since we are building P2, parent feature (org.eclipse.platform) would be resolved from an update site. Well, almost. The parent feature happened to include one bundle from the reactor (org.eclipse.update.configurator I think). So, almost everything was resolved from the update site, except this one bundle, which came from the reactor, and didn't satisfy feature requirements due to the changed version.

The workaround was to use api (luckily this is all about test case preparation).

Some discussion concerning this issue seems to be happening in Bug 419201 - "mvn clean verify -Pbuild-individual-bundles" fails for Platform Compare.

Side note:
There is an ongoing effort to enable running tests during the build for particular components, under the umbrella  Bug 416904 - Allow to run tests with tycho-surefire-plugin. "In order to lower entry barrier and execution of unit tests [...]".

Best regards,

Monday, October 21, 2013

Rediscovering Mylyn (Builds)

I always have a mixed feelings when I try to write anything about Mylyn. It's just impossible to cover all its greatness it in one blogpost, and the fact that it is written as an Eclipse add-on is not helping much in promoting it amongst my linux readers (it's all because of this joke:
But let's try. First of all, Mylyn is an excellent tool to keep all your bugs in one place, which is very useful for me, as I very often jump between projects and need to switch between different areas quite fast:

Mylyn Task list - bugs from different sources in one place
But that's just a tip of the ice berg.  The true power of Mylyn is 'context' management. What is a context? Well, it's a set of files you are working with, and Mylyn's ability to track which files are important for certain bug is hard to overestimate when you get a comment like:
Can you include a "description.txt" file (or similar) that describes how to rebuild them, in case it is required in the future?

The context is just one click-away - the only thing you need is to activate your task by clicking the ball next to it:

An active task, a task without context, and an inactive task with recorded context.
So now we go to the main Mylyn functionality, that really let's the entire Eclipse shine - just compare the next two screenshots:

Have you noticed which files are presented in the 'Package Explorer' view? Yes, that's those I really need! No clutter, no list scrolling! One click and you're back to task that you've left a week ago!

But even that's not all. If you have Continuous Integration running on Jenkins/Hudson, you may connect your Eclipse to it, and get this lovely view of your jobs:
Builds view. Notifications included. No more page refreshing.
Can you see the small JUnit action? Guess what does it do :). Yes, you are right - it opens tests in a JUnit view:

Jenkins/Hudson build test result loaded into Eclipse.
And now - once you double click the stack trace - Eclipse will open a file for you - no grepping, finding, searching - everything loaded into your really Integrated Development Environment!

Of course - this is just a small part of Mylyn functionality, this is just what appeals to me most in my daily work. But managers will be happy, too, with all the project-tracking functionality, integrated via OSLC, and really powerful tools (out of scope for this blog).

Quick instructions how to install Mylyn in Fedora (packaged by me):
sudo yum install eclipse-mylyn
Pretty simple - and really worth to try out!

Thursday, August 1, 2013

Why it is worth to build open source software.

Sometimes people ask me why I always want to build everything from source, and my answer is always that I have to do it because of the  Fedora policy, which states two reasons:
  • Security: Pre-packaged program binaries and program libraries not built from the source code could contain parts that are malicious, dangerous, or just broken. Also, these are functionally impossible to patch.
  • Compiler Flags: Pre-packaged program binaries and program libraries not built from the source code were probably not compiled with standard Fedora compiler flags for security and optimization.
 But it is not all. Open Source definition is a very broad definition, and some software packages may not be usable at all without proprietary, closed and well-controlled companions. In that light, building from source is the ultimate indicator whether a software creator really gives you the right to build (and, what's more important, to patch) his/her code.

This post was inspired by this answer on fedora-java.

Friday, June 28, 2013

Kepler retrospection - was CBI a net loss?

While I was reading Kepler retrospective notes, I found this statement:
CBI was a net loss for us so far. It was a very large volume of work just to get our build back to its old state. There is benefit for others in the community to make it easier for them to run builds independently. For committers it hasn't delivered value yet.
and started immediately wondering who was the "us", and why it was "a net loss".

Fedora had it's own Eclipse build system, which was 8 x faster than current CBI build (15 minutes vs 2 hours on non-SSD drive). I've spent a lot of time getting Eclipse built with Fedora and switched to CBI before the Foundation did.

All that was (and still is) a cost, but was it really "a loss"?

I find it rather as a first step towards a really necessary move - Eclipse Foundation taking responsibility on development. The build system is first, then maybe we will get vendor-neutral architects or UX designers.

Another point is that once it is possible to easily rebuild Eclipse, we can see even right now internal Eclipse teams appearing here and there, which tend to become really valuable contributors.

Not to mention that after Kim left, it took about a month to get builds running again (at the Eclipse Foundation, we had them running in Fedora). Is it ok to have so much power depending on one person (because that is what happens if you have a large ant-based build)?

I'm sorry but I can't agree with a "net loss". It was a necessary cost. Good for the Eclipse Foundation. Good for the Eclipse.

BTW. I really hope some day UX designers or architects will be hired by Eclipse Foundation.