Category Archive for ‘gotchas’ at Ramblings

Archive for the 'gotchas' Category

02Mar10 Rails & JRuby in a Jar

4 Comments

For political reasons, I needed to ship a single jar file. I didn’t want to have the overhead of a war & an appserver, so I set out to embed my rails app within a single jar file. I needed to make some changes in order to get it to work.

This assumes Rails 2.3.5 and JRuby 1.4.0.

First, you need to create your rails app. Freeze rails and any gems required.

Next download jruby-complete. Once you’ve done so, unzip it. I’m assuming you’ve unzipped it to complete.

Note: When you repackage the jar file, DO NOT use jar. Use zip. This is very important. If you don’t, you’ll trash your jruby instance.

Copy your rails instance to complete/META-INF/jruby.home. I assume it will be complete/META-INF/jruby.home/rails.

Next create complete/META-INF/jruby.home/bin/server with the following content:


#!/usr/bin/env ruby

RAILS_ROOT = File.join(File.dirname(File.dirname(__FILE__)),'rails')

require File.join(RAILS_ROOT,'config/boot')
require 'commands/server'

The RAILS_ROOT needs to be set in order to have the proper paths within the jar file.

Next, edit complete/META-INF/jruby.home/rails/vendor/rails/railties/lib/initializer.rb In the set_root_path method, edit it so it looks like this:


    def set_root_path!
      raise 'RAILS_ROOT is not set' unless defined?(::RAILS_ROOT)
      raise 'RAILS_ROOT is not a directory' unless File.directory?(::RAILS_ROOT)
      # I changed this... mkw21 20100301
      @root_path = RAILS_ROOT
        # Pathname is incompatible with Windows, but Windows doesn't have
        # real symlinks so File.expand_path is safe.
#        if RUBY_PLATFORM =~ /(:?mswin|mingw)/
#          File.expand_path(::RAILS_ROOT)#

        # Otherwise use Pathname#realpath which respects symlinks.
#        else
#          Pathname.new(::RAILS_ROOT).realpath.to_s
#        end

      Object.const_set(:RELATIVE_RAILS_ROOT, ::RAILS_ROOT.dup) unless defined?(::RELATIVE_RAILS_ROOT)
      ::RAILS_ROOT.replace @root_path
    end

This is related to paths within the jar file.

Additionally, you need to change the initialize_logger method. (this might not be needed, see below). Change


          logger = ActiveSupport::BufferedLogger.new(configuration.log_path)


          logger = ActiveSupport::BufferedLogger.new("/tmp/transfer.log")

The idea is to change it to something definitely outside the jar. The reason I did this, and didn’t change the config in environment.rb was that the changes in environment.rb were not getting picked up. I’ve since come to the belief that this is due to an issue with the Rack LogTailer detailed at https://rails.lighthouseapp.com/projects/8994/tickets/2350-logtailer-ignores-configlog_path. So complete/META-INF/jruby.home/rails/vendor/rails/railties/lib/rails/rack/log_tailer.rb needs to be edited. Edit the EnvironmentLog assignment to match the file we’d specified. (You may be able to substitute RAILS_DEFAULT_LOGGER but I have not tested that)


      EnvironmentLog = "/tmp/transfer.log"

That’s pretty much it. Zip up your exploded jar from the complete directory: zip -r ../complete.zip *. Then you can run it via java -jar complete.jar -S server.

Enjoy!

29Jul09 JBoss port confusion

gotchas jboss

0 Comments

We ran into a case where JBoss was unable to come up; it gave the following (partial) exception:

java.rmi.server.ExportException: Port already in use: 1098; nested exception is:
java.net.BindException: Cannot assign requested address

After poking around with netstat and lsof, we couldn’t find anything that was binding to the port. I’d made the assumption that it was bound, totally missing the next line. As it turns out, we were attempting to bind to a vip which, although it existed in DNS, was not defined on the host on which the error occurred. The “cannot assign requested address” was the clue.

14May09 SSL Joys

gotchas howto tips

0 Comments

The nice thing about standards is that there are so many of them to choose from. Andrew S. Tanenbaum

I’ve been working with a Apache proxy to force SSL and https. Well, I haven’t had any control over the certificates. And they can come in so many versions, especially given that Microsoft wants to do things its own way and the Apache web server instance is sitting on a windows virtual instance.

I’ve gotten the private key in two different formats, .pfx and .pvk.

.pfx can be converted to the pem file format which Apache is expecting via the following:

openssl pkcs12 -nodes -in infile.pfx -out out.pem

You then need to edit it, stripping out everything but the private key. Once that’s accomplished you’re good to go.

.pvk, however, isn’t supported in openssl until version 1.0. Joy!

14Jan09 SSL and Java Keystores

gotchas tips

0 Comments

If you happen to change a machine’s name, be sure to delete the previous definition from the keystore. Otherwise it will complain mightily and, indeed, fail when you attempt to add in the pem file.

14Nov08 Concatenation Note to Self

gotchas

0 Comments

To concatenate in PHP you use a ‘.’, not a ‘+’. Likewise, you don’t use ‘.’ to reference an object’s members, you use ‘->’.

Move along, nothing to see.

12Nov08 DIY Maps and Linux Firefox/Flash Quirks

gotchas javascript

1 Comment

First off, let me say that I really like DIY Map. It’s quick, and responsive, with an easy to use interface, as well as allowing you to make changes on the fly easily.

That said, I discovered lastnight / this morning that there are some quirks with its updating through the Flash JavaScript Integration Kit.

First of all, the only way I’ve been able to get paths to resources to work is via relative paths. More on why I think that is the case in a moment. I was finding that resources were not being found until I used relative paths. Once I did so, that part worked just fine.

Second, in order to be able to update the map, it needs to be fed an XML data file, which is fine. Wherein lies the trouble is when you are attempting to feed a dynamic file (like a cgi script or php) — I’ve not been able to get it to work, despite having the right data in the output and the proper content type — the data works just fine when loaded from a file, however… So, my workaround is to write to a temporary file and use that file to make the changes.

Third, and this was a kicker…. The Javascript integration kit isn’t talking to Flash 9 on Firefox 3.0.3 under linux. The messages get lost out on the bit bucket. Just to make sure it wasn’t me, I also tried the examples which came with the app. They, however, work on Firefox under windows. So, I don’t know if it is something having to do with my box or what… But it ain’t working.

4+ hours spent on this. Meh. It’d be a bit more amusing if I’d gotten more sleep. I napped for about an hour around midnight, and another nap at 7:30am until I had to get up for work @ 9.

11Nov08 YUI Datasources

gotchas

0 Comments

Been a while since I’ve written. I’ve been sick and working on a side project. That said, I’ll be writing more……

Today’s note/reminder is a gotcha about YUI datasources. If you have JSON feeding the datasource and you’re getting back more fields in the results than you’re expecting, the datasource will not behave properly. For example, if you’ve declared that you’re getting back

name
id

But in reality you get

name
id
address
email

it will just sit there. Very frustrating. Very fun trying to debug, too!

25Sep08 JBoss run.sh may be harmful

gotchas jboss

0 Comments

A coworker and I discovered an issue with jboss’ run.sh (which starts the app server). The problem lies in different flavours of unix (or unix-like) shells returning different values for wait.

The relevant code is:

      # Wait until the background process exits
      WAIT_STATUS=0
      while [ "$WAIT_STATUS" -ne 127 ]; do
         JBOSS_STATUS=$WAIT_STATUS
         wait $JBOSS_PID 2>/dev/null
         WAIT_STATUS=$?
      done

This is all well and good in linux — redhat uses /bin/bash and ubuntu uses /bin/dash for /bin/sh — both of which return 127 when waiting for a process which does not exist. However, Solaris’ /bin/sh returns 0 (/bin/ksh returns 127).

So, the run.sh goes into an infinite loop, thrashing, badly. CPU gets pegged and all that fun stuff.

How to fix? Well in order to make it OS/shell dependant, we'll determine the value which is returned by wait when a process does not exist. We're guaranteed that there is one process id which won't be used in unix -- 0. So, we wait on PID 0, and use the return value, $? to determine how the environment handles the wait. The "fixed" code looks like:

      wait 0 2>/dev/null
      NO_SUCH_PID=$?
      # Wait until the background process exits
      WAIT_STATUS=0
      while [ "$WAIT_STATUS" -ne $NO_SUCH_PID ]; do
         JBOSS_STATUS=$WAIT_STATUS
         wait $JBOSS_PID 2>/dev/null
         WAIT_STATUS=$?
      done

EDIT:
This was fixed in 4.2.3 GA with the following code:

# Wait until the background process exits
      WAIT_STATUS=128
      while [ "$WAIT_STATUS" -ge 128 ]; do
         wait $JBOSS_PID 2>/dev/null
         WAIT_STATUS=$?
         if [ "${WAIT_STATUS}" -gt 128 ]; then
            SIGNAL=`expr ${WAIT_STATUS} - 128`
            SIGNAL_NAME=`kill -l ${SIGNAL}`
            echo "*** JBossAS process (${JBOSS_PID}) received ${SIGNAL_NAME} signal. ***" >&2
         fi
      done
      if [ "${WAIT_STATUS}" -lt 127 ]; then
         JBOSS_STATUS=$WAIT_STATUS
      else
         JBOSS_STATUS=0
      fi

12Sep08 Class is Class, and Instance, Instance, and never the twain shall meet

Uncategorized eating crow gotchas programming ruby

2 Comments

More about methods, it’s inspired/spurred by a comment on methods, public_methods, and private_methods by Pit Captain. It also corrects some misconceptions I had (and may have (wrongly) given others).

I’ve added a new category, “eating crow” for this and any other postings where I step back and re-evaluate my posts. This is to keep me honest, and, if y’all would, please feel free to tell me when it’s time to “eat crow”.
Continue reading ‘Class is Class, and Instance, Instance, and never the twain shall meet’

05Sep08 A “grue”some look at Statemachine and Treetop

games gotchas ruby

4 Comments

In this blog entry, dear reader, we examine the statemachine and treetop gems via an old standby, a Zork imitation. And, despite the title, you won’t find a grue.

$ ruby adventure.rb
This is the beginning. Like all tales, there's a beginning, a middle and an
end....

Paths lead n.

What do you want to do?
n

This is a path in the forest, it looks fairly well travelled.  You see a
clearing to the east

Paths lead w, n, e, s.

What do you want to do?
e

This is a clearing.  You can actually see the sky here.  Compared to the deep
dark forest, it seems a relief. A path can be seen to the west.

Paths lead w, n, e, s.

You see the following: letter.

What do you want to do?
get letter

Ok, you pick up the letter.

What do you want to do?
w

This is a path in the forest, it looks fairly well travelled.  You see a
clearing to the east

Paths lead w, n, e, s.

What do you want to do?
w

You're lost in the depths of the forest.  You're not sure where you are, nor how
to get out of there.

Paths lead w, n, e, s.

What do you want to do?
quit

Continue reading ‘A “grue”some look at Statemachine and Treetop’