Increase size and type of AWS EBS volume

I was offline for quite a while because shifting from one continent to another. But now regular posts should be rolling in again.

I am running a couple of instances in pre-production requirement mode and changed from a standard EBS volume to a IOPS volume for the DB instance or the volume with the DB files. I could not identify a reasonable increase of performance, maybe a misconception that IOPS volumes will boost performance, rather provide a defined and consistent random access I/O throughput. I must admit I did not use a value higher than 1000.

Billing IOPS

Billing IOPS

Some recommended reading:

I decided to return to a standard ESB volume for my database as its performance did not benefit from the IOPS type (the DB is not overly busy too).
You cant change type and size of an EBS volume on the fly.

Here the steps to achieve the same: Continue reading

Glassfish Tuning and Thread Dumps

Once you get into a production like stage with more data volume, more users, etc. you will find yourself pretty fast in the situation where Glassfish gets some hickups or slowness. An expected situation if you did not change the default parameters  out of the box which are chosen to make Glassfish to run even on a small box.

We ran into some kind of concurrency problems with JDBC pools and thread where Glassfish appeared to be hanging. One approach is to create thread dumps for the JVM.
With Glassfish we have a few options:

  1. jstack
    Run jps which returns you the list of applications running a JVM, choose the PID and execute
    jstack <PID>
    or jstack -F <PID> > td.log
  2. asadmin
    Go the Glassfish_HOME/bin folder and execute
    ./asadmin --user admin generate-jvm-report --type=thread > threaddump.txt
  3. kill -3 <PID>
    Supposed to create a dump in the default log folder of Glassfish. Doesnt work for me.

With the (or better more than 1) file at hand you can evaluate them by hand or use some of the tools around. I am still struggling to make the tool analyzing my dumps. They simply open the files like a editor.

tda tool

tda tool

Some References

Enforce password for Ubuntu user on EC2 instances

Using linux (Ubuntu) instances on Amazon EC2 is a quite safe thing to do, at least measured by the security provided by the platform (security groups, ACL, physical security,..). I recommend reading their security site here. At the end of the day the server is only as secure as you configure it, if you choose to open all ports running services with their default configurations and password settings, Amazon can’t help you.

When connecting to a Ubuntu server with ssh you need to provide the keyfile (somekeyfile.pem) that you can download when creating the key pair.

Key file

Key file

This 2048 bit key is required to login as regular ubuntu user. What I dislike is the fact that this user can sudo all, so once someone manage to get into you user account, he has root access too. I recommend to set a password for the ubuntu user and change the sudoers configuration.

Change the password for user ubuntu

Open the sudoers include file

sudo vi /etc/suderos.d/90-cloudimg-ubuntu or sudo vi /etc/sudoers

change last line from



ubuntu ALL=(ALL) ALL

Monitoring Glassfish V3.1.2 Options

There are 2 crucial phases you want to look under the hood of your running Glassfish or inside the JVM underneath: Performance Tuning and Health Monitoring during production.

With JMX (Java Management Extensions, Wikipedia) at hand, there are a few options to choose from.


The graphical monitoring tool is great for local deployment, it allows you to connect to a JVM on the same host or a remote host. It creates line graphs for your for all relevant from the moment you connect, it is perfect to observe a server while you do some testing or other actions, though it does not record any values while you are not connected. I have a hard time to get it running on a remote server and I do not favour the ‘open’ approach (see previous blog entry) which allows anyone to access the JVM with the disabled authentication settings. I also had situations where the JVM was frozen and it was no longer possible to access the JVM for monitoring, here I would rather have snapshots before the problem started together with server.log.



Glassfish Rest Interface

Note: You need to enable the areas you want to monitor with the admin console (or the asadmin command line) because per default all are OFF. Continue reading

Glassfish and https running secure applications

By default Glassfish listens to http on port 8080 and https on port 8181.
It is better to listen to the default ports 80 for http and 443 for https, usually you dont want the user to enter port numbers as part of the URL.

Even the Glassfish Admin Console allows to change the ports (Configurations/Server Config/Network Config/Network Listener), certain server OS such as Ubuntu do not allow non-root users (you should run Glassfish as separate user !) to ports below 1024. We can achieve this by port rerouting with the iptables command (under Ubuntu)

iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -t nat -A PREROUTING -p tcp -m tcp --dport 80 -j REDIRECT --to-ports 8080
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -t nat -A PREROUTING -p tcp -m tcp --dport 443 -j REDIRECT --to-ports 8181
iptables-save -c > /etc/iptables.rules
iptables-restore < /etc/iptables.rules

vi /etc/network/if-pre-up.d/iptablesload
iptables-restore < /etc/iptables.rules
exit 0

Additionally you can get a proper SSL certificate to stop annoying the user with a no proper certificate warning. See previous tutorial here.

SSL Error

SSL Error (Chrome)

If you operate an enterprise application with a known URL to the users, unlike a regular website where the portal should be reached with regular http, I would completely disable regular http.

Disable http

Disable http

Glassfish V3.1.2 and SSL

After almost 3 years (see previous post) I revisit the topic this time using the latest version og Glassfish 3.1.2 and GoDaddy as certificate provider. I created a certificate for a sub-domain ( this time and make use of the extremly cheap 5.99 U$/year offer (no wildcard included)

Let me summarize the key steps here: Continue reading