My Blogs on Oracle SOA and J2EE

Recovering Unreachable AWS Instance

2016-07-24T12:32:00.001-07:00

I came across this issue during one of my project some time back, posting it here to help if anyone come across the need to recover unreachable AWS instance on cloud & approach.
Instance was running RHEL 6.4 when all of a sudden the SSH connectivity was gone. After analysing the startup logs, I found that ssh service was not coming up & effectively making the instance unusable & not reachable.

The cause of this issue was a bug with RHEL 6.4 EC2 instance which adds multiple
"UseDNS no PermitRootLogin without-password" sections without newline character.

Resolution:

Remove the below erroneous entries from /etc/ssh/sshd_config file & also from /etc/rc.local:

* <<EOL >>*
UseDNS no
PermitRootLogin without-password

However without ssh service you will not be able to connect to the instance & do the fix.

If the root partition is on instance storage then you are out of luck as the storage is tied with the instance & can't be detached. If its EBS backed root partition then you can detach & attach it to any existing instance as a data storage. Once it's attached to your new instance, you should be able to mount just as another drive & access the data to do the fix.

Note: If you are eligible for free tier, consider creating a micro instance & attach the root volume of the failed instance as an additional storage to the working instance.

Once you rectify the config files and ready to re-attach the root device, make sure you provide the mount point as sda1 & not sda. If you attach the device with wrong mount point, the instance will fail to boot, even though you might have fixed the configuration issues.

Getting started with AWS - Creating your first instance

2016-07-12T12:16:00.000-07:00

If your subscription qualifies for free tier account, you can launch free tier micro instance.
This blogs uses free tier AMIs to create the instance but the same can be used for purchased instance as well.

Follow the below step by step guide to create your first AWS instance:

1. Choose AMI

If you are under free tier, you should tick the check box to filter the AMIs eligible under Free Tier Usage.

2. Choose Instance Type

Only Micro Instances are eligible for the AWS free usage tier.

3. Configure your Instance

Here you will get options to configure Network, Security, Shutdown behavior settings etc.

VPC (Virtual Private Cloud) - VPC is similar to the traditional LAN, except it is on cloud & can be further configured with routing tables, gateway to control visibility of the resource. By default, a default one will be created & ready to use.

Public IP - Make sure to check this box to automatically assign a public IP to your instance. Also, you need to make a note of the allocated public IP each time you start the instance. Alternatively, you can switch to static public IP address with additional cost.

Shutdown Behavior - Available options are:

Stop - Stops the instance. Instance data & configuration is retained & it is similar to physical shutdown of device. You won't be charged for Instance in stopped state. If any EBS volumes are attached to this instance they will still be charged.
Reboot - Reboots the instance.
Terminate - Terminates the instance, erases instance configuration & will also erase any storage volume associated with the instance.

You should set this behavior to Stop.

Enable termination protection - Protects from any accidental termination.

Monitoring - Check this box to enable detailed monitoring if you need monitoring data for every minute at additional cost. By default basic monitoring will be enabled with refresh cycle of 5 minute window.

Tenancy - By default it will be shared tenancy i.e. the instance will run on shared hardware.

Network Interface:
By default one Ethernet interface(eth0) will be available with the instance. If you have enabled Public IP option, then Primary IP field will also set to Auto-assign & disabled for any change.

Step 4: Add Storage

Here you can configure the storage for your instance. Additional volumes can be added by clicking on Add New Volume.

Step 5: Tag Instance

Tagging helps to define your own metadata to manage the instance.

Step 6 : Configure Security Group

You can create a new security group & can reuse the same with other instance.

Click Review & launch to launch the instance.

Feature Review of Oracle SOA 12c

2013-12-21T23:09:00.000-08:00

The next major release of SOA Suite will be coming soon somewhere in early 2014(No confirm timeline yet).

SOA 10g to 11g upgrade brought some radical changes to the complete SOA stack due to the architectural and conceptual changes. While this release is more feature rich and geared towards Cloud Integration & better OSB integration to SOA stack.

Oracle showcased SOA 12c in Oracle OpenWorld, 2013. Some of the feature highlight of the coming release I'm putting in this post.

JDeveloper and Em Console has undergone some changes due to the inclusion of OSB support. OSB also gets a SCA like makeover wherein you will have Proxy, Business service, Split-Joins.
Em Admin console integrates OSB services and will provide single point of access to monitor and manage both SOA & OSB services.
SCA composites can be run directly from JDeveloper with its integrated server just like standalone applications. This means debugging and deployment should be a lot easier & you can try out new changes immediately.
Cloud adapter for Cloud integration.
Inclusion of MFT(Managed File Transfer) for large file transfer

There will be more in the final version with Weblogic 12.1.x brings Dynamic Cluster & Elastic JMS. In all it will be a more unified product(with OSB support) and cloud ready.