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    Creative Commons License
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    Mon, 29 Aug 2011


    /Hosting/Amazon/EC2: Debian: Testing a Lenny to Squeeze Upgrade in Amazon AWS

    One of the things that is really lovely about cloud computing is the ability to test relatively quickly and easily test something new, before diving in and breaking a "real" server. In this case, an upgrade from Debian Lenny to Debian Squeeze. With about two years between the average Debian release, there is much opportunity for something to break when trying to jump such a large computing chasm.

    Unfortunately, Debian is not so well, and definitely not formally, supported in the Amazon AWS environment. Here is how I went about it....

    There are actually a handful (3?) of Debian Lenny EBS images in AWS us-east region at the moment. I had a look at them all and, as I recall, selected public ami-9a6b9af3 for my test. It has a 10G EBS root file system, and a very basic Debian install onboard. (Note that using an informal public AMI like this is a security risk, as there is no way to be sure nothing malicious has been installed in the image.)

    To kick off a instance and have a look at it:

    ec2-run-instances -k clayton -t t1.micro ami-9a6b9af3
    Login to the instance and make any desired modifications. (apt-get upgrade, install software, etc....) Then stop the instance:
    ec2-stop-instances i-27d7d246

    Snapshot it's volume and create a new private image (you can get the volume name from ec2-describe-instances):

    ec2-create-snapshot vol-ac46eac6
    SNAPSHOT snap-fa4ce59a vol-ac46eac6 pending

    Now register a new, private Debian Lenny AMI to work with going forward:

    ec2-register -a x86_64 -b '/dev/sda1=snap-fa4ce59a:10:false' -n 'Lenny_64_Lenny_kernel' -d '64 bit Lenny with Lenny kernel' --kernel="aki-68bb5901" --ramdisk="ari-6cbb5905"
    IMAGE ami-db13d3b2

    Now start up a new instance to make sure the image we made actually works:

    ec2-run-instances -k clayton -t t1.micro ami-db13d3b2
    INSTANCE i-35acaf54 ami-db13d3b2 pending

    Login:

    # uname -a Linux ip-10-244-177-141.ec2.internal 2.6.24-10-xen #1 SMP Tue Sep 8 18:30:05 UTC 2009 x86_64 GNU/Linux

    I went ahead at this point and verified that the above Lenny kernel WOULD NOT work for an upgrade to Squeeze (because of the new udev in Squeeze).

    So now create a new image based upon the previous image, this time with a Squeeze kernel which I will borrow from ami-80e915e9: aki-427d952b

    ec2-stop-instances i-35acaf54
    INSTANCE        i-35acaf54      running stopping
    
    ec2-create-snapshot vol-4ab61e20
    SNAPSHOT        snap-5e17be3e   vol-4ab61e20    pending
    
    ec2-register -a x86_64 -b '/dev/sda1=snap-5e17be3e:10:false' -n 'Lenny_64_Squeeze_kernel' -d '64 bit Lenny with Squeeze kernel' --kernel="aki-427d952b"
    IMAGE   ami-ab13d3c2
    
    ec2-run-instances -k clayton -t t1.micro ami-ab13d3c2
    INSTANCE        i-45b9ba24      ami-ab13d3c2                    pending
    
    # uname -a
    Linux ip-10-244-177-141.ec2.internal 2.6.26-2-xen-amd64 #1 SMP Mon Jun 13 18:44:16 UTC 2011 x86_64 GNU/Linux
    

    And it worked: kernel aki-427d952b is compatible with both Lenny and Squeeze.

    posted at: 05:04 | path: /Hosting/Amazon/EC2 | permanent link to this entry

    Fri, 26 Aug 2011


    /Admin/SSH: Some SSH Tricks

    You can re-use existing SSH connections by adding this to ~/.ssh/config file:

    Host *
    ControlMaster auto
    ControlPath ~/.ssh/master-%r@%h:%p

    Thereafter, after you login and open a connection to an SSH server, if you open another connection from another terminal, it will re-use the first connection. No need to login again, no need to wait for the connection to be re-negotiated. Over a slow, long-distance SSH connection, this can slow the wait time from tens of seconds to two seconds. This applies to SCP transfers as well. Much saved time.

    If you have a long list of servers you log into regularly, particularly on non-standard ports, these connections can also be aliased in the ~/.ssh/config file:

    Host my-chosen-alias
      Hostname server.com
      IdentityFile /path/to/id_rsa
      User root
      Port 10122
    
    Thereafter, "ssh my-chosen-alias" will connect to root@server.com on port 10122. Unfortunately SCP does not seem to respect these aliases, or at least I have not found out how to make that work. But this is a way, for instance, to transparently get backuppc[1] to connect to a backup client using a non-standard port.

    [1] http://blog.langex.net/index.cgi/Admin/backups/backuppc/

    posted at: 06:22 | path: /Admin/SSH | permanent link to this entry