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From gertjanol <>
Subject [GitHub] libcloud pull request: RFC for AWS SignatureVersion 4 for EC2
Date Mon, 02 Feb 2015 14:48:18 GMT
GitHub user gertjanol opened a pull request:

    RFC for AWS SignatureVersion 4 for EC2 

    As shortly discussed with @Kami in #407, this patch adds support for Signature Version
4 to the `SignedAWSConnection` class. v4 will be used when a Driver-class selects `EC2V4Connection`
as its `connectionCls`. In this patch this is only enabled for the the new Frankfurt region,
represented by a new `EC2EUCentralNodeDriver` class. 
    Haven't created any tests yet, since this is just the PoC. If this has any chance of getting
merged in, I'll do the tests.
    I would like some feedback and thoughts on this work.
    Some questions:
    * Is this the way to go, with the Connection-classes specifying a version, and the Driver
classes specifying the Connection class to use?
    * I've chosen the `pre_connect_hook` to do the work, because we need both the headers
and the parameters to calculate the signature. Hope that's ok?
    * I’ve tested all regions for EC2 and all seem to work fine with the v4 authentication.
I haven’t tested the only other part that uses the `SignedAWSConnection`, the `ELBConnection`,
but I’m guessing that that also supports V4. It would reduce complexity if we could drop
support for V2 in the SignedAWSConnection altogether. 
    * The credential scope, as explained [here](
needs the service we are requesting. This should be just ‘ec2’ for compute service. I
found no existing way to retrieve this, so I introduced a [new class variable](
in the `EC2Connection`. I don’t like this, so maybe there is a better way?
    * This patch now only works for GET-requests, but the EC2-driver doesn't use anything
else. I think S3 uses other methods, but seems to have its own authentication routines. Why
is that? Should I take other methods into consideration here?
    * Performance of calculating this signature sucks :(. Haven't done any measuring, but
v2 seems way faster.

You can merge this pull request into a Git repository by running:

    $ git pull aws-signature-v4

Alternatively you can review and apply these changes as the patch at:

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #444
commit 653126a5b09365b5ae2204171f5dbf519c742cb4
Author: Gertjan Oude Lohuis <>
Date:   2015-02-02T14:00:57Z

    Working example of SignatureVersion 4 for AWS EC2

commit 74f5b2f9d50ff60e19fb427a515d2a44a2754346
Author: Gertjan Oude Lohuis <>
Date:   2015-02-02T14:03:47Z

    Make supported nodes for EC2EUCentralNodeDriver available


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