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From Sam Corbett <sam.corb...@cloudsoftcorp.com>
Subject Re: [DISCUSSION] Determining which Brooklyn node address to advertise
Date Wed, 15 Feb 2017 12:59:27 GMT
Interesting problem Svet. Your proposal is a neat way of sidestepping 
the problem of updating many security groups as the set of HA nodes 
changes.

Let me rephrase it to see if I understand correctly.

Suppose we have:
* _n_ Brooklyn servers in an HA cluster (that could be across many 
clouds / regions within a cloud)
* _c_ clouds that Brooklyn can deploy to
* _m_ instances across those clouds.

We want to avoid the n+1th Brooklyn node requiring _m_ security group 
updates.

You propose that the manager of the Brooklyn HA cluster maintain at 
least _c_ security groups (one per security group scope - e.g. AWS EC2 
region - per cloud). Each of these groups has _n_ records. When the HA 
cluster is resized each group is modified to add or remove a record as 
appropriate.

Do I have this correct?

Sam


On 14/02/2017 15:42, Svetoslav Neykov wrote:
> I'm trying to restrict access to the machines managed by Brooklyn using security groups
- tightening jclouds' default behaviour of opening the "inboundPorts" to any source.
> Brooklyn obviously needs to have access to all managed machines. This means it needs
to figure out the address it uses to access each machine and white list it in the machine's
security group.
> This is kind of related to the email thread "[PROPOSAL] Separate management addresses
from the concept of an entity's public address" [1], but in reverse. Instead of figuring out
which machine IP to use I need to do the reverse - which Brooklyn node IP will access the
machine.
> It becomes more complicated when HA is introduced into the mix. Any node that becomes
a master needs to be able to access the machines. This means the security groups need to be
updated in such cases.
>
> Two questions follow:
>    1. How to determine which IP faces managed machines? There's no one fixed answer here.
Depending on the target cloud and location configuration it varies.
>    2. How to keep the list of IPs from above point in sync, for each of the members of
the HA cluster?
>
> Don't think we can actually answer q1. That's why the solution I'm thinking of is:
>    * Always open the external IP to the machines. The external IP is as reported by "LocalhostExternalIpLoader".
>    * Assign a predefined SG to all machines in the HA cluster - manually/out of band,
since the machines are not managed by Brooklyn. Let Brooklyn know the SG name, defaulting
to "management-<cluster-id>". White list the SG as a source for all managed machines.
This will allow Brooklyn to access managed machines on both the public and private IPs. It
moves the responsibility of assigning the SG to new HA member machines to whoever is managing
the Brooklyn cluster. We could then update the management SG with **all** private IPs in the
HA cluster (need to advertise them in the meta data) or leave it again to the manager of the
cluster.
>
> Would be really cool to have HA clusters manage/heal themselves.
>
> Tangentially related - [2] which IP do we use for the "url" field int he HA member nodes
metadata in REST API (currently empty for the Karaf dist). If it's always the public IP then
it doesn't work for private/VPN instances. It is important for this to be the right one because:
>    * Users are redirected to the master node
>    * Automated systems need to know which is the current master. On failover the old
master (if still around) will redirect to the new master. Workaround is to keep a local copy
of the HA members and iterate over them until it hits MASTER - but it's still important that
the URLs are accessible.
>
> Svet
>
> [1] https://lists.apache.org/list.html?dev@brooklyn.apache.org:lte=1y:%5BPROPOSAL%5D%20Separate%20management%20addresses%20from%20the%20concept%20of%20an%20entity%27s%20public%20address
> [2] https://issues.apache.org/jira/browse/BROOKLYN-436


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