How disable powerdns in microbosh and bosh ?


Guillaume Berche
 

Hi,

I understand that by default the micro-bosh has DNS enabled (i.e. hosts a
powerDNS servers that gets injected by default in all VMs it manages). If
the dns entry [1] is specified, additional DNS resolvers will be added to
/etc/resolv.conf and the micro bosh powerDNS will remain (at the end as the
last fallback ?) When micro-bosh is only used to instanciate a multi-vm
bosh instance which does not rely on FQDN but rather on IP addresses, then
it would make sense to disable DNS on microbosh to avoid bosh failing to
resolve Iaas FQDN in case microbosh is down.

On a multi-vm bosh cluter, it seems the power DNS would be disabled if any
of the necessary dns property is missing [3], even through spec file [2]
isn't explicit about it.

I however wonder what's the best way to disable the DNS job in the
micro-bosh, as the dns properties are typically not set in the microbosh
manifest. Searching through forums I only found [4] mentionning specifying
the "dynamic" type for the micro-bosh network implicitly disables the
powerDNS job. I don't understand why there is a link between the two. Is
there a more explict way to configure micro-bosh DNS ? Where are director
properties [2] default values for micro set, and can they be overriden from
the manifest file ? I tried assigning an empty dns.adress in the micro bosh
manifest, but the bosh micro cli did not pick the modification "Will skip
deploy due to no changes". Am I on the right track ?

apply_spec:
properties:
dns:
#Define an empty DNS address to disable the microbosh power DNS
running by default.
address:

I tried looking at the concourse pipeline config and resources to get
inspiration but could not find related bosh config yet.

Thanks in advance,

Guillaume.

[0] https://bosh.io/docs/create-micro-manifest.html
*MicroBOSH has a nameserver component called powerDNS. If, after you deploy
MicroBOSH, you use it deploy other software, MicroBOSH will create VMs as
it deploys that software. VMs that MicroBOSH creates use the powerDNS on
their parent VM to resolve IP addresses.*
[1] http://bosh.io/docs/networks.html
[2]
https://github.com/cloudfoundry/bosh/blob/05806e445d4784b5c44721dfe7dc89aeb353de66/release/jobs/director/spec#L149
[3]
https://github.com/cloudfoundry/bosh/blob/7cd8b976a0489e47947c7f9ffc1c2db77dc5e3da/release/jobs/director/templates/director.yml.erb.erb#L67-L84
[4] https://groups.google.com/a/cloudfoundry.org/d/msg/bosh-users/6lfnOXMlBEU/hAJiewKL7wAJ

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