[receiver/statsdreceiver] Add ability to customize permissions of socket when using UDS server

[thomas-gouveia]

Component(s)

receiver/statsd

Is your feature request related to a problem? Please describe.

We have some apps deployed in Kubernetes configured to send metrics to Datadog through the unix datagram socket managed by the Datadog agent in /var/run/datadog/dsd.socket. We're currently exploring a solution to deploy a drop-in replacement of the Datadog agent using a combination of statsdreceiver and datadogreceiver in the collector.

We have a PoC deployed and that works properly, but we have a little issue with the permissions of the socket bind by the statsdreceiver. If the application doesn't run with the same user than the collector, it won't be able to write to the socket because of the following permissions on the socket (default one I assume):

ls -l /var/run/

total 0
srwx-w--w- 1 root root 0 Feb  10 13:53 statsd-receiver.sock

So only owner of the socket is able to write (in that case, root). In comparison the Datadog agent socket has the following permissions:

ls -l /var/run/datadog 

total 0
srwx-w--w- 1 root root 0 Jan  3 15:53 dsd.socket

Describe the solution you'd like

To solve the issue, I propose to call a chmod with 0622 right after the bind call to ensure permissions of the socket are managed by the receiver itself.

If needed, we can also introduce in the configuration a new attribute to allow customization of permissions, and make 0622 as default :

config:
  receivers:
    statsd:
      transport: unixgram
      endpoint: /path/to/statsd.socket
      perms: 0622

Describe alternatives you've considered

• Usage of initContainers running as root to run chmod/chown: it works but if the collector restarts, permissions are reset when it binds again.
• Usage of fsGroup, not working

Additional context

I can propose a fix for this issue 👍

[github-actions]

Pinging code owners:

• receiver/statsd: @jmacd @dmitryax

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[jmacd]

Looks good to me, please go ahead!

[thomas-gouveia]

Sorry for my late response @jmacd, missed the notification! Will open the PR 👍