Systemd integration

[JulienBalestra]

On systemd platform, it could be useful to use sd_notify.

This will improve the integration of the agent with Systemd and allow to create a datadog agent unit with the following directive:

[Service]
Type=notify

Then, any other application with a dependency on the Datadog agent could use with leverage the following directive without writing any custom wait-for-agent:

[Unit]
Requires=datadog-agent.service
After=datadog-agent.service

An example of this implementation is etcd

[masci]

Agreed this would be useful, I already have a card in our backlog to implement the readiness protocol but patches are welcome 😜