2020-11-09 08:25:14 +00:00
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---
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title: Using DHCP for the unikernels
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author: reynir
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---
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# Using DHCP for the unikernels
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2020-11-10 11:03:14 +00:00
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Setting up a simple DHCP server for the bridge was fairly simple using systemd-networkd.
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It's as simple as adding `DHCPServer=true` in the `.network` file for the bridge.
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It is possible to configure more options under the `[DHCPServer]` section.
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While DHCP *does* work, I *did* have problems using Canopy.
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The unikernel would crash with an exception caused by DNS failing to resolve the hostname for the git repository.
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The problem was especially evident with the default DNS resolver of anycast.censurfridns.dk as well as Google's 8.8.8.8.
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With the ISPs DNS resolver it worked *most* of the time.
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It seems the unikernel waits no more than *five seconds* for the hostname to resolve, or fetching the git repository.
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Browsing the code, it was not immediately obvious where the five seconds is coming from or how to change it.
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When it crashes it seems it took a bit longer than usual to get a lease through DHCP.
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A possible contributing factor is that systemd-networkd creates with `no-carrier`.
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A workaround mentioned in the corresponding [issue](https://github.com/systemd/systemd/issues/9252) suggests creating a configured dummy interface.
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When there's already a running unikernel connected to the bridge it forces systemd-networkd to configure the bridge.
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However, this does not seem to remove the problem entirely.
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More investigation is required...
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