56 lines
2.1 KiB
Nix
56 lines
2.1 KiB
Nix
{ pkgs, ... }:
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{
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# Service to wait for DNS resolution to be actually functional
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# This is needed because network-online.target and wait-online.service
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# don't guarantee DNS works - they only check that interfaces are configured.
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#
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# Problem: NFS mounts using Consul DNS names (data-services.service.consul)
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# fail at boot because DNS resolution isn't ready even though network is "online"
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#
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# Solution: Actively test DNS resolution before considering network truly ready
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systemd.services.wait-for-dns-ready = {
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description = "Wait for DNS resolution to be functional";
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after = [
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"systemd-networkd-wait-online.service"
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"systemd-resolved.service"
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"network-online.target"
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];
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wants = [ "network-online.target" ];
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wantedBy = [ "multi-user.target" ];
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serviceConfig = {
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Type = "oneshot";
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RemainAfterExit = true;
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ExecStart = pkgs.writeShellScript "wait-for-dns-ready" ''
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# Test DNS resolution by attempting to resolve data-services.service.consul
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# This ensures the full DNS path works: interface → gateway → Consul DNS
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echo "Waiting for DNS resolution to be ready..."
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for i in {1..30}; do
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# Use getent which respects /etc/nsswitch.conf and systemd-resolved
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if ${pkgs.glibc.bin}/bin/getent hosts data-services.service.consul >/dev/null 2>&1; then
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echo "DNS ready: data-services.service.consul resolved successfully"
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exit 0
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fi
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# Also test a public DNS name to distinguish between general DNS failure
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# vs Consul-specific issues (helpful for debugging)
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if ! ${pkgs.glibc.bin}/bin/getent hosts www.google.com >/dev/null 2>&1; then
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echo "Attempt $i/30: General DNS not working yet, waiting..."
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else
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echo "Attempt $i/30: General DNS works but Consul DNS not ready yet, waiting..."
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fi
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sleep 1
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done
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echo "Warning: DNS not fully ready after 30 seconds"
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echo "NFS mounts with 'nofail' option will handle this gracefully"
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exit 0 # Don't block boot - let nofail mounts handle DNS failures
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'';
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};
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};
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}
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