96ba0ca283
During a configuration switch, changed units are stopped in the old
configuration, then started in the new configuration (i.e. after
running the activation script and running "systemctl daemon-reload").
This ensures that services are stopped using the ExecStop/ExecStopPost
commands from the old configuration.
However, for some services it's undesirable to stop them; in
particular dhcpcd, which deconfigures its network interfaces when it
stops. This is dangerous when doing remote upgrades - usually things
go right (especially because the switch script ignores SIGHUP), but
not always (see 9aa69885f0). Likewise,
sshd should be kept running for as long as possible to prevent a
lock-out if the switch fails.
So the new option ‘stopIfChanged = false’ causes "systemctl restart"
to be used instead of "systemctl stop" followed by "systemctl start".
This is only proper for services that don't have stop commands. (And
it might not handle dependencies properly in some cases, but I'm not
sure.)
134 lines
4.2 KiB
Nix
134 lines
4.2 KiB
Nix
{ config, pkgs, ... }:
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with pkgs.lib;
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let
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inherit (pkgs) dhcpcd;
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# Don't start dhclient on explicitly configured interfaces or on
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# interfaces that are part of a bridge.
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ignoredInterfaces =
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map (i: i.name) (filter (i: i.ipAddress != null) (attrValues config.networking.interfaces))
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++ concatLists (attrValues (mapAttrs (n: v: v.interfaces) config.networking.bridges))
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++ config.networking.dhcpcd.denyInterfaces;
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# Config file adapted from the one that ships with dhcpcd.
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dhcpcdConf = pkgs.writeText "dhcpcd.conf"
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''
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# Inform the DHCP server of our hostname for DDNS.
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hostname
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# A list of options to request from the DHCP server.
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option domain_name_servers, domain_name, domain_search, host_name
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option classless_static_routes, ntp_servers, interface_mtu
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# A ServerID is required by RFC2131.
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# Commented out because of many non-compliant DHCP servers in the wild :(
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#require dhcp_server_identifier
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# A hook script is provided to lookup the hostname if not set by
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# the DHCP server, but it should not be run by default.
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nohook lookup-hostname
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# Ignore peth* devices; on Xen, they're renamed physical
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# Ethernet cards used for bridging. Likewise for vif* and tap*
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# (Xen) and virbr* and vnet* (libvirt).
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denyinterfaces ${toString ignoredInterfaces} peth* vif* tap* tun* virbr* vnet* vboxnet*
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'';
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# Hook for emitting ip-up/ip-down events.
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exitHook = pkgs.writeText "dhcpcd.exit-hook"
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''
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#exec >> /var/log/dhcpcd 2>&1
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#set -x
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params="IFACE=$interface REASON=$reason"
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# only works when interface is wireless and wpa_supplicant has a control socket
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# but we allow it to fail silently
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${optionalString config.networking.wireless.enable ''
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params+=" $(${pkgs.wpa_supplicant}/sbin/wpa_cli -i$interface status 2>/dev/null | grep ssid | sed 's|^b|B|;s|ssid|SSID|' | xargs)"
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''}
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if [ "$reason" = BOUND -o "$reason" = REBOOT ]; then
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# Restart ntpd. We need to restart it to make sure that it
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# will actually do something: if ntpd cannot resolve the
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# server hostnames in its config file, then it will never do
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# anything ever again ("couldn't resolve ..., giving up on
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# it"), so we silently lose time synchronisation.
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${config.system.build.systemd}/bin/systemctl try-restart ntpd.service
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${config.system.build.systemd}/bin/systemctl start ip-up.target
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fi
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#if [ "$reason" = EXPIRE -o "$reason" = RELEASE -o "$reason" = NOCARRIER ] ; then
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# ${config.system.build.systemd}/bin/systemctl start ip-down.target
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#fi
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'';
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in
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{
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###### interface
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options = {
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networking.dhcpcd.denyInterfaces = mkOption {
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default = [];
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description = ''
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Disable the DHCP client for any interface which's name matches
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any of the shell glob patterns in this list. The purpose of
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this option is blacklist virtual interfaces such as those
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created by Xen, libvirt, LXC, etc.
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'';
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};
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};
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###### implementation
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config = mkIf config.networking.useDHCP {
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boot.systemd.services.dhcpcd =
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{ description = "DHCP Client";
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wantedBy = [ "network.target" ];
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# Stopping dhcpcd during a reconfiguration is undesirable
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# because it brings down the network interfaces configured by
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# dhcpcd. So do a "systemctl restart" instead.
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stopIfChanged = false;
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path = [ dhcpcd pkgs.nettools pkgs.openresolv ];
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serviceConfig =
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{ Type = "forking";
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PIDFile = "/run/dhcpcd.pid";
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ExecStart = "@${dhcpcd}/sbin/dhcpcd dhcpcd --config ${dhcpcdConf}";
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ExecReload = "${dhcpcd}/sbin/dhcpcd --rebind";
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StandardError = "null";
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Restart = "always";
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};
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};
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environment.systemPackages = [ dhcpcd ];
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environment.etc =
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[ { source = exitHook;
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target = "dhcpcd.exit-hook";
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}
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];
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powerManagement.resumeCommands =
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''
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# Tell dhcpcd to rebind its interfaces if it's running.
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${config.system.build.systemd}/bin/systemctl reload dhcpcd.service
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'';
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};
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}
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