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60 lines
2.9 KiB
Plaintext
60 lines
2.9 KiB
Plaintext
In many cases, network configuration makes it necessary to run several daemons:
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dhcp, zeroconf, ppp, openvpn and such. They need to be controlled,
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and in many cases you also want to babysit them. runsvdir is a good tool for this.
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examples/var_service directory provides a few examples. It is meant to be used
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this way: copy it somewhere (say, /var/service) and run something like
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env - PATH=... <other vars=...> runsvdir /var/service &
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from one of system startup scripts. (Google "man runsvdir" and "man runsv"
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for more info about these tools).
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Some existing examples:
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var_service/dhcp_if -
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controls a udhcpc instance which provides dhpc-assigned IP
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address on interface named "if". Copy/rename this directory as needed to run
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udhcpc on other interfaces (var_service/dhcp_if/run script uses _foo suffix
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of the parent directory as interface name). When IP address is obtained or lost,
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var_service/dhcp_if/dhcp_handler is run. It saves new config data to
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/var/run/service/fw/dhcp_if.ipconf and (re)starts /var/service/fw service.
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This example can be used as a template for other dynamic network link services
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(ppp/vpn/zcip).
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var_service/ifplugd_if -
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watches link status of interface if. Downs and ups /var/service/dhcp_if
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service accordingly. In effect, it allows you to unplug/plug-to-different-network
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and have your IP properly re-negotiated at once.
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var_service/dhcp_if_pinger -
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Uses var_service/dhcp_if's data (/var/service/dhcp_if/dhcp_if.out file)
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to determine router IP. Pings it. If ping fails, restarts /var/service/dhcp_if
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service. Basically, an example of watchdog service for networks
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which are not reliable and need babysitting.
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var_service/fw -
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A *one-shot* service which reconfigures network based on current known state
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of ALL interfaces. Uses conf/*.ipconf (static config) and /var/run/service/fw/*.ipconf
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(dynamic config from dhcp/ppp/vpn/etc) to determine what to do.
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One-shot-ness of this service means that it shuts itself off after single run.
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IOW: it is not a constantly running daemon sort of thing.
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It starts, it configures the network, it shuts down, all done
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(unlike infamous NetworkManagers which sit in RAM forever, doing hell knows what).
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However, any dhcp/ppp/vpn or similar service can restart it anytime
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when it senses the change in network configuration.
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This even works while fw service runs: if dhcp signals fw to (re)start
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while fw runs, fw will not stop after its execution, but will re-execute once,
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picking up dhcp's new configuration.
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This is achieved very simply by having
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# Make ourself one-shot
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sv o .
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at the very beginning of fw/run script, not at the end.
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Therefore, any "sv u /var/run/service/fw" command by any other
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script "undoes" o(ne-shot) command if fw still runs, thus
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runsv will rerun it; or start it in a normal way if fw is not running.
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System administrators are expected to edit fw/run script, since
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network configuration needs are likely to be very complex and different
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for non-trivial installations.
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