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| 1 | In many cases, network configuration makes it necessary to run several daemons: |
| 2 | dhcp, zeroconf, ppp, openvpn and such. They need to be controlled, |
| 3 | and in many cases you also want to babysit them. runsvdir is a good tool for this. |
| 4 | examples/var_service directory provides a few examples. It is meant to be used |
| 5 | this way: copy it somewhere (say, /var/service) and run something like |
| 6 | |
| 7 | env - PATH=... <other vars=...> runsvdir /var/service & |
| 8 | |
| 9 | from one of system startup scripts. (Google "man runsvdir" and "man runsv" |
| 10 | for more info about these tools). |
| 11 | |
| 12 | Some existing examples: |
| 13 | |
| 14 | var_service/dhcp_if - |
| 15 | controls a udhcpc instance which provides dhpc-assigned IP |
| 16 | address on interface named "if". Copy/rename this directory as needed to run |
| 17 | udhcpc on other interfaces (var_service/dhcp_if/run script uses _foo suffix |
| 18 | of the parent directory as interface name). When IP address is obtained or lost, |
| 19 | var_service/dhcp_if/dhcp_handler is run. It saves new config data to |
| 20 | /var/run/service/fw/dhcp_if.ipconf and (re)starts /var/service/fw service. |
| 21 | This example can be used as a template for other dynamic network link services |
| 22 | (ppp/vpn/zcip). |
| 23 | |
| 24 | var_service/ifplugd_if - |
| 25 | watches link status of interface if. Downs and ups /var/service/dhcp_if |
| 26 | service accordingly. In effect, it allows you to unplug/plug-to-different-network |
| 27 | and have your IP properly re-negotiated at once. |
| 28 | |
| 29 | var_service/dhcp_if_pinger - |
| 30 | Uses var_service/dhcp_if's data (/var/service/dhcp_if/dhcp_if.out file) |
| 31 | to determine router IP. Pings it. If ping fails, restarts /var/service/dhcp_if |
| 32 | service. Basically, an example of watchdog service for networks |
| 33 | which are not reliable and need babysitting. |
| 34 | |
| 35 | var_service/fw - |
| 36 | A *one-shot* service which reconfigures network based on current known state |
| 37 | of ALL interfaces. Uses conf/*.ipconf (static config) and /var/run/service/fw/*.ipconf |
| 38 | (dynamic config from dhcp/ppp/vpn/etc) to determine what to do. |
| 39 | One-shot-ness of this service means that it shuts itself off after single run. |
| 40 | IOW: it is not a constantly running daemon sort of thing. |
| 41 | It starts, it configures the network, it shuts down, all done |
| 42 | (unlike infamous NetworkManagers which sit in RAM forever, doing hell knows what). |
| 43 | |
| 44 | However, any dhcp/ppp/vpn or similar service can restart it anytime |
| 45 | when it senses the change in network configuration. |
| 46 | This even works while fw service runs: if dhcp signals fw to (re)start |
| 47 | while fw runs, fw will not stop after its execution, but will re-execute once, |
| 48 | picking up dhcp's new configuration. |
| 49 | This is achieved very simply by having |
| 50 | # Make ourself one-shot |
| 51 | sv o . |
| 52 | at the very beginning of fw/run script, not at the end. |
| 53 | Therefore, any "sv u /var/run/service/fw" command by any other |
| 54 | script "undoes" o(ne-shot) command if fw still runs, thus |
| 55 | runsv will rerun it; or start it in a normal way if fw is not running. |
| 56 | |
| 57 | System administrators are expected to edit fw/run script, since |
| 58 | network configuration needs are likely to be very complex and different |
| 59 | for non-trivial installations. |
| 60 |