cdist configuration management Latest manual: https://www.cdi.st/manual/latest/ Home page: https://www.cdi.st
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* The scanner, 2020-10-29, Hacking Villa Diesbach
** Motivation
- The purpose of cdist is to ensure systems are in a configured state
- If systems reboot into a clean (think: netboot) state they are
stuck in an unconfigured mode
- We can either trigger *from* those machines
- this is what cdist trigger is for
- Or we can regulary *scan* for machines
- This method does not need any modification to standard OS
** How it works
- cdist scan uses the all nodes multicast group ff02::1
- It sends a ping packet there in regular intervals
- This even works in non-IPv6 networks, as all operating systems
are IPv6 capable and usually IPv6 enabled by default
- Link local is always accessible!
- cdist scan receives an answer from all alive hosts
- These results are stored in ~/.cdist/scan/${hostip}
- We record the last_seen date ~/.cdist/scan/${hostip}/last_seen
- After a host is detected, cdist *can* try to configure it
- It saves the result (+/- logging needs to be defined) in
~/.cdist/scan/${hostip}/{config, install}_result
- If logging is saved: maybe in ~/.cdist/scan/${hostip}/{config, install}_log
- Final naming TBD
** Benefits from the scanning approach
- We know when a host is alive/dead
- We can use standard OS w/o trigger customisation
- Only requirement: we can ssh into it
- Can make use f.i. of Alpine Linux w/ ssh keys feeding in
- We can trigger regular reconfiguration
- If alive && last_config_time > 1d -> reconfigure
- Data can be exported to f.i. prometheus
- Record when configured (successfully)
- Record when seen
- Enables configurations in stateless environments
** Sample output v2020-10-29
23:14] bridge:~% sudo cdist scan -b -I wlan0 -vv
VERBOSE: cdist: version 6.8.0-36-g91d99bf0
VERBOSE: scan: Host fe80::21d:72ff:fe86:46b is alive
VERBOSE: scan: Host fe80::ce2d:e0ff:fed4:2611 is alive
VERBOSE: scan: Host fe80::21b:fcff:feee:f4c1 is alive
VERBOSE: scan: Host fe80::e2ff:f7ff:fe00:20e6 is alive
VERBOSE: scan: Host fe80::20d:b9ff:fe49:ac11 is alive
VERBOSE: scan: Host fe80::9e93:4eff:fe6c:c1f4 is alive
VERBOSE: scan: Host fe80::ce32:e5ff:fe79:7ea7 is alive
VERBOSE: scan: Host fe80::219:d2ff:feb2:2e12 is alive
VERBOSE: scan: Host fe80::d66d:6dff:fe33:e00 is alive
VERBOSE: scan: Host fe80::21b:fcff:feee:f446 is alive
VERBOSE: scan: Host fe80::21b:fcff:feee:f4b1 is alive
VERBOSE: scan: Host fe80::20d:b9ff:fe4c:547d is alive
VERBOSE: scan: Host fe80::bad8:12ff:fe65:313d is alive
VERBOSE: scan: Host fe80::42b0:34ff:fe6f:f6f0 is alive
VERBOSE: scan: Host fe80::ba69:f4ff:fec5:6041 is alive
VERBOSE: scan: Host fe80::f29f:c2ff:fe7c:275e is alive
VERBOSE: scan: Host fe80::ba69:f4ff:fec5:8db7 is alive
VERBOSE: scan: Host fe80::42b0:34ff:fe6f:f863 is alive
VERBOSE: scan: Host fe80::21b:fcff:feee:f4bc is alive
...