35 lines
1.7 KiB
Org Mode
35 lines
1.7 KiB
Org Mode
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* The scanner, 2020-10-29, Hacking Villa Diesbach
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** Motivation
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- The purpose of cdist is to ensure systems are in a configured state
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- If systems reboot into a clean (think: netboot) state they are
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stuck in an unconfigured mode
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- We can either trigger *from* those machines
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- this is what cdist trigger is for
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- Or we can regulary *scan* for machines
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- This method does not need any modification to standard OS
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** How it works
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- cdist scan uses the all nodes multicast group ff02::1
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- It sends a ping packet there in regular intervals
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- This even works in non-IPv6 networks, as all operating systems
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are IPv6 capable and usually IPv6 enabled by default
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- Link local is always accessible!
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- cdist scan receives an answer from all alive hosts
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- These results are stored in ~/.cdist/scan/${hostip}
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- We record the last_seen date ~/.cdist/scan/${hostip}/last_seen
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- After a host is detected, cdist *can* try to configure it
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- It saves the result (+/- logging needs to be defined) in
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~/.cdist/scan/${hostip}/{config, install}_result
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- If logging is saved: maybe in ~/.cdist/scan/${hostip}/{config, install}_log
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- Final naming TBD
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** Benefits from the scanning approach
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- We know when a host is alive/dead
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- We can use standard OS w/o trigger customisation
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- Only requirement: we can ssh into it
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- Can make use f.i. of Alpine Linux w/ ssh keys feeding in
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- We can trigger regular reconfiguration
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- If alive && last_config_time > 1d -> reconfigure
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- Data can be exported to f.i. prometheus
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- Record when configured (successfully)
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- Record when seen
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- Enables configurations in stateless environments
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