While troubleshooting tor & bitcoind issues, I've restarted bitcoind two times in a row, and discovered (just accidentally, as I have bitcoind and lnd logs tailed in the same tmux split screen) that lnd is shutting itself down:
Aug 12 12:55:25 odroid-hc1 lnd[5606]: 2021-08-12 12:55:25.120 [ERR] NTFN: Unable to fetch block header: Post "http://127.0.0.1:8332": dial tcp 127.0.0.1:8332: connect: connection refused
Aug 12 12:55:25 odroid-hc1 lnd[5606]: 2021-08-12 12:55:25.304 [INF] CRTR: Pruning channel graph using block 0000000000000000000c7620d7807edfad1c475f204f5c17da4601e2a6e13945 (height=695396)
Aug 12 12:55:37 odroid-hc1 lnd[5606]: 2021-08-12 12:55:37.500 [INF] DISC: GossipSyncer(02ad6fb8d693dc1e4569bcedefadf5f72a931ae027dc0f0c544b34c1c6f3b9a02b): applying gossipFilter(start=0001-01-01 00:00:00 +0000 UTC, end=0001-01-01 00:00:00 +0000 UTC)
Aug 12 12:55:37 odroid-hc1 lnd[5606]: 2021-08-12 12:55:37.501 [INF] DISC: GossipSyncer(036d2ac71176151db04fdac839a0ddea9f3a584f6c23bb0b4ac72c323124ec506b): applying gossipFilter(start=2021-08-12 12:55:37.501421413 +0300 EEST m=+1873248.185437149, end=2157-09-18 19:23:52.501421413 +0300 EEST)
Aug 12 12:56:21 odroid-hc1 lnd[5606]: 2021-08-12 12:56:21.460 [INF] HLCK: Health check: chain backend, call: 2 failed with: -28: Verifying blocks..., backing off for: 2m0s
Aug 12 12:56:37 odroid-hc1 lnd[5606]: 2021-08-12 12:56:37.501 [INF] DISC: Broadcasting 49 new announcements in 5 sub batches
Aug 12 12:58:21 odroid-hc1 lnd[5606]: 2021-08-12 12:58:21.476 [CRT] SRVR: Health check: chain backend failed after 3 calls
Aug 12 12:58:21 odroid-hc1 lnd[5606]: 2021-08-12 12:58:21.476 [INF] SRVR: Sending request for shutdown
Aug 12 12:58:21 odroid-hc1 lnd[5606]: 2021-08-12 12:58:21.516 [INF] LTND: Received shutdown request.
Aug 12 12:58:21 odroid-hc1 lnd[5606]: 2021-08-12 12:58:21.517 [INF] LTND: Shutting down...
Aug 12 12:58:21 odroid-hc1 lnd[5606]: 2021-08-12 12:58:21.517 [INF] LTND: Gracefully shutting down.
...
Aug 12 12:59:58 odroid-hc1 lnd[5606]: 2021-08-12 12:59:58.385 [INF] LTND: Shutdown complete
Aug 12 12:59:58 odroid-hc1 systemd[1]: lnd.service: Succeeded.
systemctl status now is:
Loaded: loaded (/etc/systemd/system/lnd.service; enabled; vendor preset: enabled)
Active: inactive (dead) since Thu 2021-08-12 12:59:58 EEST; 9min ago
Process: 5587 ExecStartPre=/usr/local/bin/lndcache.sh (code=exited, status=0/SUCCESS)
Process: 5606 ExecStart=/home/lnd/lnd.go/bin/lnd --profile=9000 (code=exited, status=0/SUCCESS)
Main PID: 5606 (code=exited, status=0/SUCCESS)
So it has SUCCESS status, meaning systemd will not restart lnd in case of this bail out, even if I have Restart=on-failure, as this was not reported as failure. This is risk for "silently" losing lightning functionality...
v0.13.1-betaLinux odroid-hc1 4.19.0-17-armmp-lpae #1 SMP Debian 4.19.194-3 (2021-07-18) armv7l GNU/Linuxv0.21.1Keep restarting bitcoind until lnd shuts down with success result
lnd process should exit with non-zero result.
lnd exits with success result.