electric-eye checks the availability of HTTP endpoints, and publishes the
results as Prometheus metrics.
Sample tshark capture while running electric-eye monitoring
www.example.com:
1 0.000000000 192.168.0.6 → 208.67.222.123 DNS 75 Standard query 0x050f A www.example.com
2 0.000016688 192.168.0.6 → 208.67.222.123 DNS 75 Standard query 0x1489 AAAA www.example.com
3 0.013770783 208.67.222.123 → 192.168.0.6 DNS 91 Standard query response 0x050f A www.example.com A 93.184.216.34
4 0.013771031 208.67.222.123 → 192.168.0.6 DNS 103 Standard query response 0x1489 AAAA www.example.com AAAA 2606:2800:220:1:248:1893:25c8:1946
5 0.014361111 192.168.0.6 → 93.184.216.34 TCP 74 59616 → 80 [SYN] Seq=0 Win=64240 Len=0 MSS=1460 SACK_PERM=1 TSval=582720675 TSecr=0 WS=128
6 0.022834941 93.184.216.34 → 192.168.0.6 TCP 74 80 → 59616 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1452 SACK_PERM=1 TSval=3632580192 TSecr=582720675 WS=512
7 0.022887273 192.168.0.6 → 93.184.216.34 TCP 66 59616 → 80 [ACK] Seq=1 Ack=1 Win=64256 Len=0 TSval=582720683 TSecr=3632580192
8 0.023096061 192.168.0.6 → 93.184.216.34 HTTP 175 GET / HTTP/1.1
9 0.031894241 93.184.216.34 → 192.168.0.6 TCP 66 80 → 59616 [ACK] Seq=1 Ack=110 Win=144896 Len=0 TSval=3632580201 TSecr=582720683
10 0.031894476 93.184.216.34 → 192.168.0.6 HTTP 1090 HTTP/1.1 200 OK (text/html)
11 0.031894523 93.184.216.34 → 192.168.0.6 TCP 66 80 → 59616 [FIN, ACK] Seq=1025 Ack=110 Win=144896 Len=0 TSval=3632580202 TSecr=582720683
12 0.031930599 192.168.0.6 → 93.184.216.34 TCP 66 59616 → 80 [ACK] Seq=110 Ack=1025 Win=64128 Len=0 TSval=582720692 TSecr=3632580202
13 0.032136452 192.168.0.6 → 93.184.216.34 TCP 66 59616 → 80 [FIN, ACK] Seq=110 Ack=1026 Win=64128 Len=0 TSval=582720692 TSecr=3632580202
14 0.041598396 93.184.216.34 → 192.168.0.6 TCP 66 80 → 59616 [ACK] Seq=1026 Ack=111 Win=144896 Len=0 TSval=3632580210 TSecr=582720692