certinfo

Get information about the certificate from one or more hostnames.

Usage

Usage:
  certinfo HOSTNAME [HOSTNAME ...] [flags]

Flags:
  -h, --help                    help for certinfo
  -o, --output text|json|none   output format, one of: text|json|none.
                                If set to "json", certinfo will output all information about the certificate (default "text")
  -p, --port int                port to look for TLS certificates on (default 443)
  -r, --retry int               retry request if transient problems occur (default 5)
  -t, --threshold int           exit certinfo with exit code 1 if a certificate expiration time is less than this (in days)
      --timeout int             timeout on TCP dialing (in seconds) (default 5)
  -v, --verbose                 log connections
      --version                 version for certinfo

Examples

get certificate for google.io

certinfo google.io

output:

Host: google.io:443
Certs:
    Issuer:     GTS CA 1C3 (Google Trust Services LLC)
    Subject:    *.google.io
    Not Before: Monday, 12 July 2021 at 07:24:53 (CEST)
    Not After:  Monday, 4 October 2021 at 07:24:52 (CEST)
    DNS names:  *.google.io google.io

get certificate from google.io and output the complete certificate information as json

certinfo --output json --verbose google.io

output:

2018/11/04 19:19:15 connecting to google.io:443
[
  {
    "Host": "google.io",
    "Port": 443,
    "Certs": [
      {
        // snip many fields!
      }
    ]
  }
]

get certificate for google.io and check if the certificate is valid for more than 30 days

certinfo --output none --threshold 30 google.io

output:

there is no output if the certificate expires more than 30 days

get certificate for google.io and check if the certificate is valid for more than 20 days

certinfo --output none --threshold 20 google.io

output:

Problem running certinfo: certificate for *.google.io expires in 60.10 days (at 2021-09-14T17:47:02Z)

get certificate for google.io and extract the expiration date

certinfo --output json example.io | jq -r '.[].Certs[].NotBefore'

output:

2021-06-22T17:47:03Z

using in a cronjob with healthchecks.io

0 2 * * * root result=$(certinfo google.io); curl -fsS -X POST --data-raw "$result" "https://healthchecks.example.com/ping/<UID>$([ $? != 0 ] && echo -n /fail)" > /dev/null

inspired by certinfo