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Certificate validity

On this page
  1. Settings
  2. When is it healthy?
  3. The days remaining
  4. Example
  5. Good to know

The Certificate validity sensor connects to a host over TLS, reads its certificate and checks how many days remain before it expires. Use it so that no certificate ever expires unnoticed — on your websites, your APIs or your partners' endpoints.

In the wizard: SSL certificate.

Settings#

Setting Description
Host The host whose certificate to read, for example edi.partner.example.
Alert before expiry Number of days before expiry at which the check fails, from 1 to 730.

The check always runs once a day.

When is it healthy?#

When the certificate expires in more days than Alert before expiry. The sensor watches the expiry date; to fail on any certificate error (wrong name, untrusted chain), add an HTTP sensor with Verify SSL certificate on.

The days remaining#

The number of days before expiry is recorded with every check and charted: it decreases day after day, then jumps back up when the certificate is renewed.

Partner EDI — TLS certificate over three months: the days remaining before expiry fall to about ten, then jump back to about 400 when the certificate is renewed.
The days remaining before expiry, charted: the renewal shows as a jump back up.

Example#

Partner EDI — TLS certificate: host edi.partner.example, alert 14 days before expiry, severity Major. The incident opens two weeks before the deadline and is resolved by itself once the partner renews.

Good to know#

The sensor connects on port 443.