Web / Caddy Server Interview questions
Explain the lifecycle of a Caddy TLS certificate?
A certificate under Caddy's management moves through a repeating cycle rather than a one-time setup, driven by CertMagic's background maintenance loop.
flowchart TD
A[Site block loaded with public hostname] --> B{Valid cert already in storage?}
B -- No --> C[Start ACME order with CA]
C --> D[Complete challenge: HTTP-01, TLS-ALPN-01, or DNS-01]
D --> E[CA issues certificate]
E --> F[Store cert and key on disk]
F --> G[Serve HTTPS traffic]
B -- Yes --> G
G --> H{Cert within ~30 days of expiry?}
H -- Yes --> C
H -- No --> G
On first load, Caddy checks its storage for an existing valid certificate; if none exists, it starts an ACME order, completes a challenge to prove domain control, receives the issued certificate, and writes it to storage before serving HTTPS. From then on, a background check runs continuously: once the certificate nears its expiry window, the same order-challenge-issue sequence repeats automatically, so a live site theoretically never needs a human to touch its certificate again.
On first load, if no valid certificate exists yet, Caddy's next step is:
The certificate lifecycle loop is driven by:
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