(*Cache).SetOptions does not check for default intervals

[jameshartig]

What version of the package are you using?

v0.19.2

What are you trying to do?

Start caddy without any tls but multiple http servers. We have a boilerplate default config (below) and then modify the config at runtime using the admin server.

What steps did you take?

Started caddy with the following default config:

{
  "admin": {
    "listen": "unix//var/run/caddy/caddy.sock|0600"
  },
  "apps": {
    "http": {
      "grace_period": "30s",
      "servers": {
        "default": {
          "automatic_https": {
            "disable": true
          },
          "idle_timeout": "650s",
          "listen": [
            ":7080"
          ],
          "max_header_bytes": 1048576,
          "metrics": {},
          "read_header_timeout": "1m",
          "read_timeout": "3m",
          "routes": [
            {
              "@id": "$last-default-404",
              "handle": [
                {
                  "handler": "static_response",
                  "status_code": "404"
                }
              ]
            }
          ],
          "write_timeout": "5m"
        },
        "metrics": {
          "automatic_https": {
            "disable": true
          },
          "listen": [
            ":7081"
          ],
          "routes": [
            {
              "@id": "$last-metrics-404",
              "handle": [
                {
                  "handler": "static_response",
                  "status_code": "404"
                }
              ]
            }
          ]
        }
      },
      "shutdown_delay": "5s"
    }
  },
  "logging": {
    "logs": {
      "default": {
        "level": "ERROR"
      }
    },
    "sink": {
      "writer": {
        "output": "stderr"
      }
    }
  },
  "storage": {
    "module": "file_system",
    "root": "/var/lib/caddy"
  }
}

I believe we didn't try to initially configure caddy until after it started to log the below panic.

We do make a small configuration change as soon as the server starts which is probably what triggered this.

What did you expect to happen, and what actually happened instead?

I expected it to start up correctly.

There was a panic on startup caused by a timer being started with a non-positive interval.

{"level":"info","ts":1739472209.4884524,"msg":"no autosave file exists","autosave_file":"/opt/caddy/autosave.json"}
{"level":"info","ts":1739472209.4886894,"msg":"using provided configuration","config_file":"/opt/caddy/caddy.json","config_adapter":""}
{"level":"error","ts":1739472209.526402,"logger":"tls.cache.maintenance","msg":"panic","cache":"0xc000478180","error":"non-positive interval for NewTicker","stack":"goroutine 12 [running]:\ngithub.com/caddyserver/certmagic.(*Cache).maintainAssets.func1()\n\tgithub.com/caddyserver/[email protected]/maintain.go:48 +0x85\npanic({0x16b4c80?, 0x1e6e450?})\n\truntime/panic.go:914 +0x21f\ntime.NewTicker(0xc0002b4070?)\n\ttime/tick.go:22 +0xe5\ngithub.com/caddyserver/certmagic.(*Cache).maintainAssets(0xc000478180, 0x0)\n\tgithub.com/caddyserver/[email protected]/maintain.go:57 +0x207\ncreated by github.com/caddyserver/certmagic.NewCache in goroutine 1\n\tgithub.com/caddyserver/[email protected]/cache.go:127 +0x1f6\n"}
... repeats several times ...

This doesn't happen every time as its a race condition between (*Cache)SetOptions being called and the maintainAssets goroutine being scheduled.

How do you think this should be fixed?

The (*Cache).SetOptions should do the same thing as NewCache and check for non-positive intervals and set them to their defaults.

Please link to any related issues, pull requests, and/or discussion

It seems like the TLS module in caddy does which I believe to be the only possible place that could have caused this. If SetOptions is called before the maintainAssets is scheduled then it could set the intervals to 0. I haven't figured out why the TLS app is being provisioned but I believe it has something to do with the http app always having a default TLS app.

	certCacheMu.Lock()
	if certCache == nil {
		certCache = certmagic.NewCache(cacheOpts)
	} else {
		certCache.SetOptions(cacheOpts)
	}
	certCacheMu.Unlock()

Bonus: What do you use CertMagic for, and do you find it useful?