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Redirects

redirects lists the responses that told the client to go somewhere else, grouped by route. It flags two things: a redirect that happens over and over (a storm), and a redirect that goes to another host.

wiretrail checkout.har redirects

   6x  [302] GET cdn.shop.example/img/hero.png [storm]
  -> cdn.shop.example
  entries: e000007, e000020, e000039, e000053, e000067, e000074

   1x  [301] GET www.shop.example/ [cross-host]
  -> shop.example
  entries: e000000

What counts as a redirect

A response with status 301, 302, 303, 307 or 308, or any response that has a redirect URL. Redirects are grouped by host, method, normalized path and status.

Tag Meaning
[storm] The group has five or more requests.
[cross-host] The redirect target is on a different host from the request.

-> cdn.shop.example is the host of the target. The six requests above all ask for /img/hero.png and are sent to /img/hero.webp. The page keeps asking for the old URL, so every view pays for a redirect. The fix is to use the final URL. The 301 from www.shop.example to the bare host is a one-off and is the expected way to canonicalize a host.

-> host is shown only when the entry's redirectURL is a full URL. WireTrail reads that field and not the Location header. When it is relative, such as /b.png, or empty, WireTrail cannot read a host from it. The group is listed without a target and is never marked [cross-host]:

wiretrail quirks/relative-redirect.har redirects

   6x  [302] GET cdn.test.example/a.png [storm]
  entries: e000000, e000001, e000002, e000003, e000004, e000005

The ranked finding

A redirect group of five or more requests becomes a LOW redirect-storm finding in summary, diagnose and auto. It is LOW, the lowest level, because a redirect costs a round trip and not a failure.

JSON

wiretrail checkout.har redirects --top 2 --json | jq '.result.groups[] | del(.entry_ids)'

{
  "host": "cdn.shop.example",
  "method": "GET",
  "norm_path": "/img/hero.png",
  "status": 302,
  "count": 6,
  "target_host": "cdn.shop.example",
  "cross_host": false,
  "is_storm": true,
  "first_offset_ms": 420.0,
  "last_offset_ms": 36400.0
}
{
  "host": "www.shop.example",
  "method": "GET",
  "norm_path": "/",
  "status": 301,
  "count": 1,
  "target_host": "shop.example",
  "cross_host": true,
  "is_storm": false,
  "first_offset_ms": 0.0,
  "last_offset_ms": 0.0
}

Exit code

redirects exits 1 only when a group is a storm. A capture with one redirect exits 0.

  • Timeline shows when each redirect happened.
  • Errors for requests that failed rather than redirected.