How can I check response header names with case sensitivity?

Oh Dear provides flexible uptime check configuration, allowing you to define criteria for when a site is considered "down", including expected response status codes (e.g. 2*), required (or missing) body text and specific HTTP headers.

HTTP header names are case-insensitive but header values are case-sensitive. As such Oh Dear only verifies header values with case sensitivity - not the header names.

For example, if your check expects the header X-Custom-Header: Production, we will match the value Production exactly, but will accept any casing for the header name (e.g. x-custom-header, X-CUSTOM-HEADER, etc).

It is possible that you need to support legacy integrations (such as customers expecting exact header names) and need Oh Dear to verify your middleware is applying correct transformations.

Even though we are unable to directly support this we would suggest adding a new custom header as part of your intermediate process. Assuming a new header does not also break your integrations this would allow us to verify your transformations are being applied without checking case-sensitivity directly.

You could add an x-ohdear-verify header (with any value) to your existing middleware process and configure Oh Dear to catch this with x-ohdear-verify CONTAINS *.