x-pack/filebeat/input/http_endpoint: config.URL can be empty resulting in panic

[efd6]

We have seen an integration using the http_endpoint input that fails with a panic due to a misconfiguration.

Input 'http_endpoint' failed with: input panic with: http: invalid pattern
goroutine 197 [running]:
runtime/debug.Stack()
	runtime/debug/stack.go:24 +0x65
github.com/elastic/beats/v7/filebeat/input/v2/input-stateless.configuredInput.Run.func1()
	github.com/elastic/beats/v7/filebeat/input/v2/input-stateless/stateless.go:81 +0x7f
panic({0x55fbecb7bfc0, 0x55fbed39ef80})
	runtime/panic.go:884 +0x212
net/http.(*ServeMux).Handle(0xc000bb8780, {0x0, 0x0}, {0x55fbed3a4680?, 0xc00076de60})
	net/http/server.go:2497 +0x25f
github.com/elastic/beats/v7/x-pack/filebeat/input/http_endpoint.(*pool).serve(_, {0xc000bba830, {0xc000253780, 0x3f}, {{0x55fbebe57b10, 0x8}, {0x55fbebe57b10, 0x8}, {0x55fbebe4fba1, 0x5}, ...}, ...}, ...)
	github.com/elastic/beats/v7/x-pack/filebeat/input/http_endpoint/input.go:140 +0x63f
github.com/elastic/beats/v7/x-pack/filebeat/input/http_endpoint.(*httpEndpoint).Run(_, {0xc000bba830, {0xc000253780, 0x3f}, {{0x55fbebe57b10, 0x8}, {0x55fbebe57b10, 0x8}, {0x55fbebe4fba1, 0x5}, ...}, ...}, ...)
	github.com/elastic/beats/v7/x-pack/filebeat/input/http_endpoint/input.go:88 +0x6c
github.com/elastic/beats/v7/filebeat/input/v2/input-stateless.configuredInput.Run({{_, _}}, {0xc000bba830, {0xc000253780, 0x3f}, {{0x55fbebe57b10, 0x8}, {0x55fbebe57b10, 0x8}, {0x55fbebe4fba1, ...}, ...}, ...}, ...)
	github.com/elastic/beats/v7/filebeat/input/v2/input-stateless/stateless.go:97 +0x24b
github.com/elastic/beats/v7/filebeat/input/v2/compat.(*runner).Start.func1()
	github.com/elastic/beats/v7/filebeat/input/v2/compat/compat.go:114 +0x215
created by github.com/elastic/beats/v7/filebeat/input/v2/compat.(*runner).Start
	github.com/elastic/beats/v7/filebeat/input/v2/compat/compat.go:111 +0xd8

This happens when the url config option is empty. The default value set for this is "/", however, in this case that appears not to have been set. The validation code should check that the config is correct in this field to provide a more user-friendly error in the logs.

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)

[bhapas]

@efd6 Should this be backported to 8.11 ?

[efd6]

Yeah, I think so.