reverseproxy: Add `handle_response` blocks to `reverse_proxy` (#3710) (#4021)

* reverseproxy: Add `handle_response` blocks to `reverse_proxy` (#3710)

* reverseproxy: complete handle_response test

* reverseproxy: Change handle_response matchers to use named matchers

reverseproxy: Add support for changing status code

* fastcgi: Remove obsolete TODO

We already have d.Err("transport already specified") in the reverse_proxy parsing code which covers this case

* reverseproxy: Fix support for "4xx" type status codes

* Apply suggestions from code review

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

* caddyhttp: Reorganize response matchers

* reverseproxy: Reintroduce caddyfile.Unmarshaler

* reverseproxy: Add comment mentioning Finalize should be called

Co-authored-by: Maxime Soulé <btik-git@scoubidou.com>
Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

1 files changed, 193 insertions, 0 deletions

diff --git a/caddytest/integration/caddyfile_adapt/reverse_proxy_handle_response.txt b/caddytest/integration/caddyfile_adapt/reverse_proxy_handle_response.txt
new file mode 100644
index 0000000..35d9631
--- /dev/null
+++ b/caddytest/integration/caddyfile_adapt/reverse_proxy_handle_response.txt
@@ -0,0 +1,193 @@
+:8884
+
+reverse_proxy 127.0.0.1:65535 {
+	@accel header X-Accel-Redirect *
+	handle_response @accel {
+		respond "Header X-Accel-Redirect!"
+	}
+
+	@another {
+		header X-Another *
+	}
+	handle_response @another {
+		respond "Header X-Another!"
+	}
+
+	@401 status 401
+	handle_response @401 {
+		respond "Status 401!"
+	}
+
+	handle_response {
+		respond "Any! This should be last in the JSON!"
+	}
+
+	@403 {
+		status 403
+	}
+	handle_response @403 {
+		respond "Status 403!"
+	}
+
+	@multi {
+		status 401 403
+		status 404
+		header Foo *
+		header Bar *
+	}
+	handle_response @multi {
+		respond "Headers Foo, Bar AND statuses 401, 403 and 404!"
+	}
+
+	@changeStatus status 500
+	handle_response @changeStatus 400
+}
+----------
+{
+	"apps": {
+		"http": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						":8884"
+					],
+					"routes": [
+						{
+							"handle": [
+								{
+									"handle_response": [
+										{
+											"match": {
+												"headers": {
+													"X-Accel-Redirect": [
+														"*"
+													]
+												}
+											},
+											"routes": [
+												{
+													"handle": [
+														{
+															"body": "Header X-Accel-Redirect!",
+															"handler": "static_response"
+														}
+													]
+												}
+											]
+										},
+										{
+											"match": {
+												"headers": {
+													"X-Another": [
+														"*"
+													]
+												}
+											},
+											"routes": [
+												{
+													"handle": [
+														{
+															"body": "Header X-Another!",
+															"handler": "static_response"
+														}
+													]
+												}
+											]
+										},
+										{
+											"match": {
+												"status_code": [
+													401
+												]
+											},
+											"routes": [
+												{
+													"handle": [
+														{
+															"body": "Status 401!",
+															"handler": "static_response"
+														}
+													]
+												}
+											]
+										},
+										{
+											"match": {
+												"status_code": [
+													403
+												]
+											},
+											"routes": [
+												{
+													"handle": [
+														{
+															"body": "Status 403!",
+															"handler": "static_response"
+														}
+													]
+												}
+											]
+										},
+										{
+											"match": {
+												"headers": {
+													"Bar": [
+														"*"
+													],
+													"Foo": [
+														"*"
+													]
+												},
+												"status_code": [
+													401,
+													403,
+													404
+												]
+											},
+											"routes": [
+												{
+													"handle": [
+														{
+															"body": "Headers Foo, Bar AND statuses 401, 403 and 404!",
+															"handler": "static_response"
+														}
+													]
+												}
+											]
+										},
+										{
+											"match": {
+												"status_code": [
+													500
+												]
+											},
+											"status_code": 400
+										},
+										{
+											"routes": [
+												{
+													"handle": [
+														{
+															"body": "Any! This should be last in the JSON!",
+															"handler": "static_response"
+														}
+													]
+												}
+											]
+										}
+									],
+									"handler": "reverse_proxy",
+									"upstreams": [
+										{
+											"dial": "127.0.0.1:65535"
+										}
+									]
+								}
+							]
+						}
+					]
+				}
+			}
+		}
+	}
+}