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Version: 3.5

Debug Function

5xx response status code#

Similar 5xx status codes such as 500, 502, 503, etc., are the status codes in response to a server error. When a request has a 5xx status code; it may come from APISIX or Upstream. How to identify the source of these response status codes is a very meaningful thing. It can quickly help us determine the problem. (When modifying the configuration show_upstream_status_in_response_header in conf/config.yaml to true, all upstream status codes will be returned, not only 5xx status.)

How to identify the source of the 5xx response status code#

In the response header of the request, through the response header of X-APISIX-Upstream-Status, we can effectively identify the source of the 5xx status code. When the 5xx status code comes from Upstream, the response header X-APISIX-Upstream-Status can be seen in the response header, and the value of this response header is the response status code. When the 5xx status code is derived from APISIX, there is no response header information of X-APISIX-Upstream-Status in the response header. That is, only when the status code of 5xx is derived from Upstream will the X-APISIX-Upstream-Status response header appear.

Example#

Example 1: 502 response status code comes from Upstream (IP address is not available)

$ curl http://127.0.0.1:9180/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "methods": ["GET"],
    "upstream": {
        "nodes": {
            "127.0.0.1:1": 1
        },
        "type": "roundrobin"
    },
    "uri": "/hello"
}'

Test:

$ curl http://127.0.0.1:9080/hello -v
......
< HTTP/1.1 502 Bad Gateway
< Date: Wed, 25 Nov 2020 14:40:22 GMT
< Content-Type: text/html; charset=utf-8
< Content-Length: 154
< Connection: keep-alive
< Server: APISIX/2.0
< X-APISIX-Upstream-Status: 502
<
<html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>openresty</center>
</body>
</html>

It has a response header of X-APISIX-Upstream-Status: 502.

Example 2: 502 response status code comes from APISIX

$ curl http://127.0.0.1:9180/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "plugins": {
        "fault-injection": {
            "abort": {
                "http_status": 500,
                "body": "Fault Injection!\n"
            }
        }
    },
    "uri": "/hello"
}'

Test：

$ curl http://127.0.0.1:9080/hello -v
......
< HTTP/1.1 500 Internal Server Error
< Date: Wed, 25 Nov 2020 14:50:20 GMT
< Content-Type: text/plain; charset=utf-8
< Transfer-Encoding: chunked
< Connection: keep-alive
< Server: APISIX/2.0
<
Fault Injection!

There is no response header for X-APISIX-Upstream-Status.

Example 3: Upstream has multiple nodes, and all nodes are unavailable

$ curl http://127.0.0.1:9180/apisix/admin/upstreams/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "nodes": {
        "127.0.0.3:1": 1,
        "127.0.0.2:1": 1,
        "127.0.0.1:1": 1
    },
    "retries": 2,
    "type": "roundrobin"
}'
$ curl http://127.0.0.1:9180/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/hello",
    "upstream_id": "1"
}'

Test：

$ curl http://127.0.0.1:9080/hello -v
< HTTP/1.1 502 Bad Gateway
< Date: Wed, 25 Nov 2020 15:07:34 GMT
< Content-Type: text/html; charset=utf-8
< Content-Length: 154
< Connection: keep-alive
< Server: APISIX/2.0
< X-APISIX-Upstream-Status: 502, 502, 502
<
<html>
<head><title>502 Bad Gateway</title></head>
<body>
<center><h1>502 Bad Gateway</h1></center>
<hr><center>openresty</center>
</body>
</html>

It has a response header of X-APISIX-Upstream-Status: 502, 502, 502.