通过网关访问集群，当请求返回结果为空时，网关会认为节点不可用

[liukuijun666]

Problem description

通过网关访问集群，当请求返回结果为空时，网关会认为节点不可用

场景

集群配置跨域

http.cors.enabled: true
http.cors.allow-origin: "*"

默认允许的 Method 有：OPTIONS,HEAD,GET,POST,PUT,DELETE。

使用异常 Method 直接请求集群

# curl -ku'admin:xxx' -H'Content-Type: application/json' -X PRI https://10.0.0.1:9205/_cat/indices
curl: (52) Empty reply from server

使用异常 Method 通过网关请求集群

# curl -ku'admin:xxx' -H'Content-Type: application/json' -X PRI http://10.0.0.1:8002/_cat/indices
{"error":true,"message":"the server closed connection before returning the first response byte. Make sure the server returns 'Connection: close' response header before closing the connection"}

同时网关会输出节点不可用的日志

[01-16 13:39:15] [INF] [actions.go:46] node [10.0.0.1:9206] is not available

当异常的请求足够多，所有的节点都被认为不可用时，网关会输出集群不可用的日志

[01-16 13:39:15] [INF] [actions.go:345] es_cluster_test has active hosts: 0
[01-16 13:39:15] [INF] [actions.go:354] elasticsearch [es_cluster_test] is not available

在网关输出集群不可用日志后，正常的请求也会失败。

# curl -u'admin:xxx' -H'Content-Type: application/json' -X GET http://localhost:8002/_cat/indices
{"error":true,"message":"Elasticsearch [es_cluster_test] Service Unavailable"}

当网关输出集群可用的日志后，正常的请求才会成功。

[01-16 13:58:34] [INF] [actions.go:377] elasticsearch [es_cluster_test] is available

# curl -u'admin:xxx' -H'Content-Type: application/json' -X GET http://localhost:8002/_cat/indices
green open .security CyFkDI31Rj-Q5ybreWit3Q 1 2 8 0 114.8kb 38.2kb