health-check.md

title
Health Check

Health Checks for Upstream

Health Check of Apache APISIX is based on lua-resty-healthcheck.

Note:

• We only start the health check when the upstream is hit by a request. There won't be any health check if an upstream is configured but isn't in used.
• If there is no healthy node can be chosen, we will continue to access the upstream.
• We won't start the health check when the upstream only has one node, as we will access it whether this unique node is healthy or not.
• Active health check is required so that the unhealthy node can recover.

Configuration instructions

Configuration item	Configuration type	Value type	Value option	Defaults	Description
upstream.checks.active.type	Active check	string	http https tcp	http	The type of active check.
upstream.checks.active.timeout	Active check	integer		1	The timeout period of the active check (unit: second).
upstream.checks.active.concurrency	Active check	integer		10	The number of targets to be checked at the same time during the active check.
upstream.checks.active.http_path	Active check	string		/	The HTTP request path that is actively checked.
upstream.checks.active.host	Active check	string		${upstream.node.host}	The hostname of the HTTP request actively checked.
upstream.checks.active.port	Active check	integer	1 to 65535	${upstream.node.port}	The host port of the HTTP request that is actively checked.
upstream.checks.active.https_verify_certificate	Active check	boolean		true	Active check whether to check the SSL certificate of the remote host when HTTPS type checking is used.
upstream.checks.active.req_headers	Active check	array		[]	Active check When using HTTP or HTTPS type checking, set additional request header information.
upstream.checks.active.healthy.interval	Active check (healthy node)	integer	>= 1	1	Active check (healthy node) check interval (unit: second)
upstream.checks.active.healthy.http_statuses	Active check (healthy node)	array	200 to 599	[200, 302]	Active check (healthy node) HTTP or HTTPS type check, the HTTP status code of the healthy node.
upstream.checks.active.healthy.successes	Active check (healthy node)	integer	1 to 254	2	Active check (healthy node) determine the number of times a node is healthy.
upstream.checks.active.unhealthy.interval	Active check (unhealthy node)	integer	>= 1	1	Active check (unhealthy node) check interval (unit: second)
upstream.checks.active.unhealthy.http_statuses	Active check (unhealthy node)	array	200 to 599	[429, 404, 500, 501, 502, 503, 504, 505]	Active check (unhealthy node) HTTP or HTTPS type check, the HTTP status code of the non-healthy node.
upstream.checks.active.unhealthy.http_failures	Active check (unhealthy node)	integer	1 to 254	5	Active check (unhealthy node) HTTP or HTTPS type check, determine the number of times that the node is not healthy.
upstream.checks.active.unhealthy.tcp_failures	Active check (unhealthy node)	integer	1 to 254	2	Active check (unhealthy node) TCP type check, determine the number of times that the node is not healthy.
upstream.checks.active.unhealthy.timeouts	Active check (unhealthy node)	integer	1 to 254	3	Active check (unhealthy node) to determine the number of timeouts for unhealthy nodes.
upstream.checks.passive.healthy.http_statuses	Passive check (healthy node)	array	200 to 599	[200, 201, 202, 203, 204, 205, 206, 207, 208, 226, 300, 301, 302, 303, 304, 305, 306, 307, 308]	Passive check (healthy node) HTTP or HTTPS type check, the HTTP status code of the healthy node.
upstream.checks.passive.healthy.successes	Passive check (healthy node)	integer	0 to 254	5	Passive checks (healthy node) determine the number of times a node is healthy.
upstream.checks.passive.unhealthy.http_statuses	Passive check (unhealthy node)	array	200 to 599	[429, 500, 503]	Passive check (unhealthy node) HTTP or HTTPS type check, the HTTP status code of the non-healthy node.
upstream.checks.passive.unhealthy.tcp_failures	Passive check (unhealthy node)	integer	0 to 254	2	Passive check (unhealthy node) When TCP type is checked, determine the number of times that the node is not healthy.
upstream.checks.passive.unhealthy.timeouts	Passive check (unhealthy node)	integer	0 to 254	7	Passive checks (unhealthy node) determine the number of timeouts for unhealthy nodes.
upstream.checks.passive.unhealthy.http_failures	Passive check (unhealthy node)	integer	0 to 254	5	Passive check (unhealthy node) The number of times that the node is not healthy during HTTP or HTTPS type checking.

Configuration example

curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
    "uri": "/index.html",
    "plugins": {
        "limit-count": {
            "count": 2,
            "time_window": 60,
            "rejected_code": 503,
            "key": "remote_addr"
        }
    },
    "upstream": {
         "nodes": {
            "127.0.0.1:1980": 1,
            "127.0.0.1:1970": 1
        },
        "type": "roundrobin",
        "retries": 2,
        "checks": {
            "active": {
                "timeout": 5,
                "http_path": "/status",
                "host": "foo.com",
                "healthy": {
                    "interval": 2,
                    "successes": 1
                },
                "unhealthy": {
                    "interval": 1,
                    "http_failures": 2
                },
                "req_headers": ["User-Agent: curl/7.29.0"]
            },
            "passive": {
                "healthy": {
                    "http_statuses": [200, 201],
                    "successes": 3
                },
                "unhealthy": {
                    "http_statuses": [500],
                    "http_failures": 3,
                    "tcp_failures": 3
                }
            }
        }
    }
}'

The health check status can be fetched via GET /v1/healthcheck in Control API.