--- title: Health Check --- ## Health Checks for Upstream Health Check of Apache APISIX is based on [lua-resty-healthcheck](https://github.com/Kong/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 ```shell 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](./control-api.md).