Health Check
New to Kuma? You don’t need this policy, check
MeshHealthCheck
instead. If you want to use theHealthCheck
policy, remember that it requires the TrafficRoute policy to function properly.
Health Check is an outbound policy. Dataplanes whose configuration is modified are in the
sources
matcher.
This policy enables Kong Mesh to keep track of the health of every data plane proxy, with the goal of minimizing the number of failed requests in case a data plane proxy is temporarily unhealthy.
By creating an HealthCheck
resource we can instruct a data plane proxy to keep track of the health status for any other data plane proxy. When health-checks are properly configured, a data plane proxy will never send a request to another data plane proxy that is considered unhealthy. When an unhealthy proxy returns to a healthy state, Kong Mesh will resume sending requests to it again.
This policy provides active checks. If you want to configure passive checks, please utilize the Circuit Breaker policy. Data plane proxies with active checks will explicitly send requests to other data plane proxies to determine if target proxies are healthy or not. This mode generates extra traffic to other proxies and services as described in the policy configuration.
Usage
As usual, we can apply sources
and destinations
selectors to determine how health-checks will be performed across our data plane proxies.
The HealthCheck
policy supports both L4/TCP (default) and L7/HTTP checks.
Examples
apiVersion: kuma.io/v1alpha1
kind: HealthCheck
mesh: default
metadata:
name: web-to-backend-check
spec:
sources:
- match:
kuma.io/service: web_default_svc_80
destinations:
- match:
kuma.io/service: backend_default_svc_80
conf:
interval: 10s
timeout: 2s
unhealthyThreshold: 3
healthyThreshold: 1
initialJitter: 5s # optional
intervalJitter: 6s # optional
intervalJitterPercent: 10 # optional
healthyPanicThreshold: 60 # optional, by default 50
failTrafficOnPanic: true # optional, by default false
noTrafficInterval: 10s # optional, by default 60s
eventLogPath: "/tmp/health-check.log" # optional
alwaysLogHealthCheckFailures: true # optional, by default false
reuseConnection: false # optional, by default true
tcp: # only one of tcp or http can be defined
send: Zm9v
receive:
- YmFy
- YmF6
http:
path: /health
requestHeadersToAdd:
- append: false
header:
key: Content-Type
value: application/json
- header:
key: Accept
value: application/json
expectedStatuses: [200, 201]
We will apply the configuration with kubectl apply -f [..]
.
HTTP
HTTP health checks are executed using HTTP 2
-
path
- HTTP path which will be requested during the health checks -
expectedStatuses
(optional) - list of status codes which should be considered as a healthy during the checks- only statuses in the range
[100, 600)
are allowed - by default, when this property is not provided only responses with
status code
200
are being considered healthy
- only statuses in the range
-
requestHeadersToAdd
(optional) - list of headers which should be added to every health check request:-
append
(default, optional) - should the value of the provided header be appended to already existing headers (if present) -
header
:-
key
- the name of the header -
value
(optional) - the value of the header
-
-
TCP
-
send
- Base64 encoded content of the message which should be sent during the health checks -
receive
list of Base64 encoded blocks of strings which should be found in the returning message which should be considered as healthy- when checking the response, “fuzzy” matching is performed such that each block must be found, and in the order specified, but not necessarily contiguous;
- if
receive
section won’t be provided or will be empty, checks will be performed as “connect only” and will be marked as successful when TCP connection will be successfully established.
Matching
HealthCheck
is an Outbound Connection Policy.
The only supported value for destinations.match
is kuma.io/service
.
All options
$schema: http://json-schema.org/draft-04/schema#
$ref: #/definitions/HealthCheck
definitions
HealthCheck
- ## Health Check
- HealthCheck defines configuration for health checking.
- Type:
object
- This schema accepts additional properties.
- Properties
- sources
- List of selectors to match dataplanes that should be configured to do health checks.
- Type:
array
- Items
- $ref: #/definitions/kuma.mesh.v1alpha1.Selector
- destinations
- List of selectors to match services that need to be health checked.
- Type:
array
- Items
- $ref: #/definitions/kuma.mesh.v1alpha1.Selector
- conf
- Configuration for various types of health checking.
- $ref: #/definitions/kuma.mesh.v1alpha1.HealthCheck.Conf
- sources
kuma.mesh.v1alpha1.HealthCheck.Conf
- ## Conf
- Conf defines configuration for various types of health checking.
- Type:
object
- This schema accepts additional properties.
- Properties
- interval
- Interval between consecutive health checks.
- Type:
string
- String format must be a "regex"
- The value must match this pattern:
^([0-9]+\.?[0-9]*|\.[0-9]+)s$
- timeout
- Maximum time to wait for a health check response.
- Type:
string
- String format must be a "regex"
- The value must match this pattern:
^([0-9]+\.?[0-9]*|\.[0-9]+)s$
- unhealthy_threshold
- Number of consecutive unhealthy checks before considering a host unhealthy.
- Type:
integer
- healthy_threshold
- Number of consecutive healthy checks before considering a host healthy.
- Type:
integer
- initial_jitter
- If specified, Envoy will start health checking after for a random time in ms between 0 and initialjitter. This only applies to the first health check._
- Type:
string
- String format must be a "regex"
- The value must match this pattern:
^([0-9]+\.?[0-9]*|\.[0-9]+)s$
- interval_jitter
- If specified, during every interval Envoy will add intervaljitter to the wait time._
- Type:
string
- String format must be a "regex"
- The value must match this pattern:
^([0-9]+\.?[0-9]*|\.[0-9]+)s$
- intervaljitterpercent
- If specified, during every interval Envoy will add intervalms * intervaljitterpercent / 100 to the wait time. If intervaljitterms and intervaljitterpercent are both set, both of them will be used to increase the wait time._
- Type:
integer
- healthypanicthreshold
- Allows to configure panic threshold for Envoy cluster. If not specified, the default is 50%. To disable panic mode, set to 0%.
- Type:
number
- failtrafficon_panic
- If set to true, Envoy will not consider any hosts when the cluster is in 'panic mode'. Instead, the cluster will fail all requests as if all hosts are unhealthy. This can help avoid potentially overwhelming a failing service.
- Type:
boolean
- eventlogpath
- Specifies the path to the file where Envoy can log health check events. If empty, no event log will be written.
- Type:
string
- alwaysloghealthcheckfailures
- If set to true, health check failure events will always be logged. If set to false, only the initial health check failure event will be logged. The default value is false.
- Type:
boolean
- notrafficinterval
- The "no traffic interval" is a special health check interval that is used when a cluster has never had traffic routed to it. This lower interval allows cluster information to be kept up to date, without sending a potentially large amount of active health checking traffic for no reason. Once a cluster has been used for traffic routing, Envoy will shift back to using the standard health check interval that is defined. Note that this interval takes precedence over any other. The default value for "no traffic interval" is 60 seconds.
- Type:
string
- String format must be a "regex"
- The value must match this pattern:
^([0-9]+\.?[0-9]*|\.[0-9]+)s$
- tcp
- http
- reuse_connection
- Reuse health check connection between health checks. Default is true.
- Type:
boolean
- interval
kuma.mesh.v1alpha1.HealthCheck.Conf.Http
- ## Http
- Http defines optional Http configuration which will instruct the service the health check will be made for is an http service. It's mutually exclusive with the Tcp block so when provided you can't provide the Tcp configuration
- Type:
object
- This schema accepts additional properties.
- Properties
- path
- The HTTP path which will be requested during the health check (ie. /health) +required
- Type:
string
- requestheadersto_add
- The list of HTTP headers which should be added to each health check request +optional
- Type:
array
- expected_statuses
- List of HTTP response statuses which are considered healthy +optional
- Type:
array
- Items
- ##### U Int 32 Value
- Wrapper message for
uint32
. The JSON representation forUInt32Value
is JSON number. - Type:
integer
- path
kuma.mesh.v1alpha1.HealthCheck.Conf.Http.HeaderValue
- ## Header Value
- Type:
object
- This schema accepts additional properties.
- Properties
- key
- Header name +required
- Type:
string
- value
- Header value +optional
- Type:
string
- key
kuma.mesh.v1alpha1.HealthCheck.Conf.Http.HeaderValueOption
- ## Header Value Option
- Type:
object
- This schema accepts additional properties.
- Properties
- header
- Key/Value representation of the HTTP header +required
- $ref: #/definitions/kuma.mesh.v1alpha1.HealthCheck.Conf.Http.HeaderValue
- append
- The bool value which if true (default) will mean the header values should be appended to already present ones +optional
- Type:
boolean
- header
kuma.mesh.v1alpha1.HealthCheck.Conf.Tcp
- ## Tcp
- Tcp defines optional configuration for specifying bytes to send and expected response during the health check
- Type:
object
- This schema accepts additional properties.
- Properties
- send
- Bytes which will be send during the health check to the target
- Type:
string
- receive
- Bytes blocks expected as a response. When checking the response, “fuzzy” matching is performed such that each block must be found, and in the order specified, but not necessarily contiguous.
- Type:
array
- Items
- ##### Bytes Value
- Wrapper message for
bytes
. The JSON representation forBytesValue
is JSON string. - Type:
string
- send
kuma.mesh.v1alpha1.Selector
- ## Selector
- Selector defines structure for selecting tags for given dataplane
- Type:
object
- This schema accepts additional properties.
- Properties
- match
- Tags to match, can be used for both source and destinations
- Type:
object
- This schema accepts additional properties.
- Properties
- match
Generated with json-schema-md-doc