Configuring Timeouts
To limit how long Linkerd will wait before failing an outgoing request to another service, you can configure timeouts. Timeouts specify the maximum amount of time to wait for a response from a remote service to complete after the request is sent. If the timeout elapses without receiving a response, Linkerd will cancel the request and return a 504 Gateway Timeout response.
Timeouts can be specified either using HTTPRoutes or using legacy ServiceProfiles. Since HTTPRoute is a newer configuration mechanism intended to replace ServiceProfiles, prefer the use of HTTPRoute timeouts unless a ServiceProfile already exists for the Service.
Using HTTPRoutes
Linkerd supports timeouts as specified in GEP-1742, for outbound HTTPRoutes with Service parents.
Each rule in an HTTPRoute may
define an optional timeouts
object, which can define request
and/or backendRequest
fields:
timeouts.request
specifies the total time to wait for a request matching this rule to complete (including retries). This timeout starts when the proxy receives a request, and ends when successful response is sent to the client.timeouts.backendRequest
specifies the time to wait for a single request to a backend to complete. This timeout starts when a request is dispatched to a backend, and ends when a response is received from that backend. This is a subset of thetimeouts.request
timeout. If the request fails and is retried (if applicable), thebackendRequest
timeout will be restarted for each retry request.
Timeout durations are specified specified as strings using the Gateway API duration format specified by GEP-2257 (e.g. 1h/1m/1s/1ms), and must be at least 1ms. If either field is unspecified or set to 0, the timeout configured by that field will not be enforced.
For example:
spec:
rules:
- matches:
- path:
type: RegularExpression
value: /authors/[^/]*\.json"
method: GET
timeouts:
request: 600ms
backendRequest: 300ms
Using ServiceProfiles
Each route in a ServiceProfile may define a request timeout for requests matching that route. This timeout secifies the maximum amount of time to wait for a response (including retries) to complete after the request is sent.
spec:
routes:
- condition:
method: HEAD
pathRegex: /authors/[^/]*\.json
name: HEAD /authors/{id}.json
timeout: 300ms
Check out the timeouts section of the books demo for a tutorial of how to configure timeouts using ServiceProfiles.
Monitoring Timeouts
Requests which reach the timeout will be canceled, return a 504 Gateway Timeout response, and count as a failure for the purposes of effective success rate. Since the request was canceled before any actual response was received, a timeout will not count towards the actual request volume at all. This means that effective request rate can be higher than actual request rate when timeouts are configured. Furthermore, if a response is received just as the timeout is exceeded, it is possible for the request to be counted as an actual success but an effective failure. This can result in effective success rate being lower than actual success rate.