- HTTPProxy Fundamentals
- Virtual Hosts
- Inclusion and Delegation
- TLS Termination
- Upstream TLS
- Request Routing
- External Service Routing
- Request Rewriting
- Upstream Health Checks
- Client Authorization
- TLS Delegation
- Rate Limiting
- Access logging
- Annotations Reference
- API Reference
- Deployment Options
- Contour Configuration
- Upgrading Contour
- Enabling TLS between Envoy and Contour
- Redeploy Envoy
- AWS with NLB
- External Authorization
- JSON logging
- Migrating to HTTPProxy
- Prometheus Metrics
- PROXY Protocol Support
- Resource Limits
- Envoy Administration Access
- Contour Debug Logging
- Envoy Debug Logging
- Visualize the Contour Graph
- Show Contour xDS Resources
- Profiling Contour
- Contour Operator
- Support Policy
- Compatibility Matrix
- Contour Deprecation Policy
- Release Process
- Frequently Asked Questions
A HTTPProxy object must have at least one route or include defined.
In this example, any requests to
multi-path.bar.com/blog/* will be routed to the Service
All other requests to the host
multi-path.bar.com will be routed to the Service
# httpproxy-multiple-paths.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: multiple-paths namespace: default spec: virtualhost: fqdn: multi-path.bar.com routes: - conditions: - prefix: / # matches everything else services: - name: s1 port: 80 - conditions: - prefix: /blog # matches `multi-path.bar.com/blog` or `multi-path.bar.com/blog/*` services: - name: s2 port: 80
In the following example, we match on headers and send to different services, with a default route if those do not match.
# httpproxy-multiple-headers.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: multiple-paths namespace: default spec: virtualhost: fqdn: multi-path.bar.com routes: - conditions: - header: name: x-os contains: ios services: - name: s1 port: 80 - conditions: - header: name: x-os contains: android services: - name: s2 port: 80 - services: - name: s3 port: 80
Each Route entry in a HTTPProxy may contain one or more conditions.
These conditions are combined with an AND operator on the route passed to Envoy.
Conditions can be either a
prefix or a
Paths defined are matched using prefix conditions. Up to one prefix condition may be present in any condition block.
Prefix conditions must start with a
/ if they are present.
header conditions there is one required field,
name, and six operator fields:
presentis a boolean and checks that the header is present. The value will not be checked.
notpresentsimilarly checks that the header is not present.
containsis a string, and checks that the header contains the string.
notcontainssimilarly checks that the header does not contain the string.
exactis a string, and checks that the header exactly matches the whole string.
notexactchecks that the header does not exactly match the whole string.
One of the key HTTPProxy features is the ability to support multiple services for a given path:
# httpproxy-multiple-upstreams.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: multiple-upstreams namespace: default spec: virtualhost: fqdn: multi.bar.com routes: - services: - name: s1 port: 80 - name: s2 port: 80
In this example, requests for
multi.bar.com/ will be load balanced across two Kubernetes Services,
This is helpful when you need to split traffic for a given URL across two different versions of an application.
Building on multiple upstreams is the ability to define relative weights for upstream Services. This is commonly used for canary testing of new versions of an application when you want to send a small fraction of traffic to a specific Service.
# httpproxy-weight-shfiting.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: weight-shifting namespace: default spec: virtualhost: fqdn: weights.bar.com routes: - services: - name: s1 port: 80 weight: 10 - name: s2 port: 80 weight: 90
In this example, we are sending 10% of the traffic to Service
s1, while Service
s2 receives the remaining 90% of traffic.
HTTPProxy weighting follows some specific rules:
- If no weights are specified for a given route, it’s assumed even distribution across the Services.
- Weights are relative and do not need to add up to 100. If all weights for a route are specified, then the “total” weight is the sum of those specified. As an example, if weights are 20, 30, 20 for three upstreams, the total weight would be 70. In this example, a weight of 30 would receive approximately 42.9% of traffic (30/70 = .4285).
- If some weights are specified but others are not, then it’s assumed that upstreams without weights have an implicit weight of zero, and thus will not receive traffic.
Per route, a service can be nominated as a mirror. The mirror service will receive a copy of the read traffic sent to any non mirror service. The mirror traffic is considered read only, any response by the mirror will be discarded.
This service can be useful for recording traffic for later replay or for smoke testing new deployments.
apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: traffic-mirror namespace: default spec: virtualhost: fqdn: www.example.com routes: - conditions: - prefix: / services: - name: www port: 80 - name: www-mirror port: 80 mirror: true
Each Route can be configured to have a timeout policy and a retry policy as shown:
# httpproxy-response-timeout.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: response-timeout namespace: default spec: virtualhost: fqdn: timeout.bar.com routes: - timeoutPolicy: response: 1s idle: 10s retryPolicy: count: 3 perTryTimeout: 150ms services: - name: s1 port: 80
In this example, requests to
timeout.bar.com/ will have a response timeout policy of 1s.
This refers to the time that spans between the point at which complete client request has been processed by the proxy, and when the response from the server has been completely processed.
timeoutPolicy.responseThis field can be any positive time period or “infinity”. This timeout covers the time from the end of the client request to the end of the upstream response. By default, Envoy has a 15 second value for this timeout. More information can be found in Envoy’s documentation. Note that a value of 0s will be treated as if the field were not set, i.e. by using Envoy’s default behavior.
timeoutPolicy.idleThis field can be any positive time period or “infinity”. By default, there is no per-route idle timeout. Note that the default connection manager idle timeout of 5 minutes will apply if this is not set. More information can be found in Envoy’s documentation. Note that a value of 0s will be treated as if the field were not set, i.e. by using Envoy’s default behavior.
TimeoutPolicy durations are expressed as per the format specified in the ParseDuration documentation. Example input values: “300ms”, “5s”, “1m”. Valid time units are “ns”, “us” (or “µs”), “ms”, “s”, “m”, “h”. The string ‘infinity’ is also a valid input and specifies no timeout.
retryPolicy: A retry will be attempted if the server returns an error code in the 5xx range, or if the server takes more than
retryPolicy.perTryTimeoutto process a request.
retryPolicy.countspecifies the maximum number of retries allowed. This parameter is optional and defaults to 1.
retryPolicy.perTryTimeoutspecifies the timeout per retry. If this field is greater than the request timeout, it is ignored. This parameter is optional. If left unspecified,
timeoutPolicy.requestwill be used.
Load Balancing Strategy
Each route can have a load balancing strategy applied to determine which of its Endpoints is selected for the request. The following list are the options available to choose from:
RoundRobin: Each healthy upstream Endpoint is selected in round robin order (Default strategy if none selected).
WeightedLeastRequest: The least request load balancer uses different algorithms depending on whether hosts have the same or different weights in an attempt to route traffic based upon the number of active requests or the load at the time of selection.
Random: The random strategy selects a random healthy Endpoints.
RequestHash: The request hashing strategy allows for load balancing based on request attributes. An upstream Endpoint is selected based on the hash of an element of a request. Requests that contain a consistent value in a HTTP request header for example will be routed to the same upstream Endpoint. Currently only hashing of HTTP request headers is supported.
Cookie: The cookie load balancing strategy is similar to the request hash strategy and is a convenience feature to implement session affinity, as described below.
More information on the load balancing strategy can be found in Envoy’s documentation.
The following example defines the strategy for the route
# httpproxy-lb-strategy.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: lb-strategy namespace: default spec: virtualhost: fqdn: strategy.bar.com routes: - conditions: - prefix: / services: - name: s1-strategy port: 80 - name: s2-strategy port: 80 loadBalancerPolicy: strategy: WeightedLeastRequest
The below example demonstrates how header hash load balancing policies can be configured:
# httpproxy-lb-request-hash.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: lb-request-hash namespace: default spec: virtualhost: fqdn: request-hash.bar.com routes: - conditions: - prefix: / services: - name: httpbin port: 8080 loadBalancerPolicy: strategy: RequestHash requestHashPolicies: - headerHashOptions: headerName: X-Some-Header terminal: true - headerHashOptions: headerName: User-Agent
In this example, if a client request contains the
X-Some-Header header, the value of the header will be hashed and used to route to an upstream Endpoint. This could be used to implement a similar workflow to cookie-based session affinity by passing a consistent value for this header. If it is present, because it is set as a
terminal hash option, Envoy will not continue on to process to
User-Agent header to calculate a hash. If
X-Some-Header is not present, Envoy will use the
User-Agent header value to make a routing decision.
Session affinity, also known as sticky sessions, is a load balancing strategy whereby a sequence of requests from a single client are consistently routed to the same application backend.
Contour supports session affinity on a per route basis with
# httpproxy-sticky-sessions.yaml apiVersion: projectcontour.io/v1 kind: HTTPProxy metadata: name: httpbin namespace: default spec: virtualhost: fqdn: httpbin.davecheney.com routes: - services: - name: httpbin port: 8080 loadBalancerPolicy: strategy: Cookie
Session affinity is based on the premise that the backend servers are robust, do not change ordering, or grow and shrink according to load. None of these properties are guaranteed by a Kubernetes cluster and will be visible to applications that rely heavily on session affinity.
Any perturbation in the set of pods backing a service risks redistributing backends around the hash ring.