Envoy Cluster SubSet Load Balancing

README.md

Envoy Cluster SubSet Load Balancing

This gist is part of a blog post:

• Full repository: https://github.com/hermanbanken/envoy-xds/
• Blog post: https://www.hermanbanken.nl/2020/08/24/custom-envoy-xds-golang-cluster-subsets/

static-alternative.yaml

# Requires Envoy >= 1.14.
# Validate:
# $ docker run -v $PWD:/data envoyproxy/envoy /usr/local/bin/envoy -c /data/config-equivalent.yaml
#
# Docs: https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/subsets
# Other examples: https://www.envoyproxy.io/docs/envoy/latest/configuration/overview/examples
static_resources:
  listeners:
    - name: listener0
      address: { socket_address: { address: "0.0.0.0", port_value: 80 } }
      filter_chains:
      - filters:
        - name: envoy.filters.network.http_connection_manager
          typed_config:
            "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
            codec_type: AUTO
            stat_prefix: ingress_http
            http_filters:
            - name: envoy.filters.http.header_to_metadata
              typed_config:
                "@type": type.googleapis.com/envoy.extensions.filters.http.header_to_metadata.v3.Config
                request_rules:
                - header: x-slice
                  on_header_present:
                    metadata_namespace: envoy.lb
                    key: slice
            - name: envoy.filters.http.router
            route_config:
              name: local_route
              virtual_hosts:
              - name: local_service
                domains: ["*"]
                routes:
                - match: { prefix: "/" }
                  route: { cluster: target, host_rewrite_literal: target }
  clusters:
  - connect_timeout: 1s
    name: target
    type: strict_dns
    http2_protocol_options: {}
    lb_subset_config:
      fallback_policy: ANY_ENDPOINT
      default_subset: { "slice": "default" }
      subset_selectors:
        - keys: ["slice"]
          fallback_policy: NO_FALLBACK
    load_assignment:
      cluster_name: target
      endpoints:
      - lb_endpoints:
        - metadata:
            filter_metadata: { "envoy.lb": { "slice": "target-1" } }
          endpoint:
            address:
              socket_address:
                address: target-1
                port_value: 80
        - metadata:
            filter_metadata: { "envoy.lb": { "slice": "target-1" } }
          endpoint:
            address:
              socket_address:
                address: target-2
                port_value: 80
        - metadata:
            filter_metadata: { "envoy.lb": { "slice": "target-1" } }
          endpoint:
            address:
              socket_address:
                address: target-3
                port_value: 80