Configuration: Dynamic from filesystem

You can start Envoy with dynamic configuration by using files that implement the xDS protocol.

When the files are changed on the filesystem, Envoy will automatically update its configuration.

At a minimum, you will need to start Envoy configured with the following sections:

  • node to uniquely identify the proxy node.

  • dynamic_resources to tell Envoy where to find its dynamic configuration.

For the given example you will also need two dynamic configuration files:

You can also add an admin section if you wish to monitor Envoy or retrieve stats or configuration information.

The following sections walk through the dynamic configuration provided in the demo dynamic filesystem configuration file.

node

The node should specify cluster and id.

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node:
  cluster: test-cluster
  id: test-id

dynamic_resources:
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dynamic_resources

The dynamic_resources specify where to load dynamic configuration from.

In this example, the configuration is provided by the yaml files set below.

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  id: test-id

dynamic_resources:
  cds_config:
    path: /var/lib/envoy/cds.yaml
  lds_config:
    path: /var/lib/envoy/lds.yaml

admin:
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resources - listeners

The linked lds_config should be an implementation of a Listener discovery service (LDS).

The following example of a dynamic LDS file, configures an HTTP listener on port 10000.

All domains and paths are matched and routed to the service_envoyproxy_io cluster.

The host headers are rewritten to www.envoyproxy.io

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resources:
- "@type": type.googleapis.com/envoy.config.listener.v3.Listener
  name: listener_0
  address:
    socket_address:
      address: 0.0.0.0
      port_value: 10000
  filter_chains:
  - filters:
      name: envoy.http_connection_manager
      typed_config:
        "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
        stat_prefix: ingress_http
        http_filters:
        - name: envoy.router
        route_config:
          name: local_route
          virtual_hosts:
          - name: local_service
            domains:
            - "*"
            routes:
            - match:
                prefix: "/"
              route:
                host_rewrite_literal: www.envoyproxy.io
                cluster: example_proxy_cluster
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resources - clusters

The linked cds_config should be an implementation of a Cluster discovery service (CDS).

In the following example of a dynamic CDS file, the example_proxy_cluster cluster proxies over TLS to https://www.envoyproxy.io.

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resources:
- "@type": type.googleapis.com/envoy.config.cluster.v3.Cluster
  name: example_proxy_cluster
  connect_timeout: 1s
  type: strict_dns
  typed_extension_protocol_options:
    envoy.extensions.upstreams.http.v3.HttpProtocolOptions:
      "@type": type.googleapis.com/envoy.extensions.upstreams.http.v3.HttpProtocolOptions
      explicit_http_config:
        http2_protocol_options: {}
  load_assignment:
    cluster_name: example_proxy_cluster
    endpoints:
    - lb_endpoints:
      - endpoint:
          address:
            socket_address:
              address: www.envoyproxy.io
              port_value: 443
  transport_socket:
    name: envoy.transport_sockets.tls
    typed_config:
      "@type": type.googleapis.com/envoy.extensions.transport_sockets.tls.v3.UpstreamTlsContext
      sni: www.envoyproxy.io
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