Dynamic configuration (filesystem)¶
This example walks through configuring Envoy using filesystem-based dynamic configuration.
It demonstrates how configuration provided to Envoy dynamically can be updated without restarting the server.
Step 1: Start the proxy container¶
Change directory to examples/dynamic-config-fs
in the Envoy repository.
Build and start the containers.
This should also start two upstream HTTP
echo servers, service1
and service2
.
$ pwd
envoy/examples/dynamic-config-fs
$ docker-compose build --pull
$ docker-compose up -d
$ docker-compose ps
Name Command State Ports
------------------------------------------------------------------------------------------------------------------------
dynamic-config-fs_proxy_1 /docker-entrypoint.sh /usr ... Up 0.0.0.0:10000->10000/tcp, 0.0.0.0:19000->19000/tcp
dynamic-config-fs_service1_1 /bin/echo-server Up 8080/tcp
dynamic-config-fs_service2_1 /bin/echo-server Up 8080/tcp
Step 2: Check web response¶
You should be able to make a request to port 10000
, which will be served by service1
.
$ curl -s http://localhost:10000
Request served by service1
HTTP/2.0 GET /
Host: localhost:10000
User-Agent: curl/7.72.0
Accept: */*
X-Forwarded-Proto: http
X-Request-Id: 6672902d-56ca-456c-be6a-992a603cab9a
X-Envoy-Expected-Rq-Timeout-Ms: 15000
Step 3: Dump Envoy’s dynamic_active_clusters
config¶
If you now dump the proxy’s dynamic_active_clusters
configuration, you should see it is configured with the example_proxy_cluster
pointing to service1
.
$ curl -s http://localhost:19000/config_dump | jq -r '.configs[1].dynamic_active_clusters'
[
{
"cluster": {
"@type": "type.googleapis.com/envoy.config.cluster.v3.Cluster",
"name": "example_proxy_cluster",
"type": "LOGICAL_DNS",
"connect_timeout": "5s",
"dns_lookup_family": "V4_ONLY",
"load_assignment": {
"cluster_name": "example_proxy_cluster",
"endpoints": [
{
"lb_endpoints": [
{
"endpoint": {
"address": {
"socket_address": {
"address": "service1",
"port_value": 8080
}
}
}
}
]
}
]
}
},
"last_updated": "2020-10-25T20:37:05.838Z"
}
]
Step 4: Edit cds.yaml
inside the container to update upstream cluster¶
The example setup provides Envoy with two dynamic configuration files:
configs/cds.yaml
to provide a Cluster discovery service (CDS).configs/lds.yaml
to provide a Listener discovery service (LDS).
Edit cds.yaml
inside the container and change the cluster address
from service1
to service2
:
6 cluster_name: example_proxy_cluster
7 endpoints:
8 - lb_endpoints:
9 - endpoint:
10 address:
11 socket_address:
12 address: service1
13 port_value: 8080
You can do this using sed
inside the container:
docker-compose exec -T proxy sed -i s/service1/service2/ /var/lib/envoy/cds.yaml
Step 5: Check Envoy uses updated configuration¶
Checking the web response again, the request should now be handled by service2
:
$ curl http://localhost:10000 | grep "served by"
Request served by service2
Dumping the dynamic_active_clusters,
the example_proxy_cluster
should now be configured to proxy to service2
:
$ curl -s http://localhost:19000/config_dump | jq -r '.configs[1].dynamic_active_clusters'
[
{
"cluster": {
"@type": "type.googleapis.com/envoy.config.cluster.v3.Cluster",
"name": "example_proxy_cluster",
"type": "LOGICAL_DNS",
"connect_timeout": "5s",
"dns_lookup_family": "V4_ONLY",
"load_assignment": {
"cluster_name": "example_proxy_cluster",
"endpoints": [
{
"lb_endpoints": [
{
"endpoint": {
"address": {
"socket_address": {
"address": "service2",
"port_value": 8080
}
}
}
}
]
}
]
}
},
"last_updated": "2020-10-25T20:37:05.838Z"
}
]
See also
- Dynamic configuration (filesystem) quick start guide
Quick start guide to filesystem-based dynamic configuration of Envoy.
- Envoy admin quick start guide
Quick start guide to the Envoy admin interface.
- Dynamic configuration (control plane) sandbox
Configure Envoy dynamically with the Go Control Plane.