2.7 KiB
Proxy
etcd can now run as a transparent proxy. Running etcd as a proxy allows for easily discovery of etcd within your infrastructure, since it can run on each machine as a local service. In this mode, etcd acts as a reverse proxy and forwards client requests to an active etcd cluster. The etcd proxy does not participant in the consensus replication of the etcd cluster, thus it neither increases the resilience nor decreases the write performance of the etcd cluster.
etcd currently supports two proxy modes: readwrite
and readonly
. The default mode is readwrite
, which forwards both read and write requests to the etcd cluster. A readonly
etcd proxy only forwards read requests to the etcd cluster, and returns HTTP 501
to all write requests.
The proxy will shuffle the list of cluster members periodically to avoid sending all connections to a single member.
Using an etcd proxy
To start etcd in proxy mode, you need to provide three flags: proxy
, listen-client-urls
, and initial-cluster
(or discovery
).
To start a readwrite proxy, set -proxy on
; To start a readonly proxy, set -proxy readonly
.
The proxy will be listening on listen-client-urls
and forward requests to the etcd cluster discovered from in initial-cluster
or discovery
url.
Start an etcd proxy with a static configuration
To start a proxy that will connect to a statically defined etcd cluster, specify the initial-cluster
flag:
etcd -proxy on -listen-client-urls 127.0.0.1:8080 -initial-cluster infra0=http://10.0.1.10:2380,infra1=http://10.0.1.11:2380,infra2=http://10.0.1.12:2380
Start an etcd proxy with the discovery service
If you bootstrap an etcd cluster using the discovery service, you can also start the proxy with the same discovery
.
To start a proxy using the discovery service, specify the discovery
flag. The proxy will wait until the etcd cluster defined at the discovery
url finishes bootstrapping, and then start to forward the requests.
etcd -proxy on -listen-client-urls 127.0.0.1:8080 -discovery https://discovery.etcd.io/3e86b59982e49066c5d813af1c2e2579cbf573de
Fallback to proxy mode with discovery service
If you bootstrap a etcd cluster using discovery service with more than the expected number of etcd members, the extra etcd processes will fall back to being readwrite
proxies by default. They will forward the requests to the cluster as described above. For example, if you create a discovery url with size=5
, and start ten etcd processes using that same discovery url, the result will be a cluster with five etcd members and five proxies. Note that this behaviour can be disabled with the proxy-fallback
flag.