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Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2020-01-16 09:35:10 +01:00
parent ec151309dd
commit 0736ccb18e
2 changed files with 14 additions and 7 deletions
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19
plugin/traffic/README.md
View File

@@ -11,8 +11,9 @@ and draining of clusters. The cluster information is retrieved from a service
discovery manager that implements the service discovery protocols that Envoy
[implements](https://www.envoyproxy.io/docs/envoy/latest/api-docs/xds_protocol).
A Cluster is defined as: "A cluster is a group of logically similar endpoints that Envoy connects
to. Each cluster has a name, which *traffic* extends to be a domain name.
A Cluster is defined as: "A group of logically similar endpoints that Envoy connects
to." Each cluster has a name, which *traffic* extends to be a domain name. See
"Naming Clusters" below.
The use case for this plugin is when a cluster has endpoints running in multiple
(Kubernetes?) clusters and you need to steer traffic to (or away) from these endpoints, i.e.
@@ -49,18 +50,26 @@ traffic {
* node **ID** is how *traffic* identifies itself to the control plane. This defaults to `coredns`.
## Naming Clusters
When a cluster is named this usually consists out of a single word, i.e. "cluster-v0", or "web". The
*traffic* plugins uses the name(s) specified in the Server Block to create fully qualified domain
names. For example if the Server Block specifies `lb.example.org` as one of the names, and
"cluster-v0" is one of the load balanced cluster, *traffic* will respond to query asking for
`cluster-v0.lb.example.org.` and the same goes for `web`; `web.lb.example.org`.
## Examples
~~~ corefile
example.org {
lb.example.org {
traffic grpc://127.0.0.1:18000
debug
log
}
~~~
This will add load balancing for domains under example.org; the upstream information comes from
10.12.13.14; depending on received assignments, replies will be let through as-is or are load balanced.
This will load balance any names under `lb.example.org` using the data from the manager running on
localhost on port 18000. The node ID will default to `coredns`.
## Also See

2
plugin/traffic/xds/assignment.go
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@@ -20,14 +20,12 @@ func (a *assignment) SetClusterLoadAssignment(cluster string, cla *xdspb.Cluster
defer a.mu.Unlock()
_, ok := a.cla[cluster]
if !ok {
log.Debugf("Adding cluster %q", cluster)
a.cla[cluster] = cla
return
}
if cla == nil {
return
}
log.Debugf("Updating cluster %q", cluster)
a.cla[cluster] = cla
}