34 lines
1.2 KiB
Markdown
34 lines
1.2 KiB
Markdown
HA endpoints for K8s
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====================
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The following components require a highly available endpoints:
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* etcd cluster,
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* kube-apiserver service instances.
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The former provides the
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[etcd-proxy](https://coreos.com/etcd/docs/latest/proxy.html) service to access
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the cluster members in HA fashion.
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The latter relies on a 3rd side reverse proxies, like Nginx or HAProxy, to
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achieve the same goal.
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Etcd
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----
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Etcd proxies are deployed on each node in the `k8s-cluster` group. A proxy is
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a separate etcd process. It has a `localhost:2379` frontend and all of the etcd
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cluster members as backends. Note that the `access_ip` is used as the backend
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IP, if specified. Frontend endpoints cannot be accessed externally as they are
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bound to a localhost only.
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The `etcd_access_endpoint` fact provides an access pattern for clients. And the
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`etcd_multiaccess` (defaults to `false`) group var controlls that behavior.
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When enabled, it makes deployed components to access the etcd cluster members
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directly: `http://ip1:2379, http://ip2:2379,...`. This mode assumes the clients
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do a loadbalancing and handle HA for connections. Note, a pod definition of a
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flannel networking plugin always uses a single `--etcd-server` endpoint!
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Kube-apiserver
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--------------
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TODO(bogdando) TBD
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