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c12s-kubespray/docs/netcheck.md
Bogdan Dobrelya d5b21b34c2 Add advanced net check for DNS K8s app 
* Add an option to deploy K8s app to test e2e network connectivity
  and cluster DNS resolve via Kubedns for nethost/simple pods
  (defaults to false).
* Parametrize existing k8s apps templates with kube_namespace and
  kube_config_dir instead of hardcode.
* For CoreOS, ensure nameservers from inventory to be put in the
  first place to allow hostnet pods connectivity via short names
  or FQDN and hostnet agents to pass as well, if netchecker
  deployed.

Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
2016-11-28 13:23:25 +01:00

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Network Checker Application

With the deploy_netchecker var enabled (defaults to false), Kargo deploys a Network Checker Application from the 3rd side l23network/mcp-netchecker docker images. It consists of the server and agents trying to reach the server by usual for Kubernetes applications network connectivity meanings. Therefore, this automagically verifies a pod to pod connectivity via the cluster IP and checks if DNS resolve is functioning as well.

The checks are run by agents on a periodic basis and cover standard and host network pods as well. The history of performed checks may be found in the agents' application logs.

To get the most recent and cluster-wide network connectivity report, run from any of the cluster nodes:

curl http://localhost:31081/api/v1/connectivity_check

Note that Kargo does not invoke the check but only deploys the application, if requested.

There are related application specifc variables:

netchecker_port: 31081
agent_report_interval: 15
netcheck_namespace: default
agent_img: "quay.io/l23network/mcp-netchecker-agent:v0.1"
server_img: "quay.io/l23network/mcp-netchecker-server:v0.1"

Note that the application verifies DNS resolve for FQDNs comprising only the combination of the netcheck_namespace.dns_domain vars, for example the netchecker-service.default.cluster.local. If you want to deploy the application to the non default namespace, make sure as well to adjust the searchdomains var so the resulting search domain records to contain that namespace, like:

search: foospace.cluster.local default.cluster.local ...
nameserver: ...