k8s-app-config

k8s-app-config

A very simple application config helper CLI utility. Useful for bootstrapping applications in kubernetes where the application needs to be aware of the runtime state of other components in kubernetes.

Note: This is considered a prototype and the CLI is likely to change

The inspiration for this utility is based on the functionality of https://github.com/kubernetes/kubernetes/blob/master/cluster/addons/fluentd-elasticsearch/es-image/elasticsearch_logging_discovery.go (Copyright 2017 The Kubernetes Authors. Apache 2.0 License)

The idea here is that this functionality might be useful for configuring other appliations in the same manner.

Example

Configuring the discovery hosts for elasticsearch.

The hosts command allows for the retrieval of host (pod) ips of a given service with the capability to wait for a minimum number of pods to register with the service. This means we don't have to have any prior knowledge of pod level ips to configure an elasticsearch cluster.

$ k8s-app-config hosts --namespace kube-system --service elasticsearch-loging \
    --wait 5 --min-hosts 2 --format 'discovery.zen.ping.unicast.hosts: "{{ join .hosts "," }}"'

The above will wait 5 minutes for a minimum of 2 hosts (pods) to register with the specified service