Kubernetes – FQDN work

kubectl_fqdn.sh

#!/usr/bin/env bash

# This small Gist is meant to hold some ideas of scraping useful information from Kubernetes.
# First trials, which were more complex (or just deprecated) are commented for documentation.

## get all services with NS and name

# kubectl get services -A -o json | jq '[ .items[].metadata | { "name": .name, "namespace": .namespace } ]'
# kubectl get services -A -o json | jq '[ .items[].metadata | { name, namespace } ]'

k8s_services=$( \
    kubectl get services --all-namespaces -o json \
    | jq '[ .items[].metadata | pick( .name, .namespace ) ]' \
)


## get local service FQDN appendix

svc_appendix=".svc.$( \
    kubectl get cm coredns -n kube-system -o jsonpath="{.data.Corefile}" \
    | grep ".local " \
    | awk -F ' ' '{print $2}' \
)"


## get local FQDNs

# fqdn_data=$( while IFS= read -r line; do
# echo ${line} | jq --arg x ${svc_appendix} '. + { "fqdn": (.name + "." + .namespace + $x) }'
# done < <( echo ${k8s_services} | jq -c '.[]' ) | jq -c -s . )

service_fqdn=$( \
    echo "${k8s_services}" \
    | jq --arg x ${svc_appendix} '[ .[] | .name as $name | .namespace as $ns | . + {"fqdn": ( $name + "." + $ns + $x )} ]'
)


## get FQDNs of Ingress Manifests

ingress_paths="$( \
    kubectl get --all-namespaces ingress -o json 2> /dev/null \
    | jq -r '.items[] | .spec.rules[] | .host as $host | .http.paths[] | ( $host + (if .path != "/" then .path else "" end))' \
    | sort \
)"
ingress_fqdns="$( \
    echo "${ingress_paths}" \
    | grep -v /$ 
)"
ingress_json="$( \
    echo $ingress_fqdns \
    | jq --raw-input '.' \
    | jq -s \
)"