helm: translate the edgeDNSServer -> edgeDNSServers using a tempate

[jkremser]

When deploying 0.8.3 with using old value.yaml file, the .Values.k8gb.edgeDNSServer would not be passed correctly to the deployment as env var. (it's basically not read anywhere in the current helm chart and thrown away)

Hiding the ugliness into _helpers.tpl as impl detail

the logic is following:
when edgeDNSServers is set in values.yaml or using --set .., then these values are being used, otherwise edgeDNSServer is tried

edit: if edgeDNSServers contains only one entry with "1.1.1.1" (default value coming from our values.yaml) and the edgeDNSServer is not empty, then edgeDNSServer wins

some examples:

# simulating using outdated custom value file (translation done properly, even if the 1.1.1.1 was coming from the defaults)
helm template .  --set k8gb.edgeDNSServer=1.1.1.2 | grep EDGE_DNS_SERVERS -A1
            - name: EDGE_DNS_SERVERS
              value: 1.1.1.2

# if not specified, using the 1.1.1.1 from defaults values.yaml bundled w/ the chart
helm template . | grep EDGE_DNS_SERVERS -A1
            - name: EDGE_DNS_SERVERS
              value: 1.1.1.1

# suggested usage - using the new option and forgot the old one
helm template .  --set k8gb.edgeDNSServers={1.1.1.2} | grep EDGE_DNS_SERVERS -A1
            - name: EDGE_DNS_SERVERS
              value: 1.1.1.2

# hybrids
helm template .  --set k8gb.edgeDNSServer=1.1.1.3 --set k8gb.edgeDNSServers={1.1.1.2} | grep EDGE_DNS_SERVERS -A1
            - name: EDGE_DNS_SERVERS
              value: 1.1.1.2

helm template .  --set k8gb.edgeDNSServer=1.1.1.3 --set k8gb.edgeDNSServers={1.1.1.1} | grep EDGE_DNS_SERVERS -A1
            - name: EDGE_DNS_SERVERS
              value: 1.1.1.3

helm template .  --set k8gb.edgeDNSServer=1.1.1.3 --set k8gb.edgeDNSServers="{1.1.1.1,1.2.3.4}" | grep EDGE_DNS_SERVERS -A1
            - name: EDGE_DNS_SERVERS
              value: 1.1.1.1,1.2.3.4

Signed-off-by: Jirka Kremser [email protected]

[somaritane]

LGTM, @jkremser !

[k0da]

LGTM