'Helm3 Using Lookup Function to Load a Variable

I am currently attempting to use the lookup function via Helm 3.1 to load a variable during installation.

{{ $ingress := (lookup "v1" "Ingress" "mynamespace" "ingressname").status.loadBalancer.ingress[0].hostname }}

Of course, this returns, "bad character [." If I remove it, it returns "nil pointer evaluating interface {}.loadBalancer".

Is what I am attempting to do even possible?

Thanks

kuberneteskubernetes-helmhelm3


Solution 1:[1]

You are attempting to use "normal" array indexing syntax, but helm charts use "golang templates" and thus array indexing is done via the index function

{{ $ingress := (index (lookup "v1" "Ingress" "mynamespace" "ingressname").status.loadBalancer.ingress 0).hostname }}

after further thought, I can easily imagine that nil pointer error happening during helm template runs, since lookup returns map[] when running offline

In that case, you'd want to use the index function for every path navigation:

{{ $ingress := (index (index (index (index (index (lookup "v1" "Ingress" "mynamespace" "ingressname") "status") "loadBalancer")  "ingress") 0) "hostname") }}

or, assert the lookup is in "offline" mode and work around it:

      {{ $ingress := "fake.example.com" }}
      {{ $maybeLookup := (lookup "v1" "Ingress" "mynamespace" "ingressname") }}
      {{ if $maybeLookup }}
      {{   $ingress = (index $maybeLookup.status.loadBalancer.ingress 0).hostname }}
      {{ end }}

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