External-dns: Is the external-dns application factored to accept all parameters as environment variables?

Created on 30 Sep 2020 · 8Comments · Source: kubernetes-sigs/external-dns

Had trouble finding this info in the docs

I want to wrap this in a helm chart. It would be easier for me to parameterize my charts if I could inject env vars for config instead of passing the app args like this:

        image: k8s.gcr.io/external-dns/external-dns:v0.7.3
        args:
        - --source=service
        - --source=ingress
        - --domain-filter=external-dns-test.gcp.zalan.do # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
        - --provider=google
#        - --google-project=zalando-external-dns-test # Use this to specify a project different from the one external-dns is running inside
        - --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
        - --registry=txt
        - --txt-owner-id=my-identifier

Just wondering if it supports env vars for its config- sorry if that is already explained in the docs somewhere!

kindocumentation

Source

red8888

Most helpful comment

Hi,
Yes this should be possible because it uses kingpin as argument parser lib
https://github.com/kubernetes-sigs/external-dns/blob/79ea64884bbfc89f9c1f444c9dddd5ce361f31ad/pkg/apis/externaldns/types.go#L290

So you should be fine by using env vars prefixed with EXTERNAL_DNS_ and all hyphens converted to underscore.
Regards,
Johannes

jgrumboe on 1 Oct 2020

👍2

All 8 comments

So you should be fine by using env vars prefixed with EXTERNAL_DNS_ and all hyphens converted to underscore.
Regards,
Johannes

jgrumboe on 1 Oct 2020

👍2

I'm not seeing this in the documentation anywhere, but maybe I missed it. It would be nice have this detail in the official documentation somewhere.

/kind documentation
/remove-kind support

seanmalloy on 2 Oct 2020

@seanmalloy
There's a little abstract in the FAQ.
https://github.com/kubernetes-sigs/external-dns/blob/master/docs/faq.md#how-do-i-configure-multiple-sources-via-environment-variables-also-applies-to-domain-filters

But it's not quite clear that this syntax should work for every option.

jgrumboe on 2 Oct 2020

@jgrumboe nice find. I agree we should add some additional details to the documentation.

seanmalloy on 2 Oct 2020

Guess I'll close this? or leave open till the docs are created?

Here is why I want this. If the app can be 100% configured with env vars then it means writing a helm chart to support it would be trivial. the chart could be totally ignorant of the apps actual config and just allow you to set arbitrary env vars

I actually asked about this in the github page for the community chart: https://github.com/bitnami/charts/issues/3905. right now that chart has all this specific config for passing in args, but if the same thing can be done with env vars I feel like that would be a more maintainable approach?

red8888 on 5 Oct 2020

or leave open till the docs are created?

I think we should leave it open until the documentation is updated.

seanmalloy on 5 Oct 2020

👍1

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