How to force string value with variable substitution?

[artem-nefedov]

I'm using variable substitution to replace values in the manifests applied by Kustomization (using substituteFrom).
In my case, I have a value that contains only numbers, but I need it applied as a string.

If I do foo: '${myvar}' or foo: "${myvar}", it does not work, and instead I get an integer value: foo: 123.
If I do foo: '"${myvar}"', it also does not work, and instead I get a string value with literal quotes inside: foo: '"123"'.

How do I get foo: "123"?

[kingdonb]

foo: "\"${foo}\""

This is super awkward, but I believe this is how it's done. There was a thread on the CNCF slack #flux about this, credit to Ben A for finding the workaround. https://cloud-native.slack.com/archives/CLAJ40HV3/p1623953195127500?thread_ts=1623949464.122200&cid=CLAJ40HV3

[rmartine-ias]

This workaround no longer works. See here for our solution: #1839 (comment)

[kingdonb]

This is not ideal as a solution, but you're right, the old solution does not work (since already maybe 10 minor versions ago) and it does not work in 2.0.0-rc.1, the current latest version.

There is an answer for this, this is an unfortunate limitation of using envsubst. I think I understand the issue as being that the YAML gets parsed and quotes get consumed, before envsubst happens. Templating can be done with a pre-parse rather than post-YAML-parsing solution, with a templating solution like one in Weave GitOps Enterprise as example:

• https://docs.gitops.weave.works/docs/gitops-templates/supported-langs/

Note the "templating" kind, which has lots of advantages over envsubst.

Then you have access to Go templating functions, you can do advanced things like parsing a semver into a struct, or simple things like ensure the value gets quoted when it's substituted.

This doesn't solve it for OSS Flux users, but it is a solution that might work, depending on your use case. I'm glad you found a workaround for now.

[fgeck]

Is there any workaround when the variable substitution is not done in a helm template, but e.g. for a standard cert-manager certificate resource?
Example where CERTIFICATE_DOMAIN is a wildcard like *.myfancydomain.com :

apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: "${CERTIFICATE_NAME}"
  namespace: edge
spec:
  secretName: "${CERTIFICATE_NAME}"
  issuerRef:
    name: my-cert
    kind: ClusterIssuer
  dnsNames:
    - "${CERTIFICATE_DOMAIN}"

[stefanprodan]

To force the conversion of variables to string see the docs here: https://fluxcd.io/flux/components/kustomize/kustomizations/#post-build-substitution-of-numbers-and-booleans