gomplate throw error "map has no entry for key \"spectra\"

[rameshkjha]

I am trying to run gomplate on my overlay kustomization directory and running into an error
gomplate --input-dir ./spectra/ --output-dir kustomize-config --datasource config=./base/config.yaml

ERR error="template: spectra/kustomization.yaml:7:23: executing "spectra/kustomization.yaml" at <.spectra.instance.name>: map has no entry for key "spectra""

Here is my directory structure and file content. Appreciate any input on what is wrong here ? Thanks in advance !

kustomize
| | base
| config.yaml
| |spectra
| |kustomization.yaml

file 1) ./base/config.yaml
spectra:
instance:
name: kustomize-dashboardsvc
stage:
name: alpha

file 2) ./spectra/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:

• ../base

namespace: "{{ .spectra.instance.name }}"

commonLabels:
stage: "{{ .spectra.stage.name }}"

[hairyhenderson]

Hi @rameshkjha, thanks for filing this - I've converted it to a discussion since this isn't a bug report or feature request.

The --datasource flag defines a datasource that can be accessed with the datasource/ds function. You're using it to define a datasource named config. So in this case you could access it with something like this:

namespace: "{{ (ds "config").spectra.instance.name }}"

You can also use the context as an alternative which makes for nicer (IMO) syntax, but there are tradeoffs. For your usage I'd recommend it. To use that you need the --context/-c flag:

$ gomplate ... --context config=./base/config.yaml
...

Then, you can access the context and the datasources attached to it with .:

namespace: "{{ .config.spectra.instance.name }}"

There's a special-case available as well, most useful if you know you'll only ever have a single datasource on the context, which is to use . as the name instead of something like config:

$ gomplate ... --context .=./base/config.yaml
...

Then you can use syntax like you listed:

namespace: "{{ .spectra.instance.name }}"

Please read the docs for further information around datasources and the context. Hope this helps!

[rameshkjha]

@hairyhenderson
Thank you very much for explaining it and helping out with various options for my usecase.

Both the combination worked for me.

gomplate --input-dir ./spectra/ --output-dir kustomize-config --context .=./base/config.yaml
namespace: "{{ .spectra.instance.name }}"

gomplate --input-dir ./spectra/ --output-dir kustomize-config --context config=./base/config.yaml
namespace: "{{ .config.spectra.instance.name }}"

I have just started exploring gomplate and loving it.
Appreciate your help.

[hairyhenderson]

@rameshkjha Glad that helped! Can you mark my response as an answer? Thanks 🙂

[rameshkjha]

Marking it as answered.