kustomize should leave all ConfigMap values as quoted strings, since no other type is legal.

What happened?

We have a YAML string in a ConfigMap that contains a variable (e.g. ${TEST}) which will be replaced with a string AFTER running kustomize --build .

The problem is that the quotes are removed from the string by kustomize and then if that variable is replaced with something like true, the ConfigMap will be invalid since true is interpreted as a boolean value instead of a string and that is not allowed in a ConfigMap.

What did you expect to happen?

I expect kustomize to leave a quoted string quoted.

How can we reproduce it (as minimally and precisely as possible)?

# kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - "configmap.yaml"

# resources.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: test-object
data:
  pci: '${TEST}'

Expected output

apiVersion: v1
data:
  pci: '${TEST}'
kind: ConfigMap
metadata:
  name: test-object

Actual output

apiVersion: v1
data:
  pci: ${TEST}
kind: ConfigMap
metadata:
  name: test-object

Note the missing quotes. If that variable is then templated with a boolean or integer, this is a significant problem.

Kustomize version

v5.3.0

Operating system

MacOS

Potentially related to: #5124

@akbar-mohammad

cc/ @akbar-mohammad @sibucan

This problem kinda sucks because the original YAML will have quotes that are not preserved between the conversion of kustomize template->JSON->YAML, and if we desire to keep them, there's no way to indicate to kustomize that they shouldn't be removed. Suppose we start with this YAML kustomize template:

apiVersion: v1
kind: ConfigMap
data:
  test1: "${TEMPLATE_VAR1}"
  test2: "{TEMPLATE_VAR2}"
  test3: "true"
  test4: "test4"
metadata:
  name: config

When executing kustomize build, it'll read the kustomization.yaml file and render the manifest. I've narrowed the path down to the JSONToYAML() function used by the build command here:

kustomize/api/resource/resource.go

Line 371 in 33caee5

return yaml.JSONToYAML(json)

This function is supposed to take a JSON byte array and turns it into valid YAML:

JSON:

{"apiVersion":"v1","data":{"test1":"${TEMPLATE_VAR1}","test2":"{TEMPLATE_VAR2}","test3":"true","test4":"test4"},"kind":"ConfigMap","metadata":{"name":"config"}}

FINAL RESULT

apiVersion: v1
data:
  test1: ${TEMPLATE_VAR1}
  test2: '{TEMPLATE_VAR2}'
  test3: "true"
  test4: test4
kind: ConfigMap
metadata:
  name: config

My assumption is that any string that isn’t already a valid JSON type (such as a sub structure with {} or a boolean true) gets its quotes stripped (You can test the code out in this playground link: https://go.dev/play/p/rFUUlFjPk5f):

This may be related to #5432
/assign

Our investigation suggests that the YAML parser is doing the right thing, but the fact that quotes are removed when we explicitly need them, and there appears to be no way to force them to be kept, is very problematic in our use case.

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/triage accepted

I am currently short on time to continue working on this.

For future contributors looking to fix this issue: any fixes for this issue need to be submitted to https://github.com/yaml/go-yaml, as per kubernetes-sigs/yaml#115 (comment).

/unassign

/assign

fix: quote ConfigMap and Secret data values in YAML output

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`kustomize` should leave all ConfigMap values as quoted strings, since no other type is legal. #5558

What happened?

What did you expect to happen?

How can we reproduce it (as minimally and precisely as possible)?

Expected output

Actual output

Kustomize version

Operating system

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kustomize should leave all ConfigMap values as quoted strings, since no other type is legal. #5558

Description

What happened?

What did you expect to happen?

How can we reproduce it (as minimally and precisely as possible)?

Expected output

Actual output

Kustomize version

Operating system

Activity

spkane commented on Feb 29, 2024

spkane commented on Feb 29, 2024

sibucan commented on Feb 29, 2024

stormqueen1990 commented on Feb 29, 2024

spkane commented on Feb 29, 2024

k8s-triage-robot commented on May 29, 2024

stormqueen1990 commented on May 29, 2024

stormqueen1990 commented on May 29, 2024

stormqueen1990 commented on Aug 30, 2025

HarshithaMS005 commented on Sep 17, 2026

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`kustomize` should leave all ConfigMap values as quoted strings, since no other type is legal. #5558