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Improve Nested foreach Documentation #1474

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Improve Nested foreach Documentation #1474

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c63b68a
Clarify nested foreach referencing in Kyverno documentation
Denish3436 Feb 14, 2025
5f36f6a
Add for older kyverno version
Denish3436 Feb 21, 2025
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32 changes: 30 additions & 2 deletions content/en/docs/writing-policies/mutate.md
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Expand Up @@ -1168,7 +1168,7 @@ spec:
secretName: mytlscertsecret
```

This type of advanced mutation can be performed with nested foreach loops as shown below. Notice that in the JSON patch, the `path` value references the current index of `tls[]` as `{{elementIndex0}}` and the current index of `hosts[]` as `{{elementIndex1}}`. In the `value` field, the `{{element}}` variable still references the current value of the `hosts[]` array being processed.
This type of advanced mutation can be performed with nested foreach loops as shown below. Notice that in the JSON patch, the `path` value references the current index of `tls[]` as `{{elementIndex0}}` and the current index of `hosts[]` as `{{elementIndex1}}`. In the `value` field, the `{{element1}}` variable still references the current value of the `hosts[]` array being processed.
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maybe add a statement here that looks something like the following:

While {{elementIndex0}} can be used to reference the current index of tls[] you can use {{element0}} to access the current element in the tls[] being processed in the foreach loop. Similarly {{element1}} can be used to access the hosts[] value in the nested for each.

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@iamsgarg-ob Thanks for the feedback, I'll make the required changes

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@iamsgarg-ob I have updated the required changes, could you plz review it...

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LGTM


```yaml
apiVersion: kyverno.io/v1
Expand All @@ -1187,13 +1187,41 @@ spec:
mutate:
foreach:
- list: request.object.spec.tls[]
as: element0 # Outer loop element (tls array)
foreach:
- list: "element.hosts"
as: element1 # Inner loop element (hosts array)
patchesJson6902: |-
- path: /spec/tls/{{elementIndex0}}/hosts/{{elementIndex1}}
op: replace
value: "{{ replace_all('{{element}}', '.old.com', '.new.com') }}"
value: "{{ replace_all('{{element1}}', '.old.com', '.new.com') }}"
```
For older Kyverno versions that do not support as:, elements can be accessed directly using {{element0}} and {{element1}}.

```yaml
apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
name: replace-dns-suffix-legacy
spec:
background: false
rules:
- name: replace-dns-suffix
match:
any:
- resources:
kinds:
- Ingress
mutate:
foreach:
- list: request.object.spec.tls[]
foreach:
- list: element.hosts
patchesJson6902: |-
- path: /spec/tls/{{elementIndex0}}/hosts/{{elementIndex1}}
op: replace
value: "{{ replace_all('{{element}}', '.old.com', '.new.com') }}"
```

## GitOps Considerations

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