Variable substitution does not work in Traefik IngressRoutes

[christiaangoossens]

Description

Variable substitution for widget keys, as added in #1043 does not seem to work with Traefik IngressRoutes.

Any combination of inputting it in an annotation seems to be broken. However, jameswynn/helm-charts#9 (comment) suggests that this issue might be isolated to Traefik IngressRoutes only, provided the poster only tested with normal Ingresses. Copying that example does not result in a working environment.

Only error shown is: "Error attempting k8s environment variable substitution.". It seems that the JSON.parse throws an error when any variable substitution occurs:

homepage/src/utils/config/service-helpers.js

Line 299 in c6770d2

constructedService = JSON.parse(substituteEnvironmentVars(JSON.stringify(constructedService)));

homepage version

v0.8.13

Installation method

Other (please describe above)

Configuration

No response

Container Logs

Listening on port 3000
[2024-05-29T10:28:43.093Z] info: custom.css was copied to the config folder
[2024-05-29T10:28:43.094Z] info: custom.js was copied to the config folder
[2024-05-29T10:28:43.196Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.445Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.471Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.799Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.800Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.828Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.887Z] error: <service-helpers> Error attempting k8s environment variable substitution.
[2024-05-29T10:28:43.893Z] error: <credentialedProxyHandler> HTTP Error 401 calling http://internal-example-path

Browser Logs

No response

Troubleshooting

Tried and confirmed working:

• Looking up if the env var is set in the container by doing a kubectl exec and running echo $HOMEPAGE_VAR_KEY_EXAMPLE.
• Use of the environment variable directly in the ConfigMap for Homepage, like:

  services:    
    - Group1:
      - App1:
        href: http://example.com
        widget:
            type: example
            url: http://internal-example-path
            key: "{{HOMEPAGE_VAR_KEY_EXAMPLE}}"

This correctly works with the widget I was using (replaced with example for the example). All data loads.

Tried and confirmed broken:

• Adding an annotation to the Traefik IngressRoute with: gethomepage.dev/widget.key: "{{HOMEPAGE_VAR_KEY_EXAMPLE}}"
• Adding an annotation to the Traefik IngressRoute with: gethomepage.dev/widget.key: {{HOMEPAGE_VAR_KEY_EXAMPLE}}
• Adding an annotation to the Traefik IngressRoute with: gethomepage.dev/widget.key: '{{HOMEPAGE_VAR_KEY_EXAMPLE}}'
• Adding an annotation to the Traefik IngressRoute with: gethomepage.dev/widget.key: '"{{HOMEPAGE_VAR_KEY_EXAMPLE}}"'
• Adding an annotation to the Traefik IngressRoute with: gethomepage.dev/widget.key: "'{{HOMEPAGE_VAR_KEY_EXAMPLE}}'"

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Thanks for posting a discussion about homepage here on GitHub. Homepage now uses a fancy new AI tool thanks to our friends at Glime, so the answer below is the AI bot's attempt to answer your question. If you feel it's sufficient you can mark the answer and close this post, otherwise feel free to leave it open of course!

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---

Based on the information provided, it seems that you are encountering an issue with environment variable substitution in Kubernetes when using Traefik IngressRoutes with Homepage. The error message "Error attempting k8s environment variable substitution." indicates that the substitution process is failing.

Given that you have confirmed the environment variable is correctly set within the container and that direct use of the environment variable in the ConfigMap works as expected, the issue appears to be specific to the annotation-based substitution within Traefik IngressRoutes.

The various formats you have tried for the annotations suggest that the issue is not with the syntax of the annotation itself. Instead, it could be related to how Homepage processes these annotations or a limitation within the Traefik IngressRoute's handling of such substitutions.

To troubleshoot this issue further, I would recommend the following steps:

1. Ensure that the version of Homepage you are using supports environment variable substitution in the way you are attempting. Check the documentation or release notes for any known issues or limitations regarding this feature.

2. Review the Homepage logs in more detail to see if there are any additional error messages or stack traces that could provide more insight into where the substitution process is failing.

3. If possible, test with a simpler setup or different types of Kubernetes resources (such as a standard Ingress) to confirm if the issue is isolated to Traefik IngressRoutes.

4. Consider reaching out to the Homepage community or maintainers for assistance. You can use the GitHub discussions or issues to ask for help or report a potential bug.

5. As a workaround, you may continue using the direct environment variable substitution in the ConfigMap if that is working for your use case.

If you would like to provide additional information or have specific questions about the steps above, please let me know, and I will do my best to assist you further.

This comment was generated by Glime.

[christiaangoossens]

Possible solution might be to replace the separate parsing in try/catch with the following code instead:

Object.keys(ingress.metadata.annotations).forEach((annotation) => {
          if (annotation.startsWith(ANNOTATION_WIDGET_BASE)) {
            shvl.set(
              constructedService,
              annotation.replace(`${ANNOTATION_BASE}/`, ""),
              substituteEnvironmentVars(ingress.metadata.annotations[annotation]),
            );
          }
        });

This would however remove variable substitution from other fields, which might need the substituteEnvironmentVars() call on their own.

Can any maintainer confirm the bug/solution?

[christiaangoossens]

For anyone coming across this, the variable handling does not currently strip whitespace and quotes! So, if you encode your Kubernetes secret wrong, you might end up with whitespace after your api key, which then fails the JSON.stringify() call.

If you are creating your Kubernetes secret, remember to do echo -n "secret" | base64 instead of just echo.

I have submitted a PR to strip these automatically, preventing this failure case: #3642

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