chore: update readme

[namkyu1999]

What this PR does / why we need it:

I updated installation.md for ARM users. Briefly, the official MongoDB Helm chart does not support ARM, so I added commands for users to install Litmus with an unofficial MongoDB image.

Special notes for your reviewer:

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• DCO signed
• Chart Version bumped
• Variables are documented in the README.md

[Jasstkn]

Hi @namkyu1999! Thank you for your proposed changes. However, I would like to avoid putting some third-party image as officially recommended by Litmus maintainers.

I think that we can just refer to the original issue: bitnami/charts#7305 and propose an example how to override the image repository and tag via helm values.

Let me know what do you think about it?

[namkyu1999]

Hi @Jasstkn, Thanks for the comment.
Let me correct one thing I said. In this installation, We continue to utilize the official MongoDB Helm charts created by Bitnami. But they use bitnami/mongodb image by default. So I just override helm values by --set flag like below.

helm install chaos litmuschaos/litmus --namespace=litmus \
--set portal.frontend.service.type=NodePort \
--set mongodb.image.registry=ghcr.io/zcube \
--set mongodb.image.repository=bitnami-compat/mongodb \
--set mongodb.image.tag=6.0.5

Is this still a non-recommended way?

[Jasstkn]

Hi @Jasstkn, Thanks for the comment. Let me correct one thing I said. In this installation, We continue to utilize the official MongoDB Helm charts created by Bitnami. But they use bitnami/mongodb image by default. So I just override helm values by --set flag like below.

helm install chaos litmuschaos/litmus --namespace=litmus \
--set portal.frontend.service.type=NodePort \
--set mongodb.image.registry=ghcr.io/zcube \
--set mongodb.image.repository=bitnami-compat/mongodb \
--set mongodb.image.tag=6.0.5

Is this still a non-recommended way?

I don't want to include in the README recommendation to use specific third-party image. So basically, leave the section with the ARM use-case, add link to the Bitnami issue and add a command like the following:

helm install chaos litmuschaos/litmus --namespace=litmus \
--set portal.frontend.service.type=NodePort \
--set mongodb.image.registry=<put_registry> \
--set mongodb.image.repository=<put_image_repository> \
--set mongodb.image.tag=<put_image_tag>

[namkyu1999]

Hi @Jasstkn ,
I updated it like below.

## ARM support
## Litmus helm chart depends on bitnami/mongodb, which uses a mongodb image not supported on ARM.
## To install Litmus on an ARM-based server, use a custom MongoDB ARM image instead of the default.
# helm install chaos litmuschaos/litmus --namespace=litmus \
# --set mongodb.image.registry=<put_registry> \
# --set mongodb.image.repository=<put_image_repository> \
# --set mongodb.image.tag=<put_image_tag>

Can you take a look at this one again, please?

[Jasstkn]

@namkyu1999 thank you for the contribution! merged 🚀