Helm install dependency charts without root helm

There's no actual requirement that a Helm chart contain any templates of its own. It's possible to have a Helm chart that only contains dependencies; then running helm install on that "parent" chart would install all of the dependencies.

It would be valid to run helm create to build a new chart, then delete the values.yaml file and template directory from the generator, and fill in the requirements in Chart.yaml.

In your setup you're just installing infrastructure services. Occasionally you will see a dependency-only chart like this used to install several application components as well; this is sometimes called an umbrella chart. There are potential problems around umbrella charts where Helm likes to combine together dependencies: if different application components depend on different major versions of some chart there can be a conflict, and if you have multiple components that each depend on, say, Redis, an umbrella-chart installation will typically install just one shared Redis rather than an isolated Redis per component.

There are a number of ways to group multiple helm install commands into a single execution. Just writing a simple shell script will often work, depending on your needs. General-purpose automation tools (Ansible, Salt Stack, Chef) may have ways to run Helm, or if not, then to run arbitrary commands. There are also a couple of Helm-specific tools here: Helmsman is simpler and Helmfile more complex, but both let you "install" a collection of related charts without necessarily building an umbrella chart.

What you describe at the beginning of your question is called "Umbrella Charts". These are Charts that are used to bundle other Charts and manage these as one unit.

If this is not what you want to do (that's how I understand your question), then you are required to use other tools. One such tool is Helmfile, which allows you to define a list of Helm Charts, their versions and Helm Values. You can then install/upgrade/uninstall all referenced Helm Charts in one go.

Another option is to use kluctl (disclaimer: I'm the main developer of it). It basically allows you to do the same as offered by Helmfile, but in a different way/style. Kluctl focuses on Kustomize deployments while allowing you to easily pull-in third-party Helm Charts.

Having the mentioned Helm Charts in a Kluctl deployment would require you to have a kluctl deployment project that looks like this:

my_project
├── third-party
│   ├── rabbit
│   │   ├── kustomization.yaml
│   │   ├── helm-chart.yaml
│   │   └── helm-values.yaml
│   ├── redis
│   │   ├── kustomization.yaml
│   │   ├── helm-chart.yaml
│   │   └── helm-values.yaml
│   └── deployment.yaml
├── deployment.yaml
└── .kluctl.yaml

my_project/deployment.yaml

vars:
- values:
    # this is arbitrary yaml
    my:
      ns: my-namespace
# this is also possible, loading vars from a file...
# many other sources are supported as well
# - file: my-config.yaml

deployments:
- include: third-party

commonLabels:
  my.example.com/deployment: my-example-deployment
  my.example.com/target: {{ target.name }}

my_project/third-party/deployment.yaml

deployments:
- path: rabbit
- path: redis

my_project/third-party/rabbit/kustomization.yaml

resources:
# this file is auto-generated by the helm-integration
- deploy.yaml

my_project/third-party/rabbit/helm-chart.yaml

helmChart:
  repo: https://charts.bitnami.com/bitnami
  chartName: rabbitmq
  chartVersion: 10.3.2
  releaseName: my-rabbit
  # my.ns comes from the 'vars' defined in the root deployment.yaml
  namespace: "{{ my.ns }}"
  output: deploy.yaml

my_project/third-party/rabbit/helm-values.yaml

auth:
  username: my-user
  password: you-would-of-course-never-do-this

my_project/third-party/redis/helm-chart.yaml and helm-values.yaml

Basically the same as for rabbitmq, but with redis specific settings.

my_project/.kluctl.yaml

targets:
- name: dev
  context: my-dev-cluster-context

Using kluctl

Based on the above example, you would then run kluctl helm-pull from the root project directory, which will then pre-pull all involved Helm Charts and write the contents besides the helm-chart.yaml files. These pre-pulled Charts are meant to be added to you version control (this might change in the future).

After that, you can run commands like kluctl diff -t dev, kluctl deploy -t dev and kluctl prune -t dev to work with the deployment.

kluctl helm-upgrade will help you while upgrading the pre-pulled Helm Charts.

Fully working example

A fully working example can be found here. The shown yamls from above are only meant to give an idea about the Helm related stuff.