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Helmfile

Helmfile is a declarative spec for deploying Helm charts. It lets you:

  • Keep a directory of chart value files and maintain changes in version control.
  • Apply CI/CD to configuration changes.
  • Environmental chart promotion.
  • Periodically sync to avoid skew in environments.

To avoid upgrades for each iteration of helm, the helmfile executable delegates to helm - as a result, helm must be installed.

All information is saved in the helmfile.yaml file.

In case we need custom yamls, we'll use kustomize.

Installation

Helmfile is not yet in the distribution package managers, so you'll need to install it manually.

Gather the latest release number.

wget {{ bin_url }} -O helmfile_linux_amd64
chmod +x helmfile_linux_amd64
mv helmfile_linux_amd64 ~/.local/bin/helmfile

Usage

How to deploy a new chart

When we want to add a new chart, the workflow would be:

  • Run helmfile deps && helmfile diff to check that your existing charts are updated, if they are not, run helmfile apply.
  • Configure the release in helmfile.yaml specifying: name: Deployment name.
  • namespace: K8s namespace to deploy.
  • chart: Chart release.
  • values: path pointing to the values file created above.
  • Create a directory with the {{ chart_name }}.
    mkdir {{ chart_name }}
    
  • Get a copy of the chart values inside that directory.
    helm inspect values {{ package_name }} > {{ chart_name }}/values.yaml
    
  • Edit the values.yaml file according to the chart documentation. Be careful becase some charts specify the docker image version in the name. Comment out that line because upgrading the chart version without upgrading the image tag can break the service.
  • Run helmfile deps to update the lock file.
  • Run helmfile diff to check the changes.
  • Run helmfile apply to apply the changes.

Keep charts updated

Updating charts with helmfile is easy as long as you don't use environments, you run helmfile deps, then helmfile diff and finally helmfile apply. The tricky business comes when you want to use environments to reuse your helmfile code and don't repeat yourself.

This is my suggested workflow, I've opened an issue to see if the developers agree with it:

As of today, helmfile doesn't support lock files per environment, that means that the lock file needs to be shared by all of them. At a first sight this is a good idea, because it forces us to have the same versions of the charts in all the environments.

The problem comes when you want to upgrade the charts of staging, test that they work and then apply the same changes in production. You'd start the process by running helmfile deps, which will read the helmfiles and update the lock file to the latest version. From this point on you need to be careful on executing the next steps in order so as not to break production.

  • Tell your team that you're going to do the update operation, so that they don't try to run helmfile against any environment of the cluster.
  • Run helmfile --environment=staging diff to review the changes to be introduced.

    To be able to see the differences of long diff files, you can filter it with egrep.

    helmfile diff | egrep -A20 -B20 "^.{5}(\-|\+)"
    

    It will show you all the changed lines with the 20 previous and next ones. * Once you agree on them, run helmfile --environment=staging apply to apply them. * Check that all the helm deployments are well deployed with helm list -A | grep -v deployed * Wait 20 minutes to see if the monitoring system or your fellow partners start yelling at you. * If something breaks up, try to fix it up, if you see it's going to delay you to the point that you're not going to be able to finish the upgrade in your working day, it's better to revert back to the working version of that chart and move on with the next steps. Keep in mind that since you run the apply to the last of the steps of this long process, the team is blocked by you. So prioritize to commit the next stable version to the version control repository. * Once you've checked that all the desired upgrades are working, change the context to the production cluster and run helmfile --environment=production diff. This review should be quick, as it should be the same as the staging one. * Now upgrade the production environment with helmfile --environment=production apply. * Check that all the helm deployments are well deployed with helm list -A | grep -v deployed * Wait another 20 minutes and check that everything is working. * Make a commit with the new lockfile and upload it to the version control repository.

If you want the team to be involved in the review process, you can open a PR with the lock file updated with the WIP state, and upload the relevant diff of staging and production, let the discussion end and then run the apply on staging and then on production if everything goes well.

Another ugly solution that I thought was to have a lockfile per environment, and let a Makefile manage them, for example, copying it to helmfile.lock before running any command.

Uninstall charts

Helmfile still doesn't remove charts if you remove them from your helmfile.yaml. To remove them you have to either set installed: false in the release candidate and execute helmfile apply or delete the release definition from your helmfile and remove it using standard helm commands.

Force the reinstallation of everything

If you manually changed the deployed resources and want to reset the cluster state to the helmfile one, use helmfile sync which will reinstall all the releases.

Multi-environment project structure

helmfile can handle environments with many different project structures. Such as the next one:

├── README.md
├── helmfile.yaml
├── vars
│   ├── production_secrets.yaml
│   ├── production_values.yaml
│   ├── default_secrets.yaml
│   └── default_values.yaml
├── charts
│   ├── local_defined_chart_1
│   └── local_defined_chart_2
├── templates
│   ├── environments.yaml
│   └── templates.yaml
├── base
│   ├── README.md
│   ├── helmfile.yaml
│   ├── helmfile.lock
│   ├── repos.yaml
│   ├── chart_1
│   │   ├── secrets.yaml
│   │   ├── values.yaml
│   │   ├── production_secrets.yaml
│   │   ├── production_values.yaml
│   │   ├── default_secrets.yaml
│   │   └── default_values.yaml
│   └── chart_2
│       ├── secrets.yaml
│       ├── values.yaml
│       ├── production_secrets.yaml
│       ├── production_values.yaml
│       ├── default_secrets.yaml
│       └── default_values.yaml
└── service_1
    ├── README.md
    ├── helmfile.yaml
    ├── helmfile.lock
    ├── repos.yaml
    ├── chart_1
    │   ├── secrets.yaml
    │   ├── values.yaml
    │   ├── production_secrets.yaml
    │   ├── production_values.yaml
    │   ├── default_secrets.yaml
    │   └── default_values.yaml
    └── chart_2
        ├── secrets.yaml
        ├── values.yaml
        ├── production_secrets.yaml
        ├── production_values.yaml
        ├── default_secrets.yaml
        └── default_values.yaml

Where:

  • There is a general README.md that introduces the repository.
  • Optionally there could be a helmfile.yaml file at the root with a glob pattern so that it's easy to run commands on all children helmfiles.

    helmfiles:
        - ./*/helmfile.yaml
    
    * There is a vars directory to store the variables and secrets shared by the charts that belong to different services. * There is a templates directory to store the helmfile code to reuse through templates and layering. * The project structure is defined by the services hosted in the Kubernetes cluster. Each service contains:

    • A README.md to document the service implementation.
    • A helmfile.yaml file to configure the service charts.
    • A helmfile.lock to lock the versions of the service charts.
    • A repos.yaml to define the repositories to fetch the charts from.
    • One or more chart directories that contain the environment specific and shared chart values and secrets.
  • There is a base service that manages all the charts required to keep the cluster running, such as the ingress, csi, cni or the cluster-autoscaler.

Using helmfile environments

To customize the contents of a helmfile.yaml or values.yaml file per environment, add them under the environments key in the helmfile.yaml:

environments:
  default:
  production:

The environment name defaults to default, that is, helmfile sync implies the default environment. So it's a good idea to use staging as default to be more robust against human errors. If you want to specify a non-default environment, provide a --environment NAME flag to helmfile like helmfile --environment production sync.

In the environments definition we'll load the values and secrets from the vars directory with the next snippet.

environments:
  default:
    secrets:
      - ../vars/default_secrets.yaml
    values:
      - ../vars/default_values.yaml
  production:
    secrets:
      - ../vars/production_secrets.yaml
    values:
      - ../vars/production_values.yaml

As this snippet is going to be repeated on every helmfile.yaml we'll use a state layering for it.

To install a release only in one environment use:

environments:
  default:
  production:

---

releases:
- name: newrelic-agent
  installed: {{ eq .Environment.Name "production" | toYaml }}
  # snip

Using environment specific variables

Environment Values allows you to inject a set of values specific to the selected environment, into values.yaml templates or helmfile.yaml files. Use it to inject common values from the environment to multiple values files, to make your configuration DRY.

Suppose you have three files helmfile.yaml, production.yaml and values.yaml.gotmpl

File: helmfile.yaml

environments:
  production:
    values:
      - production.yaml

---

releases:
- name: myapp
  values:
    - values.yaml.gotmpl

File: production.yaml

domain: prod.example.com

File: values.yaml.gotmpl

domain: {{ .Values | get "domain" "dev.example.com" }}

Sadly you can't use templates in the secrets files, so you'll need to repeat the code.

Loading the chart variables and secrets

For each chart definition in the helmfile.yaml we need to load it's secrets and values. We could use the next snippet:

  - name: chart_1
    values:
      - ./chart_1/values.yaml
      - ./chart_1/{{ Environment.Name }}_values.yaml
    secrets:
      - ./chart_1/secrets.yaml
      - ./chart_1/{{ Environment.Name }}_secrets.yaml

This assumes that the environment variable is set, as it's going to be shared by all the helmfiles.yaml you can add it to the vars files:

File: vars/production_values.yaml

environment: production

File: vars/default_values.yaml

environment: staging

Instead of .Environment.Name, in theory you could have used .Vars | get "environment", which could have prevented the variables and secrets of the default environment will need to be called default_values.yaml, and default_secrets.yaml, which is misleading. But you can't use .Values in the helmfile.yaml as it's not loaded when the file is parsed, and you get an error. A solution would be to layer the helmfile state files but I wasn't able to make it work.

Avoiding code repetition

Besides environments, helmfile gives other useful tricks to prevent the illness of code repetition.

Using release templates

For each chart in a helmfile.yaml we're going to repeat the values and secrets sections, to avoid it, we can use release templates:

templates:
  default: &default
    # This prevents helmfile exiting when it encounters a missing file
    # Valid values are "Error", "Warn", "Info", "Debug". The default is "Error"
    # Use "Debug" to make missing files errors invisible at the default log level(--log-level=INFO)
    missingFileHandler: Warn
    values:
    - {{`{{ .Release.Name }}`}}/values.yaml
    - {{`{{ .Release.Name }}`}}/{{`{{ .Values | get "environment" }}`}}.yaml
    secrets:
    - config/{{`{{ .Release.Name }}`}}/secrets.yaml
    - config/{{`{{ .Release.Name }}`}}/{{`{{ .Values | get "environment" }}`}}-secrets.yaml

releases:
- name: chart_1
  chart: stable/chart_1
  <<: *default
- name: chart_2
  chart: stable/chart_2
  <<: *default

If you're not familiar with YAML anchors, &default names the block, then *default references it. The <<: syntax says to "extend" (merge) that reference into the current tree.

The missingFileHandler: Warn field is necessary if you don't need all the values and secret files, but want to use the same definition for all charts.

{{` {{ .Release.Name }} `}} is surrounded by {{` and }}` so as not to be executed on the loading time of helmfile.yaml. We need to defer it until each release is actually processed by the helmfile command, such as diff or apply.

For more information see this issue.

Layering the state

You may occasionally end up with many helmfiles that shares common parts like which repositories to use, and which release to be bundled by default.

Use Layering to extract the common parts into a dedicated library helmfiles, so that each helmfile becomes DRY.

Let's assume that your code looks like:

File: helmfile.yaml

bases:
- environments.yaml

releases:
- name: metricbeat
  chart: stable/metricbeat
- name: myapp
  chart: mychart

File: environments.yaml

environments:
  development:
  production:

At run time, bases in your helmfile.yaml are evaluated to produce:

---
# environments.yaml
environments:
  development:
  production:
---
# helmfile.yaml
releases:
- name: myapp
  chart: mychart
- name: metricbeat
  chart: stable/metricbeat

Finally the resulting YAML documents are merged in the order of occurrence, so that your helmfile.yaml becomes:

environments:
  development:
  production:

releases:
- name: metricbeat
  chart: stable/metricbeat
- name: myapp
  chart: mychart

Using this concept, we can reuse the environments section as:

File: vars/environments.yaml

environments:
  default:
    secrets:
      - ../vars/staging-secrets.yaml
    values:
      - ../vars/staging-values.yaml
  production:
    secrets:
      - ../vars/production-secrets.yaml
    values:
      - ../vars/production-values.yaml

And the default release templates as:

File: templates/templates.yaml

templates:
  default: &default
  values:
  - {{`{{ .Release.Name }}`}}/values.yaml
  - {{`{{ .Release.Name }}`}}/{{`{{ .Values | get "environment" }}`}}.yaml
  secrets:
  - config/{{`{{ .Release.Name }}`}}/secrets.yaml
  - config/{{`{{ .Release.Name }}`}}/{{`{{ .Values | get "environment" }}`}}-secrets.yaml

So the service's helmfile.yaml turns out to be:

bases:
- ../templates/environments.yaml
- ../templates/templates.yaml

releases:
- name: chart_1
  chart: stable/chart_1
  <<: *default
- name: chart_2
  chart: stable/chart_2
  <<: *default

Much shorter and simple.

Managing dependencies

Helmfile support concurrency with the option --concurrency=N so we can take advantage of it and improve our deployment speed, but to ensure it works as expected we have to define the dependencies among charts. For example, if an application needs a database, it has to be deployed before hand.

releases:
  - name: vpn-dashboard
    chart: incubator/raw
    needs:
      - monitoring/prometheus-operator
  - name: prometheus-operator
    namespace: monitoring
    chart: prometheus-community/kube-prometheus-stack

Debugging helmfile

Error: "release-name" has no deployed releases

This may happen when you try to install a chart and it fails. The best solution until this issue is resolved is to use helm delete --purge {{ release-name }} and then apply again.

Error: failed to download "stable/metrics-server" (hint: running helm repo update may help)

I had this issue if verify: true in the helmfile.yaml file. Comment it or set it to false.

Cannot patch X field is immutable

You may think that deleting the resource, usually a deployment or daemonset will fix it, but helmfile apply will end without any error, the resource won't be recreated , and if you do a helm list, the deployment will be marked as failed.

The solution we've found is disabling the resource in the chart's values so that it's uninstalled an install it again.

This can be a problem with the resources that have persistence. To patch it, edit the volume resource with kubectl edit pv -n namespace volume_pvc, change the persistentVolumeReclaimPolicy to Retain, apply the changes to uninstall, and when reinstalling configure the chart to use that volume (easier said than done).


Last update: 2022-06-08