162 lines
4.4 KiB
Markdown
162 lines
4.4 KiB
Markdown
# The Helmfile Best Practices Guide
|
||
|
||
This guide covers the Helmfile’s considered patterns for writing advanced helmfiles. It focuses on how helmfile should be structured and executed.
|
||
|
||
## Missing keys and Default values
|
||
|
||
helmfile tries its best to inform users for noticing potential mistakes.
|
||
|
||
One example of how helmfile achieves it is that, `helmfile` fails when you tried to access missing keys in environment values.
|
||
|
||
That is, the following example let `helmfile` fail when you have no `eventApi.replicas` defined in environment values.
|
||
|
||
```
|
||
{{ .Environment.Values.eventApi.replicas | default 1 }}
|
||
```
|
||
|
||
In case it isn't a mistake and you do want to allow missing keys, use the `getOrNil` template function:
|
||
|
||
```
|
||
{{ .Environment.Values | getOrNil "eventApi.replicas" }}
|
||
```
|
||
|
||
This result in printing `<no value` in your template, that may or may not result in a failure.
|
||
|
||
If you want a kind of default values that is used when a missing key was referenced, use `default` like:
|
||
|
||
```
|
||
{{ .Environment.Values | getOrNil "eventApi.replicas" | default 1 }}
|
||
```
|
||
|
||
Now, you get `1` when there is no `eventApi.replicas` defined in environment values.
|
||
|
||
## Release Template / Conventional Directory Structure
|
||
|
||
Introducing helmfile into a large-scale project that involes dozens of releases often results in a lot of repetitions in `helmfile.yaml` files.
|
||
|
||
The example below shows repetitions in `namespace`, `chart`, `values`, and `secrets`:
|
||
|
||
```yaml
|
||
releases:
|
||
# *snip*
|
||
- name: heapster
|
||
namespace: kube-system
|
||
chart: stable/heapster
|
||
version: 0.3.2
|
||
values:
|
||
- "./config/heapster/values.yaml"
|
||
- "./config/heapster/{{ .Environment.Name }}.yaml"
|
||
secrets:
|
||
- "./config/heapster/secrets.yaml"
|
||
- "./config/heapster/{{ .Environment.Name }}-secrets.yaml"
|
||
|
||
- name: kubernetes-dashboard
|
||
namespace: kube-system
|
||
chart: stable/kubernetes-dashboard
|
||
version: 0.10.0
|
||
values:
|
||
- "./config/kubernetes-dashboard/values.yaml"
|
||
- "./config/kubernetes-dashboard/{{ .Environment.Name }}.yaml"
|
||
values:
|
||
- "./config/kubernetes-dashboard/secrets.yaml"
|
||
- "./config/kubernetes-dashboard/{{ .Environment.Name }}-secrets.yaml"
|
||
```
|
||
|
||
This is where Helmfile's advanced feature called Release Template comes handy.
|
||
|
||
It allows you to abstract away the repetitions in releases into a template, which is then included and executed by using YAML anchor/alias:
|
||
|
||
```yaml
|
||
templates:
|
||
default: &default
|
||
chart: stable/{{`{{ .Release.Name }}`}}
|
||
namespace: kube-system
|
||
# 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:
|
||
- config/{{`{{ .Release.Name }}`}}/values.yaml
|
||
- config/{{`{{ .Release.Name }}`}}/{{`{{ .Environment.Name }}`}}.yaml
|
||
secrets:
|
||
- config/{{`{{ .Release.Name }}`}}/secrets.yaml
|
||
- config/{{`{{ .Release.Name }}`}}/{{`{{ .Environment.Name }}`}}-secrets.yaml
|
||
|
||
releases:
|
||
- name: heapster
|
||
<<: *default
|
||
- name: kubernetes-dashboard
|
||
<<: *default
|
||
```
|
||
|
||
See the [issue 428](https://github.com/roboll/helmfile/issues/428) for more context on how this is supposed to work.
|
||
|
||
## Layering
|
||
|
||
You may occasionally end up with many helmfiles that shares common parts like which repositories to use, and whichi release to be bundled by default.
|
||
|
||
Use Layering to extract te common parts into a dedicated *library helmfile*s, so that each helmfile becomes DRY.
|
||
|
||
Let's assume that your `helmfile.yaml` looks like:
|
||
|
||
```
|
||
{ readFile "commons.yaml" }}
|
||
---
|
||
{{ readFile "environments.yaml" }}
|
||
---
|
||
releases:
|
||
- name: myapp
|
||
chart: mychart
|
||
```
|
||
|
||
Whereas `commons.yaml` contained a monitoring agent:
|
||
|
||
```yaml
|
||
releases:
|
||
- name: metricbaet
|
||
chart: stable/metricbeat
|
||
```
|
||
|
||
And `environments.yaml` contained well-known environments:
|
||
|
||
```yaml
|
||
environments:
|
||
development:
|
||
production:
|
||
```
|
||
|
||
At run time, template expressions in your `helmfile.yaml` are executed:
|
||
|
||
```yaml
|
||
releases:
|
||
- name: metricbaet
|
||
chart: stable/metricbeat
|
||
---
|
||
environments:
|
||
development:
|
||
production:
|
||
---
|
||
releases:
|
||
- name: myapp
|
||
chart: mychart
|
||
```
|
||
|
||
Resulting YAML documents are merged in the order of occurrence,
|
||
so that your `helmfile.yaml` becomes:
|
||
|
||
```yaml
|
||
environments:
|
||
development:
|
||
production:
|
||
|
||
releases:
|
||
- name: metricbaet
|
||
chart: stable/metricbeat
|
||
- name: myapp
|
||
chart: mychart
|
||
```
|
||
|
||
Great!
|
||
|
||
Now, repeat the above steps for each your `helmfile.yaml`, so that all your helmfiles becomes DRY.
|