github/container.training
1
0
Fork 0
mirror of https://github.com/jpetazzo/container.training.git synced 2026-07-18 04:19:43 +00:00
Code Issues Packages Projects Releases Wiki Activity

👀 Review and suggestions for new Helm content

Browse Source
This commit is contained in:
Jerome Petazzoni
2021-04-05 19:02:30 +02:00
committed by Julien Girardin
parent 2160aa7f40
commit bb1b225026
2 changed files with 160 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
slides/k8s/helm-dependencies.md
View File

@@ -2,7 +2,7 @@
- Helm charts can have *dependencies* on other charts
- These dependencies will help us to share or reuse* components
- These dependencies will help us to share or reuse components
(so that we write and maintain less manifests, less templates, less code!)
@@ -230,6 +230,8 @@ use Bitnami's Redis chart.
---
class: extra-details
## Passing templates
- We can even pass template `{{ include "template.name" }}`, but warning:
@@ -238,7 +240,7 @@ use Bitnami's Redis chart.
- evaluated in the context of the child, with no access to parent variables
<!-- FIXME <jp> pas sûr d'avoir bien compris cette partie-là 😅 -->
<!-- FIXME this probably deserves an example, but I can't imagine one right now 😅 -->
---
@@ -292,6 +294,27 @@ use Bitnami's Redis chart.
---
## Embedding a dependency multiple times
- What if we need multiple copies of the same subchart?
(for instance, if we need two completely different Redis servers)
- We can declare a dependency multiple times, and specify an `alias`:
```yaml
dependencies:
- name: redis
version: '*'
alias: querycache
- name: redis
version: '*'
alias: celeryqueue
```
- `.Chart.Name` will be set to the `alias`
---
class: extra-details
## Compatibility with Helm 2

187
slides/k8s/helm-values-schema-validation.md
View File

@@ -1,91 +1,151 @@
## Helm and invalid values
- A lot of Helm charts let us specify an image tag like this:
```bash
helm install ... --set image.tag=v1.0
```
- What happens if we make a small mistake, like this:
```bash
helm install ... --set imagetag=v1.0
```
- Or even, like this:
```bash
helm install ... --set image=v1.0
```
🤔
---
## Helm mistake
- What if I put wrong values and deploy the helm chart ?
## Making mistakes
.exercice[
- In the first case:
- Install a helm release with wrong values:
- we set `imagetag=v1.0` instead of `image.tag=v1.0`
`helm install broken-release --set=foo=bar --set=ImAgeTAg=toto`
]
- Helm will ignore that value (if it's not used anywhere in templates)
- What happened ?
- the chart is deployed with the default value instead
- The `broken-release` is installed 😨
- In the second case:
- Is-it really broken ?
- we set `image=v1.0` instead of `image.tag=v1.0`
- Not really: helm just ignored the values it doesn't know about 😓
- `image` will be a string instead of an object
- Is there something we can do to avoid mistakes ?
- Helm will *probably* fail when trying to evaluate `image.tag`
---
## Preventing mistakes
- To prevent the first mistake, we need to tell Helm:
*"let me know if any additional (unknonw) value was set!"*
- To prevent the second mistake, we need to tell Helm:
*"`image` should be an object, and `image.tag` should be a string!"*
- We can do this with *values schema validation*
---
## Helm values schema validation
- With *values schema validation*, we can write a spec representing the possible
values accepted by the chart.
- We can write a spec representing the possible values accepted by the chart
- Moving away from the spec make helm bailing out the installation/upgrade
- Helm will check the validity of the values before trying to install/upgrade
- It uses [jsonschema](https://json-schema.org/) language which is a
- If it finds problems, it will stop immediately
`"a vocabulary that allows you to annotate and validate JSON documents."`
- The spec uses [JSON Schema](https://json-schema.org/):
- But can be adapted like here to validate any markup language that consist in
`map|dict|associativearray` and `list|array|sequence|tuple` like *yaml*
*JSON Schema is a vocabulary that allows you to annotate and validate JSON documents.*
- JSON Schema is designed for JSON, but can easily work with YAML too
(or any language with `map|dict|associativearray` and `list|array|sequence|tuple`)
---
.exercise[
- Let's create a `values.schema.json`:
```json
{
"$schema": "http://json-schema.org/schema#",
## In practice
- We need to put the JSON Schema spec in a file called `values.schema.json`
(at the root of our chart; right next to `values.yaml` etc.)
- The file is optional
- We don't need to register or declare it in `Chart.yaml` or anywhere
- Let's write a schema that will verify that ...
- `image.repository` is an official image (string without slashes or dots)
- `image.pullPolicy` can only be `Always`, `Never`, `IfNotPresent`
---
## `values.schema.json`
```json
{
"$schema": "http://json-schema.org/schema#",
"type": "object",
"properties": {
"image": {
"type": "object",
"properties": {
"image": {
"type": "object",
"properties": {
"repository": {
"type": "string",
"pattern": "^[a-z0-9-_]+$"
},
"pullPolicy": {
"type": "string",
"pattern": "^(Always|Never|IfNotPresent)$"
} } } } }
```
]
"repository": {
"type": "string",
"pattern": "^[a-z0-9-_]+$"
},
"pullPolicy": {
"type": "string",
"pattern": "^(Always|Never|IfNotPresent)$"
}
}
}
}
}
```
---
## Testing Helm validation
- Now we can test to install Wrong release:
## Testing our schema
- Let's try to install a couple releases with that schema!
.exercise[
- Run:
- Try an invalid `pullPolicy`:
```bash
helm install broken --set image.pullPolicy=ShallNotPass
```
`helm install broken --set image=image.pullPolicy=ShallNotPass`
- Try an invalid value:
```bash
helm install should-break --set ImAgeTAg=toto
```
- Run:
`helm install should-break --set=foo=bar --set=ImAgeTAg=toto`
]
- First fails, but second one still pass even if we put a `values.schema.json` !
- The first one fails, but the second one still passes ...
- Why ?
- Why?
---
## Bailing out on unkown properties
- We told helm more about valid properties but not what to do with non-existing ones
- We told Helm what properties (values) were valid
- We can fix that with `"additionalProperties": false`:
- We didn't say what to do about additional (unknown) properties!
- We can fix that with `"additionalProperties": false`
.exercise[
@@ -94,15 +154,38 @@
{
"$schema": "http://json-schema.org/schema#",
"type": "object",
"additionalProperties": false,
"properties": {
"image": { [...] }
},
"additionalProperties": false
}
...
```
- And test again: `helm install should-break --set=foo=bar --set=ImAgeTAg=toto`
]
---
## Testing with unknown properties
.exercise[
- Try to pass an extra property:
```bash
helm install should-break --set ImAgeTAg=toto
```
- Try to pass an extra nested property:
```bash
helm install does-it-work --set image.hello=world
```
]
The first command should break.
The second will not.
`"additionalProperties": false` needs to be specified at each level.
???
:EN:- Helm schema validation
:FR:- Validation de schema Helm