🏠Helm dependencies

slides/helm.yml

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+title: |
+  Packaging d'applications
+  et CI/CD pour Kubernetes
+
+chat: "[Gitter](https://gitter.im/jpetazzo/training-202102-online)"
+
+gitrepo: github.com/jpetazzo/container.training
+
+slides: https://2021-02-enix.container.training/
+
+#slidenumberprefix: "#SomeHashTag — "
+
+exclude:
+- self-paced
+
+content:
+- shared/title.md
+#- logistics.md
+- k8s/intro.md
+- shared/about-slides.md
+- shared/prereqs.md
+- shared/webssh.md
+- shared/connecting.md
+#- shared/chat-room-im.md
+#- shared/chat-room-zoom.md
+- shared/toc.md
+-
+  - k8s/helm-intro.md
+  - k8s/helm-chart-format.md
+  - k8s/helm-create-basic-chart.md
+  - k8s/helm-create-better-chart.md
+  - k8s/helm-dependencies.md
+  - k8s/helm-advanced.md
+  - k8s/helm-secrets.md
+  - k8s/cert-manager.md
+  - k8s/gitlab.md
+  - |
+    # (Extra content)
+  - k8s/prometheus.md
+

slides/k8s/helm-dependencies.md

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+# Creating even better charts
+
+- We will going to use dependencies to write less code
+
+- reuse a community chart for redis
+
+- We will see how it improve the developer life as well as the one of the user
+
+- We will see that sometimes dependencies could also remove a lot of code
+
+---
+
+## Assertions about dockercoins
+
+- Every image is custom except the one of redis
+
+- It's is quite logic that deployment are custom except of the one of redis
+
+- So if redis is not custom can we use templates of someone else ?
+
+- Yes, through dependencies
+
+---
+
+## Add redis dependency
+
+- In `Chart.yaml` fill the `dependencies` section:
+  ```yaml
+    dependencies:
+      - name: redis
+        version: 11.0.5
+        repository: https://charts.bitnami.com/bitnami
+        condition: redis.enabled
+  ```
+- `condition` will trigger at install or upgrade to template or not the dependency
+
+- Now, we can tell helm to fetch the dependency by running `helm dependency update`
+
+  (abbv `helm dep up`)
+
+- Another file has been created: `Chart.lock`. What should we do with this file ?
+
+  - Short answer: add it to the source tree.
+---
+
+## Chart.lock
+
+- The real command to fetch dependency is `helm depedency build`
+
+  (abbv `helm dep build`)
+
+- It looks into the `Chart.lock` to fetch the exact version
+
+- So what's the matter with the version in `Chart.yaml`.
+
+  - This is indicative version for the `helm dep update` *dependency resolution* process
+  - You can specify loose version requirements
+    ```yaml
+      dependencies:
+        - name: redis
+          version: >=11 <12
+          repository: https://charts.bitnami.com/bitnami
+    ```
+- We don't need to `helm dep build` after `helm dep up` : it's included
+
+---
+
+## Dependency live matters ?
+
+- Every dependency lives in the `charts/` dependency
+
+- Downloaded dependencies will stay in compress binary format (`.tgz`)
+
+- Should we commit dependency ?
+
+- Pro:
+
+  - more resilient to internet/mirror failures/decomissioning
+
+- Cons:
+
+  - Tracking binary files in source tree may require additionnal tools (like git-lfs) to be done correctly
+
+---
+
+## Dependency tuning
+
+- If we install our chart it will not work as the name of the redis service is not `redis`
+
+- Debug:
+
+  - Service name is `{{ template "redis.fullname" . }}-master`
+
+  - `redis.fullname` looks like
+    ```
+      {{- define "redis.fullname" -}}
+      {{- if .Values.fullnameOverride -}}
+      {{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" -}}
+      {{- else -}}
+      [...]
+      {{- end }}
+      {{- end }}
+    ```
+---
+## Passing variable
+
+- If we pass `fullnameOverride=redis`, we will make the template part to output `redis`
+
+- We can pass variables from top-level to children, editing parent's `values.yaml`:
+   ```yaml
+     redis: # Name of the dependency
+       fullnameOverride: redis # Value passed to redis
+       cluster:                # Other values passed to redis
+         enabled: false
+   ```
+- We can even pass template `{{ include "template.name" }}`, but warning:
+
+   - Need to be evaluated with the `tpl` function, on the child side
+   - Evaluated in the context of the child, with no access to parent variables
+
+- User can also set variables with `--set=` or with `--values=`
+
+---
+## Embedding dependency
+
+- To remove `-master`, we will need a bit more the values to pass.
+
+- We need to edit the chart templates.
+
+- First of all we need to decompress the chart
+
+- Adjust `Chart.yaml` and reference to it
+  ```yaml
+    dependencies:
+      - name: redis
+        version: '*' # No need to constraint version, from local files
+  ```
+
+- Run `helm dep update`
+
+- We can edit the template and test installation !
+---
+
+class: extra-details
+
+## Chart v1
+
+- Chart `apiVersion: v1` is the only version supported by helm v2
+
+- Chart v1 is also supported by helm v3
+
+- To be used, if we're looking for compatibility
+
+- Instead of `Chart.yaml` it use a separated file `requirements.yaml`
+
+- We should commit the created `requirements.lock` instead of `Charts.lock`
+
+---
+
+???
+
+:EN: - helm dependencies
+:FR: - dépendences helm
+