livebook: add env variables and fix docker image (#16880)

**Description**
<!--
Please include a summary of the change and which issue is fixed. Please
also include relevant motivation and context. List any dependencies that
are required for this change.
-->

* Fix Livebook container image source and upgrade to latest version
* Add environment variables, mostly for clustering of multiple replicas

**⚙️ Type of change**

- [ ] ⚙️ Feature/App addition
- [ ] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [x] 🔃 Refactor of current code

**🧪 How Has This Been Tested?**
<!--
Please describe the tests that you ran to verify your changes. Provide
instructions so we can reproduce. Please also list any relevant details
for your test configuration
-->

I've used a local KIND cluster and `helm template` => `kubectl install`

**📃 Notes:**
<!-- Please enter any other relevant information here -->

**✔️ Checklist:**

- [x] ⚖️ My code follows the style guidelines of this project
- [x] 👀 I have performed a self-review of my own code
- [x] #️⃣ I have commented my code, particularly in hard-to-understand
areas
- [ ] 📄 I have made corresponding changes to the documentation
- [x] ⚠️ My changes generate no new warnings
- [ ] 🧪 I have added tests to this description that prove my fix is
effective or that my feature works
- [x] ⬆️ I increased versions for any altered app according to semantic
versioning

---

_Please don't blindly check all the boxes. Read them and only check
those that apply.
Those checkboxes are there for the reviewer to see what is this all
about and
the status of this PR with a quick glance._

charts/dev/livebook/Chart.yaml

@@ -1,7 +1,7 @@
 kubeVersion: ">=1.24.0-0"
 apiVersion: v2
 name: livebook
-version: 3.0.13
+version: 3.1.0
 appVersion: latest
 description: Livebook is a web application for writing interactive and collaborative code notebooks for Elixir
 home: https://truecharts.org/charts/incubator/livebook

charts/dev/livebook/questions.yaml

@@ -16,11 +16,24 @@ questions:
                                     type: dict
                                     attrs:
                                       - variable: LIVEBOOK_PASSWORD
-                                        label: "LIVEBOOK_PASSWORD"
+                                        label: "Password (LIVEBOOK_PASSWORD)"
                                         description: "Password needed to access livebook (must be at least 12 characters)"
                                         schema:
                                           type: string
-                                          default: "livebookiscool"
+                                          required: true
+                                          private: true
+                                      - variable: LIVEBOOK_DEBUG
+                                        label: "Debug Logging (LIVEBOOK_DEBUG)"
+                                        description: >
+                                          enables verbose logging, when set to "true". Disabled by default.
+                                        schema:
+                                          type: boolean
+                                      - variable: LIVEBOOK_UPDATE_INSTRUCTIONS_URL
+                                        label: "Update instruction URL (LIVEBOOK_UPDATE_INSTRUCTIONS_URL)"
+                                        description: >
+                                          sets the URL to direct the user to for updating Livebook when a new version becomes available.
+                                        schema:
+                                          type: string
 # Include{serviceRoot}
         - variable: main
           label: "Main Service"

charts/dev/livebook/templates/_secrets.tpl

@@ -0,0 +1,15 @@
+{{/* Define the secrets */}}
+{{- define "livebook.secrets" -}}
+{{- $secretName := (printf "%s-secrets" (include "tc.v1.common.lib.chart.names.fullname" $)) }}
+{{/* Base64 encoding is intended, application expects a b64 formatted value */}}
+{{- $secretKeyBase := randAlphaNum 48 | b64enc -}}
+{{- $cookie := randAlphaNum 20 -}}
+{{- with (lookup "v1" "Secret" .Release.Namespace $secretName) -}}
+  {{- $secretKeyBase = index .data "LIVEBOOK_SECRET_KEY_BASE" | b64dec -}}
+  {{- $cookie = index .data "LIVEBOOK_COOKIE" | b64dec -}}
+{{- end }}
+enabled: true
+data:
+  LIVEBOOK_SECRET_KEY_BASE: {{ $secretKeyBase }}
+  LIVEBOOK_COOKIE: {{ $cookie }}
+{{- end -}}

charts/dev/livebook/templates/common.yaml

@@ -1,2 +1,13 @@
 {{/* Render the templates */}}
-{{ include "tc.v1.common.loader.all" . }}
+{{/* Make sure all variables are set properly */}}
+{{- include "tc.v1.common.loader.init" . }}
+
+{{/* Render secrets for livebook */}}
+{{- $secrets := include "livebook.secrets" . | fromYaml -}}
+{{- if $secrets -}}
+  {{- $_ := set .Values.secret "secrets" $secrets -}}
+{{- end -}}
+
+{{/* Render the templates */}}
+{{ include "tc.v1.common.loader.apply" . }}
+

charts/dev/livebook/values.yaml

@@ -1,7 +1,7 @@
 image:
   pullPolicy: IfNotPresent
-  repository: livebook/livebook
-  tag: latest@sha256:99c321de38ad781df509cfd3e452805f04627589a435645faa889a963bd7d1f5
+  repository: ghcr.io/livebook-dev/livebook
+  tag: 0.12.1@sha256:11c5691efc8e35bf0eee9c336ff029e674bcf4146ec39021b1ef75c1b17fb775
 persistence:
   data:
     enabled: true
@@ -19,12 +19,34 @@ service:
     ports:
       main:
         port: 8787
-        protocol: tcp
-        targetPort: 8080
+  headless:
+    enabled: true
+    primary: false
+    clusterIP: None
+    ports:
+      headless:
+        enabled: true
+        port: "{{ .Values.service.main.ports.main.port }}"
 workload:
   main:
     podSpec:
       containers:
         main:
           env:
-            LIVEBOOK_PASSWORD: livebookiscool
+            # A_ because these variables are sorted alphabetically and this one needs to come first.
+            A_POD_IP:
+              fieldRef:
+                fieldPath: status.podIP
+            LIVEBOOK_CLUSTER: '{{ printf "dns:%s-headless" (include "tc.v1.common.lib.chart.names.fullname" .) }}'
+            LIVEBOOK_DISTRIBUTION: name
+            LIVEBOOK_NODE: livebook@$(A_POD_IP)
+            LIVEBOOK_PORT: "{{ .Values.service.main.ports.main.port }}"
+            LIVEBOOK_HOME: "{{ .Values.persistence.data.mountPath }}"
+            LIVEBOOK_SECRET_KEY_BASE:
+              secretKeyRef:
+                name: secrets
+                key: LIVEBOOK_SECRET_KEY_BASE
+            LIVEBOOK_COOKIE:
+              secretKeyRef:
+                name: secrets
+                key: LIVEBOOK_COOKIE