helm-charts/homeassistant/templates/_helpers.tpl

{{/*
Render the body of a container "resources:" block from a values dict of the form

  resources:
    limitFactor: 3          # optional, default 3
    requests: { cpu, memory, ephemeral-storage / ephemeralStorage, ... }
    limits:   { ... }       # optional, every entry optional

Rules (variant B, see issue #19):
  - requests are rendered as given (camelCase "ephemeralStorage" is normalized
    to the Kubernetes key "ephemeral-storage").
  - an explicitly set limit always wins.
  - a missing memory / ephemeral-storage limit is computed as
    limitFactor x the corresponding request.
  - a missing cpu limit is NOT set at all (the kubelet then treats CPU as
    unlimited; CPU is compressible, so this cannot kill the workload).

Usage (the values path to the resources dict varies per chart):
  resources:
    {{- include "homeassistant.resources" .Values.<app>.resources | nindent 12 }}

NOTE: charts in this repo deliberately have no dependencies, so this helper is
duplicated into every chart's templates/_helpers.tpl with the chart's name as
define prefix. This file in template-chart is the reference implementation.
*/}}
{{- define "homeassistant.resources" -}}
{{- $resources := . | default dict -}}
{{- $factor := 3.0 -}}
{{- if not (kindIs "invalid" $resources.limitFactor) -}}
{{- $factor = float64 $resources.limitFactor -}}
{{- end -}}
{{- $requests := dict -}}
{{- range $key, $value := ($resources.requests | default dict) -}}
{{- if not (kindIs "invalid" $value) -}}
{{- $_ := set $requests (include "homeassistant.resourceKey" $key) $value -}}
{{- end -}}
{{- end -}}
{{- $limits := dict -}}
{{- range $key, $value := ($resources.limits | default dict) -}}
{{- if not (kindIs "invalid" $value) -}}
{{- $_ := set $limits (include "homeassistant.resourceKey" $key) $value -}}
{{- end -}}
{{- end -}}
{{- range $key, $request := $requests -}}
{{- if and (ne $key "cpu") (not (hasKey $limits $key)) -}}
{{- $_ := set $limits $key (include "homeassistant.multiplyQuantity" (dict "quantity" $request "factor" $factor)) -}}
{{- end -}}
{{- end -}}
{{- $out := dict -}}
{{- with $requests }}{{- $_ := set $out "requests" . }}{{- end -}}
{{- with $limits }}{{- $_ := set $out "limits" . }}{{- end -}}
{{- toYaml $out -}}
{{- end -}}

{{/*
Normalize a resource name from values to its Kubernetes key.
*/}}
{{- define "homeassistant.resourceKey" -}}
{{- if eq . "ephemeralStorage" -}}ephemeral-storage{{- else -}}{{ . }}{{- end -}}
{{- end -}}

{{/*
Multiply a Kubernetes quantity by a factor, keeping its suffix.
Input: dict "quantity" <string|number> "factor" <float64>.
Handles plain numbers ("2", "0.5", 1073741824), decimal ("1.5Gi"), binary
("512Mi", "1Gi", "10Ki") and milli/SI suffixes ("100m", "500M"). Integer
results are printed without a decimal point.
*/}}
{{- define "homeassistant.multiplyQuantity" -}}
{{- $quantity := printf "%v" .quantity -}}
{{- $number := regexFind "^[0-9]+(\\.[0-9]+)?" $quantity -}}
{{- if not $number -}}
{{- fail (printf "cannot parse resource quantity %q" $quantity) -}}
{{- end -}}
{{- $suffix := trimPrefix $number $quantity -}}
{{- if not (regexMatch "^(m|k|M|G|T|P|E|Ki|Mi|Gi|Ti|Pi|Ei)?$" $suffix) -}}
{{- fail (printf "unsupported resource quantity suffix %q in %q" $suffix $quantity) -}}
{{- end -}}
{{- $product := mulf (float64 $number) .factor -}}
{{- if eq $product (floor $product) -}}
{{- printf "%d%s" (int64 $product) $suffix -}}
{{- else -}}
{{- printf "%v%s" $product $suffix -}}
{{- end -}}
{{- end -}}

{{/*
Render the replica count for a Deployment/StatefulSet.

Input: dict
  "scaleDown"  the chart-global .Values.scaleDown flag (may be nil)
  "replicas"   the workload's replicas value (may be nil)

Rules (issue #25):
  - scaleDown: true takes precedence and always yields 0.
  - otherwise an explicitly set replicas value is used as given, including an
    explicit 0 — Helm's "default" would swallow 0, hence the explicit
    kindIs "invalid" nil check.
  - a missing replicas value defaults to 1.

Usage (the values path to the workload's replicas varies per chart):
  replicas: {{ include "homeassistant.replicas" (dict "scaleDown" .Values.scaleDown "replicas" .Values.<app>.replicas) }}

NOTE: like the resources helper above, this is duplicated into every chart's
templates/_helpers.tpl with the chart's name as define prefix. This file in
template-chart is the reference implementation.
*/}}
{{- define "homeassistant.replicas" -}}
{{- if .scaleDown -}}
0
{{- else if not (kindIs "invalid" .replicas) -}}
{{- .replicas -}}
{{- else -}}
1
{{- end -}}
{{- end -}}

{{/*
Merge a user-supplied values sub-tree onto a dict of chart defaults so that a
null / empty override falls back to the defaults instead of erasing them.

Input: dict "defaults" <dict> "given" <dict|nil> "path" <string, optional
values path used in error messages>. Output: YAML of the merged dict (consume
it with fromYaml).

Why this exists (issue #99): Helm merges values maps recursively, but an
override key written without children — e.g. a leftover

  securityContext:

after deleting its last remaining sub-key — is YAML null. Where the chart
defines a default, Helm treats that null as a deletion of the default; the
template then renders "securityContext: null". The workload starts and reports
healthy while being unhardened, so nothing points at the mistake. The same
shape erases a probe (it disappears) or the resources block (no requests, no
computed limits). This helper defines the opposite semantics: an empty block
means "chart defaults apply".

Rules:
  - a nil "given" is treated as an empty dict (all defaults apply).
  - a key whose override value is null keeps the default (nulls never delete).
  - a key present in both as a map is merged recursively, so a partially
    filled block only overrides the keys it actually sets.
  - a scalar override for a key the defaults define as a map is rejected with
    a message naming the values path, instead of failing later with a template
    field error.
  - any other set value wins as given, including an explicit false or 0 —
    Helm's "default" and sprig's "mergeOverwrite" would both swallow those
    zero values, hence the explicit kindIs "invalid" nil check.
  - keys only present in the override are passed through unchanged.

NOTE: like the helpers above, this is duplicated into every chart's
templates/_helpers.tpl with the chart's name as define prefix, because charts
in this repo deliberately have no dependencies.
*/}}
{{- define "homeassistant.defaultedDict" -}}
{{- $defaults := .defaults | default dict -}}
{{- $given := .given -}}
{{- $path := .path | default "value" -}}
{{- if kindIs "invalid" $given -}}
{{- $given = dict -}}
{{- end -}}
{{- if not (kindIs "map" $given) -}}
{{- fail (printf "%s must be a mapping or null, got %s (%v)" $path (kindOf $given) $given) -}}
{{- end -}}
{{- $out := deepCopy $defaults -}}
{{- range $key, $value := $given -}}
{{- if not (kindIs "invalid" $value) -}}
{{- $default := index $defaults $key -}}
{{- if and (kindIs "map" $value) (kindIs "map" $default) -}}
{{- $_ := set $out $key (fromYaml (include "homeassistant.defaultedDict" (dict "defaults" $default "given" $value "path" (printf "%s.%s" $path $key)))) -}}
{{- else if kindIs "map" $default -}}
{{- fail (printf "%s.%s must be a mapping or null, got %s (%v)" $path $key (kindOf $value) $value) -}}
{{- else -}}
{{- $_ := set $out $key $value -}}
{{- end -}}
{{- end -}}
{{- end -}}
{{- toYaml $out -}}
{{- end -}}

{{/*
Pick one sub-block out of a values block that may itself be null.

Input: dict "block" <dict|nil> "key" <string> "path" <string>.
Returns YAML of dict "value" <the sub-block, may be nil>, after rejecting a
non-mapping block with a message that names the values path. Needed because
".Values.securityContext" can itself be erased.
*/}}
{{- define "homeassistant.subBlock" -}}
{{- $block := .block -}}
{{- if kindIs "invalid" $block -}}
{{- $block = dict -}}
{{- end -}}
{{- if not (kindIs "map" $block) -}}
{{- fail (printf "%s must be a mapping or null, got %s (%v)" .path (kindOf $block) $block) -}}
{{- end -}}
{{- toYaml (dict "value" (index $block .key)) -}}
{{- end -}}

{{/*
The effective security contexts, probes and resources (issue #99).

The defaults below MUST stay in sync with the corresponding blocks in
values.yaml, which stays the documented, user-facing place for them; this copy
is only the fallback for the case where an override has erased the block.

Like several other charts here, this one keeps replicas, resources, probes and
securityContext at the TOP level of values.yaml, so the paths in the error
messages have no chart-name prefix.

IMPORTANT - this chart's hardening is a DOCUMENTED DEVIATION and the fallbacks
reproduce it exactly rather than restoring the repo standard:

  - The pod context is deliberately EMPTY: the official Home Assistant
    container must start as root (s6-overlay performs its setup as uid 0 and
    the image supports no non-root user), so runAsNonRoot / runAsUser are not
    set.
  - capabilities.add keeps NET_RAW: Home Assistant's device discovery (DHCP
    watcher, ping/arp integrations) uses raw sockets and logs "Operation not
    permitted" without it.

The probes address the container port by its name ("http").
*/}}
{{- define "homeassistant.podSecurityContext" -}}
{{- $given := (fromYaml (include "homeassistant.subBlock" (dict "block" . "key" "pod" "path" "securityContext"))).value -}}
{{- $defaults := dict -}}
{{- include "homeassistant.defaultedDict" (dict "defaults" $defaults "given" $given "path" "securityContext.pod") -}}
{{- end -}}

{{- define "homeassistant.containerSecurityContext" -}}
{{- $given := (fromYaml (include "homeassistant.subBlock" (dict "block" . "key" "container" "path" "securityContext"))).value -}}
{{- $defaults := dict
      "allowPrivilegeEscalation" false
      "readOnlyRootFilesystem" true
      "capabilities" (dict "drop" (list "ALL") "add" (list "NET_RAW")) -}}
{{- include "homeassistant.defaultedDict" (dict "defaults" $defaults "given" $given "path" "securityContext.container") -}}
{{- end -}}

{{- define "homeassistant.livenessProbe" -}}
{{- $defaults := dict
      "httpGet" (dict "path" "/" "port" "http")
      "periodSeconds" 10
      "timeoutSeconds" 5
      "failureThreshold" 3 -}}
{{- include "homeassistant.defaultedDict" (dict "defaults" $defaults "given" . "path" "livenessProbe") -}}
{{- end -}}

{{- define "homeassistant.readinessProbe" -}}
{{- $defaults := dict
      "httpGet" (dict "path" "/" "port" "http")
      "periodSeconds" 10
      "timeoutSeconds" 5
      "failureThreshold" 3 -}}
{{- include "homeassistant.defaultedDict" (dict "defaults" $defaults "given" . "path" "readinessProbe") -}}
{{- end -}}

{{- define "homeassistant.startupProbe" -}}
{{- $defaults := dict
      "httpGet" (dict "path" "/" "port" "http")
      "periodSeconds" 10
      "timeoutSeconds" 5
      "failureThreshold" 30 -}}
{{- include "homeassistant.defaultedDict" (dict "defaults" $defaults "given" . "path" "startupProbe") -}}
{{- end -}}

{{/*
The effective resources block, fed into the resources helper above so that an
erased "resources:" still yields the chart's requests and computed limits
instead of a container without any resource accounting.
*/}}
{{- define "homeassistant.effectiveResources" -}}
{{- $defaults := dict
      "limitFactor" 3
      "requests" (dict "cpu" 0.2 "memory" "512Mi" "ephemeralStorage" "128Mi") -}}
{{- $merged := fromYaml (include "homeassistant.defaultedDict" (dict "defaults" $defaults "given" . "path" "resources")) -}}
{{- include "homeassistant.resources" $merged -}}
{{- end -}}