helm-charts/minecraft-server/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 "minecraft-server.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. The reference implementation lives in template-chart.
*/}}
{{- define "minecraft-server.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 "minecraft-server.resourceKey" $key) $value -}}
{{- end -}}
{{- end -}}
{{- $limits := dict -}}
{{- range $key, $value := ($resources.limits | default dict) -}}
{{- if not (kindIs "invalid" $value) -}}
{{- $_ := set $limits (include "minecraft-server.resourceKey" $key) $value -}}
{{- end -}}
{{- end -}}
{{- range $key, $request := $requests -}}
{{- if and (ne $key "cpu") (not (hasKey $limits $key)) -}}
{{- $_ := set $limits $key (include "minecraft-server.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 "minecraft-server.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 "minecraft-server.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 -}}

{{/*
Resolve the server container's resources.

The JVM heap (minecraft.resources.memory, in GiB) and the container's memory
request used to be configured in two unrelated places - the heap was a value,
the request and limit were hardcoded in the template - so raising the heap did
not raise the container's memory. Here an unset memory request is derived from
the heap instead, which keeps the two from drifting apart; an explicitly set
request always wins. The limit follows from the request via the limitFactor
rule in "minecraft-server.resources".

Since chart 4.0.0 the values block first goes through "defaultedDict" (issue
#99), so an erased "server.resources:" falls back to the chart's requests and
computed limits instead of rendering a container without any resource
accounting. The fallback deliberately leaves the memory request unset, exactly
as values.yaml does, so the derivation from the JVM heap below still applies.

Input: the root context.
*/}}
{{- define "minecraft-server.serverResources" -}}
{{- $defaults := dict
      "limitFactor" 3
      "requests" (dict "cpu" "2" "ephemeral-storage" "100Mi") -}}
{{- $resources := fromYaml (include "minecraft-server.defaultedDict" (dict "defaults" $defaults "given" .Values.server.resources "path" "server.resources")) -}}
{{- $requests := deepCopy ($resources.requests | default dict) -}}
{{- if kindIs "invalid" $requests.memory -}}
{{- $_ := set $requests "memory" (printf "%vGi" .Values.minecraft.resources.memory) -}}
{{- end -}}
{{- $_ := set $resources "requests" $requests -}}
{{- include "minecraft-server.resources" $resources -}}
{{- 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 "minecraft-server.replicas" (dict "scaleDown" .Values.scaleDown "replicas" .Values.server.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. The reference
implementation lives in template-chart.
*/}}
{{- define "minecraft-server.replicas" -}}
{{- if .scaleDown -}}
0
{{- else if not (kindIs "invalid" .replicas) -}}
{{- .replicas -}}
{{- else -}}
1
{{- end -}}
{{- end -}}

{{/*
Guard: curseforge, ftb and curseforgeServerpack are mutually exclusive.

Enabling more than one used to render a duplicate TYPE env entry, where the
last one silently won. Fail loudly instead.
*/}}
{{- define "minecraft-server.validateModpackSources" -}}
{{- $enabled := list -}}
{{- if .Values.curseforge.enabled -}}{{- $enabled = append $enabled "curseforge" -}}{{- end -}}
{{- if .Values.ftb.enabled -}}{{- $enabled = append $enabled "ftb" -}}{{- end -}}
{{- if .Values.curseforgeServerpack.enabled -}}{{- $enabled = append $enabled "curseforgeServerpack" -}}{{- end -}}
{{- if gt (len $enabled) 1 -}}
{{- fail (printf "minecraft-server: curseforge, ftb and curseforgeServerpack are mutually exclusive, but these are enabled at the same time: %s - enable at most one modpack source" (join ", " $enabled)) -}}
{{- end -}}
{{- if and .Values.curseforgeServerpack.enabled (not .Values.curseforgeServerpack.downloadUrl) -}}
{{- fail "minecraft-server: curseforgeServerpack.enabled is true but curseforgeServerpack.downloadUrl is not set - the init container would download an empty URL" -}}
{{- 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": no readOnlyRootFilesystem, no
dropped capabilities, no allowPrivilegeEscalation: false. 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. The reference implementation
lives in template-chart.
*/}}
{{- define "minecraft-server.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 "minecraft-server.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, and indexing into nil inside a
template is not an error but silently yields nothing.
*/}}
{{- define "minecraft-server.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 and probes (issue #99); the resources block is
covered by "minecraft-server.serverResources" above.

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. The
sync is not left to discipline: rendering with every one of these blocks set to
null is byte-identical to rendering the defaults, so a drift shows up.

This chart's deviations from the repo baseline, which a "cleaned up" standard
fallback would silently undo:

  - uid/gid are pinned to 1000, the image's "minecraft" user. The image's
    entrypoint normally starts as root and drops to that user via gosu;
    starting as the user directly takes the non-root branch, which skips the
    recursive chown of /data and the write to /etc/nsswitch.conf that would
    fail on a read-only root filesystem. It is also the uid that owns the
    existing world data on the PVC.
  - fsGroupChangePolicy is OnRootMismatch, not Always: a recursive chown of a
    32Gi world on every pod start costs minutes.
  - the capabilities block carries an explicit empty "add" list alongside
    "drop: [ALL]", matching values.yaml.
  - all three probes run the image's own mc-health script as an EXEC probe -
    a real Minecraft server-list ping via mc-monitor against SERVER_PORT.
    There is no HTTP endpoint to fall back to, so a probe default rebuilt as
    an httpGet would leave this workload with no working probe at all.
  - the startup budget is 15s x 80 = 20 minutes, because on a fresh volume the
    image downloads the server jar and, for FTB/CurseForge modpacks, the whole
    modpack before the world even starts loading.
*/}}
{{- define "minecraft-server.podSecurityContext" -}}
{{- $given := (fromYaml (include "minecraft-server.subBlock" (dict "block" . "key" "pod" "path" "securityContext"))).value -}}
{{- $defaults := dict
      "runAsNonRoot" true
      "runAsUser" 1000
      "runAsGroup" 1000
      "fsGroup" 1000
      "fsGroupChangePolicy" "OnRootMismatch" -}}
{{- include "minecraft-server.defaultedDict" (dict "defaults" $defaults "given" $given "path" "securityContext.pod") -}}
{{- end -}}

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

{{- define "minecraft-server.livenessProbe" -}}
{{- $defaults := dict
      "exec" (dict "command" (list "mc-health"))
      "periodSeconds" 30
      "timeoutSeconds" 10
      "failureThreshold" 3 -}}
{{- include "minecraft-server.defaultedDict" (dict "defaults" $defaults "given" . "path" "livenessProbe") -}}
{{- end -}}

{{- define "minecraft-server.readinessProbe" -}}
{{- $defaults := dict
      "exec" (dict "command" (list "mc-health"))
      "periodSeconds" 15
      "timeoutSeconds" 10
      "failureThreshold" 3 -}}
{{- include "minecraft-server.defaultedDict" (dict "defaults" $defaults "given" . "path" "readinessProbe") -}}
{{- end -}}

{{- define "minecraft-server.startupProbe" -}}
{{- $defaults := dict
      "exec" (dict "command" (list "mc-health"))
      "periodSeconds" 15
      "timeoutSeconds" 10
      "failureThreshold" 80 -}}
{{- include "minecraft-server.defaultedDict" (dict "defaults" $defaults "given" . "path" "startupProbe") -}}
{{- end -}}