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feat(common): abstract service-discovery topology in serviceDiscovery.envFlat #1746

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9 changes: 9 additions & 0 deletions charts/lerian-common/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,15 @@ via `include` by the product charts that declare it as a dependency.
`configmap.<KEY>` > `defaults.<KEY>` > `""`, presence-based). Each chart opts into
its own SUBSET + ORDER via `keys` and its per-key defaults via `defaults`; adoption
is a zero-diff refactor, before optionally migrating to the derivation helpers above.
`serviceDiscovery.envFlat` additionally accepts OPTIONAL topology inputs
(`serviceName`, `namespace`, `servicePort`, `ingressHost`) that DERIVE
`SD_INTERNAL_ADDRESS` (`<serviceName>.<namespace>.svc.cluster.local`, only when both
given), `SD_INTERNAL_PORT` (`servicePort | toString`) and `SD_EXTERNAL_ADDRESS`
(`ingressHost`); each stays `""` when its inputs are absent. It also bakes the
opinionated platform defaults `SD_PREFER_VIEW="internal"`, `SD_TLS_SKIP_VERIFY="true"`,
`SD_EXTERNAL_PORT="443"`, `SD_INTERNAL_SCHEME="http"` unconditionally. All of these are
lowest precedence — per key: `configmap.SD_<KEY>` (legacy) > `defaults.SD_<KEY>`
(grouped param) > derived/opinionated default > `""`.
Comment on lines +22 to +30

@coderabbitai coderabbitai Bot Jul 24, 2026

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📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Narrow the no-derivation claim to exclude serviceDiscovery.envFlat.

The preceding flat-passthrough description still says that serviceDiscovery.envFlat reproduces native blocks byte-for-byte with no derivation, while this section documents topology-derived values and baked defaults. Update the generic description to apply only to the truly flat helpers.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@charts/lerian-common/README.md` around lines 22 - 30, The generic
flat-passthrough description should exclude serviceDiscovery.envFlat because
that helper derives topology values and applies platform defaults. Update the
description to apply only to the truly flat helpers, while preserving the
documented precedence and derivation behavior for serviceDiscovery.envFlat.

- **In-cluster host primitives:** `lerian-common.internalHost`, `lerian-common.internalURL`.
- **Resource helpers:** `lerian-common.hpa`, `.service`, `.serviceAccount`, `.pdb`, `.ingress`.
- **Deployment pod-spec fragments:** `lerian-common.scheduling`, `.imagePullSecrets`,
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85 changes: 63 additions & 22 deletions charts/lerian-common/templates/_service_discovery.tpl
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Expand Up @@ -148,22 +148,49 @@ Inputs (dict):

{{/*
==============================================================================
lerian-common.serviceDiscovery.envFlat — flat-passthrough SD_* block.
lerian-common.serviceDiscovery.envFlat — SD_* block with topology abstraction.

Reproduces the chart's EXISTING native SD_* env block byte-for-byte (no
derivation, no `global.serviceDiscovery`). It encodes the canonical SD contract:
the known key set + each key's STANDARD default. A chart opts into the SUBSET and
ORDER it currently emits via `keys`, and overrides any per-key default via
`defaults` (e.g. plugin-fees' whitespace-padded SD_ADDRESS). See
`lerian-common.env.flatBlock` (this file) for precedence/quoting semantics.
Emits the canonical SD_* env block, delegating to `lerian-common.env.flatBlock`
(this file) for the ordered `KEY: value` rendering, quoting and precedence.

It encodes the platform SD contract in two tiers of baked default:

1. OPINIONATED SCALAR DEFAULTS (unconditional platform standard, apply even
with no topology inputs):
SD_PREFER_VIEW = "internal"
SD_TLS_SKIP_VERIFY = "true"
SD_EXTERNAL_PORT = "443"
SD_INTERNAL_SCHEME = "http"
SD_TLS = "false"
SD_ADDRESS = "localhost:8500"
SD_ENABLED = "false"
(timeouts / SD_ALLOW_STALE / SD_WORKLOAD default to "")

2. TOPOLOGY-DERIVED DEFAULTS (computed from the OPTIONAL topology inputs; each
stays "" when its inputs are absent, keeping a topology-less caller working):
SD_EXTERNAL_ADDRESS = ingressHost (else "")
SD_INTERNAL_ADDRESS = "<serviceName>.<namespace>.svc.cluster.local"
(only when BOTH serviceName AND namespace given; else "")
SD_INTERNAL_PORT = servicePort | toString (else "")

Both tiers are the LOWEST-precedence source: a caller `defaults.SD_<KEY>` (the
grouped param) and a `configmap.SD_<KEY>` (legacy override) still WIN over them.

Precedence per key (from `lerian-common.env.flatBlock`, presence-based):
configmap.SD_<KEY> > defaults.SD_<KEY> > derived/opinionated default > ""

Usage (component configmap.yaml — replaces the hand-written SD_* block):

# midaz-ledger / midaz-crm — full 17-key block, standard defaults:
# topology-driven, full block, standard defaults:
{{- include "lerian-common.serviceDiscovery.envFlat" (dict
"configmap" .Values.ledger.configmap) | nindent 2 }}
"configmap" .Values.ledger.configmap
"serviceName" (include "midaz-ledger.fullname" .)
"namespace" (include "global.namespace" $)
"servicePort" .Values.ledger.service.port
"ingressHost" (include "lerian-common.firstIngressHost" (dict "ingress" .Values.ledger.ingress))
) | nindent 2 }}

# plugin-fees — 7-key subset with its padded defaults:
# plugin-fees — 7-key subset with its padded defaults (topology optional):
{{- include "lerian-common.serviceDiscovery.envFlat" (dict
"configmap" .Values.fees.configmap
"keys" (list "SD_ADDRESS" "SD_ENABLED" "SD_EXTERNAL_ADDRESS"
Expand All @@ -175,30 +202,44 @@ Usage (component configmap.yaml — replaces the hand-written SD_* block):
"SD_WORKLOAD" " ")) | nindent 2 }}

Inputs (dict):
configmap (req) the component's `.configmap` map (native override source)
keys (opt) ordered subset to emit; defaults to the full 17-key block in
the canonical (alphabetical) order midaz emits
defaults (opt) per-key default overrides (chart-specific defaults win over
the standard defaults baked in here)
configmap (req) the component's `.configmap` map (legacy override source, WINS)
keys (opt) ordered subset to emit; defaults to the full 17-key block in
the canonical (alphabetical) order midaz emits
defaults (opt) per-key default overrides (grouped param; win over the
derived/opinionated defaults baked in here, lose to configmap)
serviceName (opt) in-cluster service name — with `namespace`, derives SD_INTERNAL_ADDRESS
namespace (opt) resolved namespace — with `serviceName`, derives SD_INTERNAL_ADDRESS
servicePort (opt) in-cluster port — derives SD_INTERNAL_PORT (via toString)
ingressHost (opt) external host — derives SD_EXTERNAL_ADDRESS
==============================================================================
*/}}
{{- define "lerian-common.serviceDiscovery.envFlat" -}}
{{- /* Topology-derived defaults (lowest precedence; "" when inputs absent). */ -}}
{{- $externalAddress := .ingressHost | default "" -}}
{{- $internalAddress := "" -}}
{{- if and .serviceName .namespace -}}
{{- $internalAddress = printf "%s.%s.svc.cluster.local" .serviceName .namespace -}}
{{- end -}}
{{- $internalPort := "" -}}
{{- if .servicePort -}}
{{- $internalPort = .servicePort | toString -}}
{{- end -}}
{{- $std := dict
"SD_ADDRESS" "localhost:8500"
"SD_ALLOW_STALE" ""
"SD_DIAL_TIMEOUT" ""
"SD_ENABLED" "false"
"SD_EXTERNAL_ADDRESS" ""
"SD_EXTERNAL_PORT" ""
"SD_INTERNAL_ADDRESS" ""
"SD_INTERNAL_PORT" ""
"SD_INTERNAL_SCHEME" ""
"SD_PREFER_VIEW" ""
"SD_EXTERNAL_ADDRESS" $externalAddress
"SD_EXTERNAL_PORT" "443"
"SD_INTERNAL_ADDRESS" $internalAddress
"SD_INTERNAL_PORT" $internalPort
"SD_INTERNAL_SCHEME" "http"
"SD_PREFER_VIEW" "internal"
"SD_RESPONSE_HEADER_TIMEOUT" ""
"SD_SEED_TIMEOUT" ""
"SD_TLS" "false"
"SD_TLS_HANDSHAKE_TIMEOUT" ""
"SD_TLS_SKIP_VERIFY" "false"
"SD_TLS_SKIP_VERIFY" "true"
"SD_WATCH_WAIT_TIME" ""
"SD_WORKLOAD" "" -}}
{{- $keys := .keys | default (list
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