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feat(mcp): derive env vars from the framework's real struct tags

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Minor to v1.1.0. Make the whole environment-variable surface derive from the
indexed component-config tags instead of a hand-maintained list that drifts.
Also folds in the scaffold-symbol fixes staged as v1.0.1 (never tagged); the
generated scaffold compiles clean against einherjar v1.0.0.

internal/envspec (new):
- Parse index struct tags into env vars {name, module, struct, field, required,
  default}. One source of truth: ParseTag, ForModule, FindStruct, All, KnownNames.

internal/tools:
- get_config_env: list the real env vars a component config reads (or all).
- check_env: flag unknown EINHERJAR_* names, required vars missing for the
  composed modules, and dead vars (set for an uncomposed module).
- get_scaffold: .env.example is now DERIVED from the index — required vars
  uncommented with a dev value, defaulted vars commented with their default.
  The scaffold now composes logz.Config (Log logz.Config) so EINHERJAR_LOG_*
  are live and documented, not hardcoded/ignored (log format is env-driven).
- validate_snippet: inject the real env-var name set into the rules package.

internal/index/builtins (wire conventions):
- Route the incremental "compose a component later" flow to get_config_env /
  check_env; distinguish framework EINHERJAR_* from app-owned APP_* (JWT).
- Compose logz.Config in the config + Run() examples, to match the scaffold.

internal/rules:
- config.unknown-env-var (twelfth rule): reject an env:"EINHERJAR_*" struct tag
  the framework doesn't declare. No-op until the server injects the name set, so
  it never fires on incomplete knowledge.

Fixed (was v1.0.1): scaffold health hook + wire builtin used logz.Logger (real:
contracts/logging.Logger) and postgres.Component (hooks take Provider); env tags
were EINHERJAR_SERVER_ADDR / EINHERJAR_PG_DATABASE (real: _HOST/_PORT / _PG_NAME).

Tests: envspec unit tests; env tools against the real data/index.json; the rule.
Verified by generating the scaffold, building it against local einherjar v1.0.0
(exit 0), and runtime-loading the composed logz.Config (EINHERJAR_LOG_LEVEL=DEBUG
-> slog.LevelDebug, EINHERJAR_LOG_JSON=true). Version bumped to v1.1.0 (badge +
serverVersion). No dependency changes.
This commit is contained in:
Rene Nochebuena
2026-08-07 16:58:24 -06:00
parent a0b803cb40
commit 8c6cf2c27a
14 changed files with 1003 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files
internal/envspec/envspec_test.go
+132
View File
@@ -0,0 +1,132 @@
package envspec
import (
"testing"
"code.nochebuena.dev/einherjar/mcp/internal/index"
)
func TestParseTag(t *testing.T) {
cases := []struct {
tag string
wantOK bool
wantName string
wantReq bool
wantDef string
wantHas bool
}{
{`env:"EINHERJAR_PG_HOST,required"`, true, "EINHERJAR_PG_HOST", true, "", false},
{`env:"EINHERJAR_PG_PORT" envDefault:"5432"`, true, "EINHERJAR_PG_PORT", false, "5432", true},
{`env:"EINHERJAR_LOG_JSON" envDefault:"false"`, true, "EINHERJAR_LOG_JSON", false, "false", true},
{`env:"-"`, false, "", false, "", false},
{`json:"x"`, false, "", false, "", false},
{``, false, "", false, "", false},
}
for _, c := range cases {
got, ok := ParseTag(c.tag)
if ok != c.wantOK {
t.Errorf("ParseTag(%q) ok=%v want %v", c.tag, ok, c.wantOK)
continue
}
if !ok {
continue
}
if got.Name != c.wantName || got.Required != c.wantReq || got.Default != c.wantDef || got.HasDefault != c.wantHas {
t.Errorf("ParseTag(%q) = %+v, want name=%q req=%v def=%q has=%v",
c.tag, got, c.wantName, c.wantReq, c.wantDef, c.wantHas)
}
}
}
// synthIndex mirrors the shape of the real index: a web module whose server
// sub-package and root both declare env vars, plus a db-postgres module.
func synthIndex() *index.Index {
return &index.Index{
Modules: []index.Module{
{
Name: "web",
Symbols: []index.Symbol{
{Kind: "type", Name: "Config", SubPackage: "server", Fields: []index.Field{
{Name: "Host", Type: "string", Tag: `env:"EINHERJAR_SERVER_HOST" envDefault:"0.0.0.0"`},
{Name: "Port", Type: "int", Tag: `env:"EINHERJAR_SERVER_PORT" envDefault:"8080"`},
}},
{Kind: "type", Name: "Config", SubPackage: "", Fields: []index.Field{
{Name: "Server", Type: "server.Config"}, // nested, no env tag
{Name: "AllowedOrigins", Type: "[]string", Tag: `env:"EINHERJAR_SERVER_CORS_ORIGINS" envSeparator:","`},
}},
},
},
{
Name: "db-postgres",
Symbols: []index.Symbol{
{Kind: "type", Name: "Config", SubPackage: "", Fields: []index.Field{
{Name: "Host", Type: "string", Tag: `env:"EINHERJAR_PG_HOST,required"`},
{Name: "Name", Type: "string", Tag: `env:"EINHERJAR_PG_NAME,required"`},
{Name: "Port", Type: "int", Tag: `env:"EINHERJAR_PG_PORT" envDefault:"5432"`},
}},
},
},
},
}
}
func TestForModule(t *testing.T) {
idx := synthIndex()
got := ForModule(idx, "web")
if len(got) != 3 { // 2 server + 1 CORS; the nested Server field is not a leaf
t.Fatalf("ForModule(web) = %d vars, want 3: %+v", len(got), got)
}
names := map[string]bool{}
for _, v := range got {
names[v.Name] = true
}
for _, want := range []string{"EINHERJAR_SERVER_HOST", "EINHERJAR_SERVER_PORT", "EINHERJAR_SERVER_CORS_ORIGINS"} {
if !names[want] {
t.Errorf("ForModule(web) missing %s", want)
}
}
if ForModule(idx, "nope") != nil {
t.Error("ForModule(unknown) should be nil")
}
}
func TestFindStruct(t *testing.T) {
idx := synthIndex()
server := FindStruct(idx, "web", "server", "Config")
if len(server) != 2 {
t.Fatalf("FindStruct(web/server/Config) = %d, want 2", len(server))
}
// The root web.Config must NOT be returned for the server selector.
for _, v := range server {
if v.Name == "EINHERJAR_SERVER_CORS_ORIGINS" {
t.Error("server selector leaked the root web.Config CORS var")
}
}
pg := FindStruct(idx, "db-postgres", "", "Config")
if len(pg) != 3 {
t.Fatalf("FindStruct(db-postgres//Config) = %d, want 3", len(pg))
}
var host envspecVarFound
for _, v := range pg {
if v.Name == "EINHERJAR_PG_HOST" {
host = envspecVarFound{found: true, required: v.Required, hasDefault: v.HasDefault}
}
}
if !host.found || !host.required || host.hasDefault {
t.Errorf("EINHERJAR_PG_HOST: %+v, want required with no default", host)
}
}
type envspecVarFound struct {
found, required, hasDefault bool
}
func TestKnownNames(t *testing.T) {
names := KnownNames(synthIndex())
if _, ok := names["EINHERJAR_PG_NAME"]; !ok {
t.Error("KnownNames missing EINHERJAR_PG_NAME")
}
if _, ok := names["EINHERJAR_PG_DATABASE"]; ok {
t.Error("KnownNames must not contain the bogus EINHERJAR_PG_DATABASE")
}
}