Einherjar
For those who come after.
A Go framework built from battle-tested production code — organized for teams, documented for the developer who was never in the room.
The Name
In Norse mythology, the Einherjar are the chosen — warriors who fell in battle and were carried to Valhalla by the Valkyries. There they train, day after day, preparing for Ragnarök. Not for themselves. For what comes after.
This framework carries that name deliberately. Every interface defined here, every architectural decision recorded, every module boundary enforced exists for the developer who will build on this code without ever speaking to its authors. No tribal knowledge. No implicit conventions. The documentation is the system.
What Is This
Einherjar is a collection of composable Go modules, each addressing one infrastructure concern. The mental model is Spring Boot starters — not one framework binary, but a curated set of independent modules with isolated dependency graphs.
Each module is its own go.mod. Import only what your service needs. A minimal CRUD
API requires exactly three: core + web + one db-*.
Modules
| Module | Version | Purpose | Depends on |
|---|---|---|---|
contracts |
v1.0.0 | Pure interfaces. The constitution of the framework. | — |
core |
v1.0.0 | Lifecycle, logging, errors, validation | contracts |
web |
v1.0.0 | HTTP server, middleware, routing, health | contracts core |
auth |
v1.0.0 | Auth middleware, RBAC | contracts core web |
auth-jwt |
v1.0.0 | JWT signing, token pairs, refresh | contracts core auth |
auth-firebase |
— | Firebase authentication (deferred) | contracts core auth |
db-postgres |
v1.0.0 | PostgreSQL client | contracts core |
db-mysql |
v1.0.0 | MySQL client | contracts core |
db-sqlite |
v1.0.0 | SQLite client | contracts core |
cache-valkey |
v1.0.0 | Valkey / Redis-compatible cache | contracts core |
storage-minio |
v1.0.0 | Object storage | contracts core |
telemetry |
v1.0.0 | OpenTelemetry — main packages only |
contracts core |
worker |
v1.0.0 | Concurrent background worker pool | contracts |
httpclient |
v1.0.0 | Resilient outbound HTTP client | contracts core |
smtp |
v1.0.0 | SMTP email delivery with no-op fallback | contracts core |
Dependency Graph
graph TD
contracts["contracts\nv1.0.0"]
core["core\nv1.0.0"]
web["web\nv1.0.0"]
auth["auth\nv1.0.0"]
auth_jwt["auth-jwt\nv1.0.0"]
auth_firebase["auth-firebase\n(deferred)"]
db_postgres["db-postgres\nv1.0.0"]
db_mysql["db-mysql\nv1.0.0"]
db_sqlite["db-sqlite\nv1.0.0"]
cache_valkey["cache-valkey\nv1.0.0"]
storage_minio["storage-minio\nv1.0.0"]
telemetry["telemetry\nv1.0.0"]
worker["worker\nv1.0.0"]
httpclient["httpclient\nv1.0.0"]
smtp["smtp\nv1.0.0"]
contracts --> core
contracts --> web
core --> web
contracts --> auth
core --> auth
web --> auth
contracts --> auth_jwt
core --> auth_jwt
auth --> auth_jwt
contracts --> auth_firebase
core --> auth_firebase
auth --> auth_firebase
contracts --> db_postgres
core --> db_postgres
contracts --> db_mysql
core --> db_mysql
contracts --> db_sqlite
core --> db_sqlite
contracts --> cache_valkey
core --> cache_valkey
contracts --> storage_minio
core --> storage_minio
contracts --> telemetry
core --> telemetry
contracts --> worker
contracts --> httpclient
core --> httpclient
contracts --> smtp
core --> smtp
classDef foundation fill:#b45309,stroke:#78350f,color:#fff
classDef weblayer fill:#1d4ed8,stroke:#1e3a8a,color:#fff
classDef datalayer fill:#15803d,stroke:#14532d,color:#fff
classDef standalone fill:#6d28d9,stroke:#4c1d95,color:#fff
classDef deferred fill:#6b7280,stroke:#374151,color:#fff,stroke-dasharray:5 5
class contracts,core foundation
class web,auth,auth_jwt weblayer
class auth_firebase deferred
class db_postgres,db_mysql,db_sqlite,cache_valkey,storage_minio datalayer
class telemetry,worker,httpclient,smtp standalone
Arrow direction: dependency flows downward — a module above provides interfaces consumed by the module below it.
| Colour | Layer |
|---|---|
| Amber | Foundation — contracts, core |
| Blue | Web layer — web, auth, auth-jwt |
| Green | Data layer — db-*, cache-*, storage-* |
| Purple | Standalone — telemetry, worker, httpclient, smtp |
| Grey (dashed) | Deferred — not yet released |
Data modules (db-*, cache-*, storage-*) never import web. Repositories do
not know HTTP exists. This boundary is absolute.
The Law
contracts is the constitution of this framework — pure interfaces, zero
dependencies, permanent signatures. Changes flow outward from contracts, never
inward. Before any change to contracts, the blast radius is calculated: which
interfaces are affected, which modules implement them, which modules consume those.
Release sequence: contracts first, then implementors, then consumers.
Adding a method to a published interface is a breaking change in Go. It is not permitted without a major version bump and coordinated updates across all implementing modules.
For Those Who Come After
Good code is not written for the machine. It is not even written for the deadline. It is written for the person who will read it at 11pm six months from now, under pressure, trying to understand what this thing does and why it was built this way.
Every ADR in this organization exists because a decision was made and the reasoning
behind it matters as much as the outcome. Every interface in contracts is as small
as it can be because the developer implementing it in a new context deserves to know
exactly what is required and nothing more.
This is the standard. Not the deadline.
Legal
Einherjar is developed and maintained by NOCHEBUENADEV, the trade name of its founder operating as a Persona Física con Actividad Empresarial (PFAE) under Mexican law. A PFAE is a natural person — an individual — who conducts business under their own legal identity. There is no separate corporate entity: the copyright holder is the individual behind NOCHEBUENADEV.
All modules are licensed under the GNU Affero General Public License v3.0 (AGPL-3.0). See the LICENSE file in each repository.
Contributions are accepted under the terms of the Contributor License Agreement. Contributors retain ownership of their work; they grant NOCHEBUENADEV a perpetual, irrevocable license that includes the right to relicense.