confd

go-ruby-confd/confd

A pure-Go (CGO=0) Ruby-facing adapter over github.com/abtreece/confd — the maintained pure-Go fork of kelseyhightower/confd.

confd renders configuration files from Go text/templates whose data comes from a backend key/value store (env, file, etcd, consul, vault, redis, …). confd is already pure Go and is the reference implementation, so this package does not reimplement any of it: it imports confd's own packages (pkg/backends, pkg/template, pkg/memkv, pkg/util) and adds a small, importable Go API plus the seams a Ruby interpreter (go-embedded-ruby / rbgo) will later wire. 100% compatibility means running confd's actual code, not a hand-port.

Install

go get github.com/go-ruby-confd/confd

Requires Go 1.26+.

Usage

Render a template to a string (no disk or network for the caller)

out, err := confd.RenderString(
    `host={{getv "/db/host"}} up={{toUpper (getv "/db/host")}}`,
    map[string]string{"/db/host": "pg1"},
    confd.WithKeys("/db"),
)
// out == "host=pg1 up=PG1"

All of confd's template functions — getv, getvs, gets, exists, base64Encode, json, toUpper, map, seq, … — are reachable, because it is confd's own function map doing the rendering.

Render from a real backend

b, _ := confd.EnvBackend()          // reads OS environment variables
defer b.Close()
out, _ := confd.RenderWithBackend(`v={{getv "/app/host"}}`, b, confd.WithKeys("/app"))

f, _ := confd.FileBackend([]string{"data.yaml"}, "*.yaml")  // reads YAML/JSON

Process a confd config directory

p, _ := confd.NewProcessor(confd.ProcessorConfig{
    ConfDir: "/etc/confd",           // conf.d/*.toml + templates/*.tmpl
    Backend: b,
})
_ = p.Once()                         // render every resource once, write target files

// interval mode (blocking; run in a goroutine)
stop, done, errCh := make(chan bool), make(chan bool), make(chan error, 1)
go p.RunInterval(30, stop, done, errCh)

Backends

The env and file backends need nothing external and are the always-available path. The remote backends are constructed through confd's own backends.New; they are not mocked into a false pass — supply a real endpoint, or use the in-memory MemoryClient seam for tests and for the interpreter.

Design

• Backend — selects a confd backend via backends.New.
• MemoryClient — an in-memory backends.StoreClient (the one piece of StoreClient logic this package owns, so tests/rbgo can inject KV data).
• Processor — runs confd's template processing over a config directory (Once / RunInterval); watch/interval sits behind a seam so tests do not block.
• RenderString / RenderWithBackend — render a single template body to a string. confd's byte-level renderer and default function map are unexported, so these drive confd's real template.Process against an ephemeral, internally-managed temp directory and return the produced bytes; the network is never touched.

Licensing

This package is BSD-3-Clause (the go-ruby-confd/confd authors; see LICENSE, with SPDX headers on every source file).

The dependency github.com/abtreece/confd is MIT-licensed (Copyright © 2013 Kelsey Hightower). It is imported and built from source, not vendored or forked into this repository, so this project's own code does not mix licenses. Consumers of a compiled binary that links confd must observe confd's MIT terms for that portion.

Benchmarks

See BENCHMARKS.md. Because this package imports confd rather than reimplementing it, confd itself is the performance reference and the adapter overhead is negligible.