codesnips
go 13 lines · 1 tab

Safe YAML decoding (KnownFields) for config files

Leah Thompson Jan 2026
1 tab 
package config

import (
  "io"

  "gopkg.in/yaml.v3"
)

func DecodeStrict(r io.Reader, dst any) error {
  dec := yaml.NewDecoder(r)
  dec.KnownFields(true)
  return dec.Decode(dst)
}
1 file · go Explain with highlit

YAML configuration is convenient, but it’s also a footgun when typos silently get ignored. I enable KnownFields(true) so unknown keys cause an error, which turns “silent misconfig” into a fast failure. That is especially useful during refactors when fields are renamed. I also decode from an io.Reader so the same code works for local files, embedded config, or S3 objects. In production, I combine this with a strict schema-like struct and a validation step that enforces invariants (timeouts must be > 0, lists must be non-empty, etc.). The goal is to make config errors noisy and actionable, not mysterious. This pattern is small and dependency-light, but it saves a lot of time when debugging environment drift.

Related snips

go 
package api

import (
  "net/http"
  "runtime/debug"
)

Expose build metadata for debugging deploys

go observability build
by Leah Thompson 1 tab
typescript 
export interface RetryOptions {
  retries: number;
  baseMs: number;
  maxMs: number;
  signal?: AbortSignal;
  onRetry?: (attempt: number, delay: number, err: unknown) => void;

Exponential backoff with jitter for retries

typescript reliability retry
by codesnips 2 tabs
go 
package dbutil

import (
  "context"

  "github.com/jackc/pgconn"

Retry Postgres serialization failures with bounded attempts

go postgres transactions
by Leah Thompson 1 tab
go 
package files

import (
  "context"
  "time"

Presigned S3 upload URLs (AWS SDK v2)

go aws s3
by Leah Thompson 1 tab
go 
package deps

import (
  "net"
  "net/http"
  "time"

HTTP client tuned for production: timeouts, transport, and connection reuse

go http client
by Leah Thompson 1 tab
go 
package api

import (
  "io"
  "net/http"
  "os"

Safe multipart uploads using temp files (bounded memory)

go http uploads
by Leah Thompson 1 tab

Share this code

Here's the card — post it anywhere.

Safe YAML decoding (KnownFields) for config files — share card
Link copied