github.com/caddyserver/certmagic v0.23.0: FileStorage

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify certmagic.FileStorage in pkg:golang/github.com/caddyserver/certmagic@v0.23.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/caddyserver/certmagic@v0.23.0
Demonstrate these symbols/APIs:
  - certmagic.FileStorage

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:8b7e45ffe0de788940e03dd91bb9388290392cb90ae4477b8fe2dd7c784fc444","contract":["certmagic.FileStorage.Store and certmagic.FileStorage.Load write and retrieve byte payloads for a given key","certmagic.FileStorage.Exists reports true for existing keys and false for missing keys","certmagic.FileStorage.Stat returns KeyInfo with accurate size and terminal status for stored files","certmagic.FileStorage.List enumerates stored keys matching prefix recursively and non-recursively","certmagic.FileStorage.Lock and certmagic.FileStorage.Unlock provide mutual exclusion via filesystem locks","certmagic.FileStorage.Delete removes stored keys and makes subsequent Exists return false"],"goal":"verify certmagic.FileStorage in pkg:golang/github.com/caddyserver/certmagic@v0.23.0","kind":"HOW","packages":["pkg:golang/github.com/caddyserver/certmagic@v0.23.0"],"schemaVersion":1,"symbols":["certmagic.FileStorage"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/caddyserver/certmagic@v0.23.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/caddyserver/certmagic@v0.23.0","symbols":["certmagic.FileStorage"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.25.0

require github.com/caddyserver/certmagic v0.23.0

require (
	github.com/caddyserver/zerossl v0.1.5 // indirect
	github.com/klauspost/cpuid/v2 v2.3.0 // indirect
	github.com/libdns/libdns v1.1.1 // indirect
	github.com/mholt/acmez/v3 v3.1.6 // indirect
	github.com/miekg/dns v1.1.72 // indirect
	github.com/zeebo/blake3 v0.2.4 // indirect
	go.uber.org/multierr v1.11.0 // indirect
	go.uber.org/zap v1.27.1 // indirect
	go.uber.org/zap/exp v0.3.0 // indirect
	golang.org/x/crypto v0.50.0 // indirect
	golang.org/x/mod v0.35.0 // indirect
	golang.org/x/net v0.53.0 // indirect
	golang.org/x/sync v0.20.0 // indirect
	golang.org/x/sys v0.43.0 // indirect
	golang.org/x/text v0.36.0 // indirect
	golang.org/x/tools v0.44.0 // indirect
)

code.pfad.fr/check v1.1.0 h1:GWvjdzhSEgHvEHe2uJujDcpmZoySKuHQNrZMfzfO0bE=
code.pfad.fr/check v1.1.0/go.mod h1:NiUH13DtYsb7xp5wll0U4SXx7KhXQVCtRgdC96IPfoM=
github.com/caddyserver/certmagic v0.23.0 h1:CfpZ/50jMfG4+1J/u2LV6piJq4HOfO6ppOnOf7DkFEU=
github.com/caddyserver/certmagic v0.23.0/go.mod h1:9mEZIWqqWoI+Gf+4Trh04MOVPD0tGSxtqsxg87hAIH4=
github.com/caddyserver/zerossl v0.1.5 h1:dkvOjBAEEtY6LIGAHei7sw2UgqSD6TrWweXpV7lvEvE=
github.com/caddyserver/zerossl v0.1.5/go.mod h1:CxA0acn7oEGO6//4rtrRjYgEoa4MFw/XofZnrYwGqG4=
github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/go-jose/go-jose/v4 v4.1.3 h1:CVLmWDhDVRa6Mi/IgCgaopNosCaHz7zrMeF9MlZRkrs=
github.com/go-jose/go-jose/v4 v4.1.3/go.mod h1:x4oUasVrzR7071A4TnHLGSPpNOm2a21K9Kf04k1rs08=
github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/klauspost/cpuid/v2 v2.3.0 h1:S4CRMLnYUhGeDFDqkGriYKdfoFlDnMtqTiI/sFzhA9Y=
github.com/klauspost/cpuid/v2 v2.3.0/go.mod h1:hqwkgyIinND0mEev00jJYCxPNVRVXFQeu1XKlok6oO0=
github.com/letsencrypt/challtestsrv v1.4.2 h1:0ON3ldMhZyWlfVNYYpFuWRTmZNnyfiL9Hh5YzC3JVwU=
github.com/letsencrypt/challtestsrv v1.4.2/go.mod h1:GhqMqcSoeGpYd5zX5TgwA6er/1MbWzx/o7yuuVya+Wk=
github.com/letsencrypt/pebble/v2 v2.10.0 h1:Wq6gYXlsY6ubqI3hhxsTzdyotvfdjFBxuwYqCLCnj/U=
github.com/letsencrypt/pebble/v2 v2.10.0/go.mod h1:Sk8cmUIPcIdv2nINo+9PB4L+ZBhzY+F9A1a/h/xmWiQ=
github.com/libdns/libdns v1.1.1 h1:wPrHrXILoSHKWJKGd0EiAVmiJbFShguILTg9leS/P/U=
github.com/libdns/libdns v1.1.1/go.mod h1:4Bj9+5CQiNMVGf87wjX4CY3HQJypUHRuLvlsfsZqLWQ=
github.com/mholt/acmez/v3 v3.1.6 h1:eGVQNObP0pBN4sxqrXeg7MYqTOWyoiYpQqITVWlrevk=
github.com/mholt/acmez/v3 v3.1.6/go.mod h1:5nTPosTGosLxF3+LU4ygbgMRFDhbAVpqMI4+a4aHLBY=
github.com/miekg/dns v1.1.72 h1:vhmr+TF2A3tuoGNkLDFK9zi36F2LS+hKTRW0Uf8kbzI=
github.com/miekg/dns v1.1.72/go.mod h1:+EuEPhdHOsfk6Wk5TT2CzssZdqkmFhf8r+aVyDEToIs=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
github.com/zeebo/assert v1.1.0 h1:hU1L1vLTHsnO8x8c9KAR5GmM5QscxHg5RNU5z5qbUWY=
github.com/zeebo/assert v1.1.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
github.com/zeebo/blake3 v0.2.4 h1:KYQPkhpRtcqh0ssGYcKLG1JYvddkEA8QwCM/yBqhaZI=
github.com/zeebo/blake3 v0.2.4/go.mod h1:7eeQ6d2iXWRGF6npfaxl2CU+xy2Fjo2gxeyZGCRUjcE=
github.com/zeebo/pcg v1.0.1 h1:lyqfGeWiv4ahac6ttHs+I5hwtH/+1mrhlCtVNQM2kHo=
github.com/zeebo/pcg v1.0.1/go.mod h1:09F0S9iiKrwn9rlI5yjLkmrug154/YRW6KnnXVDM/l4=
go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
go.uber.org/multierr v1.11.0 h1:blXXJkSxSSfBVBlC76pxqeO+LN3aDfLQo+309xJstO0=
go.uber.org/multierr v1.11.0/go.mod h1:20+QtiLqy0Nd6FdQB9TLXag12DsQkrbs3htMFfDN80Y=
go.uber.org/zap v1.27.1 h1:08RqriUEv8+ArZRYSTXy1LeBScaMpVSTBhCeaZYfMYc=
go.uber.org/zap v1.27.1/go.mod h1:GB2qFLM7cTU87MWRP2mPIjqfIDnGu+VIO4V/SdhGo2E=
go.uber.org/zap/exp v0.3.0 h1:6JYzdifzYkGmTdRR59oYH+Ng7k49H9qVpWwNSsGJj3U=
go.uber.org/zap/exp v0.3.0/go.mod h1:5I384qq7XGxYyByIhHm6jg5CHkGY0nsTfbDLgDDlgJQ=
golang.org/x/crypto v0.50.0 h1:zO47/JPrL6vsNkINmLoo/PH1gcxpls50DNogFvB5ZGI=
golang.org/x/crypto v0.50.0/go.mod h1:3muZ7vA7PBCE6xgPX7nkzzjiUq87kRItoJQM1Yo8S+Q=
golang.org/x/mod v0.35.0 h1:Ww1D637e6Pg+Zb2KrWfHQUnH2dQRLBQyAtpr/haaJeM=
golang.org/x/mod v0.35.0/go.mod h1:+GwiRhIInF8wPm+4AoT6L0FA1QWAad3OMdTRx4tFYlU=
golang.org/x/net v0.53.0 h1:d+qAbo5L0orcWAr0a9JweQpjXF19LMXJE8Ey7hwOdUA=
golang.org/x/net v0.53.0/go.mod h1:JvMuJH7rrdiCfbeHoo3fCQU24Lf5JJwT9W3sJFulfgs=
golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
golang.org/x/sys v0.43.0 h1:Rlag2XtaFTxp19wS8MXlJwTvoh8ArU6ezoyFsMyCTNI=
golang.org/x/sys v0.43.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
golang.org/x/text v0.36.0 h1:JfKh3XmcRPqZPKevfXVpI1wXPTqbkE5f7JA92a55Yxg=
golang.org/x/text v0.36.0/go.mod h1:NIdBknypM8iqVmPiuco0Dh6P5Jcdk8lJL0CUebqK164=
golang.org/x/tools v0.44.0 h1:UP4ajHPIcuMjT1GqzDWRlalUEoY+uzoZKnhOjbIPD2c=
golang.org/x/tools v0.44.0/go.mod h1:KA0AfVErSdxRZIsOVipbv3rQhVXTnlU6UhKxHd1seDI=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

package main

import (
	"context"
	"fmt"
	"os"
	"path/filepath"

	"github.com/caddyserver/certmagic"
)

func main() {
	ctx := context.Background()

	tmpDir, err := os.MkdirTemp("", "certmagic-filestorage-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp dir: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	storage := &certmagic.FileStorage{
		Path: filepath.Join(tmpDir, "storage"),
	}

	key := "sites/example.com/cert.pem"
	content := []byte("dummy certificate content")

	// Store data
	if err := storage.Store(ctx, key, content); err != nil {
		fmt.Fprintf(os.Stderr, "failed to store: %v\n", err)
		os.Exit(1)
	}

	// Check existence
	if !storage.Exists(ctx, key) {
		fmt.Fprintf(os.Stderr, "key does not exist: %s\n", key)
		os.Exit(1)
	}

	// Load data
	loaded, err := storage.Load(ctx, key)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to load: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("Loaded stored key %s: %s\n", key, string(loaded))

	// Stat metadata
	info, err := storage.Stat(ctx, key)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to stat: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("Stat: key=%s, size=%d, isTerminal=%v\n", info.Key, info.Size, info.IsTerminal)

	// List keys
	keys, err := storage.List(ctx, "sites", true)
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to list: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("Listed %d keys under 'sites': %v\n", len(keys), keys)

	// Lock and Unlock
	lockName := "renewal-lock"
	if err := storage.Lock(ctx, lockName); err != nil {
		fmt.Fprintf(os.Stderr, "failed to acquire lock: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("Acquired lock successfully")

	if err := storage.Unlock(ctx, lockName); err != nil {
		fmt.Fprintf(os.Stderr, "failed to release lock: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("Released lock successfully")

	// Delete key
	if err := storage.Delete(ctx, key); err != nil {
		fmt.Fprintf(os.Stderr, "failed to delete: %v\n", err)
		os.Exit(1)
	}
	fmt.Printf("Deleted key: %s\n", key)
}

{
  "schemaVersion": 1,
  "goal": "verify certmagic.FileStorage in pkg:golang/github.com/caddyserver/certmagic@v0.23.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/caddyserver/certmagic@v0.23.0"
  ],
  "symbols": [
    "certmagic.FileStorage"
  ]
}

package main

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/caddyserver/certmagic"
)

func main() {
	ctx := context.Background()

	tmpDir, err := os.MkdirTemp("", "certmagic-contract-*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to create temp directory: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	storage := &certmagic.FileStorage{
		Path: filepath.Join(tmpDir, "store"),
	}

	// 1. FileStorage.Store and FileStorage.Load write and retrieve byte payloads for a given key
	testKey := "certificates/example.com/cert.crt"
	testVal := []byte("sample-certificate-binary-content-data")

	if err := storage.Store(ctx, testKey, testVal); err != nil {
		fmt.Fprintf(os.Stderr, "Store failed: %v\n", err)
		os.Exit(1)
	}

	loadedVal, err := storage.Load(ctx, testKey)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Load failed: %v\n", err)
		os.Exit(1)
	}
	if !bytes.Equal(loadedVal, testVal) {
		fmt.Fprintf(os.Stderr, "Load returned %q, expected %q\n", loadedVal, testVal)
		os.Exit(1)
	}

	// 2. FileStorage.Exists reports true for existing keys and false for missing keys
	if !storage.Exists(ctx, testKey) {
		fmt.Fprintf(os.Stderr, "Exists(%q) = false, expected true\n", testKey)
		os.Exit(1)
	}
	missingKey := "certificates/nonexistent.com/cert.crt"
	if storage.Exists(ctx, missingKey) {
		fmt.Fprintf(os.Stderr, "Exists(%q) = true, expected false\n", missingKey)
		os.Exit(1)
	}

	// 3. FileStorage.Stat returns KeyInfo with accurate size and terminal status for stored files
	info, err := storage.Stat(ctx, testKey)
	if err != nil {
		fmt.Fprintf(os.Stderr, "Stat failed: %v\n", err)
		os.Exit(1)
	}
	if info.Key != testKey {
		fmt.Fprintf(os.Stderr, "Stat Key = %q, expected %q\n", info.Key, testKey)
		os.Exit(1)
	}
	if info.Size != int64(len(testVal)) {
		fmt.Fprintf(os.Stderr, "Stat Size = %d, expected %d\n", info.Size, len(testVal))
		os.Exit(1)
	}
	if !info.IsTerminal {
		fmt.Fprintf(os.Stderr, "Stat IsTerminal = false, expected true for leaf file\n")
		os.Exit(1)
	}

	// 4. FileStorage.List enumerates stored keys matching prefix recursively and non-recursively
	nestedKey := "certificates/example.com/cert.key"
	nestedVal := []byte("sample-key-binary-content-data")
	if err := storage.Store(ctx, nestedKey, nestedVal); err != nil {
		fmt.Fprintf(os.Stderr, "Store nested failed: %v\n", err)
		os.Exit(1)
	}

	recursiveList, err := storage.List(ctx, "certificates", true)
	if err != nil {
		fmt.Fprintf(os.Stderr, "List recursive failed: %v\n", err)
		os.Exit(1)
	}
	if len(recursiveList) < 2 {
		fmt.Fprintf(os.Stderr, "List recursive expected at least 2 keys, got %d: %v\n", len(recursiveList), recursiveList)
		os.Exit(1)
	}

	// 5. FileStorage.Lock and FileStorage.Unlock provide mutual exclusion via filesystem locks
	lockName := "storage-sync-lock"
	if err := storage.Lock(ctx, lockName); err != nil {
		fmt.Fprintf(os.Stderr, "Lock failed: %v\n", err)
		os.Exit(1)
	}

	// Test lock contention with short timeout
	ctxTimeout, cancel := context.WithTimeout(ctx, 100*time.Millisecond)
	contentionErr := storage.Lock(ctxTimeout, lockName)
	cancel()
	if contentionErr == nil {
		fmt.Fprintf(os.Stderr, "Expected lock contention error on already locked resource\n")
		os.Exit(1)
	}

	if err := storage.Unlock(ctx, lockName); err != nil {
		fmt.Fprintf(os.Stderr, "Unlock failed: %v\n", err)
		os.Exit(1)
	}

	// 6. FileStorage.Delete removes stored keys and makes subsequent Exists return false
	if err := storage.Delete(ctx, testKey); err != nil {
		fmt.Fprintf(os.Stderr, "Delete failed: %v\n", err)
		os.Exit(1)
	}
	if storage.Exists(ctx, testKey) {
		fmt.Fprintf(os.Stderr, "Exists(%q) = true after Delete, expected false\n", testKey)
		os.Exit(1)
	}

	fmt.Println("All certmagic.FileStorage contract assertions passed.")
}