From 2b7f7d863a9e77d52d453e5de60a686103bafcab Mon Sep 17 00:00:00 2001
From: Samuel Enocsson <samuel.enocsson@gmail.com>
Date: Fri, 22 May 2026 11:24:29 +0200
Subject: [PATCH] feat(config): load and validate env-var config

---
 go.mod                         |  7 ++++
 go.sum                         |  8 +++++
 internal/config/config.go      | 52 ++++++++++++++++++++++++++++++
 internal/config/config_test.go | 59 ++++++++++++++++++++++++++++++++++
 4 files changed, 126 insertions(+)
 create mode 100644 go.sum
 create mode 100644 internal/config/config.go
 create mode 100644 internal/config/config_test.go

diff --git a/go.mod b/go.mod
index bd57448..0b1cead 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,10 @@
 module github.com/shcizo/package-updater
 
 go 1.26.3
+
+require (
+	github.com/docker/docker v28.5.2+incompatible // indirect
+	github.com/google/uuid v1.6.0 // indirect
+	github.com/prometheus/client_golang v1.23.2 // indirect
+	github.com/stretchr/testify v1.11.1 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..af14773
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,8 @@
+github.com/docker/docker v28.5.2+incompatible h1:DBX0Y0zAjZbSrm1uzOkdr1onVghKaftjlSWt4AFexzM=
+github.com/docker/docker v28.5.2+incompatible/go.mod h1:eEKB0N0r5NX/I1kEveEz05bcu8tLC/8azJZsviup8Sk=
+github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
+github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/prometheus/client_golang v1.23.2 h1:Je96obch5RDVy3FDMndoUsjAhG5Edi49h0RJWRi/o0o=
+github.com/prometheus/client_golang v1.23.2/go.mod h1:Tb1a6LWHB3/SPIzCoaDXI4I8UHKeFTEQ1YCr+0Gyqmg=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
diff --git a/internal/config/config.go b/internal/config/config.go
new file mode 100644
index 0000000..80807de
--- /dev/null
+++ b/internal/config/config.go
@@ -0,0 +1,52 @@
+// Package config loads service configuration from environment variables.
+package config
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"time"
+)
+
+// Config holds all runtime configuration for the service.
+type Config struct {
+	APIKey        string
+	StacksRoot    string
+	Port          string
+	LogLevel      string
+	UpdateTimeout time.Duration
+	OptInLabel    string
+}
+
+// Load reads configuration from environment variables, applies defaults,
+// and validates required fields. Returns an error if validation fails so
+// the service can fail-fast at startup.
+func Load() (*Config, error) {
+	cfg := &Config{
+		APIKey:     os.Getenv("UPDATER_API_KEY"),
+		StacksRoot: getenvDefault("STACKS_ROOT", "/home/shcizo/self-hosted"),
+		Port:       getenvDefault("PORT", "8080"),
+		LogLevel:   getenvDefault("LOG_LEVEL", "info"),
+		OptInLabel: getenvDefault("OPT_IN_LABEL", "se.shcizo.auto-update"),
+	}
+
+	if cfg.APIKey == "" {
+		return nil, errors.New("UPDATER_API_KEY is required")
+	}
+
+	timeoutStr := getenvDefault("UPDATE_TIMEOUT", "5m")
+	d, err := time.ParseDuration(timeoutStr)
+	if err != nil {
+		return nil, fmt.Errorf("UPDATE_TIMEOUT %q is not a valid duration: %w", timeoutStr, err)
+	}
+	cfg.UpdateTimeout = d
+
+	return cfg, nil
+}
+
+func getenvDefault(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}
diff --git a/internal/config/config_test.go b/internal/config/config_test.go
new file mode 100644
index 0000000..bd50ab7
--- /dev/null
+++ b/internal/config/config_test.go
@@ -0,0 +1,59 @@
+package config_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/shcizo/package-updater/internal/config"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLoad_RequiresAPIKey(t *testing.T) {
+	t.Setenv("UPDATER_API_KEY", "")
+	_, err := config.Load()
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "UPDATER_API_KEY")
+}
+
+func TestLoad_AppliesDefaults(t *testing.T) {
+	t.Setenv("UPDATER_API_KEY", "secret")
+	t.Setenv("STACKS_ROOT", "")
+	t.Setenv("PORT", "")
+	t.Setenv("LOG_LEVEL", "")
+	t.Setenv("UPDATE_TIMEOUT", "")
+	t.Setenv("OPT_IN_LABEL", "")
+
+	cfg, err := config.Load()
+	require.NoError(t, err)
+	require.Equal(t, "secret", cfg.APIKey)
+	require.Equal(t, "/home/shcizo/self-hosted", cfg.StacksRoot)
+	require.Equal(t, "8080", cfg.Port)
+	require.Equal(t, "info", cfg.LogLevel)
+	require.Equal(t, 5*time.Minute, cfg.UpdateTimeout)
+	require.Equal(t, "se.shcizo.auto-update", cfg.OptInLabel)
+}
+
+func TestLoad_OverridesViaEnv(t *testing.T) {
+	t.Setenv("UPDATER_API_KEY", "secret")
+	t.Setenv("STACKS_ROOT", "/srv/stacks")
+	t.Setenv("PORT", "9090")
+	t.Setenv("LOG_LEVEL", "debug")
+	t.Setenv("UPDATE_TIMEOUT", "30s")
+	t.Setenv("OPT_IN_LABEL", "io.example.update")
+
+	cfg, err := config.Load()
+	require.NoError(t, err)
+	require.Equal(t, "/srv/stacks", cfg.StacksRoot)
+	require.Equal(t, "9090", cfg.Port)
+	require.Equal(t, "debug", cfg.LogLevel)
+	require.Equal(t, 30*time.Second, cfg.UpdateTimeout)
+	require.Equal(t, "io.example.update", cfg.OptInLabel)
+}
+
+func TestLoad_InvalidTimeoutErrors(t *testing.T) {
+	t.Setenv("UPDATER_API_KEY", "secret")
+	t.Setenv("UPDATE_TIMEOUT", "not-a-duration")
+	_, err := config.Load()
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "UPDATE_TIMEOUT")
+}