app/config.go
255 lines · 8094 bytes · executable
1package app
2
3import (
4 "encoding/json"
5 "errors"
6 "os"
7 "regexp"
8 "skunkyart/static"
9 "strconv"
10 "time"
11
12 "github.com/krazywarez/devianter"
13)
14
15// Release carries the build's version and description, set at link time and
16// shown by --help and the API.
17var Release struct {
18 Version string
19 Description string
20}
21
22type cacheConfig struct {
23 Enabled bool `json:"enabled"`
24 MemCache bool `json:"memcache"`
25 Path string `json:"path"`
26 MaxSize int64 `json:"max-size"`
27 Lifetime string `json:"lifetime"`
28 UpdateInterval int64 `json:"update-interval"`
29}
30
31type apiCacheConfig struct {
32 Enabled bool `json:"enabled"`
33 MaxSize int64 `json:"max-size"`
34 TTL string `json:"ttl"`
35 Stale string `json:"stale"`
36}
37
38type rateLimitConfig struct {
39 PerMinute int `json:"per-minute"`
40 Burst int `json:"burst"`
41}
42
43type config struct {
44 cfg string
45 Listen string `json:"listen"`
46 URI string `json:"uri"`
47 Cache cacheConfig `json:"cache"`
48 APICache apiCacheConfig `json:"api-cache"`
49 RateLimit rateLimitConfig `json:"rate-limit"`
50 Proxy bool `json:"proxy"`
51 Nsfw bool `json:"nsfw"`
52 HideAI bool `json:"hide-ai"`
53 Theme string `json:"theme"`
54 Language string `json:"language"`
55 UserAgent string `json:"user-agent"`
56 DownloadProxy string `json:"download-proxy"`
57 StaticPath string `json:"static-path"`
58}
59
60// CFG is the running instance's configuration, holding the defaults below until
61// ExecuteConfig overwrites them from the config file.
62var CFG = config{
63 cfg: "config.json",
64 Listen: "127.0.0.1:3003",
65 Theme: "auto",
66 Language: "auto",
67 URI: "/",
68 Cache: cacheConfig{
69 Enabled: true,
70 Path: "cache",
71 Lifetime: "1w",
72 MaxSize: 200,
73 UpdateInterval: 1,
74 },
75 APICache: apiCacheConfig{
76 Enabled: true,
77 MaxSize: 64,
78 TTL: "5i",
79 Stale: "1h",
80 },
81 RateLimit: rateLimitConfig{
82 PerMinute: 60,
83 Burst: 20,
84 },
85 StaticPath: "static",
86 UserAgent: "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36",
87 Proxy: true,
88 Nsfw: false,
89}
90
91var lifetimeParsed int64
92
93// apiCacheTTL and apiCacheStale are api-cache.ttl and api-cache.stale parsed,
94// set by ExecuteConfig.
95var apiCacheTTL, apiCacheStale time.Duration
96
97// parseLifetime reads a duration in the config's unit syntax: a number
98// followed by i (minutes), h (hours), d (days), w (weeks), m (30-day
99// months) or y (360-day years).
100func parseLifetime(s string) (time.Duration, error) {
101 if s == "" {
102 return 0, errors.New("empty lifetime")
103 }
104 numstr := regexp.MustCompile("[0-9]+").FindAllString(s, -1)
105 if len(numstr) == 0 {
106 return 0, errors.New("lifetime has no number: " + s)
107 }
108 num, _ := strconv.Atoi(numstr[len(numstr)-1])
109
110 day := 24 * time.Hour
111 var unit time.Duration
112 switch s[len(s)-1:] {
113 case "i":
114 unit = time.Minute
115 case "h":
116 unit = time.Hour
117 case "d":
118 unit = day
119 case "w":
120 unit = 7 * day
121 case "m":
122 unit = 30 * day
123 case "y":
124 unit = 360 * day
125 default:
126 return 0, errors.New("invalid unit specified: " + s[len(s)-1:])
127 }
128 return unit * time.Duration(num), nil
129}
130
131// checkCacheWritable creates the cache directory if it is missing and confirms
132// this process can actually write into it, returning the error that a real cache
133// write would hit.
134//
135// An unwritable cache directory is otherwise a silent cliff: every media request
136// still succeeds by re-downloading from the CDN, so the only symptom is one
137// "permission denied" line per request and a cache that never fills.
138func checkCacheWritable(path string) error {
139 if err := os.MkdirAll(path, 0700); err != nil {
140 return err
141 }
142 probe := path + "/.skunkyart-write-probe"
143 if err := os.WriteFile(probe, nil, 0600); err != nil {
144 return err
145 }
146 return os.Remove(probe)
147}
148
149// cfgExplicit records that -c named the config file, so a missing one is an
150// error rather than a fall-back to the defaults.
151var cfgExplicit bool
152
153// ExecuteConfig loads the config file into CFG, validates it, and starts the
154// cache rotation loop if caching is on. A missing default config.json means
155// the built-in defaults; a missing file named with -c exits. It also exits on
156// a config that cannot be parsed, that asks for caching without proxying, or
157// that points caching at a directory this process cannot write.
158func ExecuteConfig() {
159 f, err := os.ReadFile(CFG.cfg)
160 switch {
161 case err == nil:
162 tryWithExitStatus(json.Unmarshal(f, &CFG), 1)
163 case os.IsNotExist(err) && !cfgExplicit:
164 // The default file is optional: the built-in defaults are a working
165 // instance. A path given with -c is not, since a typo there would
166 // otherwise start something the operator did not configure.
167 println("no", CFG.cfg, "found; running with the built-in defaults")
168 default:
169 tryWithExitStatus(err, 1)
170 }
171
172 if CFG.Cache.Enabled && !CFG.Proxy {
173 exit("Incompatible settings detected: cannot use caching media content without proxy", 1)
174 }
175
176 if CFG.Cache.Enabled {
177 if err := checkCacheWritable(CFG.Cache.Path); err != nil {
178 exit("Cache directory is not writable by this process (uid "+
179 strconv.Itoa(os.Getuid())+"): "+err.Error()+
180 "\nGrant that uid write access to the directory, or set cache.enabled to false."+
181 "\nThe official container image runs as uid 10000, so a bind-mounted cache needs:"+
182 "\n chown -R 10000:10000 <cache dir on the host>", 1)
183 }
184
185 if CFG.Cache.Lifetime != "" {
186 d, err := parseLifetime(CFG.Cache.Lifetime)
187 if err != nil {
188 exit("config: cache.lifetime: "+err.Error(), 1)
189 }
190 lifetimeParsed = d.Milliseconds()
191 }
192 // max-size is documented in megabytes. This was 1024^2, which in Go is
193 // XOR (1026), not exponentiation — so the cap was ~1000x too small.
194 CFG.Cache.MaxSize *= 1024 * 1024
195 go InitCacheSystem()
196 if CFG.Cache.MemCache {
197 go InitMemCacheJanitor()
198 }
199 }
200
201 About = instanceAbout{
202 Proxy: CFG.Proxy,
203 Nsfw: CFG.Nsfw,
204 HideAI: CFG.HideAI,
205 Theme: CFG.Theme,
206 }
207
208 // A theme the stylesheet cannot honour would silently fall back to auto,
209 // so say so instead.
210 switch CFG.Theme {
211 case "auto", "dark", "light":
212 default:
213 exit("config: theme must be one of auto, dark, light; got "+CFG.Theme, 1)
214 }
215
216 if CFG.APICache.Enabled {
217 d, err := parseLifetime(CFG.APICache.TTL)
218 if err != nil {
219 exit("config: api-cache.ttl: "+err.Error(), 1)
220 }
221 apiCacheTTL = d
222 if CFG.APICache.Stale != "" {
223 d, err := parseLifetime(CFG.APICache.Stale)
224 if err != nil {
225 exit("config: api-cache.stale: "+err.Error(), 1)
226 }
227 apiCacheStale = d
228 }
229 }
230
231 // per-minute 0 turns the limit off; a burst below one token would
232 // refuse every request, so it is floored to one.
233 if CFG.RateLimit.PerMinute > 0 {
234 daLimiter = newRateLimiter(CFG.RateLimit.PerMinute, max(CFG.RateLimit.Burst, 1))
235 }
236
237 static.StaticPath = CFG.StaticPath
238 devianter.UserAgent = CFG.UserAgent
239}
240
241// forcedThemeCSS returns a block that pins the palette when the instance has
242// chosen a theme, or "" for "auto". Light repeats what the prefers-color-scheme
243// block already holds; dark repeats :root. Both are emitted after the
244// stylesheet so they win on order rather than on !important.
245func forcedThemeCSS() string {
246 switch CFG.Theme {
247 case "light":
248 return `
249:root{--bg:#f4f1ee;--fg:#1f2421;--fg-strong:#0d100e;--link:#1c6b78;--link-hover:#5a6b00;--edge:#8fbcae;--edge-strong:#258268;--accent:#4d27d6;--surface:#d9e8e1;--surface-sunken:#e8f0ec;--surface-alt:#e2e4f2;--surface-deep:#dbe7ef;--status-bad:#a11;--status-good:#157a3a;--status-mild:#2e8b57;--status-note:#8a007f}`
250 case "dark":
251 return `
252:root{--bg:black;--fg:rgb(234,216,216);--fg-strong:whitesmoke;--link:cadetblue;--link-hover:#d0ff00;--edge:#164e3e;--edge-strong:#258268;--accent:#4d27d6;--surface:#134134;--surface-sunken:#091f19;--surface-alt:#060820;--surface-deep:#011522;--status-bad:red;--status-good:green;--status-mild:seagreen;--status-note:rgb(160,0,147)}`
253 }
254 return ""
255}