Read every setting through viper (closes #211)

servewaf's and rproxy's settings are read through viper, bound to the same environment variable names as before, in place of the os.LookupEnv function Main passed down. NewViper turns AutomaticEnv and AllowEmptyEnv on, so a setting that is set but empty reads as set, as it did. A setting may also be given as a file, the _FILE form, which rproxy's settings now have too; rproxy still writes nothing to disk. The settings tests pass set into a viper instead of a lookup function.

Model: deepseek-v4-pro

README.md

@@ -189,12 +189,12 @@ restarting the container. `rproxy` reads only the `SWRP_` settings, and
 default, chosen for a service on the open internet. A setting that needs an
 account, a key, a token or an alert destination stays off until you give one.
 
-- Any `SWWAF_` setting can be given as a file instead, for secrets and long
+- Any `SWWAF_` or `SWRP_` setting can be given as a file instead, for secrets
-  lists: `SWWAF_ADMIN_TOKEN_FILE` names the file that holds `SWWAF_ADMIN_TOKEN`.
+  and long lists: `SWWAF_ADMIN_TOKEN_FILE` names the file that holds
-  The file's contents are the value, less one newline at the end. Setting both
+  `SWWAF_ADMIN_TOKEN`. The file's contents are the value, less one newline at
-  forms stops the start. `SWWAF_LOG_REMOTE_TLS_CA_FILE` and
+  the end. Setting both forms stops the start. `SWWAF_LOG_REMOTE_TLS_CA_FILE`
-  `SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE` already name a file, so they have no
+  and `SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE` already name a file, so they have no
-  `_FILE` form. No `SWRP_` setting has one, since `rproxy` never touches disk.
+  `_FILE` form.
 - A duration is Go's syntax, with `d` for days: `90s`, `15m`, `24h`, `7d`.
 - A size is a number of bytes with an optional `K`, `M` or `G`, in powers of
   1024: `512K`, `100M`, `5G`.

SPEC.md

@@ -31,11 +31,11 @@ to them.
   reputation sources, and send alerts.
 - Everything is set by environment variables. The names of `servewaf`'s start
   with `SWWAF_`, and those of `rproxy` with `SWRP_`. The only other inputs are
-  `servewaf`'s files:
+  files:
-    - the rule files;
+    - `servewaf`'s rule files;
-    - the state files;
+    - `servewaf`'s state files;
-    - a lookup database;
+    - `servewaf`'s lookup database;
-    - a `SWWAF_` setting given as a file;
+    - a `SWWAF_` or `SWRP_` setting given as a file;
     - the file `SWWAF_LOG_REMOTE_TLS_CA_FILE` names;
     - the file `SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE` names.
 
@@ -322,14 +322,13 @@ Conventions:
     No other setting can be switched off with `off`.
 
 - A list set to an empty value is an empty list, and replaces the default.
-- Any `SWWAF_` setting can be read from a file instead, for secrets and long
+- Any `SWWAF_` or `SWRP_` setting can be read from a file instead, for secrets
-  lists: `SWWAF_ADMIN_TOKEN_FILE` names the file that holds `SWWAF_ADMIN_TOKEN`.
+  and long lists: `SWWAF_ADMIN_TOKEN_FILE` names the file that holds
-  The file's contents are the value, less one newline at the end, and are
+  `SWWAF_ADMIN_TOKEN`. The file's contents are the value, less one newline at
-  checked as the value itself would be. Setting both forms stops the start, and
+  the end, and are checked as the value itself would be. Setting both forms
-  so does naming a file that cannot be read. `SWWAF_LOG_REMOTE_TLS_CA_FILE` and
+  stops the start, and so does naming a file that cannot be read.
-  `SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE` already hold a file name, so they have
+  `SWWAF_LOG_REMOTE_TLS_CA_FILE` and `SWWAF_CORE_RULE_SET_EXCLUSIONS_FILE`
-  no `_FILE` form. No `SWRP_` setting has one, since `rproxy` never touches
+  already hold a file name, so they have no `_FILE` form.
-  disk.
 - Settings, files included, are read once at start. Changing one means
   restarting the container. The files `servewaf` watches while it runs are its
   state files, its rule files and the lookup database.

docs/settings.md

@@ -354,9 +354,8 @@ asked in the background (see "Answering in time" under "`servewaf`" in
 ## `rproxy`
 
 `smallwebwaf rproxy` reads the settings below and no others. They are read once
-at start, and an invalid value stops the start. None can be given as a file,
+at start, and an invalid value stops the start. Any can be given as a file, as a
-since `rproxy` never touches disk. "`rproxy`" in [`SPEC.md`](../SPEC.md) says
+`SWWAF_` setting can. "`rproxy`" in [`SPEC.md`](../SPEC.md) says what they do.
-what they do.
 
 A time here is a whole number of milliseconds above zero, such as `2000`.
 

go.mod

@@ -10,12 +10,14 @@ require (
 	github.com/maxmind/mmdbwriter v1.2.0
 	github.com/oschwald/maxminddb-golang/v2 v2.7.0
 	github.com/prometheus/client_golang v1.24.1
+	github.com/spf13/viper v1.21.0
 )
 
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/corazawaf/libinjection-go v0.3.3 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/goccy/go-json v0.10.5 // indirect
 	github.com/goccy/go-yaml v1.19.2 // indirect
 	github.com/gotnospirit/makeplural v0.0.0-20180622080156-a5f48d94d976 // indirect
@@ -25,14 +27,22 @@ require (
 	github.com/kylelemons/godebug v1.1.0 // indirect
 	github.com/magefile/mage v1.17.0 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/petar-dambovaliev/aho-corasick v0.0.0-20250424160509-463d218d4745 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.70.1 // indirect
 	github.com/prometheus/procfs v0.21.1 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
+	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/tidwall/gjson v1.18.0 // indirect
 	github.com/tidwall/match v1.1.1 // indirect
 	github.com/tidwall/pretty v1.2.1 // indirect
 	github.com/valllabh/ocsf-schema-golang v1.0.3 // indirect
+	go.yaml.in/yaml/v3 v3.0.5 // indirect
 	go4.org/netipx v0.0.0-20231129151722-fdeea329fbba // indirect
 	golang.org/x/net v0.58.0 // indirect
 	golang.org/x/sync v0.23.0 // indirect

go.sum

@@ -12,8 +12,12 @@ github.com/corazawaf/libinjection-go v0.3.3 h1:NhbXKRfRpqKzBMzv8zpCcnjyEw7BCVhBO
 github.com/corazawaf/libinjection-go v0.3.3/go.mod h1:Ik/+w3UmTWH9yn366RgS9D95K3y7Atb5m/H/gXzzPCk=
 github.com/foxcpp/go-mockdns v1.2.0 h1:omK3OrHRD1IWJz1FuFBCFquhXslXoF17OvBS6JPzZF0=
 github.com/foxcpp/go-mockdns v1.2.0/go.mod h1:IhLeSFGed3mJIAXPH2aiRQB+kqz7oqu8ld2qVbOu7Wk=
+github.com/frankban/quicktest v1.14.6 h1:7Xjx+VpznH+oBnejlPUj8oUpdxnVs4f8XU8WnHkI4W8=
+github.com/frankban/quicktest v1.14.6/go.mod h1:4ptaffx2x8+WTWXmUCuVU6aPUX1/Mz7zb5vbUoiM6w0=
 github.com/fsnotify/fsnotify v1.10.1 h1:b0/UzAf9yR5rhf3RPm9gf3ehBPpf0oZKIjtpKrx59Ho=
 github.com/fsnotify/fsnotify v1.10.1/go.mod h1:TLheqan6HD6GBK6PrDWyDPBaEV8LspOxvPSjC+bVfgo=
+github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9LvH92wZUgs=
+github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/goccy/go-json v0.10.5 h1:Fq85nIqj+gXn/S5ahsiTlK3TmC85qgirsdTP/+DeaC4=
 github.com/goccy/go-json v0.10.5/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
 github.com/goccy/go-yaml v1.19.2 h1:PmFC1S6h8ljIz6gMRBopkjP1TVT7xuwrButHID66PoM=
@@ -34,6 +38,10 @@ github.com/kaptinlin/jsonschema v0.4.6 h1:vOSFg5tjmfkOdKg+D6Oo4fVOM/pActWu/ntkPs
 github.com/kaptinlin/jsonschema v0.4.6/go.mod h1:1DUd7r5SdyB2ZnMtyB7uLv64dE3zTFTiYytDCd+AEL0=
 github.com/klauspost/compress v1.19.1 h1:VsB4HPswih7mmZ8WleSFQ75c/Ui1M4trX5oAsJnhSlk=
 github.com/klauspost/compress v1.19.1/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
+github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
+github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
 github.com/magefile/mage v1.17.0 h1:dS4tkq997Ism03akafC8509iqDjeE7TNTexI25Y7sXM=
@@ -58,8 +66,24 @@ github.com/prometheus/common v0.70.1 h1:1HvjP4D5oL3t8RsPlwxA9onvvStjtIHYE5XuuwOi
 github.com/prometheus/common v0.70.1/go.mod h1:VdFUQDMZK3VLkurFUVhia6uys/0suUp86TJz5qbJRhc=
 github.com/prometheus/procfs v0.21.1 h1:GljZCt+zSTS+NZq88cyQ1LjZ+RCHp3uVuabBWA5+OJI=
 github.com/prometheus/procfs v0.21.1/go.mod h1:aB55Cww9pdSJVHk0hUf0inxWyyjPogFIjmHKYgMKmtY=
+github.com/rogpeppe/go-internal v1.9.0 h1:73kH8U+JUqXU8lRuOHeVHaa/SZPifC7BkcraZVejAe8=
+github.com/rogpeppe/go-internal v1.9.0/go.mod h1:WtVeX8xhTBvf0smdhujwtBcq4Qrzq/fJaraNFVN+nFs=
+github.com/sagikazarmark/locafero v0.11.0 h1:1iurJgmM9G3PA/I+wWYIOw/5SyBtxapeHDcg+AAIFXc=
+github.com/sagikazarmark/locafero v0.11.0/go.mod h1:nVIGvgyzw595SUSUE6tvCp3YYTeHs15MvlmU87WwIik=
+github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 h1:+jumHNA0Wrelhe64i8F6HNlS8pkoyMv5sreGx2Ry5Rw=
+github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8/go.mod h1:3n1Cwaq1E1/1lhQhtRK2ts/ZwZEhjcQeJQ1RuC6Q/8U=
+github.com/spf13/afero v1.15.0 h1:b/YBCLWAJdFWJTN9cLhiXXcD7mzKn9Dm86dNnfyQw1I=
+github.com/spf13/afero v1.15.0/go.mod h1:NC2ByUVxtQs4b3sIUphxK0NioZnmxgyCrfzeuq8lxMg=
+github.com/spf13/cast v1.10.0 h1:h2x0u2shc1QuLHfxi+cTJvs30+ZAHOGRic8uyGTDWxY=
+github.com/spf13/cast v1.10.0/go.mod h1:jNfB8QC9IA6ZuY2ZjDp0KtFO2LZZlg4S/7bzP6qqeHo=
+github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
+github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/spf13/viper v1.21.0 h1:x5S+0EU27Lbphp4UKm1C+1oQO+rKx36vfCoaVebLFSU=
+github.com/spf13/viper v1.21.0/go.mod h1:P0lhsswPGWD/1lZJ9ny3fYnVqxiegrlNrEmgLjbTCAY=
 github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
 github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
+github.com/subosito/gotenv v1.6.0 h1:9NlTDc1FTs4qu0DDq7AEtTPNw6SVm7uBMsUCUjABIf8=
+github.com/subosito/gotenv v1.6.0/go.mod h1:Dk4QP5c2W3ibzajGcXpNraDfq2IrhjMIvMSWPKKo0FU=
 github.com/tidwall/gjson v1.18.0 h1:FIDeeyB800efLX89e5a8Y0BNH+LOngJyGrIWxG2FKQY=
 github.com/tidwall/gjson v1.18.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
 github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=

internal/config/config.go

@@ -2,9 +2,8 @@
 // read. Every setting is an environment variable. The settings of `smallwebwaf
 // servewaf` start with SWWAF_, every one of them has a default, and most can be
 // given as a file instead. Those of `smallwebwaf rproxy` start with SWRP_. Each
-// of them but SWRP_WAF_BACKEND has a default, and none can be given as a file,
+// of them but SWRP_WAF_BACKEND has a default, and each can be given as a file
-// since rproxy never touches disk. SMALLWEBWAF_COMMAND chooses which of the two
+// too. SMALLWEBWAF_COMMAND chooses which of the two the image runs.
-// the image runs.
 package config
 
 import (
@@ -26,6 +25,8 @@ import (
 	"unicode"
 	"unicode/utf8"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/remotelog"
@@ -453,15 +454,16 @@ var (
 		"is in SWWAF_BLOCKLIST_URLS or is SWWAF_ASN_LIMIT_PERCENT_URL too")
 )
 
-// FromEnvironment reads the settings with lookupEnv, normally
+// FromEnvironment reads the settings through v, normally the viper
-// os.LookupEnv. A setting may instead be given as a file: the variable
+// NewViper returns, bound to the process's environment. A setting may
-// named by the setting's name with _FILE added names the file, which is
+// instead be given as a file: the variable named by the setting's name
-// read now (see lookup). A setting that is not set takes its default. A
+// with _FILE added names the file, which is read now (see lookup). A
-// setting that is set but invalid is an error that names it.
+// setting that is not set takes its default. A setting that is set but
+// invalid is an error that names it.
 //
 //nolint:funlen // one line for each setting, a list that grows with them
-func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
+func FromEnvironment(v *viper.Viper) (*Config, error) {
-	env := &environment{lookupEnv: lookupEnv}
+	env := &environment{v: v, readFiles: true}
 	cfg := &Config{
 		ListenAddr:           env.address("SWWAF_LISTEN_ADDR"),
 		InstanceName:         env.instanceName(),
@@ -580,8 +582,8 @@ func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
 // Command reads only SMALLWEBWAF_COMMAND, the command the image runs and its
 // health check checks: rproxy when it is unset or empty, or servewaf. It cannot
 // be given as a file. Any other value is an error that names the setting.
-func Command(lookupEnv func(string) (string, bool)) (string, error) {
+func Command(v *viper.Viper) (string, error) {
-	command, _ := lookupEnv("SMALLWEBWAF_COMMAND")
+	command, _ := readSetting(v, "SMALLWEBWAF_COMMAND")
 
 	switch command {
 	case "", "rproxy":
@@ -596,8 +598,8 @@ func Command(lookupEnv func(string) (string, bool)) (string, error) {
 // ServeWAFListenAddr reads only SWWAF_LISTEN_ADDR, which may be given as a
 // file, as FromEnvironment does. The health check in servewaf's container needs
 // no other setting, so it reads no other, nor a file that another names.
-func ServeWAFListenAddr(lookupEnv func(string) (string, bool)) (string, error) {
+func ServeWAFListenAddr(v *viper.Viper) (string, error) {
-	env := &environment{lookupEnv: lookupEnv}
+	env := &environment{v: v, readFiles: true}
 	listenAddr := env.address("SWWAF_LISTEN_ADDR")
 
 	return listenAddr, env.err
@@ -607,8 +609,8 @@ func ServeWAFListenAddr(lookupEnv func(string) (string, bool)) (string, error) {
 // file, as FromEnvironment does, so that the line saying a setting is
 // invalid carries it too. A file that cannot be read gives the default
 // here, and FromEnvironment then stops the start over it.
-func InstanceName(lookupEnv func(string) (string, bool)) string {
+func InstanceName(v *viper.Viper) string {
-	env := &environment{lookupEnv: lookupEnv}
+	env := &environment{v: v, readFiles: true}
 
 	return env.instanceName()
 }
@@ -624,13 +626,26 @@ func (c *Config) LogValue() slog.Value {
 }
 
 // environment is where FromEnvironment reads the settings: it notes each
-// value for the log, and keeps the first error.
+// value for the log, and keeps the first error. It reads every setting
+// through v, the viper NewViper returns, and, unless readFiles is false,
+// honours each setting's _FILE form too.
 type environment struct {
-	lookupEnv func(string) (string, bool)
+	v         *viper.Viper
+	readFiles bool
 	settings  []slog.Attr
 	err       error
 }
 
+// readSetting returns a setting's value and whether it is set, reading it
+// through v.
+func readSetting(v *viper.Viper, name string) (string, bool) {
+	if !v.IsSet(name) {
+		return "", false
+	}
+
+	return v.GetString(name), true
+}
+
 // value returns a setting's value, or its default when it is not set,
 // and notes it for the log.
 func (e *environment) value(name, defaultValue string) string {
@@ -649,10 +664,14 @@ func (e *environment) value(name, defaultValue string) string {
 // names, less one newline at their end. It notes that file's path for the
 // log. Both variables set, or a file that cannot be read, is an error.
 func (e *environment) lookup(name string) (string, bool) {
-	value, set := e.lookupEnv(name)
+	value, set := readSetting(e.v, name)
+	if !e.readFiles {
+		return value, set
+	}
+
 	fileName := name + "_FILE"
 
-	path, inFile := e.lookupEnv(fileName)
+	path, inFile := readSetting(e.v, fileName)
 	if !inFile {
 		return value, set
 	}
@@ -1198,7 +1217,7 @@ func (e *environment) logRemoteURL(name string) *url.URL {
 // unset. Its value names a file already, so, unlike the other settings,
 // it has no _FILE form. Whoever uses the file reads it.
 func (e *environment) filePath(name string) string {
-	path, _ := e.lookupEnv(name)
+	path, _ := readSetting(e.v, name)
 	e.settings = append(e.settings, slog.String(name, path))
 
 	return path
@@ -1208,7 +1227,7 @@ func (e *environment) filePath(name string) string {
 // certificates. Unset or empty, it is nil. Its value names a file
 // already, so, unlike the other settings, it has no _FILE form.
 func (e *environment) certificates(name string) *x509.CertPool {
-	path, _ := e.lookupEnv(name)
+	path, _ := readSetting(e.v, name)
 	e.settings = append(e.settings, slog.String(name, path))
 
 	if path == "" {

internal/config/config_test.go

@@ -17,6 +17,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/config"
 )
@@ -218,18 +220,22 @@ const (
 // environment is a set of environment variables, for FromEnvironment.
 type environment map[string]string
 
-// lookupEnv reads one of the variables, as os.LookupEnv does.
+// viper returns a viper Set with each of the variables, as the viper
-func (e environment) lookupEnv(name string) (string, bool) {
+// NewViper returns one bound to a process's environment.
-	value, ok := e[name]
+func (e environment) viper() *viper.Viper {
+	v := viper.New()
+	for name, value := range e {
+		v.Set(name, value)
+	}
 
-	return value, ok
+	return v
 }
 
 // fromEnvironment reads the settings from env, which must be valid.
 func fromEnvironment(t *testing.T, env environment) *config.Config {
 	t.Helper()
 
-	cfg, err := config.FromEnvironment(env.lookupEnv)
+	cfg, err := config.FromEnvironment(env.viper())
 	if err != nil {
 		t.Fatalf("settings %v: %v", env, err)
 	}
@@ -456,7 +462,7 @@ func TestPathPrefixNotStartingWithSlashStopsTheStart(t *testing.T) {
 	t.Parallel()
 
 	_, err := config.FromEnvironment(
-		environment{rateLimitExemptPaths: "/favicon.ico,assets/"}.lookupEnv)
+		environment{rateLimitExemptPaths: "/favicon.ico,assets/"}.viper())
 
 	want := rateLimitExemptPaths + `: "assets/" is not a path prefix ` +
 		`starting with /, such as /assets/`
@@ -511,7 +517,7 @@ func TestInvalidTrapPathOrErrorBurstThresholdStopsTheStart(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -639,7 +645,7 @@ func TestInvalidCoreRuleSetSettingStopsTheStart(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -764,7 +770,7 @@ func TestInvalidRemoteLogSettingStopsTheStart(t *testing.T) {
 		{logRemoteAppName, ""}, {logRemoteAppName, "my app"},
 		{logRemoteAppName, "gitéa"}, {logRemoteAppName, strings.Repeat("a", 49)},
 	} {
-		_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+		_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 		if err == nil || !strings.HasPrefix(err.Error(), tc.name+": ") {
 			t.Errorf("%s=%q: error %v, want one naming it", tc.name, tc.value, err)
 		}
@@ -781,7 +787,7 @@ func TestRemoteLogCAFileWithoutCertificateStopsTheStart(t *testing.T) {
 		t.Fatalf("write %s: %v", caFile, err)
 	}
 
-	_, err = config.FromEnvironment(environment{logRemoteTLSCAFile: caFile}.lookupEnv)
+	_, err = config.FromEnvironment(environment{logRemoteTLSCAFile: caFile}.viper())
 
 	want := logRemoteTLSCAFile + `: "` + caFile + `" holds no PEM certificate`
 	if err == nil || err.Error() != want {
@@ -796,7 +802,7 @@ func TestInstanceNameNotAnAppNameStopsTheStartOnlyWhileSending(t *testing.T) {
 
 	sending := environment{logRemoteURL: remoteURL, instanceName: spaced}
 
-	_, err := config.FromEnvironment(sending.lookupEnv)
+	_, err := config.FromEnvironment(sending.viper())
 
 	want := logRemoteAppName + `: is unset, and ` + instanceName +
 		` "fsn1 app1", its default, is not 1 to 48 printable ASCII characters ` +
@@ -826,7 +832,7 @@ func TestAppNameSetStopsTheStartWhileSending(t *testing.T) {
 		logRemoteURL:     remoteURL,
 		instanceName:     instance,
 		logRemoteAppName: "my app",
-	}.lookupEnv)
+	}.viper())
 
 	want := logRemoteAppName + `: "my app" is not 1 to 48 printable ASCII ` +
 		`characters without a space, such as blog`
@@ -957,7 +963,7 @@ func TestWebhookHeadersAreLoggedMaskedAndNeverShown(t *testing.T) {
 	// An item that is not a header is named by its place, not shown.
 	_, err := config.FromEnvironment(environment{
 		alertWebhookHeaders: "X-Team:ops," + secret,
-	}.lookupEnv)
+	}.viper())
 
 	want := alertWebhookHeaders + ": item 2 is not a header name followed by : " +
 		"and the header's value, such as Authorization:Bearer <token>"
@@ -994,7 +1000,7 @@ func TestWebhookURLIsLoggedWithoutItsPathOrQueryAndNeverShown(t *testing.T) {
 		"ftp://hooks.example/services/" + secret,
 		"https://hooks.example/services/%zz" + secret,
 	} {
-		_, err := config.FromEnvironment(environment{alertWebhookURL: value}.lookupEnv)
+		_, err := config.FromEnvironment(environment{alertWebhookURL: value}.viper())
 
 		want := alertWebhookURL + ": is not an http or https URL without a user or " +
 			"a fragment, such as https://alerts.example/smallwebwaf"
@@ -1045,7 +1051,7 @@ func TestNtfyTokenWithAControlCharacterStopsTheStartWithoutShowingIt(t *testing.
 		"set":       {alertNtfyToken: token + "\r"},
 		"in a file": {alertNtfyToken + "_FILE": writeFile(t, token+"\r\n")},
 	} {
-		_, err := config.FromEnvironment(env.lookupEnv)
+		_, err := config.FromEnvironment(env.viper())
 
 		want := alertNtfyToken + ": holds a control character, such as the " +
 			"carriage return of a Windows line end"
@@ -1062,7 +1068,7 @@ func TestInstanceNameWithAControlCharacterStopsTheStartOnlyWithNtfySet(t *testin
 
 	_, err := config.FromEnvironment(environment{
 		instanceName: name, alertNtfyURL: "https://ntfy.example/smallwebwaf-alerts",
-	}.lookupEnv)
+	}.viper())
 
 	want := instanceName + `: "fsn1app1\r" holds a control character, such as the ` +
 		`carriage return of a Windows line end, and is sent to ntfy in a header ` +
@@ -1087,7 +1093,7 @@ func TestInstanceNameNotUTF8StopsTheStart(t *testing.T) {
 		"set":       {instanceName: latin1},
 		"in a file": {instanceName + "_FILE": writeFile(t, latin1+"\n")},
 	} {
-		_, err := config.FromEnvironment(env.lookupEnv)
+		_, err := config.FromEnvironment(env.viper())
 
 		want := instanceName + `: "caf\xe9" is not valid UTF-8`
 		if err == nil || err.Error() != want {
@@ -1102,7 +1108,7 @@ func TestCodeOnBothCountryListsStopsTheStart(t *testing.T) {
 	_, err := config.FromEnvironment(environment{
 		deniedCountries:  "cn,ru",
 		allowedCountries: "de,RU",
-	}.lookupEnv)
+	}.viper())
 	if err == nil {
 		t.Fatal("ru on both country lists was accepted")
 	}
@@ -1164,7 +1170,7 @@ func TestLookupDBPathGoesWithTheFileSourceAlone(t *testing.T) {
 			lookupDBPath + ": is set while " + lookupSource + " is off; only file reads it",
 		},
 	} {
-		_, err := config.FromEnvironment(tc.env.lookupEnv)
+		_, err := config.FromEnvironment(tc.env.viper())
 		if err == nil || err.Error() != tc.want {
 			t.Errorf("settings %v: error %v, want %s", tc.env, err, tc.want)
 		}
@@ -1194,7 +1200,7 @@ func TestSettingNeedingLookupsStopsTheStartWhileTheyAreOff(t *testing.T) {
 
 			_, err := config.FromEnvironment(environment{
 				lookupSource: off, name: value,
-			}.lookupEnv)
+			}.viper())
 			if err == nil || !strings.HasPrefix(err.Error(), name+": ") ||
 				!strings.Contains(err.Error(), lookupSource+" is off") {
 				t.Errorf("error %v, want one naming %s and %s", err, name, lookupSource)
@@ -1344,7 +1350,7 @@ func TestInvalidAnomalySettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -1423,7 +1429,7 @@ func TestInvalidBiasedThresholdStopsTheStartSayingWhatIsWrong(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -1520,7 +1526,7 @@ func TestInvalidReputationSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -1535,7 +1541,7 @@ func TestASNLimitPercentURLThatIsABlocklistStopsTheStart(t *testing.T) {
 
 	_, err := config.FromEnvironment(environment{
 		blocklistURLs: dropURL + "," + asnURL, asnLimitPercentURL: asnURL,
-	}.lookupEnv)
+	}.viper())
 
 	want := asnLimitPercentURL + `: "` + asnURL + `" is in SWWAF_BLOCKLIST_URLS too`
 	if err == nil || err.Error() != want {
@@ -1662,7 +1668,7 @@ func TestInvalidDNSBLSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -1730,7 +1736,7 @@ func TestDNSBLZoneKeyIsLoggedMaskedAndNeverShown(t *testing.T) {
 		{spamhaus + "," + otherZone, `"` + spamhausMasked + `" is listed twice`},
 		{spamhaus + ",,", "has an empty item in its list"},
 	} {
-		_, err := config.FromEnvironment(environment{dnsblZones: tc.value}.lookupEnv)
+		_, err := config.FromEnvironment(environment{dnsblZones: tc.value}.viper())
 
 		want := dnsblZones + ": " + tc.want
 		if err == nil || err.Error() != want {
@@ -1783,7 +1789,7 @@ func TestInvalidAbuseIPDBSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 
 			want := tc.name + ": " + tc.want
 			if err == nil || err.Error() != want {
@@ -1897,7 +1903,7 @@ func TestInvalidCrowdSecSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(tc.env.lookupEnv)
+			_, err := config.FromEnvironment(tc.env.viper())
 			if err == nil || err.Error() != tc.want {
 				t.Errorf("error %v, want %s", err, tc.want)
 			}
@@ -2057,7 +2063,7 @@ func wantStartStopped(t *testing.T, invalid []struct{ name, value string }) {
 		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.viper())
 			if err == nil {
 				t.Fatalf("%s=%q was accepted", tc.name, tc.value)
 			}
@@ -2082,7 +2088,7 @@ func TestHostOrTransferEncodingStopsTheStart(t *testing.T) {
 		t.Run(value, func(t *testing.T) {
 			t.Parallel()
 
-			_, err := config.FromEnvironment(environment{logRequestHeaders: value}.lookupEnv)
+			_, err := config.FromEnvironment(environment{logRequestHeaders: value}.viper())
 			if err == nil || err.Error() != logRequestHeaders+": "+want {
 				t.Errorf("error %v, want %s: %s", err, logRequestHeaders, want)
 			}
@@ -2099,7 +2105,7 @@ func TestShortTokenStopsTheStartWithoutShowingIt(t *testing.T) {
 			t.Run(name+"="+value, func(t *testing.T) {
 				t.Parallel()
 
-				_, err := config.FromEnvironment(environment{name: value}.lookupEnv)
+				_, err := config.FromEnvironment(environment{name: value}.viper())
 
 				want := name + ": is shorter than 32 characters"
 				if err == nil || err.Error() != want {
@@ -2155,7 +2161,7 @@ func TestSettingFromFileIsCheckedAsTheSettingItself(t *testing.T) {
 
 	_, err := config.FromEnvironment(environment{
 		bytesLimitPerMinute + "_FILE": writeFile(t, "lots\n"),
-	}.lookupEnv)
+	}.viper())
 
 	want := bytesLimitPerMinute + `: "lots" is not a size such as 512K, 100M or 5G, or off`
 	if err == nil || err.Error() != want {
@@ -2166,7 +2172,7 @@ func TestSettingFromFileIsCheckedAsTheSettingItself(t *testing.T) {
 		logRemoteURL:               remoteURL,
 		instanceName:               instance,
 		logRemoteAppName + "_FILE": writeFile(t, "my app\n"),
-	}.lookupEnv)
+	}.viper())
 
 	want = logRemoteAppName + `: "my app" is not 1 to 48 printable ASCII ` +
 		`characters without a space, such as blog`
@@ -2181,7 +2187,7 @@ func TestSettingAndItsFileBothSetStopsTheStart(t *testing.T) {
 	_, err := config.FromEnvironment(environment{
 		metricsToken:           token,
 		metricsToken + "_FILE": writeFile(t, token),
-	}.lookupEnv)
+	}.viper())
 
 	want := metricsToken + ": is set, and so is " + metricsToken +
 		"_FILE; set only one of them"
@@ -2196,7 +2202,7 @@ func TestUnreadableSettingFileStopsTheStart(t *testing.T) {
 	dir := t.TempDir()
 
 	for _, path := range []string{filepath.Join(dir, "missing"), dir} {
-		_, err := config.FromEnvironment(environment{metricsToken + "_FILE": path}.lookupEnv)
+		_, err := config.FromEnvironment(environment{metricsToken + "_FILE": path}.viper())
 
 		want := metricsToken + "_FILE: cannot be read: "
 		if err == nil || !strings.HasPrefix(err.Error(), want) {

internal/config/rproxy.go

@@ -8,8 +8,9 @@ import (
 	"net/netip"
 	"net/url"
 	"strconv"
-	"strings"
 	"time"
+
+	"github.com/spf13/viper"
 )
 
 // RProxy is the settings of `smallwebwaf rproxy`. A size or time limit of zero
@@ -58,13 +59,14 @@ var (
 		"is not a whole number of milliseconds above zero, such as 60000, or off")
 )
 
-// RProxyFromEnvironment reads rproxy's settings with lookupEnv, normally
+// RProxyFromEnvironment reads rproxy's settings through v, normally the viper
-// os.LookupEnv. A setting that is not set takes its default, and
+// NewViper returns, bound to the process's environment. A setting that is not
-// SWRP_WAF_BACKEND, which has none, must be set. A setting that is set but
+// set takes its default, and SWRP_WAF_BACKEND, which has none, must be set. A
-// invalid is an error that names it. Since rproxy never touches disk, its
+// setting may instead be given as a file: the variable named by the setting's
-// settings have no _FILE form.
+// name with _FILE added names the file, which is read now. A setting that is
-func RProxyFromEnvironment(lookupEnv func(string) (string, bool)) (*RProxy, error) {
+// set but invalid is an error that names it.
-	env := &environment{lookupEnv: withoutFileForms(lookupEnv)}
+func RProxyFromEnvironment(v *viper.Viper) (*RProxy, error) {
+	env := &environment{v: v, readFiles: true}
 	cfg := &RProxy{
 		ListenAddr:         env.address("SWRP_LISTEN_ADDR"),
 		UpstreamURL:        env.appURL("SWRP_UPSTREAM_URL", defaultUpstreamURL),
@@ -91,9 +93,9 @@ func RProxyFromEnvironment(lookupEnv func(string) (string, bool)) (*RProxy, erro
 // SWRP_UPSTREAM_URL. The health check in rproxy's container needs no other
 // setting, so it reads no other.
 func RProxyListenAddrAndUpstreamURL(
-	lookupEnv func(string) (string, bool),
+	v *viper.Viper,
 ) (string, *url.URL, error) {
-	env := &environment{lookupEnv: withoutFileForms(lookupEnv)}
+	env := &environment{v: v, readFiles: true}
 	listenAddr := env.address("SWRP_LISTEN_ADDR")
 	upstreamURL := env.appURL("SWRP_UPSTREAM_URL", defaultUpstreamURL)
 
@@ -104,20 +106,6 @@ func RProxyListenAddrAndUpstreamURL(
 	return listenAddr, upstreamURL, nil
 }
 
-// withoutFileForms returns lookupEnv finding no setting named with _FILE, since
-// rproxy never touches disk.
-func withoutFileForms(
-	lookupEnv func(string) (string, bool),
-) func(string) (string, bool) {
-	return func(name string) (string, bool) {
-		if strings.HasSuffix(name, "_FILE") {
-			return "", false
-		}
-
-		return lookupEnv(name)
-	}
-}
-
 // LogValue makes an RProxy log as each setting's name with the value it was
 // given, or its default.
 func (c *RProxy) LogValue() slog.Value {

internal/config/rproxy_test.go

@@ -9,6 +9,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/config"
 )
 
@@ -32,11 +34,12 @@ const (
 
 // rproxyConfig reads rproxy's settings from env.
 func rproxyConfig(env map[string]string) (*config.RProxy, error) {
-	return config.RProxyFromEnvironment(func(name string) (string, bool) {
+	v := viper.New()
-		value, ok := env[name]
+	for name, value := range env {
+		v.Set(name, value)
+	}
 
-		return value, ok
+	return config.RProxyFromEnvironment(v)
-	})
 }
 
 func TestRProxyDefaults(t *testing.T) {
@@ -177,31 +180,41 @@ func TestRProxyNeedsItsBackend(t *testing.T) {
 	}
 }
 
-func TestRProxyReadsNoFile(t *testing.T) {
+func TestRProxySettingReadFromFile(t *testing.T) {
 	t.Parallel()
 
 	path := filepath.Join(t.TempDir(), "backend")
 
-	err := os.WriteFile(path, []byte("http://from-a-file:8080\n"), 0o600)
+	err := os.WriteFile(path, []byte(backendURL+"\n"), 0o600)
 	if err != nil {
 		t.Fatalf("write: %v", err)
 	}
 
-	_, err = rproxyConfig(map[string]string{wafBackend + "_FILE": path})
+	cfg, err := rproxyConfig(map[string]string{wafBackend + "_FILE": path})
-	if err == nil || !strings.HasPrefix(err.Error(), wafBackend+": is required") {
-		t.Errorf("error %v, want %s still required", err, wafBackend)
-	}
-
-	cfg, err := rproxyConfig(map[string]string{
-		wafBackend:              backendURL,
-		rproxyTimeout + "_FILE": "/nonexistent/timeout",
-	})
 	if err != nil {
-		t.Fatalf("settings: %v, with the file left unread", err)
+		t.Fatalf("settings: %v", err)
 	}
 
-	if cfg.Timeout != 2*time.Second {
+	if cfg.WAFBackend.String() != backendURL {
-		t.Errorf("timeout %v, want the default", cfg.Timeout)
+		t.Errorf("backend %v, want %s", cfg.WAFBackend, backendURL)
+	}
+}
+
+func TestRProxyUnreadableSettingFileStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+
+	for _, path := range []string{filepath.Join(dir, "missing"), dir} {
+		_, err := rproxyConfig(map[string]string{
+			wafBackend:              backendURL,
+			rproxyTimeout + "_FILE": path,
+		})
+
+		want := rproxyTimeout + "_FILE: cannot be read: "
+		if err == nil || !strings.HasPrefix(err.Error(), want) {
+			t.Errorf("%s: error %v, want one starting %s", path, err, want)
+		}
 	}
 }
 

internal/config/viper.go

@@ -0,0 +1,16 @@
+package config
+
+import "github.com/spf13/viper"
+
+// NewViper returns the viper that reads the settings: each setting's
+// environment variable, bound to its own name. Every setting of servewaf and
+// rproxy is read through it, and none is read with os.Getenv or os.LookupEnv
+// outside it. An environment variable that is set but empty is set, as one
+// that holds a value is, which viper does not take for granted.
+func NewViper() *viper.Viper {
+	v := viper.New()
+	v.AutomaticEnv()
+	v.AllowEmptyEnv(true)
+
+	return v
+}

internal/rproxy/limits_test.go

@@ -33,13 +33,9 @@ func announcedLength(size int) string {
 func TestServerHasTheFixedLimits(t *testing.T) {
 	t.Parallel()
 
-	cfg, err := config.RProxyFromEnvironment(func(name string) (string, bool) {
+	cfg, err := config.RProxyFromEnvironment(viperFrom(map[string]string{
-		if name == "SWRP_WAF_BACKEND" {
+		"SWRP_WAF_BACKEND": nowhere,
-			return nowhere, true
+	}))
-		}
-
-		return "", false
-	})
 	if err != nil {
 		t.Fatalf("settings: %v", err)
 	}

internal/rproxy/rproxy_test.go

@@ -18,6 +18,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rproxy"
@@ -341,6 +343,17 @@ func startServer(
 	return addr, out, server
 }
 
+// viperFrom returns a viper Set with each of settings, as the viper
+// config.NewViper returns one bound to a process's environment.
+func viperFrom(settings map[string]string) *viper.Viper {
+	v := viper.New()
+	for name, value := range settings {
+		v.Set(name, value)
+	}
+
+	return v
+}
+
 // startServerLogging is startServer with rproxy's request lines going to
 // requestLog and its process lines to processLog.
 func startServerLogging(
@@ -354,11 +367,7 @@ func startServerLogging(
 	}
 	maps.Copy(settings, env)
 
-	cfg, err := config.RProxyFromEnvironment(func(name string) (string, bool) {
+	cfg, err := config.RProxyFromEnvironment(viperFrom(settings))
-		value, ok := settings[name]
-
-		return value, ok
-	})
 	if err != nil {
 		t.Fatalf("settings %v: %v", settings, err)
 	}

internal/servewaf/proxy_test.go

@@ -15,6 +15,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
@@ -347,6 +349,17 @@ func serve(t *testing.T, server *servewaf.Server) {
 // at serveWAFAddr, with the settings in env on top of the defaults, and returns
 // where it listens. What it writes is dropped. SWRP_TIMEOUT_MS is a minute unless
 // env sets it, so that on a busy host SWRP_DEFAULT_DISPOSITION does not decide.
+// viperFrom returns a viper Set with each of settings, as the viper
+// config.NewViper returns one bound to a process's environment.
+func viperFrom(settings map[string]string) *viper.Viper {
+	v := viper.New()
+	for name, value := range settings {
+		v.Set(name, value)
+	}
+
+	return v
+}
+
 func startRProxy(
 	t *testing.T, serveWAFAddr, appURL string, env map[string]string,
 ) string {
@@ -359,11 +372,7 @@ func startRProxy(
 	}
 	maps.Copy(settings, env)
 
-	cfg, err := config.RProxyFromEnvironment(func(name string) (string, bool) {
+	cfg, err := config.RProxyFromEnvironment(viperFrom(settings))
-		value, ok := settings[name]
-
-		return value, ok
-	})
 	if err != nil {
 		t.Fatalf("settings %v: %v", settings, err)
 	}
@@ -423,11 +432,7 @@ func newServeWAFWith(
 
 	maps.Copy(settings, env)
 
-	cfg, err := config.FromEnvironment(func(name string) (string, bool) {
+	cfg, err := config.FromEnvironment(viperFrom(settings))
-		value, ok := settings[name]
-
-		return value, ok
-	})
 	if err != nil {
 		t.Fatalf("settings %v: %v", settings, err)
 	}

internal/smallwebwaf/healthcheck.go

@@ -10,6 +10,8 @@ import (
 	"net/url"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/servewaf"
 )
@@ -31,7 +33,7 @@ var errHealthEndpoint = errors.New("the health endpoint answered")
 // args are the arguments after `healthcheck`; it takes none, and given
 // one it names it on stderr and returns 1 without checking anything.
 func HealthCheck(
-	ctx context.Context, args []string, lookupEnv func(string) (string, bool),
+	ctx context.Context, args []string, v *viper.Viper,
 	stderr io.Writer,
 ) int {
 	if len(args) > 0 {
@@ -44,15 +46,15 @@ func HealthCheck(
 	ctx, cancel := context.WithTimeout(ctx, healthCheckTimeout)
 	defer cancel()
 
-	command, err := config.Command(lookupEnv)
+	command, err := config.Command(v)
 
 	switch {
 	case err != nil:
 		err = fmt.Errorf("invalid setting: %w", err)
 	case command == "servewaf":
-		err = checkServeWAF(ctx, lookupEnv)
+		err = checkServeWAF(ctx, v)
 	default:
-		err = checkRProxyAndApp(ctx, lookupEnv)
+		err = checkRProxyAndApp(ctx, v)
 	}
 
 	if err != nil {
@@ -65,8 +67,8 @@ func HealthCheck(
 }
 
 // checkServeWAF asks servewaf's health endpoint.
-func checkServeWAF(ctx context.Context, lookupEnv func(string) (string, bool)) error {
+func checkServeWAF(ctx context.Context, v *viper.Viper) error {
-	listenAddr, err := config.ServeWAFListenAddr(lookupEnv)
+	listenAddr, err := config.ServeWAFListenAddr(v)
 	if err != nil {
 		return fmt.Errorf("invalid setting: %w", err)
 	}
@@ -81,9 +83,9 @@ func checkServeWAF(ctx context.Context, lookupEnv func(string) (string, bool)) e
 
 // checkRProxyAndApp asks rproxy's health endpoint, and connects to the app.
 func checkRProxyAndApp(
-	ctx context.Context, lookupEnv func(string) (string, bool),
+	ctx context.Context, v *viper.Viper,
 ) error {
-	listenAddr, upstreamURL, err := config.RProxyListenAddrAndUpstreamURL(lookupEnv)
+	listenAddr, upstreamURL, err := config.RProxyListenAddrAndUpstreamURL(v)
 	if err != nil {
 		return fmt.Errorf("invalid setting: %w", err)
 	}

internal/smallwebwaf/healthcheck_test.go

@@ -125,11 +125,12 @@ func TestHealthCheckInRProxysContainer(t *testing.T) {
 	wantHealthCheck(t, settings(rproxyListenAddr, "8080"), 1,
 		"unhealthy: invalid setting: SWRP_LISTEN_ADDR: ")
 
-	// No setting of rproxy's has a form given as a file.
+	// A setting of rproxy's can be given as a file too, here the listen
+	// address, which the health check reads.
 	wantHealthCheck(t, map[string]string{
 		rproxyListenAddr + "_FILE": writeFile(t, ":"+port+"\n"),
 		rproxyUpstreamURL:          app.URL,
-	}, 1, "unhealthy: ask rproxy: ")
+	}, 0, "")
 }
 
 func TestHealthCheckFailsWithAnyOtherCommand(t *testing.T) {
@@ -145,11 +146,7 @@ func TestHealthCheckRefusesAnArgument(t *testing.T) {
 
 	var stderr bytes.Buffer
 
-	noSettings := func(string) (string, bool) {
+	got := smallwebwaf.HealthCheck(t.Context(), []string{"now"}, viperFrom(nil), &stderr)
-		return "", false
-	}
-
-	got := smallwebwaf.HealthCheck(t.Context(), []string{"now"}, noSettings, &stderr)
 
 	want := "smallwebwaf healthcheck: unexpected argument \"now\"\n"
 	if got != 1 || stderr.String() != want {
@@ -166,11 +163,7 @@ func wantHealthCheck(t *testing.T, env map[string]string, status int, message st
 
 	var stderr bytes.Buffer
 
-	got := smallwebwaf.HealthCheck(t.Context(), nil, func(name string) (string, bool) {
+	got := smallwebwaf.HealthCheck(t.Context(), nil, viperFrom(env), &stderr)
-		value, ok := env[name]
-
-		return value, ok
-	}, &stderr)
 
 	wrote := stderr.String()
 	if got != status || !strings.HasPrefix(wrote, message) ||

internal/smallwebwaf/rproxy.go

@@ -23,7 +23,7 @@ func RunRProxy(ctx context.Context, params Params) int {
 	hostname, _ := os.Hostname() // "" when the host has no name to give
 	processLog := requestlog.NewProcessLogger(params.Stdout, hostname, slog.LevelInfo)
 
-	cfg, err := config.RProxyFromEnvironment(params.LookupEnv)
+	cfg, err := config.RProxyFromEnvironment(params.Viper)
 	if err != nil {
 		processLog.Error("invalid setting", "error", err.Error())
 

internal/smallwebwaf/rproxy_test.go

@@ -43,11 +43,7 @@ const (
 func runRProxy(ctx context.Context, env map[string]string, out *output) int {
 	return smallwebwaf.RunRProxy(ctx, smallwebwaf.Params{
 		Version: testVersion,
-		LookupEnv: func(name string) (string, bool) {
+		Viper:   viperFrom(env),
-			value, ok := env[name]
-
-			return value, ok
-		},
 		Stdout:  out,
 	})
 }

internal/smallwebwaf/smallwebwaf.go

@@ -20,6 +20,8 @@ import (
 	"syscall"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
@@ -59,8 +61,9 @@ commands:
 type Params struct {
 	// Version is the version of the binary, set when it is built.
 	Version string
-	// LookupEnv reads an environment variable, normally os.LookupEnv.
+	// Viper reads the settings, normally the viper config.NewViper returns
-	LookupEnv func(string) (string, bool)
+	// for the process's environment.
+	Viper *viper.Viper
 	// Stdout receives the request log and the process's own messages.
 	Stdout io.Writer
 }
@@ -79,7 +82,7 @@ func Main(version string) int {
 		syscall.SIGTERM, os.Interrupt)
 	defer stop()
 
-	params := Params{Version: version, LookupEnv: os.LookupEnv, Stdout: os.Stdout}
+	params := Params{Version: version, Viper: config.NewViper(), Stdout: os.Stdout}
 
 	switch args[0] {
 	case "rproxy":
@@ -87,7 +90,7 @@ func Main(version string) int {
 	case "servewaf":
 		return RunServeWAF(ctx, params)
 	case "healthcheck":
-		return HealthCheck(ctx, args[1:], os.LookupEnv, os.Stderr)
+		return HealthCheck(ctx, args[1:], params.Viper, os.Stderr)
 	default:
 		return printUsage(os.Stderr)
 	}
@@ -107,9 +110,9 @@ func RunServeWAF(ctx context.Context, params Params) int {
 	// Until the settings are read, the one message is an invalid setting's
 	// error, which every SWWAF_LOG_LEVEL lets through.
 	processLog := requestlog.NewProcessLogger(params.Stdout,
-		config.InstanceName(params.LookupEnv), slog.LevelError)
+		config.InstanceName(params.Viper), slog.LevelError)
 
-	cfg, err := config.FromEnvironment(params.LookupEnv)
+	cfg, err := config.FromEnvironment(params.Viper)
 	if err != nil {
 		processLog.Error("invalid setting", "error", err.Error())
 

internal/smallwebwaf/smallwebwaf_test.go

@@ -19,6 +19,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup/lookuptest"
 	"sneak.berlin/go/smallwebwaf/internal/servewaf"
@@ -123,20 +125,29 @@ func (o *output) text() string {
 	return o.buf.String()
 }
 
+// viperFrom returns a viper Set with each of settings, as the viper
+// config.NewViper returns one bound to a process's environment.
+func viperFrom(settings map[string]string) *viper.Viper {
+	v := viper.New()
+	for name, value := range settings {
+		v.Set(name, value)
+	}
+
+	return v
+}
+
 // run runs `smallwebwaf servewaf` with the settings in env until ctx is done,
 // and returns its exit status. SWWAF_LOOKUP_SOURCE is off unless env sets it,
 // so that no test sends GeoJS its clients' addresses.
 func run(ctx context.Context, env map[string]string, out *output) int {
-	return smallwebwaf.RunServeWAF(ctx, smallwebwaf.Params{
+	v := viperFrom(env)
-		Version: testVersion,
+	if _, set := env["SWWAF_LOOKUP_SOURCE"]; !set {
-		LookupEnv: func(name string) (string, bool) {
+		v.Set("SWWAF_LOOKUP_SOURCE", "off")
-			value, ok := env[name]
-			if !ok && name == "SWWAF_LOOKUP_SOURCE" {
-				return "off", true
 	}
 
-			return value, ok
+	return smallwebwaf.RunServeWAF(ctx, smallwebwaf.Params{
-		},
+		Version: testVersion,
+		Viper:   v,
 		Stdout:  out,
 	})
 }