Deploy: main into prod (#343)

Brings `prod`, which upaas deploys, up to `main` at `9cf9cdd`, the merge of #321. `prod` was cut from `main` at `251cb3d` (1.0.0b1).

What it deploys is everything listed in #321. For running it:

- With `WEBHOOKER_ENVIRONMENT` unset, the instance runs as `prod` and sends no `Access-Control-Allow-Origin: *`.
- Each event database gains its new indexes the first time it is opened after the upgrade.
- `webhooker_delivery_retries_total` no longer counts a circuit breaker holding back a delivery that is already `retrying`.

Not in this PR yet: #340, in which the container sets its own data directory owner and mode before start. It is in progress on `next`. Once it reaches `main`, this PR carries it, because the PR follows `main`.

Model: opus-5-5
Co-authored-by: Jeffrey Paul <1+sneak@noreply.example.org>
Reviewed-on: #343

internal/config/config.go

@@ -192,9 +192,10 @@ type Config struct {
 	// alwaysBlockedNetworks stays blocked no matter what is listed
 	// here. That set is link-local plus the cloud metadata
 	// endpoints outside it that disclose credentials or user data
-	// at a provider-fixed address; it is not exhaustive of every
-	// cloud's metadata address. See alwaysBlockedNetworks for the
-	// authoritative list and the criterion it is built from.
+	// at a provider-fixed, non-public address; it is not
+	// exhaustive of every cloud's metadata address. See
+	// alwaysBlockedNetworks for the authoritative list and the
+	// criterion it is built from.
 	AllowedEgressCIDRs []netip.Prefix
 
 	params *ConfigParams
@@ -585,12 +586,14 @@ func resolveMetricsAuth() (string, string, error) {
 	)
 }
 
-// resolveEnvironment reads WEBHOOKER_ENVIRONMENT, defaulting to
-// dev, and rejects unrecognised values.
+// resolveEnvironment reads WEBHOOKER_ENVIRONMENT, defaulting to prod
+// when it is unset so a deployment that forgets the variable is not
+// silently permissive; dev must be set explicitly. It rejects
+// unrecognised values.
 func resolveEnvironment() (string, error) {
 	environment := os.Getenv("WEBHOOKER_ENVIRONMENT")
 	if environment == "" {
-		environment = EnvironmentDev
+		environment = EnvironmentProd
 	}
 
 	if environment != EnvironmentDev &&
@@ -744,12 +747,14 @@ func (c *Config) warnEgressAllowlist(log *slog.Logger) {
 
 	log.Warn(
 		"ALLOWED_EGRESS_CIDRS lets delivery targets reach these "+
-			"otherwise-blocked private/reserved networks. Anyone "+
-			"who can create a delivery target can now make this "+
-			"process issue requests into them, and read back the "+
-			"response. Link-local and the known cloud instance "+
-			"metadata endpoints outside it stay blocked "+
-			"regardless of what is listed here.",
+			"otherwise-blocked networks. Anyone who can create a "+
+			"delivery target can now make this process issue "+
+			"requests into them, and read back the response. Only "+
+			"the addresses the README lists as blocked "+
+			"unconditionally stay blocked regardless of what is "+
+			"listed here; a public cloud metadata address such as "+
+			"168.63.129.16 is reachable once it, or a block "+
+			"covering it, is listed.",
 		"allowedEgressCIDRs",
 		strings.Join(PrefixStrings(c.AllowedEgressCIDRs), ","),
 	)
@@ -772,10 +777,8 @@ func (c *Config) warnEgressAllowlist(log *slog.Logger) {
 // everyone else's wrong passwords, and the receiver's limits become
 // service-wide ceilings.
 //
-// The warning is deliberately not gated on WEBHOOKER_ENVIRONMENT. That
-// variable defaults to dev, so gating on it would silence the warning
-// for exactly the operator who forgot to configure the deployment —
-// the case it exists to catch.
+// The warning is deliberately not gated on WEBHOOKER_ENVIRONMENT:
+// behind a proxy every client shares one bucket in dev and prod alike.
 //
 // The default of trusting nobody is deliberate — trusting forwarded
 // headers from arbitrary peers lets any client choose its own bucket —

internal/config/config_test.go

@@ -44,9 +44,9 @@ func TestEnvironmentConfig(t *testing.T) {
 		isProd      bool
 	}{
 		{
-			name:   "default is dev",
-			isDev:  true,
-			isProd: false,
+			name:   "default is prod",
+			isDev:  false,
+			isProd: true,
 		},
 		{
 			name:     "explicit dev",
@@ -834,12 +834,13 @@ func TestEgressAllowlistWarning(t *testing.T) {
 			// to be able to read back which networks are open.
 			assert.Contains(t, logged, "10.0.0.0/8")
 			assert.Contains(t, logged, "127.0.0.0/8")
-			// What stays shut. Asserted on the clause naming the
-			// wider set rather than on "Link-local" alone, so the
-			// string cannot narrow back to link-local only while
-			// the always-blocked set covers ULA, CGNAT and two
-			// public metadata addresses as well.
-			assert.Contains(t, logged, "metadata endpoints outside it")
+			// What stays shut is the whole unconditional set, not
+			// link-local alone; a public metadata address is not in
+			// it, so a listed block covering it opens it.
+			assert.Contains(t, logged, "blocked unconditionally")
+			assert.Contains(t, logged, "168.63.129.16 is reachable")
+			// The listed blocks need not be private or reserved.
+			assert.NotContains(t, logged, "private/reserved")
 		})
 	}
 }
@@ -848,10 +849,9 @@ func TestEgressAllowlistWarning(t *testing.T) {
 // tells an operator a deployment behind a reverse proxy shares one
 // rate-limit bucket between every client, which turns the receiver
 // limits into service-wide ceilings and collapses login failure
-// counting. It must fire whenever TRUSTED_PROXIES is empty,
-// in any environment: WEBHOOKER_ENVIRONMENT defaults to dev, so gating
-// on it would silence the warning for exactly the operator who never
-// configured the deployment. It stays quiet once proxies are named.
+// counting. It must fire whenever TRUSTED_PROXIES is empty, in any
+// environment, because behind a proxy every client shares one bucket
+// in dev and prod alike. It stays quiet once proxies are named.
 func TestSharedRateLimitBucketWarning(t *testing.T) {
 	tests := []struct {
 		name           string
@@ -871,10 +871,6 @@ func TestSharedRateLimitBucketWarning(t *testing.T) {
 			expectWarning:  false,
 		},
 		{
-			// The default environment. An internet-exposed
-			// deployment whose operator never set
-			// WEBHOOKER_ENVIRONMENT lands here and has exactly
-			// the exposure the warning announces.
 			name:          "dev without trusted proxies warns",
 			environment:   config.EnvironmentDev,
 			expectWarning: true,