Add S3-compatible storage backend

internal/config/load_test.go

@@ -155,6 +155,61 @@ pipelines:
 	}
 }
 
+func TestLoadFileDefaultsS3Config(t *testing.T) {
+	cfg := loadConfig(t, `
+pipelines:
+  - id: s3-defaults
+    source:
+      backend: s3
+      endpoint: http://127.0.0.1:9000
+      bucket: source
+      prefix: /incoming/reports/
+    destinations:
+      - id: archive
+        backend: s3
+        endpoint: http://127.0.0.1:9000
+        bucket: destination
+`)
+
+	source := cfg.Pipelines[0].Source
+	if got, want := source.Region, DefaultS3Region; got != want {
+		t.Fatalf("source region = %q, want %q", got, want)
+	}
+	if got, want := source.Prefix, "incoming/reports"; got != want {
+		t.Fatalf("source prefix = %q, want %q", got, want)
+	}
+	if !ForcePathStyle(source.ForcePath) {
+		t.Fatal("source force_path_style = false, want true")
+	}
+	destination := cfg.Pipelines[0].Destinations[0]
+	if got, want := destination.Region, DefaultS3Region; got != want {
+		t.Fatalf("destination region = %q, want %q", got, want)
+	}
+	if !ForcePathStyle(destination.ForcePath) {
+		t.Fatal("destination force_path_style = false, want true")
+	}
+}
+
+func TestLoadFilePreservesExplicitS3ForcePathStyleFalse(t *testing.T) {
+	cfg := loadConfig(t, `
+pipelines:
+  - id: s3-force-path
+    source:
+      backend: s3
+      endpoint: https://s3.example.com
+      bucket: source
+      force_path_style: false
+    destinations:
+      - id: archive
+        backend: local
+        path: /archive
+`)
+
+	if ForcePathStyle(cfg.Pipelines[0].Source.ForcePath) {
+		t.Fatal("force_path_style = true, want explicit false")
+	}
+}
+
 func TestLoadFileRejectsDuplicatePipelineIDs(t *testing.T) {
 	assertLoadError(t, `
 pipelines:
@@ -214,6 +269,19 @@ func TestLoadFileRejectsMissingRequiredFields(t *testing.T) {
 	}
 }
 
+func TestLoadFileRejectsInvalidS3Config(t *testing.T) {
+	tests := map[string]string{
+		"prefix traversal": `pipelines: [{id: reports, source: {backend: s3, endpoint: "https://s3.example.com", bucket: source, prefix: "../reports"}, destinations: [{id: archive, backend: local, path: /archive}]}]`,
+		"prefix backslash": `pipelines: [{id: reports, source: {backend: s3, endpoint: "https://s3.example.com", bucket: source, prefix: 'a\b'}, destinations: [{id: archive, backend: local, path: /archive}]}]`,
+		"partial creds":    `pipelines: [{id: reports, source: {backend: s3, endpoint: "https://s3.example.com", bucket: source, credentials: {access_key_id_env: ACCESS_KEY_ID}}, destinations: [{id: archive, backend: local, path: /archive}]}]`,
+	}
+	for name, body := range tests {
+		t.Run(name, func(t *testing.T) {
+			assertLoadError(t, body, "")
+		})
+	}
+}
+
 func TestLoadFileDefaultsSSHConfig(t *testing.T) {
 	cfg := loadConfig(t, `
 pipelines:
@@ -398,6 +466,7 @@ func TestExampleConfigsLoad(t *testing.T) {
 		"../../examples/local-html.yml",
 		"../../examples/fan-out.yml",
 		"../../examples/ssh-destination.yml",
+		"../../examples/s3-destination.yml",
 	} {
 		t.Run(path, func(t *testing.T) {
 			if _, err := LoadFile(path); err != nil {