Support NextJS SPAs

core/__snapshots__/TestGenerateBuildPlanForExamples_node-next-spa_1.snap.json

@@ -0,0 +1,220 @@
+{
+ "caches": {
+  "apt": {
+   "directory": "/var/cache/apt",
+   "type": "locked"
+  },
+  "apt-lists": {
+   "directory": "/var/lib/apt/lists",
+   "type": "locked"
+  },
+  "next": {
+   "directory": "/app/.next/cache",
+   "type": "shared"
+  },
+  "node-modules": {
+   "directory": "/app/node_modules/.cache",
+   "type": "shared"
+  },
+  "npm-install": {
+   "directory": "/root/.npm",
+   "type": "shared"
+  }
+ },
+ "deploy": {
+  "base": {
+   "step": "packages:apt:runtime"
+  },
+  "inputs": [
+   {
+    "include": [
+     "/railpack/caddy"
+    ],
+    "step": "packages:caddy"
+   },
+   {
+    "include": [
+     "/Caddyfile"
+    ],
+    "step": "caddy"
+   },
+   {
+    "include": [
+     "out"
+    ],
+    "step": "build"
+   }
+  ],
+  "startCommand": "caddy run --config /Caddyfile --adapter caddyfile 2\u003e\u00261",
+  "variables": {
+   "CI": "true",
+   "NODE_ENV": "production",
+   "NPM_CONFIG_FUND": "false",
+   "NPM_CONFIG_PRODUCTION": "false",
+   "NPM_CONFIG_UPDATE_NOTIFIER": "false"
+  }
+ },
+ "steps": [
+  {
+   "assets": {
+    "generated-mise-toml": "[generated-mise-toml]"
+   },
+   "commands": [
+    {
+     "path": "/mise/shims"
+    },
+    {
+     "customName": "create mise config",
+     "name": "generated-mise-toml",
+     "path": "/etc/mise/config.toml"
+    },
+    {
+     "cmd": "mise install",
+     "customName": "install mise packages: node"
+    }
+   ],
+   "inputs": [
+    {
+     "image": "ghcr.io/railwayapp/railpack-builder:mise-2026.3.16"
+    }
+   ],
+   "name": "packages:mise",
+   "variables": {
+    "MISE_CACHE_DIR": "/mise/cache",
+    "MISE_CONFIG_DIR": "/mise",
+    "MISE_DATA_DIR": "/mise",
+    "MISE_INSTALLS_DIR": "/mise/installs",
+    "MISE_SHIMS_DIR": "/mise/shims"
+   }
+  },
+  {
+   "caches": [
+    "npm-install"
+   ],
+   "commands": [
+    {
+     "path": "/app/node_modules/.bin"
+    },
+    {
+     "cmd": "mkdir -p /app/node_modules/.cache"
+    },
+    {
+     "dest": "package-lock.json",
+     "src": "package-lock.json"
+    },
+    {
+     "dest": "package.json",
+     "src": "package.json"
+    },
+    {
+     "cmd": "npm ci"
+    }
+   ],
+   "inputs": [
+    {
+     "step": "packages:mise"
+    }
+   ],
+   "name": "install",
+   "variables": {
+    "CI": "true",
+    "NODE_ENV": "production",
+    "NPM_CONFIG_FUND": "false",
+    "NPM_CONFIG_PRODUCTION": "false",
+    "NPM_CONFIG_UPDATE_NOTIFIER": "false"
+   }
+  },
+  {
+   "caches": [
+    "node-modules",
+    "next"
+   ],
+   "commands": [
+    {
+     "cmd": "npm run build"
+    }
+   ],
+   "inputs": [
+    {
+     "step": "install"
+    },
+    {
+     "include": [
+      "."
+     ],
+     "local": true
+    }
+   ],
+   "name": "build",
+   "secrets": [
+    "*"
+   ],
+   "variables": {
+    "NEXT_TELEMETRY_DISABLED": "1"
+   }
+  },
+  {
+   "commands": [
+    {
+     "cmd": "mise install-into caddy@2.11.2 /railpack/caddy"
+    },
+    {
+     "path": "/railpack/caddy"
+    },
+    {
+     "path": "/railpack/caddy/bin"
+    }
+   ],
+   "inputs": [
+    {
+     "image": "ghcr.io/railwayapp/railpack-builder:mise-2026.3.16"
+    }
+   ],
+   "name": "packages:caddy",
+   "variables": {
+    "MISE_PARANOID": "1"
+   }
+  },
+  {
+   "assets": {
+    "Caddyfile": "# global options\n{\n\tadmin off\n\tpersist_config off\n\tauto_https off\n\n\tlog {\n\t\tformat json\n\t}\n\n\tservers {\n\t\ttrusted_proxies static private_ranges 100.0.0.0/8 # trust railway's proxy\n\t}\n}\n\n# site block, listens on the $PORT environment variable, automatically assigned by railway\n:{$PORT:80} {\n\tlog {\n\t\tformat json\n\t}\n\n\trespond /health 200\n\n\t# Security headers\n\theader {\n\t\t# Prevent some browsers from MIME-sniffing a response away from the declared Content-Type\n\t\tX-Content-Type-Options \"nosniff\"\n\t\t# Remove Server header\n\t\t-Server\n\t}\n\n\t# serve from the 'dist' folder (Vite builds into the 'dist' folder)\n\troot * /app/out\n\n\t# Handle static files\n\tfile_server {\n\t\thide .git\n\t\thide .env*\n\t}\n\n\t# Compression with more formats\n\tencode {\n\t\tgzip\n\t\tzstd\n\t}\n\n\t# Try files with HTML extension and handle SPA routing\n\ttry_files {path} {path}.html {path}/index.html /index.html\n}\n"
+   },
+   "commands": [
+    {
+     "name": "Caddyfile",
+     "path": "/Caddyfile"
+    },
+    {
+     "cmd": "caddy fmt --overwrite /Caddyfile"
+    }
+   ],
+   "inputs": [
+    {
+     "step": "packages:caddy"
+    }
+   ],
+   "name": "caddy",
+   "secrets": [
+    "*"
+   ]
+  },
+  {
+   "caches": [
+    "apt",
+    "apt-lists"
+   ],
+   "commands": [
+    {
+     "cmd": "sh -c 'apt-get update \u0026\u0026 apt-get install -y libatomic1'",
+     "customName": "install apt packages: libatomic1"
+    }
+   ],
+   "inputs": [
+    {
+     "image": "ghcr.io/railwayapp/railpack-runtime:mise-2026.3.16"
+    }
+   ],
+   "name": "packages:apt:runtime"
+  }
+ ]
+}

core/app/app.go

@@ -15,6 +15,8 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+var ErrNoFileFound = errors.New("unable to find a matching file")
+
 type App struct {
 	Source    string
 	globCache map[string][]string
@@ -142,6 +144,24 @@ func (a *App) FindFilesWithContent(pattern string, regex *regexp.Regexp) []strin
 	return matches
 }
 
+// ReadFirstFileOf reads the contents of the first file that exists within the application source directory
+func (a *App) ReadFirstFileOf(names ...string) (string, string, error) {
+	for _, name := range names {
+		if !a.HasFile(name) {
+			continue
+		}
+
+		contents, err := a.ReadFile(name)
+		if err != nil {
+			return "", "", err
+		}
+
+		return name, contents, nil
+	}
+
+	return "", "", ErrNoFileFound
+}
+
 // ReadFile reads the contents of a file within the application source directory
 func (a *App) ReadFile(name string) (string, error) {
 	path := filepath.Join(a.Source, name)

core/generate/template.go

@@ -2,8 +2,11 @@ package generate
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"text/template"
+
+	"github.com/railwayapp/railpack/core/app"
 )
 
 type TemplateFileResult struct {
@@ -14,21 +17,13 @@ type TemplateFileResult struct {
 // TemplateFiles will look the first file that exists in the list of potential files and render it with the given data
 // If no file is found, it will use the default contents and render it with the given data
 func (c *GenerateContext) TemplateFiles(potentialFiles []string, defaultContents string, data map[string]any) (*TemplateFileResult, error) {
-	contents := defaultContents
-	filename := ""
-
-	for _, potentialFilename := range potentialFiles {
-		if c.App.HasFile(potentialFilename) {
-			c, err := c.App.ReadFile(potentialFilename)
-			if err != nil {
-				return nil, err
-			}
-
-			contents = c
-			filename = potentialFilename
-
-			break
+	filename, contents, err := c.App.ReadFirstFileOf(potentialFiles...)
+	if err != nil {
+		if !errors.Is(err, app.ErrNoFileFound) {
+			return nil, err
 		}
+
+		contents = defaultContents
 	}
 
 	tmpl, err := template.New(filename).Parse(contents)

core/providers/java/gradle.go

@@ -64,16 +64,8 @@ func (p *JavaProvider) gradleCache(ctx *generate.GenerateContext) string {
 }
 
 func (p *JavaProvider) readBuildGradle(ctx *generate.GenerateContext) string {
-	filePath := "build.gradle"
-	if !ctx.App.HasFile(filePath) {
-		filePath = "build.gradle.kts"
-	}
-	result, err := ctx.App.ReadFile(filePath)
-	if err != nil {
-		return ""
-	} else {
-		return result
-	}
+	_, result, _ := ctx.App.ReadFirstFileOf("build.gradle", "build.gradle.kts")
+	return result
 }
 
 func isUsingSpringBoot(buildGradle string) bool {

core/providers/node/astro.go

@@ -56,21 +56,8 @@ func (p *NodeProvider) getAstroOutputDirectory(ctx *generate.GenerateContext) st
 }
 
 func (p *NodeProvider) getAstroConfigFileContents(ctx *generate.GenerateContext) string {
-	configFile := ""
-
-	if ctx.App.HasFile("astro.config.mjs") {
-		contents, err := ctx.App.ReadFile("astro.config.mjs")
-		if err == nil {
-			configFile = contents
-		}
-	} else if ctx.App.HasFile("astro.config.ts") {
-		contents, err := ctx.App.ReadFile("astro.config.ts")
-		if err == nil {
-			configFile = contents
-		}
-	}
-
-	return configFile
+	_, contents, _ := ctx.App.ReadFirstFileOf("astro.config.mjs", "astro.config.ts")
+	return contents
 }
 
 func (p *NodeProvider) getAstroEnvVars() map[string]string {

core/providers/node/next.go

@@ -0,0 +1,48 @@
+package node
+
+import (
+	"regexp"
+	"strings"
+
+	"github.com/railwayapp/railpack/core/generate"
+)
+
+const (
+	DefaultNextOutputDirectory = "out"
+	DefaultNextStartCommand    = "next start"
+)
+
+var nextConfigFiles = []string{
+	"next.config.js",
+	"next.config.mjs",
+	"next.config.ts",
+}
+
+func (p *NodeProvider) isNextSPA(ctx *generate.GenerateContext) bool {
+	if !p.isNext() {
+		return false
+	}
+
+	configFileContents := p.getNextConfigFileContents(ctx)
+	hasExportOutput := strings.Contains(configFileContents, "output: 'export'") || strings.Contains(configFileContents, "output: \"export\"")
+
+	return hasExportOutput
+}
+
+func (p *NodeProvider) getNextOutputDirectory(ctx *generate.GenerateContext) string {
+	configFileContents := p.getNextConfigFileContents(ctx)
+	if configFileContents != "" {
+		distDirRegex := regexp.MustCompile(`distDir:\s*['"](.+?)['"]`)
+		matches := distDirRegex.FindStringSubmatch(configFileContents)
+		if len(matches) > 1 {
+			return matches[1]
+		}
+	}
+
+	return DefaultNextOutputDirectory
+}
+
+func (p *NodeProvider) getNextConfigFileContents(ctx *generate.GenerateContext) string {
+	_, contents, _ := ctx.App.ReadFirstFileOf(nextConfigFiles...)
+	return contents
+}