Function Manifest

The function manifest declares per-function configuration for the Thunder runtime. It controls the deploy flavor, routing, environment access, network allowlists, and resource limits.

• Schema: schemas/function-manifest.v2.schema.json
• JSON Schema draft: 2020-12

Versioning

The runtime accepts only manifestVersion: 2. Payloads with manifestVersion: 1 are rejected.

{
  "manifestVersion": 2
}

---

Flavors

Flavor	Description
single	Single-entrypoint function. Must not define routes.
routed-app	Multi-route application. Must define at least one route.

---

Schema Fields

Required Fields

Field	Type	Description
manifestVersion	2 (integer)	Schema version (must be 2)
name	string	Function name/slug
entrypoint	string	Entry JS/TS file path
flavor	"single" or "routed-app"	Deploy flavor
network	object	Network access policy (required)

Optional Fields

Field	Type	Description
routes	array	Route table (required for routed-app, forbidden for single)
env	object	Environment variable access controls
resources	object	Isolate resource limits
auth	object	Authentication preferences
observability	object	Logging and tracing preferences
profiles	object	Environment-specific overrides

---

env

Controls which environment variables the function can access.

Field	Type	Description
allow	string[]	List of environment variable names the function can read
secretRefs	string[]	Secret variable names resolved at runtime

{
  "env": {
    "allow": ["LOG_LEVEL", "API_BASE_URL"],
    "secretRefs": ["APP_SECRET", "DATABASE_URL"]
  }
}

---

network

Network access policy enforced per function.

Field	Type	Description
mode	"allowlist"	Network mode (only allowlist is supported)
allow	string[]	List of allowed targets (host:port format). Minimum 1 item

{
  "network": {
    "mode": "allowlist",
    "allow": [
      "api.example.com:443",
      "db.internal.corp:5432"
    ]
  }
}

Wildcard (*) is not allowed in network.allow. Targets that collide with SSRF deny ranges are rejected at deploy time.

SSRF Deny Ranges

The runtime blocks the following ranges regardless of manifest configuration:

Range	Description
127.0.0.0/8	Loopback
10.0.0.0/8	RFC 1918 private
172.16.0.0/12	RFC 1918 private
192.168.0.0/16	RFC 1918 private
169.254.0.0/16	Link-local / cloud metadata
0.0.0.0/8	Reserved
::1/128	IPv6 loopback
fc00::/7	IPv6 unique local
fe80::/10	IPv6 link-local

---

resources

Per-function isolate resource limits. These override the runtime defaults when set.

Field	Type	Default	Description
maxHeapMiB	integer	128	Per-isolate heap limit in MiB. 0 = unlimited
cpuTimeMs	integer	50000	Per-request CPU time limit in ms. 0 = unlimited
wallClockTimeoutMs	integer	60000	Per-request wall clock timeout in ms. 0 = unlimited
vfsTotalQuotaBytes	integer	10485760	Writable VFS quota per isolate (10 MiB)
vfsMaxFileBytes	integer	5242880	Max writable file size in VFS (5 MiB)
egressMaxRequestsPerExecution	integer	—	Max outbound requests per execution

{
  "resources": {
    "maxHeapMiB": 256,
    "cpuTimeMs": 30000,
    "wallClockTimeoutMs": 45000,
    "vfsTotalQuotaBytes": 20971520,
    "vfsMaxFileBytes": 10485760
  }
}

---

routes

Route table for routed-app flavor. Each route is either a function route or an asset route.

Function Route

Field	Type	Required	Description
kind	"function"	yes	Route type
path	string	yes	URL path prefix (must start with /)
entrypoint	string	yes	JS/TS entrypoint file
methods	string[]	no	Allowed HTTP methods

Asset Route

Field	Type	Required	Description
kind	"asset"	yes	Route type
path	string	yes	URL path prefix (must start with /)
assetDir	string	yes	Directory containing static files
methods	string[]	no	Only GET and HEAD are allowed

{
  "routes": [
    {
      "kind": "function",
      "path": "/api",
      "entrypoint": "./api/index.ts",
      "methods": ["GET", "POST"]
    },
    {
      "kind": "asset",
      "path": "/static",
      "assetDir": "./public"
    }
  ]
}

Validation Rules

• single flavor must not define routes.
• routed-app flavor must define at least one route.
• Function routes require a non-empty entrypoint and cannot define assetDir.
• Asset routes require a non-empty assetDir and cannot define entrypoint.
• Asset route methods, if provided, can only contain GET and HEAD.
• Routes are validated for path/method collisions at bundle time. Ambiguous overlaps fail the build.

---

auth

Field	Type	Description
verifyJwt	boolean	Whether to verify JWT tokens

{
  "auth": {
    "verifyJwt": true
  }
}

---

observability

Field	Type	Description
logLevel	string	Log level for the function
traceSamplePercent	integer	Trace sampling percentage (0-100)

{
  "observability": {
    "logLevel": "info",
    "traceSamplePercent": 10
  }
}

---

profiles

Profiles provide environment-specific overrides. Profile names must match ^[a-z][a-z0-9_-]{0,31}$.

Each profile can override: env, network, resources, auth, and observability.

{
  "profiles": {
    "staging": {
      "env": {
        "allow": ["LOG_LEVEL", "STAGING_API_URL"],
        "secretRefs": ["STAGING_SECRET"]
      },
      "network": {
        "allow": ["staging-api.example.com:443"]
      },
      "resources": {
        "maxHeapMiB": 64,
        "cpuTimeMs": 10000
      }
    },
    "production": {
      "env": {
        "allow": ["LOG_LEVEL"],
        "secretRefs": ["PROD_SECRET", "DATABASE_URL"]
      },
      "network": {
        "allow": ["api.example.com:443", "db.prod.internal:5432"]
      },
      "resources": {
        "maxHeapMiB": 256,
        "cpuTimeMs": 50000
      }
    }
  }
}

Select a profile at deploy time with the x-function-manifest-profile header.

---

Deploy API Integration

When deploying a function via POST /_internal/functions, the manifest is provided as a Base64-encoded JSON string in the x-function-manifest-b64 header.

MANIFEST_B64=$(base64 < function.manifest.json)

curl -X POST \
  -H "X-API-Key: $KEY" \
  -H "x-function-name: hello" \
  -H "x-function-manifest-b64: $MANIFEST_B64" \
  --data-binary @hello.eszip \
  http://localhost:9000/_internal/functions

To select a profile:

curl -X POST \
  -H "X-API-Key: $KEY" \
  -H "x-function-name: hello" \
  -H "x-function-manifest-b64: $MANIFEST_B64" \
  -H "x-function-manifest-profile: production" \
  --data-binary @hello.eszip \
  http://localhost:9000/_internal/functions

If the header is absent but the uploaded bundle contains an embedded manifest (from thunder bundle --manifest), the runtime resolves and applies the embedded manifest.

Validation Pipeline

1. JSON decode / parse
2. JSON Schema validation (v2, draft 2020-12)
3. Semantic checks (flavor/routes rules, SSRF denylist)

If any step fails, the response is 400 Bad Request.

Update and Reload Behavior

• PUT /_internal/functions/{name}: replaces the manifest if x-function-manifest-b64 is provided; preserves the existing manifest if omitted.
• POST /_internal/functions/{name}/reload: preserves the currently attached manifest.

Inspecting the Current Manifest

curl -H "X-API-Key: $KEY" \
  http://localhost:9000/_internal/functions/hello/manifest

Returns 200 with the resolved manifest, or 404 if no manifest is attached.

---

Example: Single Flavor

{
  "$schema": "https://thunder.dev/schemas/function-manifest.v2.schema.json",
  "manifestVersion": 2,
  "name": "hello",
  "entrypoint": "./index.ts",
  "flavor": "single",
  "env": {
    "allow": ["LOG_LEVEL"],
    "secretRefs": ["APP_SECRET"]
  },
  "network": {
    "mode": "allowlist",
    "allow": ["api.example.com:443"]
  },
  "resources": {
    "maxHeapMiB": 128,
    "cpuTimeMs": 50000,
    "wallClockTimeoutMs": 60000
  }
}

Example: Routed App Flavor

{
  "$schema": "https://thunder.dev/schemas/function-manifest.v2.schema.json",
  "manifestVersion": 2,
  "name": "my-app",
  "entrypoint": "./app/main.ts",
  "flavor": "routed-app",
  "network": {
    "mode": "allowlist",
    "allow": ["api.example.com:443", "cdn.example.com:443"]
  },
  "routes": [
    {
      "kind": "function",
      "path": "/api/users",
      "entrypoint": "./app/routes/users.ts",
      "methods": ["GET", "POST"]
    },
    {
      "kind": "function",
      "path": "/api/health",
      "entrypoint": "./app/routes/health.ts",
      "methods": ["GET"]
    },
    {
      "kind": "asset",
      "path": "/static",
      "assetDir": "./public"
    }
  ],
  "env": {
    "allow": ["NODE_ENV"],
    "secretRefs": ["DATABASE_URL"]
  },
  "resources": {
    "maxHeapMiB": 256,
    "cpuTimeMs": 30000,
    "wallClockTimeoutMs": 45000
  },
  "profiles": {
    "staging": {
      "network": {
        "allow": ["staging-api.example.com:443"]
      },
      "resources": {
        "maxHeapMiB": 64
      }
    }
  }
}

---

Watch Mode Note

thunder watch deploys functions without attaching a manifest. To use manifest-enforced behavior during development, deploy via the admin endpoint with the x-function-manifest-b64 header.