|
| 1 | +--- |
| 2 | +type: docs |
| 3 | +title: "StructuredFormat" |
| 4 | +linkTitle: "StructuredFormat" |
| 5 | +description: Detailed information on the StructuredFormat name resolution component |
| 6 | +--- |
| 7 | + |
| 8 | + |
| 9 | +The **Structured Format** name resolver enables you to explicitly define service instances using structured configuration in **JSON or YAML**, either as inline strings or external files. It is designed for scenarios where service topology is **static and known in advance**, such as: |
| 10 | + |
| 11 | +- Local development and testing |
| 12 | +- Integration or end-to-end test environments |
| 13 | +- Edge deployments |
| 14 | + |
| 15 | +## Configuration format |
| 16 | + |
| 17 | +Name resolution is configured via the [Dapr Configuration]({{< ref configuration-overview.md >}}). |
| 18 | + |
| 19 | +```yaml |
| 20 | +apiVersion: dapr.io/v1alpha1 |
| 21 | +kind: Configuration |
| 22 | +metadata: |
| 23 | + name: appconfig |
| 24 | +spec: |
| 25 | + nameResolution: |
| 26 | + component: "structuredformat" |
| 27 | + configuration: |
| 28 | + structuredType: "json" # or "yaml", "jsonFile", "yamlFile" |
| 29 | + stringValue: '{"appInstances":{"myapp":[{"ipv4":"127.0.0.1","port":4433}]}}' |
| 30 | +``` |
| 31 | +
|
| 32 | +## Spec configuration fields |
| 33 | +
|
| 34 | +| Field | Required? | Description | Example | |
| 35 | +|------------------|-----------|-----------------------------------------------------------------------------|---------| |
| 36 | +| `structuredType` | Yes | Format and source type. Must be one of: `json`, `yaml`, `jsonFile`, `yamlFile` | `json` | |
| 37 | +| `stringValue` | Conditional | Required when `structuredType` is `json` or `yaml` | `{"appInstances":{"myapp":[{"ipv4":"127.0.0.1","port":4433}]}}` | |
| 38 | +| `filePath` | Conditional | Required when `structuredType` is `jsonFile` or `yamlFile` | `/etc/dapr/services.yaml` | |
| 39 | + |
| 40 | +> **Important**: Only one of `stringValue` or `filePath` should be provided, based on `structuredType`. |
| 41 | + |
| 42 | +## `appInstances` Schema |
| 43 | + |
| 44 | +The configuration must contain a top-level `appInstances` object that maps **service IDs** to **lists of address instances**. |
| 45 | + |
| 46 | +### Supported Address Fields |
| 47 | + |
| 48 | +| Field | Type | Required? | Description | |
| 49 | +|----------|--------|-----------|-------------| |
| 50 | +| `domain` | string | No | Hostname or FQDN (e.g., `"api.example.com"`). Highest priority. | |
| 51 | +| `ipv4` | string | No | IPv4 address in dotted-decimal format (e.g., `"192.168.1.10"`). | |
| 52 | +| `ipv6` | string | No | Unbracketed IPv6 address (e.g., `"::1"`, `"2001:db8::1"`). | |
| 53 | +| `port` | int | **Yes** | TCP port number (**must be 1–65535**). | |
| 54 | + |
| 55 | +> **Notes**: |
| 56 | +> - Service IDs must be non-empty strings. |
| 57 | +> - **At least one** of `domain`, `ipv4`, or `ipv6` must be non-empty per instance. |
| 58 | +> - Invalid or missing ports will cause initialization to fail. |
| 59 | + |
| 60 | +## Address Selection Logic |
| 61 | + |
| 62 | +For each instance, the resolver selects the **first non-empty address** in this priority order: |
| 63 | + |
| 64 | +1. `domain` → e.g., `github.com` |
| 65 | +2. `ipv4` → e.g., `192.168.1.10` |
| 66 | +3. `ipv6` → e.g., `::1` |
| 67 | + |
| 68 | +The final target address is formatted as: |
| 69 | + |
| 70 | +- `host:port` for domain/IPv4 |
| 71 | +- `[ipv6]:port` for IPv6 (automatically bracketed) |
| 72 | + |
| 73 | +If a service has **multiple instances**, one is selected **uniformly at random** on each call. |
| 74 | + |
| 75 | +## Examples |
| 76 | + |
| 77 | +### Inline JSON |
| 78 | +```yaml |
| 79 | +configuration: |
| 80 | + structuredType: "json" |
| 81 | + stringValue: '{"appInstances":{"myapp":[{"ipv4":"127.0.0.1","port":4433}]}}' |
| 82 | +``` |
| 83 | +→ Resolves `"myapp"` to `127.0.0.1:4433` |
| 84 | + |
| 85 | +### Inline YAML (multi-line) |
| 86 | +```yaml |
| 87 | +configuration: |
| 88 | + structuredType: "yaml" |
| 89 | + stringValue: | |
| 90 | + appInstances: |
| 91 | + myapp: |
| 92 | + - domain: "example.com" |
| 93 | + port: 80 |
| 94 | + - ipv6: "::1" |
| 95 | + port: 8080 |
| 96 | +``` |
| 97 | +→ Possible results: `example.com:80` or `[::1]:8080` (chosen randomly) |
| 98 | + |
| 99 | +### From External File |
| 100 | +```yaml |
| 101 | +configuration: |
| 102 | + structuredType: "yamlFile" |
| 103 | + filePath: "/etc/dapr/services.yaml" |
| 104 | +``` |
| 105 | + |
| 106 | +With `/etc/dapr/services.yaml`: |
| 107 | +```yaml |
| 108 | +appInstances: |
| 109 | + backend: |
| 110 | + - ipv4: "10.0.0.5" |
| 111 | + port: 3000 |
| 112 | +``` |
| 113 | +→ Resolves `"backend"` to `10.0.0.5:3000` |
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