# CustomInjection


[API catalog](/reference/api/) · [Docker Sandboxes overview](/reference/api/sandboxes/latest/) · [Product manual](https://docs.docker.com/ai/sandboxes-api/) · [OpenAPI specification](/reference/api/sandboxes/api.yaml)

API version: v1


> This API is experimental. Features, interfaces,
> and behavior may change.




Schema constraints and annotations:

```json
{
  "additionalProperties": false,
  "description": "CustomInjection is caller-authored, non-secret metadata for a custom\nsecret: which exact hosts receive the value, in which header and format,\nand how the placeholder is shaped and delivered. Unlike secret material,\nreads return it.",
  "properties": {
    "envVar": {
      "description": "env_var optionally names a sandbox environment variable that carries the\nsecret's placeholder (never the value) as a delivery convenience.",
      "type": "string"
    },
    "format": {
      "description": "format renders the value with exactly one %s; %% escapes a literal\npercent, and any other % sequence is rejected. Empty means \"%s\".",
      "type": "string"
    },
    "header": {
      "description": "header is the HTTP header the value is written to. Routing, framing,\nand cookie headers are rejected.",
      "minLength": 1,
      "type": "string"
    },
    "hosts": {
      "description": "hosts are exact lowercase DNS names. Wildcards, IP literals, ports,\nschemes, paths, and hosts a managed integration already serves are\nrejected.",
      "items": {
        "minLength": 1,
        "type": "string"
      },
      "maxItems": 10,
      "minItems": 1,
      "type": "array"
    },
    "placeholderTemplate": {
      "description": "placeholder_template optionally shapes the placeholder for clients that\nvalidate credential shape before sending (e.g. \"sk-corp-{rand}\"). Each\n{rand} token is expanded server-side; {rand} is the only token. Empty\nuses the backend default (\"sbx-cs-{rand}\").",
      "type": "string"
    }
  },
  "required": [
    "hosts",
    "header"
  ],
  "title": "CustomInjection",
  "type": "object"
}
```