How do I configure my custom external image service?

[tulip bluff]

I'm developing the custom external image service only for my project.
I write a external service code as type ExternalImageService But I don't understand how to set this toastro.config.ts .

[reef zephyr]

Hi @tulip bluff. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

---

To configure your custom external image service in Astro, you need to define it in the astro.config.mjs file. Here's a general example of how you can do it:

import { defineConfig } from "astro/config";
import yourCustomService from './path-to-your-service';

export default defineConfig({
  image: {
    service: {
      entrypoint: yourCustomService,
      config: {
        // ... service-specific config. Optional.
      }
    }
  },
});

In this example, yourCustomService should be the exported object from your custom service file. This object should include the required methods for an external service, such as validateOptions(), getURL(), and getHTMLAttributes().

Here's an example of what your custom service might look like:

import type { ExternalImageService, ImageTransform, AstroConfig } from "astro";

const service: ExternalImageService = {
  validateOptions(options: ImageTransform, imageConfig: AstroConfig['image']) {
    const serviceConfig = imageConfig.service.config;

    // Enforce the user set max width.
    if (options.width > serviceConfig.maxWidth) {
      console.warn(`Image width ${options.width} exceeds max width ${serviceConfig.maxWidth}. Falling back to max width.`);
      options.width = serviceConfig.maxWidth;
    }

    return options;
  },
  getURL(options, imageConfig) {
    return `<https://mysupercdn.com/${options.src}?q=${options.quality}&w=${options.width}&h=${options.height}`;>
  },
  getHTMLAttributes(options, imageConfig) {
    const { src, format, quality, ...attributes } = options;
    return {
      ...attributes,
      loading: options.loading ?? 'lazy',
      decoding: options.decoding ?? 'async',
    };
  }
};

export default service;

Please replace the getURL() and getHTMLAttributes() methods with your own implementation.

For more details, you can refer to the Astro documentation on building using the Image Services API (https://docs.astro.build/en/reference/image-service-reference/#building-using-the-image-services-api).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@tulip bluff kapa.ai is still learning and improving, please let us know how it did by reacting below

[tulip bluff]

@reef zephyr type 'ExternalImageService' can't assign to '"astro/assets/services/sharp" | "astro/assets/services/squoosh" | (string & {})'

[reef zephyr]

Let me check the knowledge base for you. One moment! :books:

---

It seems like you're trying to assign a type (ExternalImageService) to a value that expects a string. In Astro, the entrypoint field in the image.service configuration expects a string that points to the location of the image service, not the type of the service.

Here's how you can correctly assign your custom external image service in the astro.config.mjs:

import { defineConfig } from "astro/config";
import yourCustomService from './path-to-your-service';

export default defineConfig({
  image: {
    service: {
      entrypoint: yourCustomService,
      config: {
        // ... service-specific config. Optional.
      }
    }
  },
});

In this example, yourCustomService should be the exported object from your custom service file. This object should include the required methods for an external service, such as validateOptions(), getURL(), and getHTMLAttributes().

For more details, you can refer to the Astro documentation on user configuration (https://docs.astro.build/en/reference/image-service-reference/#user-configuration).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@tulip bluff kapa.ai is still learning and improving, please let us know how it did by reacting below

[tulip bluff]

@reef zephyr you repeated the same information.

[reef zephyr]

Let me check the knowledge base for you. One moment! :books:

---

I apologize for the confusion. It seems there was a misunderstanding.

In Astro, you can't directly assign a custom external service to the entrypoint field in the astro.config.mjs file. The entrypoint field is a string that specifies the built-in service to use, such as 'astro/assets/services/sharp' or 'astro/assets/services/squoosh'.

Currently, Astro does not provide a direct way to use a custom external image service. The entrypoint field does not accept a custom service object, it only accepts a string that points to a built-in service.

However, you can create a local service and use it in your project. A local service provides a transform() method to perform transformations on your image, and getURL() and parseURL() methods to use an endpoint for dev mode and SSR. Here's an example of how you can create a local service:

import type { LocalImageService, AstroConfig } from "astro";

const service: LocalImageService = {
  getURL(options: ImageTransform, imageConfig: AstroConfig['image']) {
    const searchParams = new URLSearchParams();
    searchParams.append('href', typeof options.src === "string" ? options.src : options.src.src);
    options.width && searchParams.append('w', options.width.toString());
    options.height && searchParams.append('h', options.height.toString());
    options.quality && searchParams.append('q', options.quality.toString());
    options.format && searchParams.append('f', options.format);
    return `/_image?${searchParams}`;
  },
  // ... other methods
};

export default service;

Then, you can use this local service in your astro.config.mjs file:

import { defineConfig } from "astro/config";
import yourLocalService from './path-to-your-service';

export default defineConfig({
image: {
service: {
entrypoint: yourLocalService,
// ... other configurations
}
},
});

For more details, you can refer to the **Astro documentation on building using the Image Services API** (<https://docs.astro.build/en/reference/image-service-reference/#building-using-the-image-services-api>).
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