Media service

This microservice exposes a minimal REST interface to manipulate and store media content. At this moment it allows you to upload any file to Amazon S3 and allows you to manipulate images.

Running as a command line application

The npm package configures an pnp-media-service executable. You will pass configuration options
through ENV variables. Check the configuration options below.

Running as a standalone HTTP server via API

This is the recommended method for running the microservice via API. You can ignore the MICROSERVICE_PORT configuration and this will spin up a server at a random port. Then you can obtain the port the server is running by calling server.address().port. This way the microservice is not exposed in the same port than your main application and you are sure it will run in an available port.

``javascript
const mediaService = require('pnp-media-service')
const config = {
/ Check the configuration options below /
}
const server = mediaService.startServer(config, () => {
const port = server.address().port
console.log(Listening on port ${port}! Send an HTTP POST to http://127.0.0.1:${port}/media/upload for uploading files)
})
`

Running as an express router

`javascript
const mediaService = require('pnp-media-service')
const config = {
/ Check the configuration options below /
}
const router = mediaService.createRouter(config)
app.use('/media', router)
`

Invoking

Invoking the service is as simple as doing an HTTP POST request to {baseURL}/upload. The baseURL depends on how you are deploying the service. For example if you are running it as an express router mounted in /media in a server running at 127.0.0.1:3000 the URL will be: http(s)://127.0.0.1:3000/media/upload.

You need to send a JSON body with the following structure:

`javascript
{
"localPath": "", // Required (unless buffer is specified). Path to the file in the local system
"buffer": "", // Required (unless localPath is specified). Contents of the file in base64 encoding
"destinationPath": "", // Required. Path where the file will be uploaded
"contentType": "", // Optiona. MIME type of the uploaded file. If not specified the service will try to calculate a proper one
"expires": 60, // Optional. Number of seconds the file can be cached by an HTTP client
"imageOperations": { // Optional. Use only when you want to manipulate images
"width": 100,
"height": 200,
"resize": "min",
"autoRotate": true,
"normalize": false,
"appendExtension": true,
"grayscale": false
}
}
`

It will return a JSON object with the following structure:

`javascript
{
"url": "https://{bucket}.s3.amazonaws.com/{finalPath}"
}
`

The finalPath might be different to the destinationPath if you use appendExtension=true.

$3

| Variable | Description |
| --- | --- |
| width | Optional. Width of the image |
| height | Optional. Height of the image |
| resize | Optional. Used only when specifying a width or height. If not used the resized image is center cropped to the exact size specified. If "min" is used the resized image is as small as possible while ensuring its dimensions are greater than or equal to the width and height specified. If "max" is used the resized image is as large as possible while ensuring its dimensions are less than or equal to the width and height specified |
| ignoreAspectRatio | Optional. By default when specifying a width or height the aspect ratio is preserved. If you set ignoreAspectRatio to true the image will be resized ignoring it |
| autoRotate | Optional. If true, it performs an auto-orient based on the EXIF Orientation tag |
| normalize | Optional. If true it enhances the output image contrast by stretching its luminance to cover the full dynamic range |
| grayscale | Optional. If true it converts to 8-bit greyscale; 256 shades of grey |
| format | Optional. Format of the output image. Can be jpeg, png, webp or tiff. If not specified the format of the original image will be used if supported |
| appendExtension | Optional. If true the destinationPath will be modified to append an extension to the uploaded file. If you don't specify a format and the input image is not jpeg, png, webp or tiff the extension might not be calculated and the destinationPath will be kept untouch. |
| jpegOptions | Optional. JPEG codec options. You can use any of the available sharp jpeg options except for force |
| pngOptions | Optional. PNG codec options. You can use any of the available sharp png options except for force |
| webpOptions | Optional. WEBP codec options. You can use any of the available sharp webp options except for force |
| tiffOptions | Optional. TIFF codec options. You can use any of the available sharp tiff options except for force |

The contentType might be calculated if not specified but you specify an image format or appendExtension is set to true.

$3

The following code uses createClient() to invoke the service. It first spins an HTTP server and finally provides a simple upload() function:

`javascript
const mediaService = require('pnp-media-service')

let mediaClient = null
const mediaServer = mediaService.startServer(config, () => {
const port = mediaServer.address().port
const url = http://127.0.0.1:${port}/media
mediaClient = mediaService.createClient(url)
})

const upload = (localPath, destinationPath) => {
const imageOperations = {
width: 256,
height: 256,
autoRotate: true,
appendExtension: true
}
return mediaClient.upload({ localPath, destinationPath, imageOperations })
}
`

Configuration options

All configuration options can be configured using ENV variables. If using it as an express router, then configuration variables can also be passed as an argument to this method. All ENV variables can be prefixed with MEDIA_. Since one value can be configured in many ways some take precedence over others. For example for the AWS_KEY variable the value used will be the first found following this list:

- MEDIA_AWS_KEY parameter passed to createRouter() or startServer()
- AWS_KEY parameter passed to createRouter() or startServer()
- MEDIA_AWS_KEY ENV variable
- AWS_KEY ENV variable

This is the list of available configuration options:

| Variable | Description |
| --- | --- |
| AWS_KEY | AWS Key for uploading files using Amazon S3 |
| AWS_SECRET | AWS Secret for uploading files using Amazon S3 |
| AWS_S3_BUCKET | AWS S3 bucket where files will be stored |
| REQUEST_SIZE_LIMIT | The request size limit specified to body-parser in its limit setting. 50mb by default |

Testing

Create a .env file with this configuration:

``
AWS_KEY=...
AWS_SECRET=...
AWS_S3_BUCKET=...
`

Then run the tests with yarn test`