Action "lxc.file.exists"

Check if the file exists in a container.

Example

const {$status} = await nikita.lxc.file.exists({
  container: 'my_container',
  target: '/root/a_file'
})
console.info(`File exists: ${$status}`)

Todo

Push recursive directories
Handle unmatched target permissions
Handle unmatched target ownerships
Detect name from lxd_target

Implementation change

Previous implementation used lxc.query action to retrieve the content of the file and then determine if it exists or not:

lxc query --request GET /1.0/instances/container_name/files?path=file_path

It presents two problems:

The file is fetch which introduce delay and be unacceptable for large file.
The current LXD version throw an error when the file is empty, see LXD issue #11388.

The LXD API exposes a REST endpoint to obtain file metadata. However, lxc query don't support the HEAD HTTP method, see LXD issue #11383.

This implementation uses the lxc.exec action to run the existence file test directly inside the container.

Schema definitions

definitions =
  config:
    type: 'object'
    properties:
      'container':
        $ref: 'module://@nikitajs/lxd/src/init#/definitions/config/properties/container'
      'target':
        type: 'string'
        description: '''
        File location in the form of "<path>".
        '''
    required: ['container']

Handler

handler = ({config}) ->
  {$status} = await @lxc.exec
    $header: "Check if file exists in container #{config.container}"
    container: config.container
    command: "test -f #{config.target}"
    code: [0, 1]
  exists: $status

Exports

module.exports =
  handler: handler
  metadata:
    definitions: definitions
    shy: true

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