FTP - Mechanic

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FTP
The FTP action can upload and download files via FTP, SFTP, or FTPS. The files to be uploaded are evaluated using file generators. Downloaded file data is available either as an UTF-8 string, or as a base64-encoded string, and can be used in followup task runs via mechanic/actions/perform.
A connecting service like Couchdrop can be used to relay these uploads on to other cloud locations, like Dropbox, Google Drive, and Amazon S3.
A single FTP action may download a maximum of 20MB of data, across all downloaded files.
Options
Option
Description
host
Required; the hostname of the destination server
user
Required; a string
uploads
Optional; an object whose keys are file paths (relative or absolute), and whose values are file generators​
downloads
Optional; an array of file paths (relative or absolute) to download
mode
Optional; only available for FTP; can be set to "ascii"
password
Optional; a string
port
Optional; an integer specifying the server port on which FTP or SFTP is available
private_key_pem
Optional; only available for SFTP; a PEM-formatted certificate for authentication
protocol
Optional; can be "ftp", "sftp", or "ftps"
Authentication
The user option is always required.
When connecting to an FTP or FTPS server, authenticate with the password option.
When connecting to an SFTP server, authenticate using either password or private_key_pem. PEM certificates may be given directly in the task code:
{% capture private_key_pem %}
-----BEGIN OPENSSH PRIVATE KEY-----
l0UGrDQWWbOpUsLENHwD5ya478pmRXarmDj5Wh31B54nmuq7be4ZKD5eh9nEV42JCl4mX6
...
pZ/WFoT82brhooSfJDue14C0Y=
-----END OPENSSH PRIVATE KEY-----
{% endcapture %}
​
{% action "ftp" %}
  {
    "host": "example.com",
    "port": 22,
    "user": "sftp_user",
    "private_key_pem": {{ private_key_pem | json }}
    "uploads": {
      "success.txt": "hooray!"
    }
  }
{% endaction %}
File paths
Both uploads and downloads allow the task author to define file paths. If only the filename is given (e.g. "sample.pdf"), the file will be resolved in the home directory of the user. If a relative path (e.g. "subdirectory/sample.pdf") or absolute path (e.g. "/tmp/sample.pdf") is given, it will be respected accordingly.
Example
This example action results in (a) an upload to an absolute path, starting from the server root, (b) an upload to a nested directory within the user's home folder, and (c) an upload to a nested directory in another user's home folder (which may fail, depending on filesystem permissions).
{% action "ftp" %}
  {
    ...
    "uploads": {
      "/absolute/path/to/success.txt": "hooray!",
      "relative/path/to/success.txt": "hooray!",
      "../another/relative/path/to/success.txt": "hooray!"
    }
  }
{% endaction %}
Result
This action returns the following data structure, most useful in combination with mechanic/actions/perform (see Responding to action results):
{
  "log": "connect: ftp.couchdrop.io, 21\n< 220 Couchdrop FTPD\n> USER ********\n< 331 Username ok, send password.\n> PASS ********\n< 230 Welcome ********\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,153).\n> STOR journal.txt\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,98).\n> STOR table.csv\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,135).\n> STOR invoice.pdf\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,101).\n> STOR secure.zip\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,100).\n> STOR external.jpg\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,183).\n> RETR journal.txt\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n> TYPE I\n< 200 Type set to: Binary.\n> PASV\n< 227 Entering passive mode (178,128,9,71,234,149).\n> RETR table.csv\n< 125 Data connection already open. Transfer starting.\n< 226 Transfer complete.\n> TYPE I\n< 200 Type set to: Binary.\n",
  "uploads": {
    "invoice.pdf": {
      "size": 7232
    },
    "secure.zip": {
      "size": 205
    },
    "external.jpg": {
      "size": 27661
    }
  },
  "downloads": {
    "journal.txt": {
      "size": 12,
      "data": "hello world!",
      "data_base64": "aGVsbG8gd29ybGQh"
    },
    "table.csv": {
      "size": 27,
      "data": "Title,SKU\nRed T-Shirt,TEE-R",
      "data_base64": "VGl0bGUsU0tVClJlZCBULVNoaXJ0LFRFRS1S"
    }
  }
}
Note that each uploaded and downloaded file is keyed by the path provided for that file in the action's options. Downloaded file data is available as a UTF-8 string; for binary data that cannot be represented in UTF-8, use the base64-encoded version, possibly in concert with the decode_base64 filter.
Testing
If a server is unavailable for testing, consider using Couchdrop, with their hosted storage service. This is a (nearly) configuration-free avenue for testing, using the hosts ftp.couchdrop.io or sftp.couchdrop.io.
Alternatively, ngrok can be used to create a public tunnel to a local FTP or SSH server. By running ngrok tcp 22 (adjusting for the appropriate local port), ngrok will generate a temporary public host and port that's appropriate for use while testing.
Uploads are processed before downloads; it can be useful to test by uploading a file, and then immediately downloading it again:
{% action "ftp" %}
  {
    "host": "ftp.couchdrop.io",
    ...
    "uploads": {
      "hello-world.txt": "hello world!"
    },
    "downloads": [
      "hello-world.txt"
    ]
  }
{% endaction %}
Example
This task compiles all SKUs with their titles and prices, and uploads it as a CSV every night or on demand.
Subscriptions
Code
mechanic/scheduler/daily
mechanic/user/trigger
{% assign csv_rows = array %}
​
{% assign header = "SKU,Title,Price" | split: "," %}
{% assign csv_rows[0] = header %}
​
{% for product in shop.products %}
  {% for variant in product.variants %}
    {% assign title = variant.title %}
    {% if title == "Default Title" %}
      {% assign title = product.title %}
    {% endif %}
​
    {% assign row = array %}
    {% assign row[row.size] = variant.sku %}
    {% assign row[row.size] = title %}
    {% assign row[row.size] = variant.price %}
​
    {% assign csv_rows[csv_rows.size] = row %}
  {% endfor %}
{% endfor %}
​
{% capture filename %}product-export-{{ "now" | date: "%Y-%m-%d" }}.csv{% endcapture %}
​
{% action "ftp" %}
  {
    "host": "example.com",
    "port": 21,
    "user": "anonymous",
    "password": null,
    "uploads": {
      {{ filename | json }}: {{ csv_rows | csv | json }}
    }
  }
{% endaction %}
Files
HTTP
Last modified 4mo ago
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Options
Authentication
File paths
Result
Testing
Example