scriptform/doc/MANUAL.md

Scriptform Manual

Table of Contents

1. Invocations
2. Form config (JSON) files
3. Field types
   • String
   • Integer
   • Float
   • Date
   • Radio
   • Select
   • Text
   • Password
   • File
4. Output
5. Callbacks
   • Script callbacks
     • Validation
     • Field Values
   • Python callbacks
6. Users

Invocations

There are multiple ways of running ScriptForm. This chapter outlines the various methods. They are listed in the order of least to most pruduction-ready.

Shell foreground

Sriptform can be run directly from the shell in the foreground. This is most useful for testing and development.

Unless the paths to your scripts are absolute, you should run Scriptform from the directory that contains the Form definition file.

Behind Apache

Enable Apache modules mod_proxy and mod_proxy_http:

$ sudo a2enmod proxy
$ sudo a2enmod proxy_http

Configure:

Redirect permanent /scriptform /scriptform/
ProxyPass /scriptform/ http://localhost:8000/
ProxyPassReverse /scriptform/ http://localhost:8000/

Make sure the path ends in a slash! (That's what the redirect is for).

Form config (JSON) files

Forms are defined in JSON format. They are referred to as Form config files. A single JSON file may contain multiple forms. Scriptform will show them on an overview page, and the user can select which form they want to fill out.

Structurally, they are made up of the following elements:

• title: Text to show at the top of each page. Required, String.
• forms: Dictionary where the key is the form id and the value is a dictionary that is the definition for a single form. Required, Dictionary.
  • title: Title for the form. Required, String.
  • description: A description of the form. May include HTML tags. Required, String.
  • submit_title: The text on the submit button of the form.
  • script: The path to an executable script of binary that will be called if the form is submitted. See also Callbacks. If this field is omitted, Scriptform will instead call a python callable (function, method) that's been registered. Scriptform will raise an error if the script isn't found, if the script isn't executable or (if the script tag is omitted) if no Python callback is registered to handle this form. String.
  • output: Determines how the output of the callback is handled. See the Output types seciton.
  • fields: List of fields in the form. Each field is a dictionary. Required, List of dictionaries.
    • name: The name of the field. This is what is passed as an environment variable to the callback.
    • title: The title for the field, shown just above the actual field.
    • type: Field type. Supported types are: string, integer, float, date, radio, select, text, password and file. For more information, see [Field types].
    • required: Whether the field is required.
    • ...: Other options, which depend on the type of field.
• users: A dictionary of users where the key is the username and the value is the plaintext password. This field is not required. Dictionary.

For example, here's a form config file that contains two forms:

{
  "title": "Test server",
  "forms": {
    "import": {
      "title": "Import data",
      "description": "Import SQL into a database",
      "submit_title": "Import",
      "script": "job_import.sh",
      "fields": [
        {
          "name": "target_db",
          "title": "Database to import to",
          "type": "select",
          "options": [
            ["devtest", "Dev Test db"],
            ["prodtest", "Prod Test db"]
          ]
        },
        {
          "name": "sql_file",
          "title": "SQL file",
          "type": "file"
        }
      ]
    },
    "add_user": {
      "title": "Add user",
      "description": "Add a user to the htaccess file or change their password",
      "submit_title": "Add user",
      "script": "job_add_user.sh",
      "fields": [
        {
          "name": "username",
          "title": "Username",
          "type": "string"
        },
        {
          "name": "password1",
          "title": "Password",
          "type": "password"
        },
        {
          "name": "password2",
          "title": "Password (Repear)",
          "type": "password"
        }
      ]
    }
  }
}

Field types

String

The string field type presents the user with a single line input field.

The string field type supports the following additional options:

• minlen: The minimum allowed length for the field.
• maxlen: The maximum allowed length for the field.

Integer

The integer field type presents the user with an input box in wich they may enter an integer number. Depending on the browser's support for HTML5 forms, the input field may have spin-buttons to increase and decrease the value.

The integer field type supports the following additional options:

• min: The minimum allowed value for the field.
• max: The maximum allowed value for the field.

Float

The float field type presents the user with an input box in which they enter a Real number (fractions).

The float field type supports the following additional options:

• min: The minimum allowed value for the field.
• max: The maximum allowed value for the field.

Please note that some real numbers cannot be represented exactly by a computer and validation may thus be approximate. E.g. 0.499999999999999 will pass the test for a maximum value of 0.5.

Date

The date field type presents the user with an input box in which they can enter a date. Depending on the browser's support for HTML5 forms, the input field may have a pop-out calendar from which the user can select a date.

The date must be entered, and will be passed to the callback, in the form YYYY-MM-DD.

The date field type supports the following additional options:

• min: The minimum allowed date (format: a string YYYY-MM-DD)
• max: The maximum allowed date (format: a string YYYY-MM-DD)

Radio

Select

Text

The text field presents the user with a field in which they can enter multi-lined text.

The text field type supports the following additional options:

• rows: The number of rows to make the input field
• cols: The number of cols to make the input filed.
• minlen: The minimum allowed length for the field.
• maxlen: The maximum allowed length for the field.

Password

• minlen: The minimum allowed length for the field.

File

The file field type presents the user with a field through which they can upload a file. Uploaded files are streamed to temporary files by Scriptform, after which the original field value is replaced with this temporary file name. This allows users to upload large files.

The original file name of the uploaded file is stored in a new variable '<field_name>__name'.

The file field type supports the following additional options:

• extensions: A list of extensions (minus leading dot) that are accepted for file uploads. For example: "extensions": ["csv", "tsv"]

No additional validatikon is done on the file contents.

Output

FIXME

  If
  its value is `escaped`, the output of the callback will have its HTML
  entities escaped and will be wrapped in PRE elements. This is the
  **default** option. If the value is `html`, the output will not be
  escaped or wrapped in PRE tags, and can thus include HTML markup. If the
  output is `raw`, the output of the script is streamed directly to the
  client's browser. This allows you to output images, binary files, etc to
  the client. The script must include the proper headers and body itself. 

All output is assumed to be UTF8, regardless of system encoding!

If the script's exit code is 0, the output of the script (stdout) is captured and shown to the user in the browser.

If a script's exit code is not 0, it is assumed an error occured. Scriptform will show the script's stderr output (in red) to the user instead of stdin.

FIXME: If the form definition has a script_raw field, and its value is true, Scriptform will pass the output of the script to the browser as-is. This allows scripts to show images, stream a file download to the browser or even show completely custom HTML output. The script's output must be a valid HTTP response, including headers and a body. Examples of raw script output can be found in the examples/raw directory.

Callbacks

Callbacks are called after the form has been submitted and its values have been validated. They are the actual implementations of the form's action.

There are two types of callbacks:

• Scripts
• Python callables (functions or methods)

Validation

Fields of the form are validated by Scriptform before the script is called. Exactly what is validated depends on the options specified in the Form Definition. For more info on that, see the Field Types section of this manual.

Scripts

A script callback can be any kind of executable, written in any kind of language. As long as it is executable, can read the environment and output things to stdout, it can be used as a callback.

Field values

Field values are passed to the script in its environment. For instance, a form field definition:

{
  "name": "ip_address",
  "title": "IP Address",
  "type": "string"
}

becomes available in a shell script as:

echo $ip_address

Uploaded files are streamed to temporary files by Scriptform. The name of the temporary file is then passed on as the field's value. For example, given the following field definition:

{
  "name": "csv_file",
  "title": "CSV file to import",
  "type": "file"
}

The contents of the file is available in a shell script as:

echo $csv_file    # output: /tmp/tmp_scriptform_Xu72bK
ROWS=$(wc -l $csv_file)
echo "The CSV file has $(expr $ROWS - 1) rows"

These temporary files are automatically cleaned up after the script's exeuction ends.

Examples of file uploads can be found in the examples/simple and examples/megacorp directories.

Python callbacks

or in a Python script as:

import os
print os.environ['ip_address']

Users

ScriptForm supports basic htauth user authentication. Users can be defined, and form access can be limited to certain users. Users are defined in the users top-level field of the form configuration file. For example, in the following form configuration file, there are two users. Only user test2 is allowed to view the form 'only_some_users'.

{
  "title": "Authorization protected",
  "users": {
    "test": "2bb80d537b1da3e38bd30361aa855686bde0eacd7162fef6a25fe97bf527a25b",
    "test2": "5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8"
  },
  "forms": {
    "only_some_users": {
      "title": "Only some users",
      "description": "You should only see this if you're user 'test2'",
      "submit_title": "Do nothing",
      "script": "job_do_nothing.sh",
      "allowed_users": ["test2"],
      "fields": []
    }
  }
}

Passwords are unsalted SHA256 hashed passwords. To generate one, you can use the --generate-pw option of Scriptform. This will ask you twice for a plaintext password and return the hash that can be used in the users element.

$ ./scriptform.py --generate-pw
Password: 
Repeat password: 
ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad

Form definitions may specify which users are allowed to view, access and submit the form. This is specified by a allowed_users field in the form definition, as can be seen in the previous form configuration example. Multiple users may be specified.

Security considerations

• Passwords have no salt. This makes them slightly easier to bruteforce en-mass.
• Scriptform does not natively support secure HTTPS connections. This means usernames and passwords are transmitted over the line in nearly plaintext. If you wish to prevent this, you should put Scriptform behind a proxy that does support Scriptform, such as Apache. For more information on that, see the "Invocations" chapter.