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scriptform/doc/MANUAL.md

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Scriptform Manual

This is the manual for version %%VERSION%%.

Table of Contents

  1. Invocations
  2. Form config (JSON) files
  3. Field types
  4. Output
  5. Script execution
  6. Users
  7. Security

Invocations

Upon starting Scriptform, it will change the working directory to the path containing the form definition you've sepcified. It will read the form definition and perform some basic sanity checks to see if, for instance, the scripts you specified exist and are executable.

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 with the -f (--foreground) option. This is most useful for testing and development:

$ /usr/bin/scriptform -p8000 -f ./formdef.json

Daemon

If you do not specify the -f option, Scriptform will go into the background:

$ /usr/bin/scriptform -p8000 ./formdef.json
$

A pid file will be written in the current directory, or to the file specified by --pid-file. A log file will be written a .log file in the current directory, or to the file specified by the --log-file option.

To stop the daemon, invoke the command with the --stop option. You must specifiy at least the --pid-file option, if the daemon was started with one.

$ /usr/bin/scriptform --pid-file /var/run/scriptform.pid --stop

Init script

An example init script is provided in the contrib directory. For the Debian package, you can find it in /usr/share/doc/scriptform/. To install it on Debian-derived systems:

sudo cp /usr/share/doc/scriptform/scriptform.init.d_debian /etc/init.d/scriptform
sudo chmod 755 /etc/init.d/scriptform
sudo update-rc.d scriptform defaults

Then, edit the init script and set the FORM_CONFIG variable.

sudo vi /etc/init.d/scriptform
FORM_CONFIG="/usr/local/scriptform/myscript/myscript.json

Finally, start it:

sudo /etc/init.d/scriptform start

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). Otherwise, you may encounter the following error:

+  TypeError: index() got an unexpected keyword argument 'form_name'

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.

  • static_dir: Path to a directory from which static files should be served. See also "Serving static files". Optional, String.

  • forms: A list of dictionaries of form definitions. Required, List of dictionaries.

    • name: Name for the form. This must be unique. It is used internally by Scriptform to refer to forms. Required, String, Unique.

    • title: Title for the form. This is shown in the list of available forms and on the form page itself as the title for the form and as the caption for the button which takes you to the form. Required, String.

    • description: A description of the form. May include HTML tags. This is shown in the list of available forms and on the form page itself. Required, String.

    • script: The path to an executable script of binary that will be called if the form is submitted. See also Callbacks. When Scriptform starts, it switches to the directory containing the form definition. You should place your scripts there or otherwise specify full paths to the scripts. Required, String.

    • submit_title: The text on the submit button of the form. Optional, String, Default: Submit.

    • output: Determines how the output of the callback is handled. See the Output section. The default value is 'escaped'. Optional, String, Default: escaped.

    • allowed_users: A list of users that are allowed to view and submit this form. Optional, List of strings.

    • hidden: If 'true', don't show the form in the list. You can still view it, if you know its name. This is useful for other forms to redirect to this forms and such.

    • style: A string of inline CSS which will be applied to the field. Optional, String.

    • 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. Required, String.

      • title: The title for the field, shown just above the actual field. Required, String.

      • type: Field type. Supported types are: string, integer, float, date, radio, checkbox, select, text, password and file. For more information, see Field types.

      • required: Whether the field is required. Optional, Boolean, Default: false.

      • hidden: If 'true', the input field is hidden. This is useful for pre-filled forms which takes it values from the GET request. Optional, boolean, Default: false.

      • ...: Other options, which depend on the type of field. For more information, see Field types. Optional.

  • 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": [
      "name": "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"
        }
      ]
    },
    {
      "name": "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"
        }
      ]
    }
  ]
}

Many more examples can be found in the examples directory in the source code.

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.
  • size: The size (in characters) of the input 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

Checkbox

The checkbox field type represents the user with a toggleble checkbox that can be either 'on' or 'off'.

If the checkbox was checked, the value 'on' is passed to the script. Otherwise, 'off' is passed. Unlike HTML forms, which send no value to the server if the checkbox was not checked, Scriptform always sends either 'on' or 'off'.

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

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

Output types

Scripts can have a few different output types. The output type is specified in the output field of the form definition. For example, the following form definition has a raw output type.:

{
    "name": "display_image",
    "title": "Show an image",
    "description": "Show an image",
    "script: "job_display_image.sh",
    "output": "raw",
    "fields": []
}

The following output types are supported:

  • escaped: the output of the callback will have its HTML entities escaped and will be wrapped in PRE elements. This is the default option.

  • html: If the value is html, the output will not be escaped or wrapped in PRE tags, and can thus include HTML markup.

  • 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. Examples of raw script output can be found in the examples/raw directory.

Exit codes

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.

Serving static files

Scriptform can serve static files. It is disabled by default. To enable it, provide a static_dir option in the top section of the form configuration:

{
    "title": "Static serve",
    "static_dir": "static",
    "forms": [
    ...

This tells Scriptform to serve static files from that location. To refer to a static file, use the /static URL:

https://example.com/static?fname=foobar.png

Will refer to the static/foobar.png file. If static_dir is a relative path, it will be relative to the form configuration (.json) file you're running.

Scriptform does not provide the browser with a content-type of the file, since it is impossible to guess. Generally, browsers do a decent job at figuring it out themselves.

Script execution

When the user submits the form, scriptform will validate the provided values. If they check out, the specified script for the form will be executed.

A script can be any kind of executable, written in any kind of language, including scripting languages. As long as it is executable, can read the environment and output things to stdout it is usable. Scippts written in scripting languages should include the shebang line that indicates which interpreter it should use:

#!/usr/bin/php
<?php
echo("Hello!");
?>

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.

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

or in a Python script as:

import os
print os.environ['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.

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": [
      "name": "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

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 limiting

You may specify a allowed_users field in a form definition. Only user names listed in the field are allowed to see and submit that form. If the user is not listed, they won't even see the form as being available.

For an example, see the (beginning of this chapter)[#users].

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 HTTPS, such as Apache. For more information on that, see the "Invocations" chapter.

Security

There are a few security issues to take into consideration when deploying Scriptform:

  • You should limit harmful forms to specific users. See the Users chapter for more information.

  • User 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 HTTPS, such as Apache. For more information on that, see the "Invocations" chapter.

  • Scriptform logs the invocation of scripts and variables to the log file for auditing purposes.

  • Scriptform is not meant to be served to the public internet. You should only use it in controlled environments where a certain level of trust is placed in the users!