scriptform/doc/MANUAL.md

Scriptform Manual

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

Table of Contents

1. Introduction
   • Terminology
2. Installation
   • Debian / Ubuntu
   • Redhat / Centos
   • Other
3. Invocations
   • Shell foreground
   • Daemon
   • Init script
     • Debian / Ubuntu
     • RedHat / Centos
   • Behind Apache
4. Tutorial
   • Your first form
   • Output types
   • Fields
   • Uploads
   • Validation
   • Further reading
5. Form config (JSON) files
6. Field types
   • String
   • Integer
   • Float
   • Date
   • Radio
   • Checkbox
   • Select
   • Text
   • Password
   • File
7. Dynamic forms
   • Supported dynamic form parts
   • Dynamic select and radio options
   • Dynamic fields
   • Notes
8. Output
   • Output types
   • Exit codes
   • Serving static files
9. Script execution
   • Validation
   • Field Values
   • Execution security policy
10. Users
    • Passwords
    • Form limiting
    • Security considerations
    • Pre-authentication with Apache
11. Form customization
    • Custom CSS
12. Security

Introduction

Scriptform is a stand-alone webserver that automatically generates forms from JSON to serve as frontends to scripts.

ScriptForm takes a JSON file which contains form definitions. It then constructs web forms from this JSON and serves these to users over HTTP. The user can select a form and fill it out. When the user submits the form, it is validated and the associated script is called. Data entered in the form is passed to the script through the environment.

Terminology

Scriptform uses various terminology to distinguish between different components of the application.

• Form configuration: The form configuration is the JSON file you write that describes your forms. A single JSON file contains some global properties (such as the title), the forms you want to define and their fields.
• Form definition: A form definition describes a single form. Multiple form definitions can be given in a single form configuration. They are defined in the "forms" property of the form configuration. This "forms" property is a list of dictionaries.
• Form field: Form definitions can contain one of more form fields. These are the fields in which users can enter information. Scriptform supports a variety of different field types, such as 'string', 'integer', 'date', etc.

Installation and configuration

Requirements

ScriptForm requires:

• Python 2.6+

No other libraries are required. Python v2.6+ is generally available by default on almost every major linux distribution. For other platforms Python is almost certainly available.

Debian / Ubuntu

Download the .deb package from:

https://github.com/fboender/scriptform/releases

Either double-click the package in a file browser or open up a terminal and type:

$ cd Downloads/
$ sudo dpkg -i scriptform-*.deb

Scriptform is now installed. For the next steps, see:

• The tutorial on how to write form configuration files.
• Invocations for how to run Scriptform and how to start it at boot time

RedHat / Centos

Download the .rpm package from:

https://github.com/fboender/scriptform/releases

Open up a terminal and type:

$ cd Downloads/
$ sudo rpm -i scriptform-*.rpm

Scriptform is now installed. For the next steps, see:

• The tutorial on how to write form configuration files.
• Invocations for how to run Scriptform and how to start it at boot time

Other Unix-like Operating Systems

Install Python v2.6+.

Download the .tar.gz package from:

https://github.com/fboender/scriptform/releases

Open up a terminal and type:

$ cd Downloads/
$ tar -vxzf scriptform-*.tar.gz
$ cd scriptform-X.Y
$ sudo make install

Scriptform is now installed. For the next steps, see:

• The tutorial on how to write form configuration files.
• Invocations for how to run Scriptform and how to start it at boot time

Invocations

Upon starting Scriptform, it will change the working directory to the path containing the form definition you've specified. 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 production 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 -p8081 -f ./formdef.json

You can specify the -r option to automatically reload the JSON file upon each request:

$ /usr/bin/scriptform -p8081 -r -f ./formdef.json

Daemon

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

$ /usr/bin/scriptform -p8081 ./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 specify 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

Debian / Ubuntu

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

RedHat / CentOs

Install the init script:

sudo cp /usr/share/doc/scriptform/scriptform.init.d_redhat /etc/init.d/scriptform
sudo chmod 755 /etc/init.d/scriptform

Then, edit the init script so it points to your form configuration file:

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

Finally, enable the init script to run at boot time:

sudo chkconfig --add scriptform
sudo chkconfig scriptform on

Now we can start it:

sudo /etc/init.d/scriptform start
Starting scriptform: 

Behind Apache

Scriptform does not support HTTPS / SSL, so for production environments you might want to run it behind an Apache server that has SSL enabled. To do so, you start Scriptform as a daemon and then forward requests to it from Apache:

$ sudo /etc/init.d/scriptform start

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:8081/
ProxyPassReverse /scriptform/ http://localhost:8081/

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'

Tutorial

Your first form

This tutorial assumes you've already installed Scriptform on your system.

Let's start off by creating a new form configuration file. Create a directory:

$ mkdir sf_tutorial
$ cd sf_tutorial

Edit a new file called sf_tutorial.json in your favorite editor and put the following in:

{
  "title": "Tutorial",
  "forms": [
    {
      "name": "System information",
      "title": "System information",
      "description": "Show information about the operating system",
      "script": "job_sysinfo.sh",
      "fields": []
    }
  ]
}

This is a form configuration with a single form definition "System information". The form has no fields; we'll get to that later. First, let's implement the job_sysinfo.sh script so we can perform a form callback.

Edit a new file in the same directory called job_sysinfo.sh:

#!/bin/sh

HOSTNAME=$(hostname -f)
MEM=$(free -h)
DISK=$(df -h)

cat << END_OF_TEXT
Hostname
========

$HOSTNAME


Memory
======

$MEM


Disk
====

$DISK
END_OF_TEXT

Fix the permisions so it is executable:

$ chmod 755 ./job_sysinfo.sh

Now start Scriptform with our newly created form configuration file:

$ scriptform -p8081 -f -r ./sf_tutorial.json

This starts the built-in webserver which will serve the form on port 8081. When you open it in your browser (http://127.0.0.1:8081/) you will immediately see the form. If we had multiple forms in this form configuration, you would first see a list of all the forms.

The -p option controls the port on which Scriptform will listen. Normally, Scriptform would go into the background and run as a daemon. We can surpress this with the -f (foreground) switch, which makes it easier to stop Scriptform by pressing Ctrl-c. The -r option tells Scriptform to reload the form configuration file on each request. This makes development much easier, since you won't have to stop and restart Scriptform whenever you make a change.

Output types

The output of our first form isn't exactly good-looking. We can change that by changing the output type of our form. There are three types: escaped, html and raw. Let's change our output to HTML.

Open the sf_tutorial.json file and add an output property to the form:

...
"script": "job_sysinfo.sh",
"output": "html",
"fields": []
...

Now modify the job_sysinfo.sh script to output HTML instead of plain text:

cat << END_OF_TEXT
<h3>Hostname</h3>
<pre>$HOSTNAME</pre>

<h3>Memory</h3>
<pre>$MEM</pre>

<h3>Disk</h3>
<pre>$DISK</pre>
END_OF_TEXT

Open http://127.0.0.1:8081 in your browser and submit the form. That looks a little better, doesn't it? The html output type lets you embed HTML in the output of the script. The default output type is escaped, which escaped any HTML and just outputs plain text wrapped in a Scriptform response header and footer. The last output type is raw, in which case Scriptform will send the exact output of your script directly to the browser. This means your script should not just output a result, but also the required HTTP headers to properly display it. This lets your send binary files (images, downloads, etc) to the browser.

Read more about output types in the 'Output types' section.

Fields

As you've seen, we've kept the fields option empty in the previous examples. The fields option lets us specify input fields that will appear in the form. Every field has at least a name, title and type. Many fields support additional options for validation, etc.

There are fields available for many types: strings, numbers, dates, dropdown boxes, file uploads, etc. For a full list see the Field types section of the user manual.

The simplest is the string field. This field type simply lets the user enter a value. Put the following in the sf_tutorial.json file, replacing the original content (or create a new json file):

{
  "title": "Tutorial step 3",
  "forms": [
    {
      "name": "hello_world",
      "title": "Hello, world!",
      "description": "Greetings",
      "script": "job_helloworld.sh",
      "fields": [
        {
          "name": "name",
          "title": "Name",
          "type": "string"
        }
      ]
    }
  ]
}

Create the job_helloworld.sh script:

#!/bin/sh

if [ -z "$name" ]; then
    name="world"
fi

echo "Hello, $name!"

Make it executable:

$ chmod 755 job_helloworld.sh

And start Scriptform (not required if it's still running and you're using the same .json file):

$ scriptform -p8081 -f -r ./sf_tutorial.json

Point your browser to http://127.0.0.01:8081. Try submitting the form with and without entering a name.

As you can see, Scriptform makes form values available to scripts through the environment. This makes it easy to implement scripts in any language you'd like. For example, this is what a script implemented in Python would look like:

#!/usr/bin/env python

import os

name = os.environ['name']
if not name:
    name = "world"

print "Hello, {0}!".format(name)

Upload

Let's extend our form with a file upload. Modify sf_tutorial.json and add an upload field:

...
{
  "name": "upload",
  "title": "Upload a file",
  "type": "file"
}
...

We'll also change it to run a different script:

...
"script": "job_upload.py",
...

The entire file now looks like this:

{
  "title": "Tutorial step 4: Uploads",
  "forms": [
    {
      "name": "hello_world",
      "title": "Hello, world!",
      "description": "Greetings",
      "script": "job_upload.sh",
      "fields": [
        {
          "name": "name",
          "title": "Name",
          "type": "string"
        },
        {
          "name": "upload",
          "title": "Upload a file",
          "type": "file"
        }
      ]
    }
  ]
}

We'll make the script output the size of the file in bytes. job_upload.sh:

#!/bin/sh

if [ -z "$name" ]; then
    name="stranger"
fi
echo "Hello, $name!"

if [ -z "$upload" ]; then
    echo "Looks like you didn't upload a file!"
else
    FILE_SIZE=$(wc -c $upload | cut -d " " -f1)
    echo "The size in bytes of $upload__name is $FILE_SIZE"
fi

When we submit the form with a file uploaded, the results look like this:

Hello, stranger!
The size in bytes of README.md is 146

Scriptform will stream the uploaded file to a temporary file (usually something like /tmp/scriptform_e4CAXk) and put the received file name in the XXXX__name variable. Temporary files are automatically removed when the script is done running, so if you want to keep it around, you should move it do a different directory.

Validation

Scriptform offers a simple way to validate form values before executing scripts. This saves you the trouble of having to do all the validation in your script. Validation is achieved by speciying additional field definition parameters.

Let's modify the previous upload example and add some validation to it. We'll make the name field have a minimum and maximum length:

{
  "name": "name",
  "title": "Name",
  "type": "string",
  "minlen": 2,
  "maxlen": 10
},

We'll change the upload field so it's required and you're only allowed to upload '.txt' files:

{
  "name": "upload",
  "title": "Upload a file",
  "type": "file",
  "required": true,
  "extensions": ["txt"]
}

Try the validation out by submitting the form with some right and wrong values and by uploading no file or a file with a wrong extension. You'll see that Scriptform validates the submitted form before the script is executed. If any validations fail, the form is shown again.

More details on validation and other additional options that can be supplied to field definitions can be found in the 'Field types' chapter.

Further reading

This concludes the tutorial for Scriptform, although it has a lot more to offer. Some suggestions on further reading materials:

• Full user manual: Everything you need to know.
• Script execution: Details on how scripts are executed.
• Users: Scriptform can do user management.
• Form customization: Learn how to customize your forms.
• Check the examples directory for many interesting examples on how to use Scriptform.

And finally, please read the Security section for important information regarding Scriptform's security.

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.

• custom_css: Path to a file containing custom CSS. It will be included in every page's header. See also "Form customization". 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.

  • run_as: Change to this user (and its groups) before running the script. Only works if Scriptform is running as root. See also Execution security policy Optional, String, Default: nobody.

  • fields: List of fields in the form. Each field is a dictionary. Optional, 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.

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

    • classes: A string of optional CSS classes to add to this field. Optional, String.

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

  • fields_from: Path to a file or executable from which to read the list of fields. See the fields option for information on fields. See the Dynamic forms chapter for more information. Optional, String.

• users: A dictionary of users where the key is the username and the value is the plain text 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",
          "required": true
        },
        {
          "name": "password1",
          "title": "Password",
          "type": "password",
          "required": true
        },
        {
          "name": "password2",
          "title": "Password (Repear)",
          "type": "password",
          "required": true
        }
      ]
    }
  ]
}

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

Field types

Scriptform supports multiple field types. Field types determine what users may enter in the field, how they are validated and how they are passed to callback scripts.

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.
• default_value: The default value.

For example:

...
"fields": [
    {
      "name": "my_string",
      "title": "My string",
      "type": "string",
      "minlen": 12,
      "maxlen": 30,
      "size": 30
    }
]
...

Integer

The integer field type presents the user with an input box in which 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.
• default_value: The default value.

For example:

...
"fields": [
    {
      "name": "uid",
      "title": "UID",
      "type": "integer",
      "min": 1000,
      "max": 2000
    }
]
...

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.
• default_value: The default value.

For example:

...
"fields": [
    {
      "name": "ammount",
      "title": "Ammount",
      "type": "float",
      "min": 10.0,
      "max": 2000.0 
    }
]
...

Please note that some real numbers cannot be represented exactly by a computer and validation may thus be approximate. E.g. 0.500000000001 might pass the test for a maximum value of 0.5. Whether it does depends on the value given, the platform, your browser, and many other factors.

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) or "today" for today.
• max: The maximum allowed date (format: a string YYYY-MM-DD) or "today" for today.
• default_value: The default value (format: a string YYYY-MM-DD) or "today" for today.

For example:

...
"fields": [
    {
      "name": "birthdate",
      "title": "Birthdate",
      "type": "date",
      "min": "1900-01-01",
      "max": "2015-01-01"
    }
]
...

Must start today or in the future (Default value today):

...
"fields": [
    {
      "name": "startdate",
      "title": "Start date",
      "type": "date",
      "min": "today",
      "default_value": "today"
    }
]
...

Radio

The radio field type lets the user pick one option from a list of options.

The radio field type supports the following additional options:

• options: The options available to the user. (list of lists, required)
• options_from: A list of available options from which the user can choose, read from an external file or executable.

Either options or options_from may be given, but not both.

For example:

...
"fields": [
    {
        "name": "network",
        "title": "To which network",
        "type": "radio",
        "options": [
            ["intra", "Whole intranet"],
            ["machine", "Acceptance machine"]
        ]
    }
]
...

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'.

The checkbox field type supports the following additional options:

• checked: Whether the checkbox should be checked by default (boolean)

For example:

...
"fields": [
    {
      "name": "receive_newsletter",
      "title": "Do you want to receive our newsletter?",
      "type": "checkbox",
      "checked": true
    }
]
...

Select

The select field presents the user with a dropdown list from which they can pick a value.

The select field type supports the following additional options:

• options: A list of available options from which the user can choose. Each item in the list is itself a list of two values: the value and the title.
• options_from: A list of available options from which the user can choose, read from an external file or executable.

Either options or options_from may be given, but not both.

For example

...
"fields": [
    {
      "name": "target_db",
      "title": "Load CSV into which database?",
      "type": "select",
      "options": [
        ["empty", "Empty database"],
        ["dev", "Development test database"],
        ["ua", "Acceptance database"]
      ]
    }
]
...

Dynamically read select options from a script:

...
"fields": [
    {
      "name": "target_db",
      "title": "Load CSV into which database?",
      "type": "select",
      "options_from": "form_loadcsv_target_db.sh"
    }
]
...

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.
• default_value: The default value.

For example:

...
"fields": [
    {
      "name": "complaint",
      "title": "Please write down your complaint",
      "type": "text",
      "rows": 6,
      "cols": 60,
      "minlen": 1,
      "maxlen": 5
    }
]
...

Password

• minlen: The minimum allowed length for the field.
• default_value: The default value.

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 validation is done on the file contents.

For example:

...
"fields": [
    {
      "name": "new_users",
      "title": "CSV file of new users",
      "type": "file",
      "extensions": ["csv"]
    }
]
...

Dynamic Forms

Often it won't be enough to have staticly defined fields in forms. For example, you may want the user to be able to select from a dynamically created list of files or databases.

Scriptform offers a way to fill in parts of a form definition file dynamically from extern files or scripts. This is done at runtime when showing or validating the form, so no restarting of scriptform is required.

Supported dynamic form parts

Currently the following parts of form definitions support dynamic form parts:

• forms.X.fields_from: Form's fields are read from a file or script.
• Fields of type select. Options for dropdowns are read from a file or script.
• Fields of type radio. Options for radio buttons are read from a file or script.

Dynamic select and radio options

Normally you'd use the options element for a select field in a form, like so:

...
"fields": [
    {
      "name": "target_db",
      "title": "Load CSV into which database?",
      "type": "select",
      "options": [
        ["empty", "Empty database"],
        ["dev", "Development test database"],
        ["ua", "Acceptance database"]
      ]
    }
]
...

Scriptform also understands the options_from field, which replaces the options field. The value should point to a normal or executable file. Depending on that, the file is read or executed and its output interpreted as JSON. The form then uses that JSON as a replacement for the options field.

For example:

...
"fields": [
    {
      "name": "target_db",
      "title": "Load CSV into which database?",
      "type": "select",
      "options_from": "form_loadcsv_target_db.sh"
    }
]
...

The script form_loadcsv_target_db.sh could look like:

#!/bin/sh

cat << END_TEXT
[
    ["test", "Test DB"],
    ["acc", "Acc DB"],
    ["prod", "Prod DB"]
]
END_TEXT

Dynamic options for radio buttons works exactly the same, except the type will be radio:

"type": "select",
"options": [
  ["empty", "Empty database"],
  ["dev", "Development test database"],
  ["ua", "Acceptance database"]
]

Dynamic fields

You can also generate all the fields in a form dynamically. For example, the following form definition will read all the fields from form_dyn_fields.sh:

{
    "name": "dyn_fields",
    "title": "Dynamic fileds",
    "description": "All the fields in this form are dynamically read from a script.",
    "submit_title": "Import",
    "script": "job_import.sh",
    "fields_from": "form_dyn_fields.sh"
}

The script form_dyn_fields.sh could look something like:

#!/bin/sh

OPTIONS=$(cat <<'END_HEREDOC'
[
    ["test", "Test DB"],
    ["acc", "Acc DB"],
    ["prod", "Prod DB"]
]
END_HEREDOC
)

cat << END_TEXT
[
    {
        "name": "target_db",
        "title": "Database to import to",
        "type": "radio",
        "options": $OPTIONS
    },
    {
        "name": "sql_file",
        "title": "SQL file",
        "type": "file"
    }
]
END_TEXT

Notes

• The executable bit must be set in order for scriptform to execute the file. Otherwise, the contents of the file is read.
• Executable scripts are always executed as the user scriptform runs at! While its not possible for the user to inject anything into the script, you should still be careful with what the scripts do.
• Dynamic parts of a form are loaded / executed each time the form is referenced, so may be read or executed often. E.g. when loading the form, when listing the forms, when showing the form, when submitting the form, when validatinng the form, etc. You should make sure executables run quickly.

Output

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

Output types

Scriptform uses the output of the script (stdout, stderr) to display something back to the user executing the script.

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

Exit codes are handled by Scriptform if the output type is not raw. Otherwise it is the script's responsibility to properly handle exit codes of subscripts and showing errors.

If the output type is escaped or html and 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.

Note: Static file serving does not require authentication. All users, including anonymous users, can view static files.

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. Scripts 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 the Scriptform backend before the script is called. If you have a HTML5 capable browser, the form will also be validated in the browser before you submit it.

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.

Form validation is somewhat limited. For example, you can force a string's minimum and maximum length, but you cannot do more advanced validation such as checking if it starts with a certain value. If you wish to do that, you will have to do the validation in the script callback for a form.

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 execution ends.

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

Execution security policy

Running arbitrary scripts from Scriptform poses somewhat of a security risk. Scriptform tries to mitigate this risk by running scripts as a different user in some cases:

• If Scriptform itelf is running as root:
  • By default, scripts will be run as user 'nobody'.
  • If a form specifies as run_as field, scripts will be executed as that user.
• If Scriptform itself is running as a non-root user, scripts will be executed as that user.

If you use an init script, Scriptform will run as user root, which will cause Scriptform to automatically drop privileges to user nobody and group nobody when executing shell scripts. This may cause "permission denied" problems! There are a few possible ways to work around this:

• Make sure the user or group nobody has rights to view and execute the scripts. The form configuration itself should probably not be viewable by user nobody since it may contain passwords.
• Modify the init or systemd script to run as a different user.
• Add run_as properties to each form definition to specify the user it should run as.

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 --generate-pw
Password: 
Repeat password: 
ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad

Note that if you're running from the repository, you'll have to run Scriptform as:

$ src/scriptform.py --generate-pw

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.

Security considerations

• Passwords have no salt. This makes them slightly easier to brute-force en-mass.
• Scriptform does not natively support secure HTTPS connections. This means usernames and passwords are transmitted over the line in nearly plain text. 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.

Pre-authentication with Apache

If you're running behind Apache or another webserver, you can use features in Apache to do the authentication for you. This allows you to use LDAP or OpenID (SSO) authentication.

You must pass the REMOTE_USER header (not environment variable!) to Scriptform to get this working. For example, in Apache:

Redirect permanent /scriptform /scriptform/
ProxyPass /scriptform/ http://localhost:8081/
ProxyPassReverse /scriptform/ http://localhost:8081/

<Location /scriptform>
    AuthType Basic
    AuthName "Restricted Files"
    AuthBasicProvider file
    AuthUserFile "/var/www/users"
    Require valid-user

    Header unset REMOTE_USER
    RequestHeader set REMOTE_USER %{REMOTE_USER}s
</Location>

If such a header is seen, Scriptform won't perform validation of the password and just assumes the username is correct.

Form customization

Custom CSS

You can customize a form input field's style using the style property of the field definition in the form configuration. It takes a string that will be put in the generated form's style="" HTML attribute. For example:

"fields": [
    {
        "name": "background",
        "title": "Different background color",
        "type": "string",
        "style": "background-color: #C0FFC0;"
    }
]

The example above will render as:

<input required="" type="text" name="background" value="" size="" class="" style="background-color: #C0FFC0;">

You can also include a global piece of CSS by specifying the custom_css property in the form definition. For example:

{
    "title": "Customized forms",
    "custom_css": "custom.css",
    "forms": [
    ...

custom.css is the path to a file which will be included in the rendered HTML page in the <style> header. If the path is relative, it will be relative to the form configuration file's location.

For a good example, see the examples/customize/ directory in the source.

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 brute-force en-mass.

• Scriptform does not natively support secure HTTPS connections. This means usernames and passwords are transmitted over the line in nearly plain text. 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. Password values are censored.

• Although Scriptform is written to be secure, it 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!. The reason for this is because it's really easy to make mistakes in validating input in the shell scripts called by Scriptform.

• Although Scriptform validates form fields, it does little to protect against things such as shell expansion attacks and such. You should validate your input, even (and perhaps most importantly) in shell scripts. If you're worried about security, you may want to write your backend scripts in a proper language such as Perl or Python.