Fake Injecting Proxy Server - in short Fips - fake and proxy within seconds

About

Fips provides three different functionalities: It can function as a Fake data server, it can function as a simple proxy server, and it can be a mixture of both, manipulating responses on the fly - defined by your own rules. As such, Fips is best used if you wish to quickly setup an endpoint and test it in your application - the backend work is currently blocked? No problem. Start the application and host a mock endpoint while proxying the remainders of your endpoints to the actual backend.

Installation

• Install rust and cargo.
• Checkout this repo.
• Dir into it and run cargo run - or cargo build if you wish to produce an executable.

Cli Arguments

Also see fips(.exe) --help

  # Start fips on this port
  --port: 8888
  # Load plugins from this directory, detault is the current directory.
  --plugins: .
  # Load configuration files from this directory. default is the current directory.
  --config: .

Hotkeys:

Tab Go to next Tab
Shift+ Tab Go to previous Tab
c clear the log output
r reload config files
Esc quit

Usage

Fipss configuration is placed in .yaml or .yml files. They are loaded at startup from the --config directory. For each request, Fips will check against the configuration files if any config object matches the current request URI. If it does, one of the four modes do apply explicitly by the configuration given.

❗ Things to keep in mind for your config:

• Fips uses regex to match against paths. /foo/bar in a config path will also match for /foo/bar/baz, so you need to be as explicit as possible if you care.
• If multiple rules match, only the first matching rule will apply.
• Rules are applied in the order they appear - order matters!.
• The config file is not checked for spelling, the server will panic if it is unable to read a configuration file due to spelling /indentation errors. To support you creating configs, fips provides a JSON schema. You can create it with the --write-schema cli argument. See the settings for vscode json-schema and vscode yaml-schema on how to point vscode to the created schema file.
• Object manipulation uses the dotpath crate. The syntax is noted below.

Example configuration in config.yaml

See also the examples directory for more example configurations.

1. Any request arriving at Fips with the URI /foo/bar will return ['this is a lot of fun']

- Mock:
    path: ^/foo/bar/$
    rules:
      - path: 
        item: ['this is a lot of fun']

2. Any request against /foo/*anything*/bar/ will be proxied to the server at localhost:4041, the Authorization Header will be forwarded

- Proxy:
    path: ^/foo/.*/bar/$
    forwardUri: 'http://localhost:4041'
    forwardHeaders:
      - 'Authorization'

2. Any request against /foo/*anything*/bar/ will be proxied to the server at localhost:4041, the content-type Header will be returned. Lastly we append another user to our response.

- Fips: 
    path: ^/foo/.*/bar/$
    forwardUri:
      "http://localhost:4041"
    backwardHeaders:
      - "content-type"
    rules:
      - path: ">>"
      {
        "firstname": "Morty",
        "lastname": "Smith",
        "status": "cloned himself"
      }

All configuration parameters for each rule type:

Configuration options for the Fips function (Mock and Proxy combination):

    # A a regex to match incoming requests. if a match is found, this rule will be applied
    path: String
    # This name will be displayed for debugging purposes
    name: String
    # Sleep for ms
    sleep: u64
    # Add these headers to the response
    headers: HashMap<String, String>,
    # Only apply a rule if the method matches these
    matchMethods: Vec<String>
    # Only apply a rule with this probability. It's best to have a fallback rule defined
    matchProbability: Option<f32>
    # Only apply a rule if the request body contains the given string
    matchBodyContains: Option<String>
    # Forward any incoming request to this uri and return the response
    forwardUri: String
    # Forward matching headers on the request
    forwardHeaders: Vec<String>
    # Return these headers from the original response
    backwardHeaders: Vec<String>,
    # Set the response status 
    responseStatus: u16 
    # Apply these transformations on the response (see rules further below)
    rules: Vec<Rules>

Configuration options for the Proxy function:

    # A a regex to match incoming requests. if a match is found, this rule will be applied
    path: String
    # This name will be displayed for debugging purposes
    name: String
    # Sleep for ms
    sleep: u64
    # Add these headers to the response
    headers: HashMap<String, String>,
    # Only apply a rule if the method matches these
    matchMethods: Vec<String>
    # Only apply a rule with this probability. It's best to have a fallback rule defined
    matchProbability: Option<f32>
    # Only apply a rule if the request body contains the given string
    matchBodyContains: Option<String>
    # Forward any incoming request to this uri and return the response
    forwardUri: String
    # Forward matching headers on the request
    forwardHeaders: Vec<String>
    # Return these headers from the original response
    backwardHeaders: Vec<String>,

Configuration options for the Mock function:

    # A a regex to match incoming requests. if a match is found, this rule will be applied
    path: String
    # This name will be displayed for debugging purposes
    name: String
    # Sleep for ms
    sleep: u64
    # Add these headers to the response
    headers: HashMap<String, String>,
    # Only apply a rule if the method matches these
    matchMethods: Vec<String>
    # Only apply a rule with this probability. It's best to have a fallback rule defined
    matchProbability: Option<f32>
    # Only apply a rule if the request body contains the given string
    matchBodyContains: Option<String>
    # Forward any incoming request to this uri and return the response
    forwardUri: String
    # Set the response status 
    responseStatus: u16 
    # Add these items to the response body
    body: Serde<Value>

Configuration options to host static files:

    # A a regex to match incoming requests. if a match is found, this rule will be applied
    path: String
    # This name will be displayed for debugging purposes
    name: String
    # Sleep for ms
    sleep: u64
    # Add these headers to the response
    headers: HashMap<String, String>,
    # Only apply a rule if the method matches these
    matchMethods: Vec<String>
    # Only apply a rule with this probability. It's best to have a fallback rule defined
    matchProbability: Option<f32>
    # Only apply a rule if the request body contains the given string
    matchBodyContains: Option<String>
    # host files from this directory
    staticBaseDir: String

Rule:

   # The json_dotpath (see more at Object manipulation on the response)
   path: String,
   # Any json serializeable item that is added to the response at the paths location
   item: Serde<Value>

Object manipulation on the response

{
  "fruit": [
    { "name": "lemon", "color": "yellow" },
    { "name": "apple", "color": "green" }
  ]
}

• "" ... the whole object
• "fruit" ... the fruits array
• "fruit.0" ... the first fruit object, {"name": "lemon", "color": "yellow"}
• "fruit.1.name" ... the second (index is 0-based) fruit's name, "apple"
• < ... first element
• > ... last element
• - or << ... prepend
• + or >> ... append
• <n, e.g. <5 ... insert before the n-th element
• >n, e.g. >5 ... insert after the n-th element

Extension

One of Fipss key features is its extension system. Fips exports a rust macro export_plugin. Your extension can make use of this macro to register a plugin. The plugins name will be matched against your configuration. If a match occurs, the pattern will be replaced with the output of your plugin. All plugins matching your OS in the plugins directory relative to the Fips binary will be loaded automatically at startup.

Example plugin implementation:

use fips::{PluginRegistrar, Function, InvocationError};
use fake::{faker::name::raw::NameWithTitle, locales::EN, Fake};
use serde_json::Value

pub struct Random;

impl Function for Random {
    fn call(&self, args: Vec<Value>) -> Result<String, InvocationError> {
        let random_fake_name: String = NameWithTitle(EN).fake();
        let json_serializable = format!("{{\"bar\": [\"{}\"]}}", random_fake_name).to_owned();
        Ok(json_serializable)
    }
}

fips::export_plugin!(register);

extern "C" fn register(registrar: &mut dyn PluginRegistrar) {
    registrar.register_function("{{Name}}", Box::new(Random));
}

Above code registers the plugin on the Fips plugin registry. The plugins name {{Name}} will be matched when a matching rule is found, the json serializeable(!) return value will be used to replace your pattern in the matching rule.

Example config.yaml

- Mock:
    path: ^/randomname/$
    rules:
        body:
          foo: '{{Name}}'

Example output of curl localhost:8888/randomname/ | jq

{
  "foo": {
    "bar": ["Ms. Destiney Metz"]
  }
}

Plugins can also be passed arguments via the configuration files. If you wish to do so, the plugin has to be configured as an object in your configuration yaml:

- Mock:
    path: ^/randomname/$
    rules:
        item:
          foo:
            plugin: '{{Name}}',
            args: [ "foo", 1, "bar" ]

Example output of curl localhost:8888/randomname/ | jq

{
  "foo": {
    "bar": ["Ms. Destiney Metz"]
  }
}

License

This Project is Licensed under the MIT License