Type:	Package
Title:	A Lightweight and Flexible Web Framework
Version:	1.3.0
Description:	A very flexible framework for building server side logic in R. The framework is unopinionated when it comes to how HTTP requests and WebSocket messages are handled and supports all levels of app complexity; from serving static content to full-blown dynamic web-apps. Fiery does not hold your hand as much as e.g. the shiny package does, but instead sets you free to create your web app the way you want.
License:	MIT + file LICENSE
URL:	https://fiery.data-imaginist.com, https://github.com/thomasp85/fiery
BugReports:	https://github.com/thomasp85/fiery/issues
Imports:	cli, fs, future, glue, httpuv, later, lifecycle, parallelly, promises, R6, reqres (≥ 1.0.0), rlang (≥ 1.1.0), sodium, stats, stringi, utils, yaml
Suggests:	callr, covr, knitr, logger, rmarkdown, testthat (≥ 3.0.0)
VignetteBuilder:	knitr
Encoding:	UTF-8
RoxygenNote:	7.3.2
Collate:	'loggers.R' 'aaa.R' 'HandlerStack.R' 'Fire.R' 'PromiseStack.R' 'additional_type_checks.R' 'fake_request.R' 'fiery-package.R' 'import-standalone-obj-type.R' 'import-standalone-types-check.R' 'request_store.R' 'zzz.R'
Config/testthat/edition:	3
NeedsCompilation:	no
Packaged:	2025-08-20 09:01:01 UTC; thomas
Author:	Thomas Lin Pedersen [cre, aut]
Maintainer:	Thomas Lin Pedersen <thomasp85@gmail.com>
Repository:	CRAN
Date/Publication:	2025-08-20 17:00:20 UTC

fiery: A Lightweight and Flexible Web Framework

Description

A very flexible framework for building server side logic in R. The framework is unopinionated when it comes to how HTTP requests and WebSocket messages are handled and supports all levels of app complexity; from serving static content to full-blown dynamic web-apps. Fiery does not hold your hand as much as e.g. the shiny package does, but instead sets you free to create your web app the way you want.

Details

fiery is a lightweight and flexible framework for web servers build on top of the httpuv package. The framework is largely event-based, letting the developer attach handlers to life-cycle events as well as defining and triggering their own events. This approach to development is common in JavaScript, but might feel foreign to R developers. Thankfully it is a rather simple concept that should be easy to gradually begin to use to greater and greater effect.

Author(s)

Maintainer: Thomas Lin Pedersen thomasp85@gmail.com (ORCID)

See Also

Useful links:

• https://fiery.data-imaginist.com

• https://github.com/thomasp85/fiery

• Report bugs at https://github.com/thomasp85/fiery/issues

Generate a New App Object

Description

The Fire generator creates a new Fire-object, which is the class containing all the app logic. The class is based on the R6 OO-system and is thus reference-based with methods and data attached to each object, in contrast to the more well known S3 and S4 systems. A fiery server is event driven, which means that it is build up and manipulated by adding event handlers and triggering events. To learn more about the fiery event model, read the event vignette. fiery servers can be modified directly or by attaching plugins. As with events, plugins has its own vignette.

Initialization

A new 'Fire'-object is initialized using the new() method on the generator:

Copying

As Fire objects are using reference semantics new copies of an app cannot be made simply be assigning it to a new variable. If a true copy of a Fire object is desired, use the clone() method.

Active bindings

Methods

Public methods

• Fire$new()

• Fire$format()

• Fire$ignite()

• Fire$start()

• Fire$reignite()

• Fire$resume()

• Fire$extinguish()

• Fire$stop()

• Fire$on()

• Fire$off()

• Fire$trigger()

• Fire$send()

• Fire$close_ws_con()

• Fire$serve_static()

• Fire$exclude_static()

• Fire$attach()

• Fire$has_plugin()

• Fire$header()

• Fire$set_data()

• Fire$get_data()

• Fire$remove_data()

• Fire$time()

• Fire$remove_time()

• Fire$delay()

• Fire$remove_delay()

• Fire$async()

• Fire$remove_async()

• Fire$set_client_id_converter()

• Fire$set_logger()

• Fire$log()

• Fire$is_running()

• Fire$safe_call()

• Fire$test_request()

• Fire$test_header()

• Fire$test_message()

• Fire$test_websocket()

• Fire$clone()

Method new()

Create a new Fire app

Usage

Fire$new(host = "127.0.0.1", port = 8080)

Arguments

Returns

A Fire object

Method format()

Human readable description of the app

Usage

Fire$format(...)

Arguments

Returns

A character vector

Method ignite()

Begin running the server. Will trigger the start event

Usage

Fire$ignite(block = TRUE, showcase = FALSE, ..., silent = FALSE)

Arguments

Method start()

Synonymous method to ignite()

Usage

Fire$start(...)

Arguments

Method reignite()

Resume a session. This is equivalent to ignite() but will also trigger the resume event

Usage

Fire$reignite(...)

Arguments

Method resume()

Synonymous method to reignite()

Usage

Fire$resume(...)

Arguments

Method extinguish()

Stop the server. Will trigger the end event

Usage

Fire$extinguish()

Method stop()

Synonymous method to extinguish()

Usage

Fire$stop()

Method on()

Add a handler to an event. See the The event cycle in fiery vignette for more information.

Usage

Fire$on(event, handler, pos = NULL, id = NULL)

Arguments

Returns

A unique string identifying the handler (either id or generated for you)

Method off()

Remove an event handler from the app.

Usage

Fire$off(handlerId)

Arguments

Method trigger()

Trigger an event in the app. This will cause any handler attached to the event to be called. See the The event cycle in fiery vignette for more information.

Usage

Fire$trigger(event, ...)

Arguments

Returns

A named list containing the return values of all handlers attached to the event

Method send()

Send a Websocket message to a client. Will trigger the send event.

Usage

Fire$send(message, id)

Arguments

Method close_ws_con()

Close a Websocket connection. Will trigger the websocket-closed event

Usage

Fire$close_ws_con(id)

Arguments

Method serve_static()

Serve a file or directory of files at a specified url path. Requests matching a file on the system never enters into the request loop but are served directly (and fast). Due to this, logging for these requests are also turned off

Usage

Fire$serve_static(
  at,
  path,
  use_index = TRUE,
  fallthrough = FALSE,
  html_charset = "utf-8",
  headers = list(),
  validation = NULL
)

Arguments

Method exclude_static()

Exclude a url path from serving static content. Only meaningful to exclude sub paths of path that are set to serve static content

Usage

Fire$exclude_static(at)

Arguments

Method attach()

Attach a plugin to the app. See the Creating and using fiery plugins vignette for more information

Usage

Fire$attach(plugin, ..., name = NULL, force = FALSE)

Arguments

Method has_plugin()

Check if the app has a plugin attached

Usage

Fire$has_plugin(name)

Arguments

Returns

A boolean indicating if the given plugin is already attached

Method header()

Add a global http header that will be applied to all responses

Usage

Fire$header(name, value)

Arguments

Method set_data()

Add data to the global data store

Usage

Fire$set_data(name, value)

Arguments

Method get_data()

Retrieve data from the global data store

Usage

Fire$get_data(name)

Arguments

Returns

The data requested. Returns NULL if the store does not contain the requested data

Method remove_data()

Remove data from the global data store

Usage

Fire$remove_data(name)

Arguments

Method time()

Add a timed evaluation that will be evaluated after the given number of seconds.

Usage

Fire$time(expr, then, after, loop = FALSE)

Arguments

Returns

A unique id identifying the handler

Method remove_time()

Remove a timed evaluation

Usage

Fire$remove_time(id)

Arguments

Method delay()

Add a delayed evaluation to be evaluated immediately at the end of the loop cycle.

Usage

Fire$delay(expr, then)

Arguments

Returns

A unique id identifying the handler

Method remove_delay()

Remove a delayed evaluation

Usage

Fire$remove_delay(id)

Arguments

Method async()

Add an asynchronous evaluation to be evaluated in another process without blocking the server. This function has been deprecated in favor of using your own async framework of choice, e.g. mirai or promises

Usage

Fire$async(expr, then)

Arguments

Returns

A unique id identifying the handler

Method remove_async()

Remove an async evaluation

Usage

Fire$remove_async(id)

Arguments

Method set_client_id_converter()

Sets the function that converts an HTTP request into a specific client id

Usage

Fire$set_client_id_converter(converter)

Arguments

Method set_logger()

Sets the logging function to use

Usage

Fire$set_logger(logger)

Arguments

Method log()

Log a message with the logger attached to the app. See loggers for build in functionality

Usage

Fire$log(
  event,
  message,
  request = NULL,
  ...,
  .logcall = sys.call(),
  .topcall = sys.call(-1),
  .topenv = parent.frame()
)

Arguments

Method is_running()

Test if an app is running

Usage

Fire$is_running()

Method safe_call()

Evaluate an expression safely, logging any errors, warnings, or messages that bubbles up

Usage

Fire$safe_call(expr, request = NULL)

Arguments

Returns

The value of the expression. If an error is caught, the condition object is returned instead

Method test_request()

Send a request directly to the request logic of a non-running app. Only intended for testing the request logic

Usage

Fire$test_request(request)

Arguments

Method test_header()

Send a request directly to the header logic of a non-running app. Only intended for testing the request logic

Usage

Fire$test_header(request)

Arguments

Method test_message()

Send a message directly to the message logic of a non-running app. Only intended for testing the websocket logic

Usage

Fire$test_message(request, binary, message, withClose = TRUE)

Arguments

Method test_websocket()

Send a message directly from a non-running app. Only intended for testing the websocket logic

Usage

Fire$test_websocket(request, message, close = TRUE)

Arguments

Method clone()

The objects of this class are cloneable with this method.

Usage

Fire$clone(deep = FALSE)

Arguments

Examples

# Create a New App
app <- Fire$new(port = 4689)

# Setup the data every time it starts
app$on('start', function(server, ...) {
    server$set_data('visits', 0)
    server$set_data('cycles', 0)
})

# Count the number of cycles
app$on('cycle-start', function(server, ...) {
    server$set_data('cycles', server$get_data('cycles') + 1)
})

# Count the number of requests
app$on('before-request', function(server, ...) {
    server$set_data('visits', server$get_data('visits') + 1)
})

# Handle requests
app$on('request', function(server, ...) {
    list(
        status = 200L,
        headers = list('Content-Type' = 'text/html'),
        body = paste('This is indeed a test. You are number', server$get_data('visits'))
    )
})

# Show number of requests in the console
app$on('after-request', function(server, ...) {
    message(server$get_data('visits'))
    flush.console()
})

# Terminate the server after 300 cycles
app$on('cycle-end', function(server, ...) {
    if (server$get_data('cycles') > 300) {
        message('Ending...')
        flush.console()
        server$extinguish()
    }
})

# Be polite
app$on('end', function(server) {
    message('Goodbye')
    flush.console()
})

## Not run: 
app$ignite(showcase = TRUE)

## End(Not run)

Create a fake request to use in testing

Description

This function creates a new request for a specific resource defined by a URL. It mimics the format of the requests provided through httpuv, meaning that it can be used in place for the requests send to the before-request, request, and after-request handlers. This is only provided so that handlers can be tested without having to start up a server.

Usage

fake_request(
  url,
  method = "get",
  app_location = "",
  content = "",
  headers = list(),
  ...,
  remote_address = "123.123.123.123"
)

Arguments

Value

A Rook-compliant environment

Examples

req <- fake_request(
    'http://www.my-fake-website.com/path/to/a/query/?key=value&key2=value2',
    content = 'Some important content'
)

# Get the main address of the URL
req[['SERVER_NAME']]

# Get the query string
req[['QUERY_STRING']]

# ... etc.

# Cleaning up connections
rm(req)
gc()

App Logging

Description

fiery has a build in logging mechanism that lets you capture event information however you like. Every user-injested warnings and errors are automatically captured by the logger along with most system errors as well. fiery tries very hard not to break due to faulty app logic. This means that any event handler error will be converted to an error log without fiery stopping. In the case of request handlers a 500L response will be send back if any error is encountered.

Usage

logger_null()

logger_console(format = "{time} - {event}: {message}")

logger_file(file, format = "{time} - {event}: {message}")

logger_switch(..., default = logger_null())

logger_logger(default_level = "INFO")

common_log_format

combined_log_format

Arguments

Format

An object of class character of length 1.

An object of class character of length 1.

Setting a logger

By default, fiery uses logger_null() which forwards warning and error messages to stderr() and ignores any other logging events. To change this behavior, set a different logger using the set_logger() method:

app$set_logger(logger)

where logger is a function taking at least the following arguments: event, message, request, time, and ....

fiery comes with some additional loggers, which either writes all logs to a file or to the console. A new instance of the file logger can be created with logger_file(file):

app$set_logger(logger_file('fiery_log.log'))

A new instance of the console logger can be create with logger_console():

app$set_logger(logger_console())

Both functions takes a format a argument that lets you customise how the log is written. Furthermore the console logger will style the logs with colour coding depending on the content if the console supports it.

As a last possibility it is possible to use different loggers dependent on the event by using the switch logger:

app$set_logger(logger_switch(warning =,
                             error = logger_file('errors.log),
                             default = logger_file('info.log')))

Automatic logs

fiery logs a number of different information by itself describing its operations during run. The following events are send to the log:

start

Will be send when the server starts up

resume

Will be send when the server is resumed

stop

Will be send when the server stops

request

Will be send when a request has been handled. The message will contain information about how long time it took to handle the request or if it was denied.

websocket

Will be send every time a WebSocket connection is established or closed as well as when a message is received or send

message

Will be send every time a message is emitted by an event handler or delayed execution handler

warning

Will be send everytime a warning is emitted by an event handler or delayed execution handler

error

Will be send everytime an error is signaled by an event handler or delayed execution handler. In addition some internal functions will also emit error event when exceptions are encountered

By default only message, warning and error events will be logged by sending them to the error stream as a message().

Access Logs

Of particular interest are logs that detail requests made to the server. These are the request events detailed above. There are different standards for how requests are logged. fiery uses the Common Log Format by default, but this can be modified by setting the access_log_format field to a glue expression that has access to the following variables:

start_time

The time the request was recieved

end_time

The time the response was send back

request

The Request object

response

The Response object

id

The client id

To change the format:

app$access_log_format <- combined_log_format

Custom logs

Apart from the standard logs described above it is also possible to send messages to the log as you please, e.g. inside event handlers. This is done through the log() method where you at the very least specify an event and a message. In general it is better to send messages through log() rather than with warning() and stop() even though the latters will eventually be caught, as it gives you more control over the logging and what should happen in the case of an exception.

An example of using log() in a handler could be:

app$on('header', function(server, id, request) {
  server$log('info', paste0('request from ', id, ' received'), request)
})

Which would log the timepoint the headers of a request has been recieved.

Select a random safe port

Description

This is a small utility function to get random safe ports to run your application on. It chooses a port within the range that cannot be registeret to IANA and thus is safe to assume are not in use.

Usage

random_port()

Value

An integer in the range 49152-65535

Examples

random_port()

Use a session cookie to store the id of the session

Description

This function constructs an ID extractor for incoming requests, the return value of which will be passed to the id argument of request, header, message etc handlers. By default, fiery uses this with default arguments.

Usage

session_id_cookie(name = "fiery_id", secure = FALSE)

Arguments

Details

A session id is looked for in the cookie matching the name arg. If it is found then the value of the cookie is returned. If it is not found then an id is generated with reqres::random_key() and attached to the response as a cookie with the given name. The cookie is set to HTTP only and Strict same site policy. Depending on secure it also sets it to only be transferred over HTTPS.

Value

A unary function taking a Request object and returning an ID for it

Note

Session ID should not be considered as authentication. If you are handling sensitive data you should consider a more secure way of identifying users across requests.