toxiproxyr

toxiproxy is an unfathful proxy; it forwards data to and from a service with various “toxic” attributes. The data might be delayed (simulating a slow network connection), dropping the connection, restricting total bandwidth, and other bits of pollution. These can be added together.

Target audience and use cases

toxiproxy is designed for use in tests; this package, as a client for toxiproxy the same. It’s primary uses will be for use in tests for packages that do things over the network. For example:

  • packages that develop new database drivers can use this to explore corner cases such as loss of the network connection, spotty connections, etc
  • packages that make heavy use of the network over existing drivers might use the package to ensure reasonable performance over slow connections

I do not expect that this package will be of interest to the vast majority of R users, and I don’t expect it to be useful within core package code.

Interface

toxiproxyr requires a toxiproxy server to be running. If you already have one configured, then you can set the environment variable TOXIPROXY_ADDR to point at the server and toxiproxyr will use this server when you run

cl <- toxiproxyr::toxiproxy_client()

Alternatively, toxiproxyr can install a server for you - this is the interface designed for testing environments like travis and appveyor. In that case, set the environment variable TOXIPROXYR_SERVER_INSTALL to true and TOXIPROXYR_SERVER_BIN_PATH to the directory to install toxiproxy into. Then, in the tests run

srv <- toxiproxyr::toxiproxy_server()

which will give you a brand new toxiproxy server srv which will be deleted once the srv object goes out of scope (this is designed for use within test_that blocks. Then create a client:

cl <- srv$client()

To interact with the server, through the client, use the methods:

cl
## <toxiproxy_client>
##   Public:
##     api: function () 
##     create: function (name, upstream, listen = NULL, enabled = TRUE) 
##     get: function (name) 
##     initialize: function (addr) 
##     list: function () 
##     remove: function (name) 
##     reset: function () 
##     server_version: function (refresh = FALSE) 
##   Private:
##     api_client: toxiproxy_api_client, R6

For example, we might create an unreliable redis proxy:

proxy <- cl$create("unreliable_redis", upstream = 6379)

Because no listen port was given, this runs on a random port:

proxy$listen
## [1] "127.0.0.1:64607"
proxy$listen_port
## [1] 64607

Connect a redis client to our new proxy

redis <- redux::hiredis(port = proxy$listen_port)
redis$PING()
## [Redis: PONG]

We can simulate a slow connection by adding latency:

system.time(redis$PING())[["elapsed"]]
## [1] 0.001
proxy$add(toxiproxyr::latency(300))
## [1] "latency_downstream"
system.time(redis$PING())[["elapsed"]]
## [1] 0.303

or simulate server or network failure by disabling the proxy entirely:

proxy$with_down(redis$PING())
## Error in redis_command(ptr, cmd): Failure communicating with the Redis server

Installation

Until the package is on CRAN, install from github

remotes::install_github("richfitz/toxiproxyr", upgrade = FALSE)

License

MIT + file LICENSE © Rich FitzJohn.

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.