Swarm Network Testing

swarm-network-testing.md

Integration testing

Network simulation

The aim is to fully simulate devp2p networks, manage connections between nodes and record interactions in a replayable journal.

A simulation framework is currently in progress on the network-testing-framework branch and currently includes the following packages:

p2p/adapters

An adapter is responsible for creating nodes and connecting them together, examples being:

• inproc - creates in-memory simulator nodes and connects them with in-memory pipes
• rlpx - creates p2p.Server nodes and connects them using TCP connections
• docker - starts Docker containers and connects them using ssh+ipc connections

p2p/protocols

Provides an interface to simplify defining sub-protocols to run on devp2p, abstracting away the following:

• provide the forever loop to read incoming messages
• automatic RLP encoding / decoding of protocol messages
• standardise error handling related to communication

See this test protocol.

p2p/simulations

Implements an event-based simulation Network which accepts incoming events to manage nodes using an adapter and send messages between nodes, and outputs simulation events to subscribers.

Example events:

• node up - a new node has started
• node down - a node has gone down
• conn up - a connection has been established between two nodes
• conn down - a connection has been severed between two nodes
• msg - a message has been sent between two nodes

A Journal is a network subscriber which records events which can then be replayed into a new network simulation.

cmd/p2psim

p2psim is a simulator REPL to perform in-memory simulations, currently implementing the following commands:

p2psim> help
add                             add new node
start <node>                    start <node>
stop <node>                     stop <node>
connect <nodeA> <nodeB>         connect <nodeA> with <nodeB>
disconnect <nodeA> <nodeB>      disconnect <nodeA> from <nodeB>
list                            list nodes
info <node>                     display info on <node>
help                            show usage
exit                            exit the simulator

A sample session:

p2psim> add
added node1 (049ffad1729ebd43e5a44b7127f9aaabf0f6a5a20848837db6b4639876b5c4bd11591d46de15bde0570fe1a26716209c1502e33a0bcdc7dafb4a67447d775138)

p2psim> add
added node2 (a21cd8771c9b6a15713b0cb042c646833dc978b5a049ca151488a5dc704b7770c9cf33c8cfc5521121fbbab09d1d3f82d635cf6419da51297d8a71a3a9853a62)

p2psim> add
added node3 (d09d6e2077f0527a97bb7347783182a8e1ba8020885ba85f970f9c72307db5b3c6f5af34b652def7342781781e2e3cb26cb103e3254c4ffa66a8865c4d1d9126)

p2psim> list
NAME    UP      ID
node1   false   049ffad1729ebd43e5a44b7127f9aaabf0f6a5a20848837db6b4639876b5c4bd11591d46de15bde0570fe1a26716209c1502e33a0bcdc7dafb4a67447d775138
node2   false   a21cd8771c9b6a15713b0cb042c646833dc978b5a049ca151488a5dc704b7770c9cf33c8cfc5521121fbbab09d1d3f82d635cf6419da51297d8a71a3a9853a62
node3   false   d09d6e2077f0527a97bb7347783182a8e1ba8020885ba85f970f9c72307db5b3c6f5af34b652def7342781781e2e3cb26cb103e3254c4ffa66a8865c4d1d9126

p2psim> start node1
started node1 (049ffad1729ebd43e5a44b7127f9aaabf0f6a5a20848837db6b4639876b5c4bd11591d46de15bde0570fe1a26716209c1502e33a0bcdc7dafb4a67447d775138)

p2psim> start node3
started node3 (d09d6e2077f0527a97bb7347783182a8e1ba8020885ba85f970f9c72307db5b3c6f5af34b652def7342781781e2e3cb26cb103e3254c4ffa66a8865c4d1d9126)

p2psim> connect node1 node3
connected node1 to node3

p2psim> info node1
ID      049ffad1729ebd43e5a44b7127f9aaabf0f6a5a20848837db6b4639876b5c4bd11591d46de15bde0570fe1a26716209c1502e33a0bcdc7dafb4a67447d775138
Up      true

Tasks

• update simulations.Network to handle message events
• implement remote node adapters (rlpx / docker) with event subscriptions
• run protocols in p2psim
• journal support in p2psim (e.g. load <journal>, save <journal>)
• add a logical clock to allow the simulation to be paused / resumed and tests to wait for logical clock durations before making assertions
• add next and step <n> commands to p2psim to step through a discrete number of events
• implement p2psim scripts for writing full network simulation scenarios
• add VM adapters to create more realistic networks (e.g. KVM / AWS / Azure)