Core Java

Java: Simulating various connection problems with Toxiproxy

Simulate various connection problems with Toxiproxy and Java’s HttpURLConnection to see what kind of errors get produced: connect timed out vs. read timed out vs. connection refused … .


System: openjdk 11.0.1 2018-10-16

  1. (.setConnectTimeout 1) => connect timed out
  2. (.setReadTimeout 1) => Read timed out on HTTPS, Read timed out on HTTP (or Toxiproxy with 5s latency or timeout )
  3. Nothing listening at the port => Connection refused
  4. Toxiproxy with no upstream configured (i.e. the port is open, but nothing happesn with the connection) => Remote host terminated the handshakeon HTTPS, Read timed out on HTTP
  5. limit_data_downstream => Premature EOF

(What I haven’t been able to simulate (yet) is “connection interrupted/broken”.)

The setup


To /etc/hosts add:

The toxiproxy setup

Start toxiproxy:

docker pull shopify/toxiproxy
# BEFORE we `run` it: case #3
docker run --rm -p 5555:5555 -p 6666:6666 -p 8474:8474 --name toxiproxy -it shopify/toxiproxy

Configure it (we could just POST to :8474 but using the CLI is easier):

$ docker exec -it toxiproxy /bin/sh
/ # cd /go/bin/
# ./toxiproxy-cli create google -l -u # BEFORE this is run: case #4
# ./toxiproxy-cli toxic add google -t latency -a latency=5000 # case #2
Added downstream latency toxic 'latency_downstream' on proxy 'google
# ./toxiproxy-cli toxic remove google -n latency_downstream
Removed toxic 'latency_downstream' on proxy 'google'

# ./toxiproxy-cli toxic add google -t  timeout -a timeout=2000 # case #2
Added downstream timeout toxic 'timeout_downstream' on proxy 'google'
# ./toxiproxy-cli toxic remove google -n timeout_downstream
Removed toxic 'timeout_downstream' on proxy 'google'

# ./toxiproxy-cli toxic add google -t limit_data -a bytes=5000 # case #5
Added downstream limit_data toxic 'limit_data_downstream' on proxy 'google'

The test code

(import '[ URL HttpURLConnection])
  (doto ^HttpURLConnection (.openConnection (URL. ""))
    ;; BEWARE: JVM *must* be started with `` to allow setting the Host:
    (.setRequestProperty "Host" "")
    (.setConnectTimeout 1000)
    (.setReadTimeout 1000))


Read my Simulating network timeouts with toxiproxy to learn why we need to bother with /etc/hosts and the Host header.

Published on Java Code Geeks with permission by Jakub Holy, partner at our JCG program. See the original article here: Java: Simulating various connection problems with Toxiproxy

Opinions expressed by Java Code Geeks contributors are their own.

Jakub Holy

Jakub is an experienced Java[EE] developer working for a lean & agile consultancy in Norway. He is interested in code quality, developer productivity, testing, and in how to make projects succeed.
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