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Last pushed: 2 months ago
Short Description
app container to provide network connection checker based on Alpine Linux
Full Description


Docker-based application container to provide
conn-check via


Project URL:
<br />
Docker hub:

The Problem

Deployments of a service have a number of different network
dependencies that require verification:

  • Connections between services (e.g. app <-> postgresql, are
    ports unblocked at the firewall(s)? If talking to a data centre
    instance do we have a route?)

  • External services (e.g. webservices such as S3)

  • Verification that the services on the other end are real
    (you're actually talking to MongoDB or rabbitmq via AMQP, not
    just another TCP service running on those ports)

  • Verification of authentication

Although many of these can be solved with smoke tests, it's not
always immediately obvious that there is a problem, or what the
problem is.

conn-check takes a simple YAML config
defining a list of checks to perform (udp, tcp, tls,
http, amqp, postgres, mongodb, redis, memcache), and
performs those checks asynchronously using Twisted's thread
pool, and outputs the results in a Nagios check standard
, so
conn-check can be run regulary as a Nagios check to continually
verify network status between services (and alert on change,
e.g. out of band firewall changes).


Run the docker container as if it were an application:

docker run --rm -it jumanjiman/conn-check -h

Details about the options and its YAML config are at

Build integrity

An unattended test harness runs on CircleCI to build and test the image.
If all tests pass on master branch in the unattended test harness,
CircleCI pushes the built image to the Docker hub.

Available tags:

  • Optimistic: jumanjiman/conn-check:latest
  • Pessimistic: jumanjiman/conn-check:<VERSION>-<date>T<time>-git-<hash>

A simple test harness uses BATS.
Output resembles:

ok 1 --help works
ok 2 successfully checks TLS to



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