README
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Docker example
This folder contains all that is needed to build an environment with a publisher, broker (mosquitto) and subscriber
using docker (ideally docker-compose). While it provides an end-to-end example its primary purpose is to act as a
starting point for producing reproducible examples (when logging an issue with the library).
Because the publisher (pub), broker (mosquitto) and subscriber (sub) run in separate containers this setup closely
simulates a real deployment. One thing to bear in mind is that the network between the containers is very fast and
reliable (but there are some techniques that can be used to simulate failures etc).
The subscriber connects via websockets whereas the publisher uses a TCP connection (this is set via environmental variables).
Note: The docker-compose file sets the context to the root of paho.golang; this is done to avoid the need for
publisher and subscriber to be in their own modules. This avoids the need to import paho.golang (which would
make using this for testing changes to autopaho difficult because go would fetch the package from git).
Usage
Ensure that you have docker and docker-compose installed.
To start everything up change into the cmd/docker folder and run:
docker-compose up --build --detach
This will start everything up in the background. You can see what is happening by running:
docker-compose logs --follow
This will display a lot of information (mosquitto is running with debug level logging). To see the subscriber logs:
docker-compose logs --follow sub
Note: Messages received by the subscriber will be written to shared/receivedMessages (you may want to delete the
contents of this file from time to time!).
To stop everything run:
docker-compose down
Feel free to copy the folder and modify the publisher/subscriber to work as you want them to!
Note: The pub and sub containers connect to mosquitto via the internal network (test-net) but mosquitto should
also be available on the host port 8883 if you wish to connect to it. This will not work if you have mosquitto
installed locally (edit the docker-compose.yml and change the published port).
Simulating Network Connection Loss
You can simulate the loss of network connectivity by disconnecting the network adapter within a container. e.g.
docker network disconnect lostpackets_test-net lostpackets_pub_1
docker network connect lostpackets_test-net lostpackets_pub_1
Directories