Docker Cookbook

306 | Chapter 10: Application Use Cases

---

if [ -z "${1}" ]; then
version="latest"
else
version="${1}"
fi
# destroy old application
curl -X DELETE -H "Content-Type: application/json" \
http://${marathon}:8080/v2/apps/app
# At this point we can query Marathon until the application is down.
sleep 1
# these lines will create a copy of app_marathon.json and update the image
# version. This is required for sing the cottect image tag, as the marathon
# configuration file does not support variables.
cp -f app_marathon.json app_marathon.json.tmp
sed -i "s/latest/${version}/g" app_marathon.json.tmp
# post the application to Marathon
curl -X POST -H "Content-Type: application/json" \
http://${marathon}:8080/v2/apps \
-d@app_marathon.json.tmp
Now you can start the Jenkins server by using 
docker-compose
and define the execu‐
tion steps in the Jenkins job configuration. 
Figure 10-2
 shows the UI where this con‐
figuration can be done.
Figure 10-2. The Jenkins UI
10.2 CI/CD: Building a Continuous Delivery Pipeline with Jenkins and Apache Mesos | 307

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Discussion
There are multiple ways to solve the problem of starting containers from within a
container. Mounting a socket used by Docker for communication between the server
and client is one of them. Additional methods may include running a container
directly within a container using a privileged container. Another way is to configure
the Docker server to receive remote API calls and configure the Docker client within
the Jenkins container to communicate with it using a full URL. This requires config‐
uring networking to allow communication between the server and the client.