container.training/slides/swarm/updatingservices.md

Updating services

• We want to make changes to the web UI

• The process is as follows:

  • edit code

  • build new image

  • ship new image

  • run new image

---

Updating a single service with service update

• To update a single service, we could do the following:

  export REGISTRY=127.0.0.1:5000
  export TAG=v0.2
  IMAGE=$REGISTRY/dockercoins_webui:$TAG
  docker build -t $IMAGE webui/
  docker push $IMAGE
  docker service update dockercoins_webui --image $IMAGE
  

• Make sure to tag properly your images: update the TAG at each iteration

  (When you check which images are running, you want these tags to be uniquely identifiable)

---

Updating services with stack deploy

• With the Compose integration, all we have to do is:

  export TAG=v0.2
  docker-compose -f composefile.yml build
  docker-compose -f composefile.yml push
  docker stack deploy -c composefile.yml nameofstack
  

--

• That's exactly what we used earlier to deploy the app

• We don't need to learn new commands!

• It will diff each service and only update ones that changed

---

Changing the code

• Let's make the numbers on the Y axis bigger!

.exercise[

• Update the size of text on our webui:

  sed -i "s/15px/50px/" dockercoins/webui/files/index.html
  

]

---

Build, ship, and run our changes

• Four steps:

  1. Set (and export!) the TAG environment variable
  2. docker-compose build
  3. docker-compose push
  4. docker stack deploy

.exercise[

• Build, ship, and run:

  export TAG=v0.2
  docker-compose -f dockercoins.yml build
  docker-compose -f dockercoins.yml push
  docker stack deploy -c dockercoins.yml dockercoins
  

]

• Because we're tagging all images in this demo v0.2, deploy will update all apps, FYI

---

Viewing our changes

• Wait at least 10 seconds (for the new version to be deployed)

• Then reload the web UI

• Or just mash "reload" frantically

• ... Eventually the legend on the left will be bigger!