cattle/upgrading/— title: Upgrading using Rancher Compose layout: rancher-default-v1.6 version: v1.6 lang: en —

Upgrading Services


After launching services, you may have decided you want to change your service to update your application. For example, the image may have been updated and you want to launch an updated version of the service. As Docker containers are immutable, in order to change your service, you will need to destroy the old containers and launch new containers. Rancher provides two methods of upgrade. The recommended in-service upgrade allows you to stop the old containers and start new containers in the same service name. An in-service upgrade is the only type of upgrade supported in the UI, and it is also supported in Rancher Compose. The rolling upgrade is only supported through Rancher Compose, which removes the old service and creates a brand new service.

Note: If you are looking to increase the scale of your service, you can either edit the scale of the service in the UI or use rancher-compose scale <serviceName>=<newNumber>.

In-Service Upgrade

Upgrading Services in the UI

Any service can be upgraded through the UI. Similar to launching services, the service will have all the Docker options that were previously selected and you will be able to update them to any new value. There are also a couple of upgrade options:

After selecting your upgrade options and defining your new service, select Upgrade.

Once all the old containers have been stopped and the new containers have become active, the service will be in an Upgraded state. At this stage, you should test your new service to ensure it’s working as expected before selecting Finish Upgrade. If your new service isn’t what you expected, you have the ability to Rollback to the original service.

Upgrading Services with Rancher Compose

With Rancher Compose, if you have chosen to do an in-service upgrade, the containers in existing services are upgraded to the provided docker-compose.yml and the original containers in the service are removed. In order to perform this action, upgrade options are passed in during a rancher-compose up command. By adding the --upgrade option, the docker-compose.yml will upgrade any services, that have the same name, in the stack to the new service definition. Just like in the UI, the in-service upgrade is a two step process as we require the user to confirm the upgrade is okay.

Step 1: Performing the Upgrade

For an upgrade, you can upgrade an entire stack or specific services within the docker-compose.yml

# Upgrades all services in the stack (i.e. docker-compose.yml)
$ rancher-compose up --upgrade
# Upgrade specific services (i.e. service1 and service2)
$ rancher-compose up --upgrade service1 service2
# Force an upgrade even though the docker-compose.yml for the services didn't change
$ rancher-compose up --force-upgrade

Upgrade Options

Option Description
--pull, -p Before doing the upgrade do an image pull on all hosts that have the image already
-d Do not block and log
--upgrade, -u, --recreate Upgrade if service has changed
--force-upgrade, --force-recreate Upgrade regardless if service has changed
--confirm-upgrade, -c Confirm that the upgrade was success and delete old containers
--rollback, -r Rollback to the previous deployed version
--batch-size “2” Number of containers to upgrade at once
--interval “1000” Update interval in milliseconds


Pull

During your upgrade, you can also perform a docker pull before the images are deployed. Since the hosts would typically have your image already cached, you might want to add in the --pull option to pull the most up-to-date images on your hosts.

# During upgrade, force a pull to the host for latest images
$ rancher-compose up --upgrade --pull

Batch Size

By default, containers of the new service are started 2 at a time during an upgrade. You can change how many containers you want upgraded at a time, by passing in --batch-size and a number. This number is how many containers will be started in the new service during the upgrade process.

# Containers of service2 will be started in batches of 3
# until the scale of the service2 is reached
$ rancher-compose up --upgrade --batch-size 3

Interval

By default, during the upgrade, there is a 2 second wait between when containers on the new service have started and when containers on the old service are removed. You can override this interval by passing in --interval and the number of milliseconds for the interval.

# Set the interval to 30 seconds, which is the time between
# when the containers of the new service have started and
# when the containers of the old service are removed
$ rancher-compose upgrade service1 service2 --interval "30000"

Starting New Containers Before Stopping Old Containers

By default, the in-service upgrade stops the existing containers, and then launch the new containers. To start the new containers before stopping the old containers, you must provide additional content in the rancher-compose.yml.

version: '2'
services:
  myservice:
    upgrade_strategy:
      start_first: true


# Upgrading myservice with the above yaml will start the new service first
$ rancher-compose up --upgrade myservice
Step 2: Confirming the upgrade

Once you have verified the upgrade passes your validation, you will need to confirm that the upgrade is complete. The confirmation is required as it allows users to rollback to their old versions if necessary. Once you have confirmed the upgrade, rolling back to the old version is no longer possible.

# Confirm that the upgrade is complete and successful
$ rancher-compose up --upgrade --confirm-upgrade

Rolling Back

After performing an upgrade, if your upgraded services have issues, Rancher provides the ability to roll back to your old service. This can only be accomplished if you have not confirmed your upgrade.

# Roll back to previous version
$ rancher-compose up --upgrade --rollback

Rolling Upgrade

A rolling upgrade is when a new service is created to replace an existing old service. Instead of having containers be removed and new containers started in the same service, a completely new service would be created. This type of upgrade is only supported with Rancher Compose. The command to perform a rolling upgrade to a new service is easy:

$ rancher-compose upgrade service1 service2

service2 is the name of the new service that you want to start in Rancher. service1 is the name of the service that you want stopped in Rancher. As service2 is deployed, the containers in service1 will be removed from Rancher. The service is not removed from Rancher, but the scale of the service will be brought to 0.

Inside the docker-compose.yml, both names of the services will need to be included. For service1, only the name of the service is required for Rancher Compose to find the service in Rancher. For service2, the service will need to be populated with all the details of the service in order for Rancher Compose to launch the service.

Example docker-compose.yml

version: '2'
services:
  service1:
  # Nothing needs to actually be placed in the file as the service is already running
  service2:
    image: wordpress
    links:
    # Define any outbound links to other services in the stack
    - db:mysql

By default, any load balancers or services linked to service1 (i.e. inbound links) will automatically be updated with a new link to service2. If you do not wish for these links to be created, you can set an option to not have them created.

Note: There is no need for a rancher-compose.yml file used while upgrading services. By default, the scale of the new service is based on the scale of the old service. You can override this scale by passing in the --scale option.

Scaling during an Upgrade

Containers are not removed from the old service until the sum of containers from the new service and old service have exceeded the final scale of the new service.

Example:

$ rancher-compose upgrade service1 service2 --scale 5

service1 has a scale of 2 containers and is upgrading to service2, which will eventually have 5 containers.

service1 service2 Notes
2 0 service1 is running with 2 containers.
2 2 service2 starts 2 containers at a time (Default Batch Size).
2 4 service2 starts another 2 containers.
1 4 After the previous step, the sum (6) of the new and old containers is greater than the final scale (5), service1 stops and removes one of the containers to maintain the final scale of 5.
1 5 service2 starts only 1 container to reach the final scale of 5.
0 5 service1 removes the last running container.

Options with the Upgrade Command

With the upgrade command, there are several options that can be passed in to customize your upgrade.

Options Description
--batch-size “2” Number of containers to upgrade at once
--scale “-1” Final number of running containers
--interval “2000” Update interval in milliseconds
--update-links Update inbound links on target service
--wait, -w Wait for upgrade to complete
--pull, -p Before doing the upgrade do an image pull on all hosts that have the image already
--cleanup, -c Remove the original service definition once upgraded, implies –wait
Batch Size

By default, containers of the new service are started 2 at a time during an upgrade. You can change how many containers you want upgraded at a time, by passing in --batch-size and a number. This number is how many containers will be started in the new service during the upgrade process.

# Containers of service2 will be started in batches of 3
# until the scale of the service2 is reached
$ rancher-compose upgrade service1 service2 --batch-size 3
Final Scale

By default, the scale of a new service is based on the scale of the old service. You can change the scale of the new service by passing in --scale and a number. The number defines the final scale of running containers you want in the new service.

# Setting the scale of service2 to 8 containers
$ rancher-compose upgrade service1 service2 --scale 8


Note: The containers of the old service will not be removed based on batch size. After the containers are launched in a particular batch, containers of the old service are stopped and removed when the sum of containers in the old and new service exceed the final scale of the new service.

Interval

By default, during the upgrade, there is a 2 second wait between when containers on the new service have started and when containers on the old service are removed. You can override this interval by passing in --interval and the number of milliseconds for the interval.

# Set the interval to 30 seconds, which is the time between
# when the containers of the new service have started and
# when the containers of the old service are removed
$ rancher-compose upgrade service1 service2 --interval "30000"

By default, any services that were linked TO the old service are also linked to the new service. If you don’t want any of these services to be linked to the new service, you can pass in --update-links="false" so that there will be no links to the new service.

# Do not set the links to the old service in the set up of the new service
$ rancher-compose upgrade service1 service2 --update-links="false"
Waiting for Upgrade to Complete

By default, Rancher Compose will exit after the upgrade has been passed to Rancher, but the upgrade process may not have been completed. By passing in the --wait or -w to the upgrade command, Rancher Compose will not exit until after the new service has completely started and the old service has been stopped.

# Wait for the upgrade to be completed
$ rancher-compose upgrade service1 service2 --wait
Pulling a new Image

By default, Rancher Compose will not pull an image if the image already exists on the host. By passing in the --pull or -p to the upgrade command, Rancher Compose will pull the image again even if the image is already on the host.

# Pull a new image even if image already exists
$ rancher-compose upgrade service1 service2 --pull
Cleanup Original Service

By default, the original service will remain in Rancher with a scale of 0 after the upgrade is complete. If you are positive that you will not need to rollback or save the original service definition, you can pass in the --cleanup or -c option with the upgrade command. This option implies that --wait as the Rancher Compose will wait for the upgrade to be completed before removing the service from Rancher.

# Cleanup service1 from Rancher after upgrade is complete
$ rancher-compose upgrade service1 service2 --cleanup