Upgrading Trains Server from v0.15 or Older

In v0.16, the Elasticsearch subsystem of Trains Server has been upgraded from version 5.6 to version 7.6. This change necessitates the migration of the database contents to accommodate the change in index structure across the different versions.

This page provides the instructions to carry out the migration process. Follow this process if you are using Trains Server version 0.15 or older, and are upgrading to v0.16 or newer.

The migration process makes use of a script that automatically performs the following:

Backup the existing Trains Server Elasticsearch data.
Launch a pair of Elasticsearch 5 and Elasticsearch 7 migration containers.
Copy the Elasticsearch indices using the migration containers.
Terminate the migration containers.
Rename the original data directory to avoid accidental reuse.

Once the migration process completes successfully, the data is no longer accessible to the older version of Trains Server, and Trains Server needs to be upgraded.

Prerequisites

Read/write permissions for the default Trains Server data directory /opt/trains/data and its subdirectories, or if you do not use this default directory, then permissions for the directory and subdirectories you do use.
A minimum of 8GB system RAM.
Minimum free disk space of at least 30% plus three times the size of your data.

Migrating the data

To migrate the data:

Shut down Trains Server, if it is up.

Linux and macOS

docker-compose -f /opt/trains/docker-compose.yml down

Windows

docker-compose -f c:\opt\trains\docker-compose-win10.yml down

Kubernetes

kubectl delete -k overlays/current_version

Kubernetes using Helm

helm del --purge trains-server
kubectl delete namespace trains

For Kubernetes and Kubernetes using Helm, connect to the node in the Kubernetes cluster that you labeled app=trains.
Download the migration package archive.
```
curl -L -O  https://github.com/allegroai/trains-server/releases/download/0.16.0/trains-server-0.16.0-migration.zip
```
If you need to download the file manually, use this direct link: trains-server-0.16.0-migration.zip.

Extract the archive.

unzip trains-server-0.16.0-migration.zip  -d /opt/trains

Migrate the data.
- Linux, macOS, and Windows if you manage your own containers.
  
  Run the migration script. If you use elevated privileges to run Docker (sudo in Linux, or admin in Windows), then use elevated privileges to run the migration script.
```
python elastic_upgrade.py [-s|--source <source_path>] [-t|--target <target_path>] [-n|--no-backup] [-p|--parallel]
```
  The optional command line parameters can be used to control the execution of the migration script:
  - <source_path> - The path to the Elasticsearch data directory in your current Trains Server deployment.
    If not specified, uses the default value of /opt/trains/data/elastic (or c:\opt\trains\data\elastic in Windows)
  - <target_path> - The path to the Elasticsearch data directory in your current Trains Server deployment.
    If not specified, uses the default value of /opt/trains/data/elastic_7 (or c:\opt\trains\data\elastic_7 in Windows)
  - no-backup - Skip creating a backup of the existing Elasticsearch data directory before performing the migration.
    If not specified, takes on the default value of False (Perform backup)
  - parallel - Copy several indices in parallel to utilize more CPU cores. If not specified, parallel indexing is turned off.
- Kubernetes
  1. Clone the trains-server-k8s repository and change to the new trains-server-k8s/upgrade-elastic directory:
```
git clone https://github.com/allegroai/trains-server-k8s.git && cd trains-server-k8s/upgrade-elastic
```
  2. Create the upgrade-elastic namespace and deployments:
```
kubectl apply -k overlays/current_version
```
    Wait for the job to be completed, to check if it's completed you can run:
```
kubectl get jobs -n upgrade-elastic
```
- Kubernetes using Helm
  1. Add the trains-server repository to your Helm client.
```
helm repo add allegroai https://allegroai.github.io/trains-server-helm/
```
    Confirm the trains-server repository is now in your Helm client.
```
helm search trains
```
    The helm search results must include allegroai/upgrade-elastic-helm.
  2. Install upgrade-elastic-helm on your cluster:
```
helm install allegroai/upgrade-elastic-helm --namespace=upgrade-elastic --name upgrade
```
    An upgrade-elastic namespace is created in your cluster, and the upgrade is deployed in it.
    
    Wait for the job to complete. To check if it completed, you can execute the following command:
```
kubectl get jobs -n upgrade-elastic
```

Finishing up

To finish up, first verify the data migration, and then conclude the upgrade.

Step 1. Verifying the data migration

Upon successful completion, the migration script renames the original Trains Server directory which contains the now migrated data, and prints a completion message:

Renaming the source directory /opt/trains/data/elastic to /opt/trains/data/elastic_migrated_<date_time>.
Upgrade completed.

All console output during the execution of the migration script is saved to a log file in the directory where the migration script executes:

<path_to_script>/upgrade_to_7_<date_time>.log

If the migration script does not complete successfully, the migration script prints the error.

For help in resolving migration issues

For help in resolving migration issues, check the allegro-trains Slack Channel, Trains Server GitHub Issues and FAQ.

Step 2. Completing the upgrade

After verifying the data migration completed successfully, you must conclude the Trains Server upgrade process.

Linux or macOS

For example, for Linux or macOS, conclude with the steps in this section. For other deployment formats, see below.

Important: Upgrading from v0.14 or older

For Linux only, if you are upgrading from Trains Server v0.14 or older, configure the Trains Agent Services

If TRAINS_HOST_IP is not provided, then Trains Agent Services will use the external public address of the Trains Server.
If TRAINS_AGENT_GIT_USER / TRAINS_AGENT_GIT_PASS are not provided, then Trains Agent Services will not be able to access any private repositories for running service tasks.
```
export TRAINS_HOST_IP=server_host_ip_here
export TRAINS_AGENT_GIT_USER=git_username_here
export TRAINS_AGENT_GIT_PASS=git_password_here
```

We recommend backing up your data and, if your configuration folder is not empty, backing up your configuration.

For example, if your data and configuration folders are in /opt/trains, then archive all data into ~/trains_backup_data.tgz, and your configuration into ~/trains_backup_config.tgz:
```
sudo tar czvf ~/trains_backup_data.tgz -C /opt/trains/data .
sudo tar czvf ~/trains_backup_config.tgz -C /opt/trains/config .
```

Download the latest docker-compose.yml file.

curl https://raw.githubusercontent.com/allegroai/trains-server/master/docker-compose.yml -o /opt/trains/docker-compose.yml

Startup Trains Server. This automatically pulls the latest Trains Server build.

docker-compose -f /opt/trains/docker-compose.yml pull
docker-compose -f /opt/trains/docker-compose.yml up -d

If issues arise during your upgrade, see the FAQ page, How do I fix Docker upgrade errors?.

Other deployment formats

To conclude the upgrade for deployment formats other than Linux, follow their upgrade instructions: