Upgrading a Cloud instance

SOC2/CI-108

Option 1 - automated upgrade

To upgrade a specific instance

export SLUG=company
export ENVIRONMENT=prod
export TARGET_VERSION=4.1.0
gh workflow run mi_upgrade.yml -f customer=$SLUG -f environment=$ENVIRONMENT -f target_src_version=$TARGET_VERSION

To upgrade all instances within an environment

Using mi2 you can generate commands to trigger automated upgrades for all instances:

for internal instances:

mi2 workflow run -filter '.metadata.labels."instance-type" == "internal" and .spec.sourcegraphApplicationVersion != "$TARGET_VERSION"' upgrade-instances

for production instances:

mi2 workflow run -filter '.metadata.labels."instance-type" == "production" and .spec.sourcegraphApplicationVersion != "$TARGET_VERSION"' upgrade-instances

for trial instances:

mi2 workflow run -filter '.metadata.labels."instance-type" == "trial" and .spec.sourcegraphApplicationVersion != "$TARGET_VERSION"' upgrade-instances

This automated workflow will generate a pull request for each instance to represent the upgrade that:

  1. Links to full logs of the automated upgrade process (retained for 90 days)
  2. Embeds a summary of an automated full instance healthcheck (retained permanently)
  3. Links to the tracking issue associated with the upgrade

To review currently open PRs for successful instance upgrades using gh:

# Sanity check to see that the PRs correspond to instances you have upgraded
gh pr list --label 'mi-upgrade'

# Save the list of PRs you are going to work with
gh pr list --label 'mi-upgrade' --json number --jq '.[].number' > upgrade-prs.txt

# Review the test plan of each PR (press 'q' to review the next one)
cat upgrade-prs.txt | xargs -n1 gh pr view

If an upgrade fails, follow the logs and figure out which step went wrong, then follow the manual upgrade to finish the upgrade.

If all is well, approve and merge each instance upgrade:

# Approve each PR
cat upgrade-prs.txt | xargs -n1 gh pr review --approve

# Merge each PR
cat upgrade-prs.txt | xargs -n1 gh pr merge --squash

Finally, update the tracking issue.

Option 2 - maual upgrade

Prereq

Follow https://github.com/sourcegraph/controller#installation to install mi2

Set environment variables

Sharing TF_TOKEN_app_terraform_io is only temporary, this is expected to change in the future.

TARGET_VERSION could be one of, release version, release candidate version, or latest. When latest is provided, mi2 will automatically figure out the latest main branch tag and persist it in config.yaml

Bash

export SLUG=company
export ENVIRONMENT=dev
export TF_TOKEN_app_terraform_io=$(gcloud secrets versions access latest --project=sourcegraph-secrets --secret=TFC_TEAM_TOKEN)
export TARGET_VERSION=4.1.0

Fish

set -x SLUG company
set -x ENVIRONMENT dev
set -x TF_TOKEN_app_terraform_io (gcloud secrets versions access latest --project=sourcegraph-secrets --secret=TFC_TEAM_TOKEN)
set -x TARGET_VERSION 4.1.0

Check out a new branch

git checkout -b $SLUG/upgrade-instance

All commands below are executed under the instance root and use auto inference to locate the instance, hence -e and -slug flags are omitted.

export INSTANCE_ID=$(mi2 instance get -e $ENVIRONMENT --slug $SLUG | jq -r '.metadata.name')
cd environments/$ENVIRONMENT/deployments/$INSTANCE_ID/

Upgrade instance - database migration

This will perform

  • health check
  • bump version in config.yaml and regenerate deployment artifacts (e.g. kustomize, cdktf)
  • backup both the GKE cluster state (e.g. manifest, disks) and Cloud SQL to create a checkpoint
  • deploy migrator as a k8s Job to perform database migration
mi2 instance upgrade -target-version $TARGET_VERSION

Confirm workload are healthy

mi2 instance check pods-health

Upgrade instance - workload update

Switch to the right gke cluster and configure kubectl context

mi2 instance workon -exec

Deploy the new workload

cd kubernetes
kustomize build --load-restrictor LoadRestrictionsNone --enable-helm . | kubectl apply -f -

Upgrade instance - health check

Confirm workload are healthy and remote version is the same as target version

mi2 instance check pods-health src-application-version

Open a pull request

You should expected changes are made to

  • config.yaml
  • kubernetes/*
  • terraform/stacks/*
  • charts/*

Commit all changes

git add .
git commit -m "$SLUG: upgrade to $TARGET_VERSION"
gh pr create --title "$SLUG: upgrade to $TARGET_VERSION"

In the PR, include output of

mi2 instance check pods-health

Merge the pull request

Make sure to merge the pull request in time so we can rollout changes to executors terraform module.

The module is configured to be auto-apply, hence no action is required.

Rollback

Depending on the failure scenario, we have different fallback strategy

Database migration failed

Our database schema is supposed to be at least n-2 (where n is the current minor version) compatible.

A failing database migration usually does not result in direct impact on customers and we do not rollout workload until database migration goes through.

For now, follow how to troubleshoot dirty databases to resolve the issue.

In the future, we will add more commands to mi2 cli to interact with migrator directlly or even provide auto-fix solution in the mi2 instance upgrade command.

New workload failed to start

We use rolling update, and usually the older pod will still be serving traffic untill the new pod is healthy. Of course, with the exception of statefulset.

If it is causing breakage to the services (e.g. uptime check is failing), we should aim to rollback as soon as possible.

It could be as simple as reverting changes to the generated k8s manifest

git restore --source=origin/main --worktree kubernetes
kustomize build --load-restrictor LoadRestrictionsNone --enable-helm . | kubectl apply -f -

or you can also rollback individual deploy/sts

kubectl rollout undo deploy <>
kubectl rollout undo sts <>

If there is a data corruption or some other more complicated cases, follow the restore process.