How to run migrator operations

The migrator is a service that runs as an initial step of the startup process for Kubernetes and Docker-compose instance deployments. This service is also designed to be invokable directly by a site administrator to perform common tasks dealing with database state.

The commands section below details the legal commands with which the migrator service can be invoked. The environments section below details how to supply those commands to a migrator instance that has access to your Sourcegraph database.

Commands

The migrator service exposes the following commands:

upgrade

The upgrade command performs database schema migrations and out-of-band migrations to rewrite existing instance data in-place into the shaped expected by a given target Sourcegraph version. This command is used by site-administrators to perform multi-version upgrades.

upgrade \
    -from=<current version> -to=<target version> \
    [-dry-run=false] \
    [-disable-animation=false] \
    [-skip-version-check=false] [-skip-drift-check=false] \
    [-unprivileged-only=false] [-noop-privileged=false] [-privileged-hash=<hash>]

Required arguments:

  • -from: The current Sourcegraph release version (without the patch; e.g., v3.36)
  • -to: The target Sorucegraph release version (without the patch; e.g., v4.0)

Optional arguments:

  • -dry-run: Print the steps of the upgrade but do not execute them.
  • -disable-animation: Print plain log messages instead of an animated progress bar.
  • -skip-version-check: Skip comparing the current instance version against -from.
  • -skip-drift-check: Skip comparing the database schema shape against the schema defined by -from.
  • -unprivileged-only and -noop-privileged: Controls behavior of schema migrations the presence of privileged definitions.

Notes:

  • Successive invocations of this command will re-attempt the last failed or attempted (but incomplete) migration. This command run as if the -ignore-single-{dirty,pending}-log flags supplied by the commands up, upto, and downto were enabled.
  • Successive invocations of this command may cause database drift when partial progress is made. When making a subsequent upgrade attempt, invoke this command with -skip-drift-check ignore the failing startup check.

drift

The drift command describes the current (live) database schema and compares it against the expected schema at the given version. The output of this command will include all relevant schema differences that could affect application correctness and performance. When schema drift is detected, a diff of the expected and actual Postgres object definitions will be shown, along with instructions on how to manually resolve the disparity.

drift \
    -db=<schema> \
    [-version=<version>] \
    [-file=<path to description file>]

Note: the drig -version argument requires the version to be specified with the v prefix, for example -version=v3.40.2

Required arguments:

  • -db: The target schema to inspect.

Mutually exclusive arguments:

Exactly one of -version and -file must be supplied.

  • -version: The instance’s current Sourcegraph release version including a patch (e.g., v3.42.1).
  • -file: The filepath to a local schema description file. This is useful for airgapped instances that do not have access to the public Sourcegraph GitHub repository or the public GCS bucket where old revisions have been backfilled.

downgrade

The downgrade command performs database schema migrations and (reverse-applied) out-of-band migrations to rewrite existing instance data in-place into the shaped expected by a given target Sourcegraph version.

downgrade \
    -from=<current version> -to=<target version> \
    [-dry-run=false] \
    [-disable-animation=false] \
    [-skip-version-check=false] [-skip-drift-check=false] \
    [-unprivileged-only=false] [-noop-privileged=false] [-privileged-hash=<hash>]

Required arguments:

  • -from: The current Sourcegraph release version (without the patch; e.g., v3.36)
  • -to: The target Sorucegraph release version (without the patch; e.g., v4.0)

Optional arguments:

  • -dry-run: Print the steps of the upgrade but do not execute them.
  • -disable-animation: Print plain log messages instead of an animated progress bar.
  • -skip-version-check: Skip comparing the current instance version against -from.
  • -skip-drift-check: Skip comparing the database schema shape against the schema defined by -from.
  • -unprivileged-only and -noop-privileged: Controls behavior of schema migrations the presence of privileged definitions.

Notes:

  • Successive invocations of this command will re-attempt the last failed or attempted (but incomplete) migration. This command run as if the -ignore-single-{dirty,pending}-log flags supplied by the commands up, upto, and downto were enabled.
  • Successive invocations of this command may cause database drift when partial progress is made. When making a subsequent downgrade attempt, invoke this command with -skip-drift-check ignore the failing startup check.

add-log

The add-log command adds an entry to the migration_logs table after a site administrator has explicitly applied the contents of a migration definition. This command may be performed by a site-administrator as part of repairing a dirty database.

add-log \
    -db=<schema> \
    -version=<version> \
    [-up=true]

Required arguments:

  • -db: The target schema to modify.
  • -version: The migration identifier noted on the log entry.

Optional arguments:

  • -up: The migration direction noted on the log entry.

validate

The validate command validates the current state of the database (both schema and data migration progress). This command is used on Sourcegraph instance startup of database-dependent services to ensure that the migrator has been run to the expected version.

validate \
    [-db=all] \
    [-skip-out-of-band-migrations=false]

Optional arguments:

  • -db: The target schema(s) to validate. Comma-separated values are allowed.
  • skip-out-of-band-migrations: Skip validation of out-of-band migrations. Validate the schema only.

Notes:

  • If DISABLE_CODE_INSIGHTS is not set and the codeinsights-db is not available, then this command will fail with the default value for the -db flag. To resolve, supply -db=frontend,codeintel instead.

up

The up command (the default behavior of the migrator service) applies all migrations defined at the time the migrator was built. This command is used on Sourcegraph instance startup to ensure the database schema is up to date prior to starting other services that depend on the database.

Users should generally prefer the command upto, which accepts more explicit bounds and does not depend on the migrator compilation version.

up \
    [-db=all] \
    [-skip-upgrade-validation=false] \
    [-skip-oobmigration-validation=false]
    [-ignore-single-dirty-log=false] [-ignore-single-pending-log=false] \
    [-unprivileged-only=false] [-noop-privileged=false] [-privileged-hash=<hash>]

Optional arguments:

  • -db: The target schema(s) to modify. Comma-separated values are allowed.
  • -skip-upgrade-validation: Skip asserting that the standard upgrade policy is being followed.
  • -skip-oobmigration-validation: Skip reading the progress of out-of-band migrations to assert completion of newly deprecated migrations.
  • -ignore-single-dirty-log and -ignore-single-pending-log: Re-attempt to apply the next migration that was marked as errored or as incomplete (respectively). See how to troubleshoot a dirty database.
  • -unprivileged-only and -noop-privileged: Controls behavior of schema migrations the presence of privileged definitions.

Notes:

  • If DISABLE_CODE_INSIGHTS is not set and the codeinsights-db is not available, then this command will fail with the default value for the -db flag. To resolve, supply -db=frontend,codeintel instead.

upto

The upto command ensures a given migration has been applied, and may apply dependency migrations.

upto \
    -db=<schema> \
    -target=<target>,<target>,... \
    [-ignore-single-dirty-log=false] [-ignore-single-pending-log=false] \
    [-unprivileged-only=false] [-noop-privileged=false] [-privileged-hash=<hash>]

Required arguments:

  • -db: The target schema to modify.
  • -target: The migration identifier(s) to target (these and unapplied descendants will be applied). Comma-separated values are accepted.

Optional arguments:

  • -ignore-single-dirty-log and -ignore-single-pending-log: Re-attempt to apply the next migration that was marked as errored or as incomplete (respectively). See how to troubleshoot a dirty database.
  • -unprivileged-only and -noop-privileged: Controls behavior of schema migrations the presence of privileged definitions.

downto

The downto command revert any applied migrations that are children of the given targets - this effectively “resets” the schema to the target version.

downto \
    -db=<schema> \
    -target=<target>,<target>,... \
    [-ignore-single-dirty-log=false] [-ignore-single-pending-log=false] \
    [-unprivileged-only=false] [-noop-privileged=false] [-privileged-hash=<hash>]

Required arguments:

  • -db: The target schema to modify.
  • -target: The migration identifier(s) to target (proper ancestors will be reverted). Comma-separated values are accepted.

Optional arguments:

  • -ignore-single-dirty-log and -ignore-single-pending-log: Re-attempt to apply the next migration that was marked as errored or as incomplete (respectively). See how to troubleshoot a dirty database.
  • -unprivileged-only and -noop-privileged: Controls behavior of schema migrations the presence of privileged definitions.

run-out-of-band-migrations

The run-out-of-band-migrations command runs out-of-band migrations within the migrator. This command may be performed by a site-administrator as part of repairing an unfinished migration.

run-out-of-band-migrations \
    [-id <id>]+ \
    [-apply-reverse=false] \
    [-disable-animation=false]

Required arguments:

  • -id: The identifier(s) of the migrations to apply. Multiple flags can be supplied. If no flag is supplied, all migrations are applied.
  • -apply-reverse: Run migrations in the reverse direction.

Optional arguments:

  • -disable-animation: Print plain log messages instead of an animated progress bar.

describe

The describe command outputs a dump of your database schema.

describe \
    -db=<schema> \
    -format=<json|psql> \
    [-out=stdout] \
    [-force=false] \
    [-no-color=false]

Required arguments:

  • -db: The target schema to describe.
  • -format: The format in which the description is output.

Optional arguments:

  • -out: The target output file. If not supplied, the output is printed to stdout.
  • -force: Overwrite the file.
  • -no-color: Do not print ANSI color sequences.

Environments

To run a migrator command, follow the guide for your Sourcegraph distribution type:

Kubernetes

Run the following commands in the root of your deploy-sourcegraph fork.

First, modify the migrator manifest to update two fields: the spec.template.spec.containers[0].args field, which selects the target operation, and the spec.template.spec.containers[0].image field, which controls the version of the migrator binary (and, consequently, the set of embedded migration definitions).

The following example uses yq, but these values may also be updated manually by opening the configure/migrator/migrator.Job.yaml file in an editor of your choice and editing the image and args key value pairs.

export MIGRATOR_SOURCEGRAPH_VERSION="..."

# Update the "image" value of the migrator container in the manifest
yq eval -i \
  '.spec.template.spec.containers[0].image = "index.docker.io/sourcegraph/migrator:" + strenv(MIGRATOR_SOURCEGRAPH_VERSION)' \
  configure/migrator/migrator.Job.yaml

# Optional (defaults to `["up", "-db", "all"]`)
# Update the "args" value of the migrator container in the manifest
yq eval -i \
  '.spec.template.spec.containers[0].args = ["add", "quoted", "arguments"]' \
  configure/migrator/migrator.Job.yaml

The corresponding changes the configure/migrator/migrator.Job.yaml file would look something like this:

image: "index.docker.io/sourcegraph/migrator:[email protected]:0dc6543f0a755e46d962ba572d501559915716fa55beb3aa644a52f081fcd57e"
args: ["upgrade", "--from=3.40.2", "--to=4.1.2"]

Next, apply the job and wait for it to complete.

kubectl delete -f configure/migrator/migrator.Job.yaml --ignore-not-found=true

# Apply the manifest and wait for the operation to complete before continuing
# Note: -1s timeout will wait "forever"
kubectl apply -f configure/migrator/migrator.Job.yaml
kubectl wait -f configure/migrator/migrator.Job.yaml --for=condition=complete --timeout=-1s

# Optionally: check migrator logs for progress
kubectl logs job.batch/migrator -f

You should see something like the following printed to the terminal:

job.batch "migrator" deleted
job.batch/migrator created
job.batch/migrator condition met

The log output of the migrator should include INFO-level logs and successfully terminate with migrator exited with code 0. If you see an error message or any of the databases have been flagged as “dirty”, please follow “How to troubleshoot a dirty database”. A dirty database will not affect your ability to use Sourcegraph however it will need to be resolved to upgrade further. If you are unable to resolve the issues, contact support at [email protected] for further assistance. Otherwise, you are now safe to upgrade Sourcegraph.

Docker / Docker compose

Run the following commands on your Docker host.

export MIGRATOR_SOURCEGRAPH_VERSION="..."

docker run \
  --rm \
  --name migrator_$MIGRATOR_SOURCEGRAPH_VERSION \
  -e PGHOST='pgsql' \
  -e PGPORT='5432' \
  -e PGUSER='sg' \
  -e PGPASSWORD='sg' \
  -e PGDATABASE='sg' \
  -e PGSSLMODE='disable' \
  -e CODEINTEL_PGHOST='codeintel-db' \
  -e CODEINTEL_PGPORT='5432' \
  -e CODEINTEL_PGUSER='sg' \
  -e CODEINTEL_PGPASSWORD='sg' \
  -e CODEINTEL_PGDATABASE='sg' \
  -e CODEINTEL_PGSSLMODE='disable' \
  -e CODEINSIGHTS_PGHOST='codeinsights-db' \
  -e CODEINSIGHTS_PGPORT='5432' \
  -e CODEINSIGHTS_PGUSER='postgres' \
  -e CODEINSIGHTS_PGPASSWORD='password' \
  -e CODEINSIGHTS_PGDATABASE='postgres' \
  -e CODEINSIGHTS_PGSSLMODE='disable' \
  --network=docker-compose_sourcegraph \
  sourcegraph/migrator:$MIGRATOR_SOURCEGRAPH_VERSION \
  # Optional (defaults to `["up", "-db", "all"]`)
  "add" "quoted" "arguments"

Observe the output of the migrator container via:

docker logs migrator_$SOURCEGRAPH_VERSION

The log output of the migrator should include INFO-level logs and successfully terminate with migrator exited with code 0. If you see an error message or any of the databases have been flagged as “dirty”, please follow “How to troubleshoot a dirty database”. A dirty database will not affect your ability to use Sourcegraph however it will need to be resolved to upgrade further. If you are unable to resolve the issues, contact support at [email protected] for further assistance. Otherwise, you are now safe to upgrade Sourcegraph.

Local development

To run the migrator locally, simply run go run ./cmd/migrator or go run ./enterprise/cmd/migrator.

Many of the commands detailed above are also available via sg. Replace migrator with sg migration .... There are a few command registered on the migrator but not on sg (e.g., upgrade and downgrade), as local environments are a bit of a different beast than environments performing upgrades only along tagged releases.