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Backup and Restore Guide for Nexus 3

This document is intended as a reference for backing up and restoring Nexus Repository Manager 3 in conjuction with using configuration as code.

WARNING

This guide assumes a restore occurs on a fresh Nexus instance. Do not perform restore operations on an existing Nexus because it will delete items and may have unintended consequences.

Additional notes and warnings

  • Blob stores are the only information which needs to be backed up via tar. The rest of the Nexus configuration should be stored as configuration as code. Because configuration will be stored as code there is no need to backup the Nexus database. Nexus configuration as code is not comprehensive enough for this statement to be completely true for all Nexus installations.
  • Configuration blob stores must always match the backed up blob stores.
  • Any backup or restore operation involving direct access to blob stores should occur while Nexus is in READ-ONLY mode.
  • When Nexus is in read-only mode, scripts which perform write operations such deleting, creating, or configuring repositories are blocked from running. This means configuration can't be restored while Nexus is in read-only mode.
  • Do not create other tasks before reconciling the blob stores to restore Nexus (a.k.a. restoring the blob stores).

Before running a backup or restore

Set environment variables on the destination Nexus to be restored.

export NEXUS_ENDPOINT='https://nexus.example.com/'
export NEXUS_USER='admin'
export NEXUS_PASSWORD='admin123'

Upload all required functions to the Nexus Script API.

ls ./functions/*.groovy | xargs -n1 -- ./scripts/upload_function.py -f

Backup Nexus

  1. Put Nexus into read-only mode. This prevents write operations on the blob stores while attempting to create a backup.

    ./scripts/upload_function.py -srf nexusFrozenState -S read-only

  2. Create a tar backup of the blobs/ directory within the Nexus data directory. This will backup all blob stores. For example, if you're running Nexus in docker, then the /nexus-data directory is the location of the Nexus data directory. The following is an example taking a backup of blobs while running Nexus within a docker container.

    CONTAINER_ID=$(docker-compose ps -q nexus3)
docker run --init --volumes-from "${CONTAINER_ID}" --rm centos:7 /usr/bin/tar -C /nexus-data -cv blobs > backup.tar

  3. Take Nexus out of read-only mode. This will allow Nexus to be used again for publishing artifacts.

    ./scripts/upload_function.py -srf nexusFrozenState -S read-write

Restore Nexus

This section assumes the worst case scenario where:

  • Your original Nexus was completely deleted including all repository configuration and blob store data.
  • Your original Nexus configuration is written in configuration as code.
  • You have a tar backup of the original blobs/ directory.
  • You're restoring to a fresh Nexus installation which has the default set of repositories configured.

Steps to restore:

  1. Delete all default repositories.

    ./scripts/upload_function.py -srf deleteAllRepositoryConfiguration -S delete

  2. Execute configuration as code to configure repositories and blob stores. This will restore repository configuration to a working state but it will not restore the repository data, yet. To learn more about repositories.json see the Nexus Repository Configuration as Code document.

    ./scripts/upload_function.py -srf repositoryConfiguration -d ./path/to/repositories.json

  3. We're now ready to restore repository data. Put Nexus into read-only mode.

    ./scripts/upload_function.py -srf nexusFrozenState -S read-only

  4. Wipe out the existing blobs directory. Again, assuming Nexus in a docker container refer to the following example.

    CONTAINER_ID=$(docker-compose ps -q nexus3)
docker run -i --init --volumes-from "${CONTAINER_ID}" centos:7 rm -rf /nexus-data/blobs

  5. Restore the blob stores from the tar backup.

    CONTAINER_ID=$(docker-compose ps -q nexus3)
docker run -i --init --volumes-from "${CONTAINER_ID}" centos:7 /usr/bin/tar -C /nexus-data -xv < backup.tar

  6. Take Nexus out of read-only mode.

    ./scripts/upload_function.py -srf nexusFrozenState -S read-write

  7. Reconcile the Nexus DB for each blob store. The following command will do this automatically. For each blob store, create and run a manual admin task of type Repair - Reconcile component database from blob store. This will create and run one task per blob store.

    ./scripts/upload_function.py -srf autoRestoreNexusBlobstores -S restore

  8. Wait for all of the tasks to finish. You can check on progress of the tasks by visiting the Nexus settings > Tasks. When all tasks finish running they will be in the state Waiting.

  9. Delete the tasks created by step 6.

    ./scripts/upload_function.py -srf autoRestoreNexusBlobstores -S delete-tasks

Learn more about the functions

All of the above functions can be found in the functions/ directory of this repository.