240 lines
9.1 KiB
Plaintext
240 lines
9.1 KiB
Plaintext
---
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layout: docs
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page_title: 'Upgrading'
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sidebar_current: 'guides-upgrade'
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description: |-
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Learn how to upgrade Nomad.
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---
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# Upgrading
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Nomad is designed to be flexible and resilient when upgrading from one Nomad
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version to the next. Upgrades should cause neither a Nomad nor a service
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outage. However, there are some restrictions to be aware of before upgrading:
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- Nomad strives to be backward compatible for at least 1 point release, so
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Nomad v0.10 hosts work with v0.9 hosts. Upgrading 2 point releases (eg v0.8
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to v0.10) may work but is untested and unsupported.
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- Nomad does _not_ support downgrading at this time. Downgrading clients
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requires draining allocations and removing the [data directory][data_dir].
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Downgrading servers safely requires re-provisioning the cluster.
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- New features are unlikely to work correctly until all nodes have been
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upgraded.
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- Check the [version upgrade details page][upgrade-specific] for important
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changes and backward incompatibilities.
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- When upgrading a Nomad Client, if it takes longer than the
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[`heartbeat_grace`][heartbeat_grace] (10s by default) period to restart, all
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allocations on that node may be rescheduled.
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Nomad supports upgrading in place or by rolling in new servers:
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- In Place: The Nomad binary can be updated on existing hosts. Running
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allocations will continue running uninterrupted.
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- Rolling: New hosts containing the new Nomad version may be added followed by
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the removal of old hosts. The old nodes must be drained to migrate running
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allocations to the new nodes.
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This guide describes both approaches.
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## Upgrade Process
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Once you have checked the [upgrade details for the new
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version][upgrade-specific], the upgrade process is as simple as updating the
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binary on each host and restarting the Nomad service.
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At a high level we complete the following steps to upgrade Nomad:
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- **Add the new version**
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- **Check cluster health**
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- **Remove the old version**
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- **Check cluster health**
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- **Upgrade clients**
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### 1. Add the new version to the existing cluster
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While it is possible to upgrade Nomad client nodes before servers, this guide
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recommends upgrading servers first as many new client features will not work
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until servers are upgraded.
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In a [federated cluster](https://learn.hashicorp.com/tutorials/nomad/federation),
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new features are not guaranteed to work until all agents in a region and the
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server nodes in the authoritative region are upgraded.
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Whether you are replacing Nomad in place on existing systems or bringing up new
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servers you should make changes incrementally, verifying cluster health at each
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step of the upgrade.
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On a single server, install the new version of Nomad. You can do this by
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joining a new server to the cluster or by replacing or upgrading the binary
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locally and restarting the Nomad service.
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### 2. Check cluster health
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[Monitor the Nomad logs][monitor] on the remaining servers to check that the
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new server has joined the cluster correctly.
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Run `nomad agent-info` on the new servers and check that the `last_log_index`
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is of a similar value to the other servers. This step ensures that changes have
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been replicated to the new server.
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```shell-session
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ubuntu@nomad-server-10-1-1-4:~$ nomad agent-info
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nomad
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bootstrap = false
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known_regions = 1
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leader = false
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server = true
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raft
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applied_index = 53460
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commit_index = 53460
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fsm_pending = 0
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last_contact = 54.512216ms
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last_log_index = 53460
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last_log_term = 1
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last_snapshot_index = 49511
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last_snapshot_term = 1
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num_peers = 2
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...
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```
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Continue with the upgrades across the servers making sure to do a single Nomad
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server at a time. You can check state of the servers with [`nomad server members`][server-members], and the state of the client nodes with [`nomad node status`][node-status].
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### 3. Remove the old versions from servers
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If you are doing an in place upgrade on existing servers this step is not
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necessary as the version was changed in place.
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If you are doing an upgrade by adding new servers and removing old servers
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from the fleet you need to ensure that the server has left the fleet safely.
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1. Stop the service on the existing host
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2. On another server issue a `nomad server members` and check the status, if
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the server is now in a left state you are safe to continue.
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3. If the server is not in a left state, issue a `nomad server force-leave <server id>`
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to remove the server from the cluster.
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Monitor the logs of the other hosts in the Nomad cluster over this period.
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### 4. Check cluster health
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Use the same actions in step #2 above to confirm cluster health.
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### 5. Upgrade clients
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Following the successful upgrade of the servers you can now update your
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clients using a similar process as the servers. You may either upgrade clients
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in-place or start new nodes on the new version. See the [Workload Migration
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Guide](https://learn.hashicorp.com/tutorials/nomad/node-drain) for instructions on how to migrate running
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allocations from the old nodes to the new nodes with the [`nomad node drain`](/docs/commands/node/drain) command.
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## Done
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You are now running the latest Nomad version. You can verify all
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Clients joined by running `nomad node status` and checking all the clients
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are in a `ready` state.
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## Upgrading to Nomad Enterprise
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The process of upgrading to a Nomad Enterprise version is identical to upgrading
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between versions of open source Nomad. The same guidance above should be
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followed and as always, prior to starting the upgrade please check the [specific
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version details](/docs/upgrade/upgrade-specific) page as some version
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differences may require specific steps.
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[data_dir]: /docs/configuration#data_dir
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[heartbeat_grace]: /docs/configuration/server#heartbeat_grace
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[monitor]: /docs/commands/monitor
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[node-status]: /docs/commands/node/status
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[server-members]: /docs/commands/server/members
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[upgrade-specific]: /docs/upgrade/upgrade-specific
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## Upgrading to Raft Protocol 3
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This section provides details on upgrading to Raft Protocol 3. Raft
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protocol version 3 requires Nomad running 0.8.0 or newer on all
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servers in order to work. Raft protocol version 2 will be removed in
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Nomad 1.4.0.
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To see the version of the Raft protocol in use on each server, use the
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`nomad operator raft list-peers` command.
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Note that the format of `peers.json` used for outage recovery is
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different when running with the latest Raft protocol. See [Manual
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Recovery Using
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peers.json](https://learn.hashicorp.com/tutorials/nomad/outage-recovery#manual-recovery-using-peersjson)
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for a description of the required format.
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When using Raft protocol version 3, servers are identified by their
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`node-id` instead of their IP address when Nomad makes changes to its
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internal Raft quorum configuration. This means that once a cluster has
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been upgraded with servers all running Raft protocol version 3, it
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will no longer allow servers running any older Raft protocol versions
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to be added.
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### Upgrading a Production Cluster to Raft Version 3
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For production raft clusters with 3 or more memebrs, the easiest way
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to upgrade servers is to have each server leave the cluster, upgrade
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its [`raft_protocol`] version in the `server` stanza (if upgrading to
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a version lower than v1.3.0), and then add it back. Make sure the new
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server joins successfully and that the cluster is stable before
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rolling the upgrade forward to the next server. It's also possible to
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stand up a new set of servers, and then slowly stand down each of the
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older servers in a similar fashion.
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For in-place raft protocol upgrades, perform the following for each
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server, leaving the leader until last to reduce the chance of leader
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elections that will slow down the process:
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* Stop the server.
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* Run `nomad server force-leave $server_name`.
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* If the upgrade is for a Nomad version lower than v1.3.0, update the
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[`raft_protocol`] in the server's configuration file to `3`.
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* Restart the server.
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* Run `nomad operator raft list-peers` to verify that the
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`RaftProtocol` for the server is now `3`.
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* On the server, run `nomad agent-info` and check that the
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`last_log_index` is of a similar value to the other servers. This
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step ensures that raft is healthy and changes are replicating to the
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new server.
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### Upgrading a Single Server Cluster to Raft Version 3
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If you are running a single Nomad server, restarting it in-place will
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result in that server not being able to elect itself as a leader. To
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avoid this, create a new [`raft.peers`][peers-json] file before
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restarting the server with the new configuration. If you have `jq`
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installed you can run the following script on the server's host to
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write the correct `raft.peers` file:
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```
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#!/usr/bin/env bash
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NOMAD_DATA_DIR=$(nomad agent-info -json | jq -r '.config.DataDir')
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NOMAD_ADDR=$(nomad agent-info -json | jq -r '.stats.nomad.leader_addr')
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NODE_ID=$(cat "$NOMAD_DATA_DIR/server/node-id")
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cat <<EOF > "$NOMAD_DATA_DIR/server/raft/peers.json"
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[
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{
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"id": "$NODE_ID",
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"address": "$NOMAD_ADDR",
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"non_voter": false
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}
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]
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EOF
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```
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After running this script, if the upgrade is for a Nomad version lower
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than v1.3.0, update the [`raft_protocol`] in the server's
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configuration to `3` and restart the server.
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[peers-json]: https://learn.hashicorp.com/tutorials/nomad/outage-recovery#manual-recovery-using-peersjson
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[`raft_protocol`]: /docs/configuration/server#raft_protocol
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