open-nomad/website/source/docs/upgrade/upgrade-specific.html.md

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docs	Upgrade Guides	docs-upgrade-specific	Specific versions of Nomad may have additional information about the upgrade process beyond the standard flow.

Upgrading Specific Versions

The upgrading page covers the details of doing a standard upgrade. However, specific versions of Nomad may have more details provided for their upgrades as a result of new features or changed behavior. This page is used to document those details separately from the standard upgrade flow.

Nomad 0.8.0

Raft Protocol Version Compatibility

When upgrading to Nomad 0.8.0 from a version lower than 0.7.0, users will need to set the -raft-protocol option to 1 in order to maintain backwards compatibility with the old servers during the upgrade. After the servers have been migrated to version 0.8.0, -raft-protocol can be moved up to 2 and the servers restarted to match the default.

The Raft protocol must be stepped up in this way; only adjacent version numbers are compatible (for example, version 1 cannot talk to version 3). Here is a table of the Raft Protocol versions supported by each Consul version:

Version	Supported Raft Protocols
0.6 and earlier	0
0.7	1
0.8	1, 2, 3

In order to enable all Autopilot features, all servers in a Nomad cluster must be running with Raft protocol version 3 or later.

Node Draining Improvements

Node draining via the node drain command or the drain API has been substantially changed in Nomad 0.8. In Nomad 0.7.1 and earlier draining a node would immediately stop all allocations on the node being drained. Nomad 0.8 now supports a migrate stanza in job specifications to control how many allocations may be migrated at once and the default will be used for existing jobs.

The drain command now blocks until the drain completes. To get the Nomad 0.7.1 and earlier drain behavior use the command: nomad node drain -enable -force -detach <node-id>

See the migrate stanza documentation and Decommissioning Nodes guide for details.

Periods in Environment Variable Names No Longer Escaped

Applications which expect periods in environment variable names to be replaced with underscores must be updated.

In Nomad 0.7 periods (.) in environment variables names were replaced with an underscore in both the env and template stanzas.

In Nomad 0.8 periods are not replaced and will be included in environment variables verbatim.

For example the following stanza:

env {
  registry.consul.addr = "${NOMAD_IP_http}:8500"
}

In Nomad 0.7 would be exposed to the task as registry_consul_addr=127.0.0.1:8500. In Nomad 0.8 it will now appear exactly as specified: registry.consul.addr=127.0.0.1:8500.

Client APIs Unavailable on Older Nodes

Because Nomad 0.8 uses a new RPC mechanism to route node-specific APIs like nomad alloc fs through servers to the node, 0.8 CLIs are incompatible using these commands on clients older than 0.8.

To access these commands on older clients either continue to use a pre-0.8 version of the CLI, or upgrade all clients to 0.8.

CLI Command Changes

Nomad 0.8 has changed the organization of CLI commands to be based on subcommands. An example of this change is the change from nomad alloc-status to nomad alloc status. All commands have been made to be backwards compatible, but operators should update any usage of the old style commands to the new style as the old style will be deprecated in future versions of Nomad.

RPC Advertise Address

The behavior of the advertised RPC address has changed to be only used to advertise the RPC address of servers to client nodes. Server to server communication is done using the advertised Serf address. Existing cluster's should not be effected but the advertised RPC address may need to be updated to allow connecting client's over a NAT.

Nomad 0.6.0

Default advertise address changes

When no advertise address was specified and Nomad's bind_addr was loopback or 0.0.0.0, Nomad attempted to resolve the local hostname to use as an advertise address.

Many hosts cannot properly resolve their hostname, so Nomad 0.6 defaults advertise to the first private IP on the host (e.g. 10.1.2.3).

If you manually configure advertise addresses no changes are necessary.

Nomad Clients

The change to the default, advertised IP also effect clients that do not specify which network_interface to use. If you have several routable IPs, it is advised to configure the client's network interface such that tasks bind to the correct address.

Nomad 0.5.5

Docker load changes

Nomad 0.5.5 has a backward incompatible change in the docker driver's configuration. Prior to 0.5.5 the load configuration option accepted a list images to load, in 0.5.5 it has been changed to a single string. No functionality was changed. Even if more than one item was specified prior to 0.5.5 only the first item was used.

To do a zero-downtime deploy with jobs that use the load option:

• Upgrade servers to version 0.5.5 or later.

• Deploy new client nodes on the same version as the servers.

• Resubmit jobs with the load option fixed and a constraint to only run on version 0.5.5 or later:

    constraint {
      attribute = "${attr.nomad.version}"
      operator  = "version"
      value     = ">= 0.5.5"
    }

• Drain and shutdown old client nodes.

Validation changes

Due to internal job serialization and validation changes you may run into issues using 0.5.5 command line tools such as nomad run and nomad validate with 0.5.4 or earlier agents.

It is recommended you upgrade agents before or alongside your command line tools.

Nomad 0.4.0

Nomad 0.4.0 has backward incompatible changes in the logic for Consul deregistration. When a Task which was started by Nomad v0.3.x is uncleanly shut down, the Nomad 0.4 Client will no longer clean up any stale services. If an in-place upgrade of the Nomad client to 0.4 prevents the Task from gracefully shutting down and deregistering its Consul-registered services, the Nomad Client will not clean up the remaining Consul services registered with the 0.3 Executor.

We recommend draining a node before upgrading to 0.4.0 and then re-enabling the node once the upgrade is complete.

Nomad 0.3.1

Nomad 0.3.1 removes artifact downloading from driver configurations and places them as a first class element of the task. As such, jobs will have to be rewritten in the proper format and resubmitted to Nomad. Nomad clients will properly re-attach to existing tasks but job definitions must be updated before they can be dispatched to clients running 0.3.1.

Nomad 0.3.0

Nomad 0.3.0 has made several substantial changes to job files included a new log block and variable interpretation syntax (${var}), a modified restart policy syntax, and minimum resources for tasks as well as validation. These changes require a slight change to the default upgrade flow.

After upgrading the version of the servers, all previously submitted jobs must be resubmitted with the updated job syntax using a Nomad 0.3.0 binary.

• All instances of $var must be converted to the new syntax of ${var}

• All tasks must provide their required resources for CPU, memory and disk as well as required network usage if ports are required by the task.

• Restart policies must be updated to indicate whether it is desired for the task to restart on failure or to fail using mode = "delay" or mode = "fail" respectively.

• Service names that include periods will fail validation. To fix, remove any periods from the service name before running the job.

After updating the Servers and job files, Nomad Clients can be upgraded by first draining the node so no tasks are running on it. This can be verified by running nomad node status <node-id> and verify there are no tasks in the running state. Once that is done the client can be killed, the data_dir should be deleted and then Nomad 0.3.0 can be launched.