68 lines
2.6 KiB
Markdown
68 lines
2.6 KiB
Markdown
---
|
|
layout: "docs"
|
|
page_title: "Upgrading Consul"
|
|
sidebar_current: "docs-upgrading-upgrading"
|
|
---
|
|
|
|
# Upgrading Consul
|
|
|
|
Consul is meant to be a long-running agent on any nodes participating in a
|
|
Consul cluster. These nodes consistently communicate with each other. As such,
|
|
protocol level compatibility and ease of upgrades is an important thing to
|
|
keep in mind when using Consul.
|
|
|
|
This page documents how to upgrade Consul when a new version is released.
|
|
|
|
## Upgrading Consul
|
|
|
|
In short, upgrading Consul is a short series of easy steps. For the steps
|
|
below, assume you're running version A of Consul, and then version B comes out.
|
|
|
|
1. On each node, install version B of Consul.
|
|
|
|
2. Shut down version A, and start version B with the `-protocol=PREVIOUS`
|
|
flag, where "PREVIOUS" is the protocol version of version A (which can
|
|
be discovered by running `consul -v` or `consul members`).
|
|
|
|
3. Once all nodes are running version B, go through every node and restart
|
|
the version B agent _without_ the `-protocol` flag.
|
|
|
|
4. Done! You're now running the latest Consul agent speaking the latest protocol.
|
|
You can verify this is the case by running `consul members` to
|
|
make sure all members are speaking the same, latest protocol version.
|
|
|
|
The key to making this work is the [protocol compatibility](/docs/compatibility.html)
|
|
of Consul. The protocol version system is discussed below.
|
|
|
|
## Protocol Versions
|
|
|
|
By default, Consul agents speak the latest protocol they can. However, each
|
|
new version of Consul is also able to speak the previous protocol, if there
|
|
were any protocol changes.
|
|
|
|
You can see what protocol versions your version of Consul understands by
|
|
running `consul -v`. You'll see output similar to that below:
|
|
|
|
```
|
|
$ consul -v
|
|
Consul v0.1.0
|
|
Consul Protocol: 1 (Understands back to: 1)
|
|
```
|
|
|
|
This says the version of Consul as well as the latest protocol version (1,
|
|
in this case). It also says the earliest protocol version that this Consul
|
|
agent can understand (0, in this case).
|
|
|
|
By specifying the `-protocol` flag on `consul agent`, you can tell the
|
|
Consul agent to speak any protocol version that it can understand. This
|
|
only specifies the protocol version to _speak_. Every Consul agent can
|
|
always understand the entire range of protocol versions it claims to
|
|
on `consul -v`.
|
|
|
|
<div class="alert alert-block alert-warning">
|
|
<strong>By running a previous protocol version</strong>, some features
|
|
of Consul, especially newer features, may not be available. If this is the
|
|
case, Consul will typically warn you. In general, you should always upgrade
|
|
your cluster so that you can run the latest protocol version.
|
|
</div>
|