82 lines
3.3 KiB
Markdown
82 lines
3.3 KiB
Markdown
|
---
|
||
|
|
layout: "docs"
|
||
|
|
page_title: "Upgrading Specific Versions"
|
||
|
|
sidebar_current: "docs-upgrading-specific"
|
||
|
|
description: |-
|
||
|
|
Specific versions of Consul may have additional information about the upgrade process beyond the standard flow.
|
||
|
|
---
|
||
|
|
|
||
|
|
# Upgrading Specific Versions
|
||
|
|
|
||
|
|
The [upgrading page](/docs/upgrading.html) covers the details of doing
|
||
|
|
a standard upgrade. However, specific versions of Consul 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 seperately from the
|
||
|
|
standard upgrade flow.
|
||
|
|
|
||
|
|
## Consul 0.5
|
||
|
|
|
||
|
|
Consul version 0.5 adds two features that complicate the upgrade process:
|
||
|
|
|
||
|
|
* ACL system includes service discovery and registration
|
||
|
|
* Internal use of tombstones to fix behavior of blocking queries
|
||
|
|
in certain edge cases.
|
||
|
|
|
||
|
|
Users of the ACL system need to be aware that deploying Consul 0.5 will
|
||
|
|
cause service registration to be enforced. This means if an agent
|
||
|
|
attempts to register a service without proper privileges it will be denied.
|
||
|
|
If the `acl_default_policy` is "allow" then clients will continue to
|
||
|
|
work without an updated policy. If the policy is "deny", then all clients
|
||
|
|
will begin to have their registration rejected causing issues.
|
||
|
|
|
||
|
|
To avoid this situation, all the ACL policies should be updated to
|
||
|
|
add something like this:
|
||
|
|
|
||
|
|
# Enable all services to be registered
|
||
|
|
service "" {
|
||
|
|
policy = "write"
|
||
|
|
}
|
||
|
|
|
||
|
|
This will set the service policy to `write` level for all services.
|
||
|
|
The blank service name is the catch-all value. A more specific service
|
||
|
|
can also be specified:
|
||
|
|
|
||
|
|
# Enable only the API service to be registered
|
||
|
|
service "api" {
|
||
|
|
policy = "write"
|
||
|
|
}
|
||
|
|
|
||
|
|
The ACL policy can be updated while running 0.4, and enforcement will
|
||
|
|
being with the upgrade to 0.5. The policy updates will ensure the
|
||
|
|
availability of the cluster.
|
||
|
|
|
||
|
|
The second major change is the new internal command used for tombstones.
|
||
|
|
The details of the change are not important, however to function the leader
|
||
|
|
node will replicate a new command to its followers. Consul is designed
|
||
|
|
defensively, and when a command that is not recognized is received, the
|
||
|
|
server will panic. This is a purposeful design decision to avoid the possibility
|
||
|
|
of data loss, inconsistensies, or security issues caused by future incompatibility.
|
||
|
|
|
||
|
|
In practice, this means if a Consul 0.5 node is the leader, all of its
|
||
|
|
followers must also be running 0.5. There are a number of ways to do this
|
||
|
|
to ensure cluster availability:
|
||
|
|
|
||
|
|
* Add new 0.5 nodes, then remove the old servers. This will add the new
|
||
|
|
nodes as followers, and once the old servers are removed, one of the
|
||
|
|
0.5 nodes will become leader.
|
||
|
|
|
||
|
|
* Upgrade the followers first, then the leader last. Using `consul info`,
|
||
|
|
you can determine which nodes are followers. Do an in-place upgrade
|
||
|
|
on them first, and finally upgrade the leader last.
|
||
|
|
|
||
|
|
* Upgrade them in any order, but ensure all are done within 15 minutes.
|
||
|
|
Even if the leader is upgraded to 0.5 first, as long as all of the followers
|
||
|
|
are running 0.5 within 15 minutes there will be no issues.
|
||
|
|
|
||
|
|
Finally, even if any of the methods above are not possible or the process
|
||
|
|
fails for some reason, it is not fatal. The older version of the server
|
||
|
|
will simply panic and stop. At that point, you can upgrade to the new version
|
||
|
|
and restart the agent. There will be no data loss and the cluster will
|
||
|
|
resume operations.
|
||
|
|
|