* Fix xDS deadlock due to syncLoop termination.
This fixes an issue where agentless xDS streams can deadlock permanently until
a server is restarted. When this issue occurs, no new proxies are able to
successfully connect to the server.
Effectively, the trigger for this deadlock stems from the following return
statement:
https://github.com/hashicorp/consul/blob/v1.18.0/agent/proxycfg-sources/catalog/config_source.go#L199-L202
When this happens, the entire `syncLoop()` terminates and stops consuming from
the following channel:
https://github.com/hashicorp/consul/blob/v1.18.0/agent/proxycfg-sources/catalog/config_source.go#L182-L192
Which results in the `ConfigSource.cleanup()` function never receiving a
response and holding a mutex indefinitely:
https://github.com/hashicorp/consul/blob/v1.18.0/agent/proxycfg-sources/catalog/config_source.go#L241-L247
Because this mutex is shared, it effectively deadlocks the server's ability to
process new xDS streams.
----
The fix to this issue involves removing the `chan chan struct{}` used like an
RPC-over-channels pattern and replacing it with two distinct channels:
+ `stopSyncLoopCh` - indicates that the `syncLoop()` should terminate soon. +
`syncLoopDoneCh` - indicates that the `syncLoop()` has terminated.
Splitting these two concepts out and deferring a `close(syncLoopDoneCh)` in the
`syncLoop()` function ensures that the deadlock above should no longer occur.
We also now evict xDS connections of all proxies for the corresponding
`syncLoop()` whenever it encounters an irrecoverable error. This is done by
hoisting the new `syncLoopDoneCh` upwards so that it's visible to the xDS delta
processing. Prior to this fix, the behavior was to simply orphan them so they
would never receive catalog-registration or service-defaults updates.
* Add changelog.
* Adding explicit MPL license for sub-package
This directory and its subdirectories (packages) contain files licensed with the MPLv2 `LICENSE` file in this directory and are intentionally licensed separately from the BSL `LICENSE` file at the root of this repository.
* Adding explicit MPL license for sub-package
This directory and its subdirectories (packages) contain files licensed with the MPLv2 `LICENSE` file in this directory and are intentionally licensed separately from the BSL `LICENSE` file at the root of this repository.
* Updating the license from MPL to Business Source License
Going forward, this project will be licensed under the Business Source License v1.1. Please see our blog post for more details at <Blog URL>, FAQ at www.hashicorp.com/licensing-faq, and details of the license at www.hashicorp.com/bsl.
* add missing license headers
* Update copyright file headers to BUSL-1.1
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* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
* Update copyright file headers to BUSL-1.1
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---------
Co-authored-by: hashicorp-copywrite[bot] <110428419+hashicorp-copywrite[bot]@users.noreply.github.com>
Receiving an "acl not found" error from an RPC in the agent cache and the
streaming/event components will cause any request loops to cease under the
assumption that they will never work again if the token was destroyed. This
prevents log spam (#14144, #9738).
Unfortunately due to things like:
- authz requests going to stale servers that may not have witnessed the token
creation yet
- authz requests in a secondary datacenter happening before the tokens get
replicated to that datacenter
- authz requests from a primary TO a secondary datacenter happening before the
tokens get replicated to that datacenter
The caller will get an "acl not found" *before* the token exists, rather than
just after. The machinery added above in the linked PRs will kick in and
prevent the request loop from looping around again once the tokens actually
exist.
For `consul-dataplane` usages, where xDS is served by the Consul servers
rather than the clients ultimately this is not a problem because in that
scenario the `agent/proxycfg` machinery is on-demand and launched by a new xDS
stream needing data for a specific service in the catalog. If the watching
goroutines are terminated it ripples down and terminates the xDS stream, which
CDP will eventually re-establish and restart everything.
For Consul client usages, the `agent/proxycfg` machinery is ahead-of-time
launched at service registration time (called "local" in some of the proxycfg
machinery) so when the xDS stream comes in the data is already ready to go. If
the watching goroutines terminate it should terminate the xDS stream, but
there's no mechanism to re-spawn the watching goroutines. If the xDS stream
reconnects it will see no `ConfigSnapshot` and will not get one again until
the client agent is restarted, or the service is re-registered with something
changed in it.
This PR fixes a few things in the machinery:
- there was an inadvertent deadlock in fetching snapshot from the proxycfg
machinery by xDS, such that when the watching goroutine terminated the
snapshots would never be fetched. This caused some of the xDS machinery to
get indefinitely paused and not finish the teardown properly.
- Every 30s we now attempt to re-insert all locally registered services into
the proxycfg machinery.
- When services are re-inserted into the proxycfg machinery we special case
"dead" ones such that we unilaterally replace them rather that doing that
conditionally.
Derek Menteer
Iryna Shustava
Ashwin Venkatesh
John Murret
hashicorp-copywrite[bot]
Ronald
Eric Haberkorn
R.B. Boyer