This new package provides a client agent implementation of an interface
for fetching the health of services.
This approach has a number of benefits:
1. It provides a much more explicit interface. Instead of everything
dependency on `RPC()` and `Cache.Get()` for many unrelated things
they can depend on a type that are named according to the behaviour
it provides.
2. It gives us a single place to vary the behaviour and migrate to
a new form of RPC (gRPC). The current implementation has two options
(cache, or direct RPC), and in the future we will have more.
It is also a great opporunity to start adding `context.Context` args
to these operations, which in the future will allow us to cancel
the operations.
3. As a concequence of the first, in the Server agent where we make
these calls we can replace the current in-memory RPC calls with
a thin adapter for the real method. This removes the `net/rpc`
machinery from the call in places where it is not needed.
This new package is quite small right now, but I think we can expect it
to grow to a more reasonable size as other RPC calls are replaced.
This change also happens to replace two very similar implementations with
a single implementation.
Previsouly it was done in Agent.Start, which is much later then it needs to be.
The new 'dns' package was required, because otherwise there would be an
import cycle. In the future we should move more of the dns server into
the dns package.
Previously, we were only returning a single ListenerPort for a single
service. However, we actually allow a single service to be serviced over
multiple ports, as well as allow users to define what hostnames they
expect their services to be contacted over. When no hosts are defined,
we return the default ingress domain for any configured DNS domain.
To show this in the UI, we modify the gateway-services-nodes API to
return a GatewayConfig.Addresses field, which is a list of addresses
over which the specific service can be contacted.
This will allow to increase cache value when DC is not valid (aka
return SOA to avoid too many consecutive requests) and will
distinguish DC being temporarily not available from DC not existing.
Implements https://github.com/hashicorp/consul/issues/8102
Blocking queries issues will still be uncancellable (that cannot be helped until we get rid of net/rpc). However this makes it so that if calling getWithIndex (like during a cache Notify go routine) we can cancell the outer routine. Previously it would keep issuing more blocking queries until the result state actually changed.
* Implements a simple, tcp ingress gateway workflow
This adds a new type of gateway for allowing Ingress traffic into Connect from external services.
Co-authored-by: Chris Piraino <cpiraino@hashicorp.com>
* Use consts for well known tagged adress keys
* Add ipv4 and ipv6 tagged addresses for node lan and wan
* Add ipv4 and ipv6 tagged addresses for service lan and wan
* Use IPv4 and IPv6 address in DNS
* Add updated github.com/miekg/dns to go modules
* Add updated github.com/miekg/dns to vendor
* Fix github.com/miekg/dns api breakage
* Decrease size when trimming UDP packets
Need more room for the header(?), if we don't decrease the size we get an
"overflow unpacking uint32" from the dns library
* Fix dns truncate tests with api changes
* Make windows build working again. Upgrade x/sys and x/crypto and vendor
This upgrade is needed because of API breakage in x/sys introduced
by the minimal x/sys dependency of miekg/dns
This API breakage has been fixed in commit
855e68c859
Refactor dns to have same behavior between A and SRV.
Current implementation returns the node name instead of the service
address.
With this fix when querying for SRV record service address is return in
the SRV record.
And when performing a simple dns lookup it returns a CNAME to the
service address.
This allows addresses to be tagged at the service level similar to what we allow for nodes already. The address translation that can be enabled with the `translate_wan_addrs` config was updated to take these new addresses into account as well.
The DNS config parameters `recursors` and `dns_config.*` are now hot
reloaded on SIGHUP or `consul reload` and do not need an agent restart
to be modified.
Config is stored in an atomic.Value and loaded at the beginning of each
request. Reloading only affects requests that start _after_ the
reload. Ongoing requests are not affected. To match the current
behavior the recursor handler is loaded and unloaded as needed on config
reload.
* Fix race condition in DNS when using cache
The healty node filtering was modifying the result from the cache, which
caused a crash when multiple queries were made to the same service
simultaneously.
We now copy the node slice before filtering to ensure we do not modify
the data stored in the cache.
* Fix wording in dns cache config doc
s/dns_max_age/cache_max_age/
Adds two new configuration parameters "dns_config.use_cache" and
"dns_config.cache_max_age" controlling how DNS requests use the agent
cache when querying servers.
* Avoid to have infinite recursion in DNS lookups when resolving CNAMEs
This will avoid killing Consul when a Service.Address is using CNAME
to a Consul CNAME that creates an infinite recursion.
This will fix https://github.com/hashicorp/consul/issues/4907
* Use maxRecursionLevel = 3 to allow several recursions
* bugfix: use ServiceTags to generate cahce key hash
* update unit test
* update
* remote print log
* Update .gitignore
* Completely deprecate ServiceTag field internally for clarity
* Add explicit test for CacheInfo cases
This implements parts of RFC 7871 where Consul is acting as an authoritative name server (or forwarding resolver when recursors are configured)
If ECS opt is present in the request we will mirror it back and return a response with a scope of 0 (global) or with the same prefix length as the request (indicating its valid specifically for that subnet).
We only mirror the prefix-length (non-global) for prepared queries as those could potentially use nearness checks that could be affected by the subnet. In the future we could get more sophisticated with determining the scope bits and allow for better caching of prepared queries that don’t rely on nearness checks.
The other thing this does not do is implement the part of the ECS RFC related to originating ECS headers when acting as a intermediate DNS server (forwarding resolver). That would take a quite a bit more effort and in general provide very little value. Consul will currently forward the ECS headers between recursors and the clients transparently, we just don't originate them for non-ECS clients to get potentially more accurate "location aware" results.
* Implementation of Weights Data structures
Adding this datastructure will allow us to resolve the
issues #1088 and #4198
This new structure defaults to values:
```
{ Passing: 1, Warning: 0 }
```
Which means, use weight of 0 for a Service in Warning State
while use Weight 1 for a Healthy Service.
Thus it remains compatible with previous Consul versions.
* Implemented weights for DNS SRV Records
* DNS properly support agents with weight support while server does not (backwards compatibility)
* Use Warning value of Weights of 1 by default
When using DNS interface with only_passing = false, all nodes
with non-Critical healthcheck used to have a weight value of 1.
While having weight.Warning = 0 as default value, this is probably
a bad idea as it breaks ascending compatibility.
Thus, we put a default value of 1 to be consistent with existing behaviour.
* Added documentation for new weight field in service description
* Better documentation about weights as suggested by @banks
* Return weight = 1 for unknown Check states as suggested by @banks
* Fixed typo (of -> or) in error message as requested by @mkeeler
* Fixed unstable unit test TestRetryJoin
* Fixed unstable tests
* Fixed wrong Fatalf format in `testrpc/wait.go`
* Added notes regarding DNS SRV lookup limitations regarding number of instances
* Documentation fixes and clarification regarding SRV records with weights as requested by @banks
* Rephrase docs
* Fixes the DNS recursor properly resolving the requests
* Added a test case for the recursor bug
* Refactored code && added a test case for all failing recursors
* Inner indentation moved into else if check
This also changes where the enforcement of the enable_additional_node_meta_txt configuration gets applied.
formatNodeRecord returns the main RRs and the meta/TXT RRs in separate slices. Its then up to the caller to add to the appropriate sections or not.
This just makes sure that if multiple services are registered with unique service addresses that we don’t blast back multiple CNAMEs for the same service DNS name and keeps us within the DNS specs.
Kit Patella