Previously the listener was being passed to a closure in a loop without
capturing the loop variable. The result is only the last listener is
used, so the http/https servers only listen on one address.
This problem is fixed by capturing the variable by passing it into a
function.
When a service is deregistered, we check whever matching services were
registered as sidecar along with it and deregister them as well.
To determine if a service is indeed a sidecar we check the
structs.ServiceNode.LocallyRegisteredAsSidecar property. However, to
avoid interal API leakage, it is excluded from JSON serialization,
meaning it is not persisted to disk either.
When the agent is restarted, this property lost and sidecars are no
longer deregistered along with their parent service.
To fix this, we now specifically save this property in the persisted
service file.
This allows for client agent to be run in a more stateless manner where they may be abruptly terminated and not expected to come back. If advertising a per-agent reconnect timeout using the advertise_reconnect_timeout configuration when that agent leaves, other agents will wait only that amount of time for the agent to come back before reaping it.
This has the advantageous side effect of causing servers to deregister the node/services/checks for that agent sooner than if the global reconnect_timeout was used.
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.
In an upcoming change we will need to pass a grpc.ClientConnPool from
BaseDeps into Server. While looking at that change I noticed all of the
existing consulOption fields are already on BaseDeps.
Instead of duplicating the fields, we can create a struct used by
agent/consul, and use that struct in BaseDeps. This allows us to pass
along dependencies without translating them into different
representations.
I also looked at moving all of BaseDeps in agent/consul, however that
created some circular imports. Resolving those cycles wouldn't be too
bad (it was only an error in agent/consul being imported from
cache-types), however this change seems a little better by starting to
introduce some structure to BaseDeps.
This change is also a small step in reducing the scope of Agent.
Also remove some constants that were only used by tests, and move the
relevant comment to where the live configuration is set.
Removed some validation from NewServer and NewClient, as these are not
really runtime errors. They would be code errors, which will cause a
panic anyway, so no reason to handle them specially here.
And into token.Store. This change isolates any awareness of token
persistence in a single place.
It is a small step in allowing Agent.New to accept its dependencies.
This will apply cache throttling parameters are properly applied:
* cache.EntryFetchMaxBurst
* cache.EntryFetchRate
When values are updated, a log is displayed in info.
This might be better handled by allowing configuration for the InMemSink interval and retail, and disabling
the global. For now this is a smaller change to remove the goroutine leak caused by tests because go-metrics
does not provide any way of shutting down the global goroutine.
With this change, Agent.New() accepts many of the dependencies instead
of creating them in New. Accepting fully constructed dependencies from
a constructor makes the type easier to test, and easier to change.
There are still a number of dependencies created in Start() which can
be addressed in a follow up.
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.
There are a couple reasons for this change:
1. agent.go is way too big. Smaller files makes code eaasier to read
because tools that show usage also include filename which can give
a lot more context to someone trying to understand which functions
call other functions.
2. these two functions call into a large number of functions already in
keyring.go.
This is a small step to allowing Agent to accept its dependencies
instead of creating them in New.
There were two fields in autoconfig.Config that were used exclusively
to load config. These were replaced with a single function, allowing us
to move LoadConfig back to the config package.
Also removed the WithX functions for building a Config. Since these were
simple assignment, it appeared we were not getting much value from them.
Making these functions allows us to cleanup how an agent is initialized. They only make use of a config and a logger, so they do not need to be agent methods.
Also cleanup the testing to use t.Run and require.
Now that it is no longer used, we can remove this unnecessary field. This is a pre-step in cleanup up RuntimeConfig->Consul.Config, which is a pre-step to adding a gRPCHandler component to Server for streaming.
Removing this field also allows us to remove one of the return values from logging.Setup.
