This is like a Möbius strip of code due to the fact that low-level components (serf/memberlist) are connected to high-level components (the catalog and mesh-gateways) in a twisty maze of references which make it hard to dive into. With that in mind here's a high level summary of what you'll find in the patch:
There are several distinct chunks of code that are affected:
* new flags and config options for the server
* retry join WAN is slightly different
* retry join code is shared to discover primary mesh gateways from secondary datacenters
* because retry join logic runs in the *agent* and the results of that
operation for primary mesh gateways are needed in the *server* there are
some methods like `RefreshPrimaryGatewayFallbackAddresses` that must occur
at multiple layers of abstraction just to pass the data down to the right
layer.
* new cache type `FederationStateListMeshGatewaysName` for use in `proxycfg/xds` layers
* the function signature for RPC dialing picked up a new required field (the
node name of the destination)
* several new RPCs for manipulating a FederationState object:
`FederationState:{Apply,Get,List,ListMeshGateways}`
* 3 read-only internal APIs for debugging use to invoke those RPCs from curl
* raft and fsm changes to persist these FederationStates
* replication for FederationStates as they are canonically stored in the
Primary and replicated to the Secondaries.
* a special derivative of anti-entropy that runs in secondaries to snapshot
their local mesh gateway `CheckServiceNodes` and sync them into their upstream
FederationState in the primary (this works in conjunction with the
replication to distribute addresses for all mesh gateways in all DCs to all
other DCs)
* a "gateway locator" convenience object to make use of this data to choose
the addresses of gateways to use for any given RPC or gossip operation to a
remote DC. This gets data from the "retry join" logic in the agent and also
directly calls into the FSM.
* RPC (`:8300`) on the server sniffs the first byte of a new connection to
determine if it's actually doing native TLS. If so it checks the ALPN header
for protocol determination (just like how the existing system uses the
type-byte marker).
* 2 new kinds of protocols are exclusively decoded via this native TLS
mechanism: one for ferrying "packet" operations (udp-like) from the gossip
layer and one for "stream" operations (tcp-like). The packet operations
re-use sockets (using length-prefixing) to cut down on TLS re-negotiation
overhead.
* the server instances specially wrap the `memberlist.NetTransport` when running
with gateway federation enabled (in a `wanfed.Transport`). The general gist is
that if it tries to dial a node in the SAME datacenter (deduced by looking
at the suffix of the node name) there is no change. If dialing a DIFFERENT
datacenter it is wrapped up in a TLS+ALPN blob and sent through some mesh
gateways to eventually end up in a server's :8300 port.
* a new flag when launching a mesh gateway via `consul connect envoy` to
indicate that the servers are to be exposed. This sets a special service
meta when registering the gateway into the catalog.
* `proxycfg/xds` notice this metadata blob to activate additional watches for
the FederationState objects as well as the location of all of the consul
servers in that datacenter.
* `xds:` if the extra metadata is in place additional clusters are defined in a
DC to bulk sink all traffic to another DC's gateways. For the current
datacenter we listen on a wildcard name (`server.<dc>.consul`) that load
balances all servers as well as one mini-cluster per node
(`<node>.server.<dc>.consul`)
* the `consul tls cert create` command got a new flag (`-node`) to help create
an additional SAN in certs that can be used with this flavor of federation.
* relax requirements for auto_encrypt on server
* better error message when auto_encrypt and verify_incoming on
* docs: explain verify_incoming on Consul clients.
This PR introduces reloading tls configuration. Consul will now be able to reload the TLS configuration which previously required a restart. It is not yet possible to turn TLS ON or OFF with these changes. Only when TLS is already turned on, the configuration can be reloaded. Most importantly the certificates and CAs.
This PR is based on #5366 and continues to centralise the tls configuration in order to be reloadable eventually!
This PR is another refactoring. No tests are changed, beyond calling other functions or cosmetic stuff. I added a bunch of tests, even though they might be redundant.
In order to be able to reload the TLS configuration, we need one way to generate the different configurations.
This PR introduces a `tlsutil.Configurator` which holds a `tlsutil.Config`. Afterwards it is responsible for rendering every `tls.Config`. In this particular PR I moved `IncomingHTTPSConfig`, `IncomingTLSConfig`, and `OutgoingTLSWrapper` into `tlsutil.Configurator`.
This PR is a pure refactoring - not a single feature added. And not a single test added. I only slightly modified existing tests as necessary.
The list of cipher suites included in this commit are consistent with
the values and precedence in the [Golang TLS documentation](https://golang.org/src/crypto/tls/cipher_suites.go).
> **Note:** Cipher suites with RC4 are still included within the list
> of accepted values for compatibility, but **these cipher suites are
> not safe to use** and should be deprecated with warnings and
> subsequently removed. Support for RC4 ciphers has already been
> removed or disabled by default in many prominent browsers and tools,
> including Golang.
>
> **References:**
>
> * [RC4 on Wikipedia](https://en.wikipedia.org/wiki/RC4)
> * [Mozilla Security Blog](https://blog.mozilla.org/security/2015/09/11/deprecating-the-rc4-cipher/)
* Upgrades to Go 1.7 and fixes vet finding and TLS behavior change.
* Fixes unit tests in a better manner by closing the client connection on errors.
We traced through and realized that https://github.com/golang/go/issues/15709
causes the output from the client to get buffered, which cuts off the alert
feedback due to the flush() call getting bypassed by the error return.
