* Added rate limiting for agent RPC calls.
* Initializes the rate limiter based on the config.
* Adds the rate limiter into the snapshot RPC path.
* Adds unit tests for the RPC rate limiter.
* Groups the RPC limit parameters under "limits" in the config.
* Adds some documentation about the RPC limiter.
* Sends a 429 response when the rate limiter kicks in.
* Adds docs for new telemetry.
* Makes snapshot telemetry look like RPC telemetry and cleans up comments.
When the metadata server is scanning the agents for potential servers
it is parsing the version number which the agent provided when it
joined. This version number has to conform to a certain format, i.e.
'n.n.n'. Without this version number properly set some tests fail with
error messages that disguise the root cause.
The default version number is currently set to 'unknown' in
version/version.go which does not parse and triggers the tests to fail.
The work around is to use a build tag 'consul' which will use the
version number set in version_base.go instead which has the correct
format and is set to the current release version.
In addition, some parts of the code also require the version number to
be of a certain value. Setting it to '0.0.0' for example makes some
tests pass and others fail since they don't pass the semantic check.
When using go build/install/test one has to remember to use '-tags
consul' or tests will fail with non-obvious error messages.
Using build tags makes the build process more complex and error prone
since it prevents the use of the plain go toolchain and - at least in
its current form - introduces subtle build and test issues. We should
try to eliminate build tags for anything else but platform specific
code.
This patch removes all references to specific version numbers in the
code and tests and sets the default version to '9.9.9' which is
syntactically correct and passes the semantic check. This solves the
issue of running go build/install/test without tags for the OSS build.
The error handling of the ACL code relies on the presence of certain
magic error messages. Since the error values are sent via RPC between
older and newer consul agents we cannot just replace the magic values
with typed errors and switch to type checks since this would break
compatibility with older clients.
Therefore, this patch moves all magic ACL error messages into the acl
package and provides default error values and helper functions which
determine the type of error.
James Phillips