* disable pure runner logging
there's a racey bug where the logger is being written to when it's closing,
but this led to figuring out that we don't need the logger at all in pure
runner really, the syslog thing isn't an in process fn thing and we don't need
the logs from attach for anything further in pure runner. so this disables the
logger at the docker level, to save sending the bytes back over the wire, this
could be a nice little performance bump too. of course, with this, it means
agents can be configured to not log debug or have logs to store at all, and
not a lot of guards have been put on this for 'full' agent mode while it hangs
on a cross feeling the breeze awaiting its demise - the default configuration
remains the same, and no behavior changes in 'full' agent are here.
it was a lot smoother to make the noop than to try to plumb in 'nil' for
stdout/stderr, this has a lot lower risk of nil panic issues for the same
effect, though it's not perfect relying on type casting, plumbing in an
interface to check has the same issues (loss of interface adherence for any
decorator), so this seems ok. defaulting to not having a logger was similarly
painful, and ended up with this. but open to ideas.
* replace usage of old null reader writer impl
* make Read return io.EOF for io.Copy usage
* fn: agent MaxRequestSize limit
Currently, LimitRequestBody() exists to install a
http request body size in http/gin server. For production
enviroments, this is expected to be used. However, in agents
we may need to verify/enforce these size limits and to be
able to assert in case of missing limits is valuable.
With this change, operators can define an agent env variable
to limit this in addition to installing Gin/Http handler.
http.MaxBytesReader is superior in some cases as it sets
http headers (Connection: close) to guard against subsequent
requests.
However, NewClampReadCloser() is superior in other cases,
where it can cleanly return an API error for this case alone
(http.MaxBytesReader() does not return a clean error type
for overflow case, which makes it difficult to use it without
peeking into its implementation.)
For lb agent, upcoming changes rely on such limits enabled
and using gin/http handler (http.MaxBytesReader) makes such
checks/safety validations difficult.
* fn: read/write clamp code adjustment
In case of overflows, opt for simple implementation
of a partial write followed by return error.
*) I/O protocol parse issues should shutdown the container as the container
goes to inconsistent state between calls. (eg. next call may receive previous
calls left overs.)
*) Move ghost read/write code into io_utils in common.
*) Clean unused error from docker Wait()
*) We can catch one case in JSON, if there's remaining unparsed data in
decoder buffer, we can shut the container
*) stdout/stderr when container is not handling a request are now blocked if freezer is also enabled.
*) if a fatal err is set for slot, we do not requeue it and proceed to shutdown
*) added a test function for a few cases with freezer strict behavior
*) Limit response http body or json response size to FN_MAX_RESPONSE_SIZE (default unlimited)
*) If limits are exceeded 502 is returned with 'body too large' in the error message
