Plugin returns "received message larger than max" error when sending payloads greater than 4194304 bytes

[broamski]

Describe the bug
When using a custom vault plugin and sending a payload greater than 4194304 bytes, the operation ends in failure due to the grpc default max receive message size of 1024 * 1024 * 4. This option does not appear to be configurable, so servicing larger requests is not possible.

To Reproduce
Steps to reproduce the behavior:

1. Write payload to plugin vault write customplugin/action @large_28mb_payload
2. See error: [ERROR] core: failed to run existence check: error="rpc error: code = ResourceExhausted desc = grpc: received message larger than max (28793489 vs. 4194304)"

Expected behavior
In plugin.Server, set the max receive size to a value similar to or the same as the max send size, which would align to the changes made for #4843.

Alternately, allow both the send and receive values to be configurable via plugin.ServeOpts.

Environment:

• Vault Server Version (retrieve with vault status): 0.10.3
• Vault CLI Version (retrieve with vault version): Vault v0.10.3 ('c69ae68faf2bf7fc1d78e3ec62655696a07454c7')
• Server Operating System/Architecture: darwin, linux

Vault server configuration file(s): Running in -dev mode.

Additional context
This impacts the ability to perform cryptographic operations (similar to that of transit engine) on larger binary files.

grpc declares these constant values as:

defaultServerMaxReceiveMessageSize = 1024 * 1024 * 4
defaultServerMaxSendMessageSize    = math.MaxInt32

[jefferai]

Would be super cool if you can test #4959

[jefferai]

I mean, #4958

[broamski]

Sure thing! I'll test this first thing tomorrow!

[broamski]

Also, thanks for the fast response!

[broamski]

I can confirm that this change does indeed allow payload sizes greater than 4194304 bytes to be successfully processed by a plugin. Thanks!

[jefferai]

Great!