Truffle: Improvement in "Could not connect" error

[wbt]

TL;DR

This proposes making an error message more helpful with additional context information.

Issue

I get the "Could not connect to your Ethereum client" error frequently, especially in load testing, regardless of Ethereum client being used. I assume that what's happening (also in issue 1461) is that the client is just getting overloaded with too many pending requests, and stops responding to new ones.

If the issue were not an overloaded server that had just successfully responded to several transactions, and really was a connectivity issue, it would be helpful to know what configuration information was being read and used.

Steps to Reproduce

Set up a basic Truffle project to work with Ganache, don't start Ganache, and run truffle migrate --reset.

Actual Results

Error message:

Could not connect to your Ethereum client. Please check that your Ethereum client:
- is running
- is accepting RPC connections (i.e., "--rpc" option is used in geth)
- is accessible over the network
- is properly configured in your Truffle configuration file (truffle.js)

Expected Results

The same error, but with more specific information about where it was trying to connect to.

Could not connect to your Ethereum client at http://127.0.0.1:7545 (Network ID: 5777).
Please check that your Ethereum client:
- is running
- is accepting RPC connections (i.e., "--rpc" option is used in geth)
- is accessible over the network
- is properly configured in your Truffle configuration file (truffle.js), especially if the server information in the first line of this error does not match what you expect.

I would only expect "Network ID" to be there if it had been specified.

Environment

• Operating System: Windows 10 pro
• Ethereum client: For this Issue, none
• Truffle version (truffle version): 4.1.15
• node version (node --version): 9.3.0
• npm version (npm --version): 6.5.0

[eggplantzzz]

I think this is a really nice idea, thanks for the suggestion!

[wbt]

Thanks! Per your comment here, that last line should probably also refer to truffle-config.js instead of truffle.js, if truffle-config is the one being used by the application when that error is encountered.

[eggplantzzz]

Yep, I changed that line about 2 days ago! It should be out in the next patch release.

[eggplantzzz]

@wbt Would you like to open a PR for this? Let me know if you want to tackle it, otherwise I'll take it on next week.

[wbt]

Go for it, and thanks!

[gnidan]

This was merged! And released! Closing. Thanks!