Validation

At its core, ssh2-sftp-client is really just a wrapper around the excellent ssh2 library. Like most wrappers, it attempts to provide some convenience at the cost of some flexibility. In this case, it attempts to provide a Promise based API around the event based ssh2 library.

Mixing both Promises and an event based model can be challenging. When things don’t work, it isn’t always clear where the problem might be. This directory contains some very simple scripts which perform some of the core basic sftp operations, but only using the ssh2 library (no Promises, no wrapper).

The scripts in this directory can be used to try and identify where a problem might be e.g. either due to the wrapper provided by ssh2-sftp-client or a bug in ssh2 or some local or site specific problem (it is always important to remember all SFTP servers are not equal and problems can arise because of either issues with the remote SFTP server implementation, network failures and firewalls etc).

Guidelines

There are some basic guidelines which can help to track down problems when something just doesn’t work and you cannot find the cause.

1. Use a very simple sftp CLI program, such as openSSH’s sftp to perform the same operation. If it works, then you have ruled out local network, firewall and remote server issues. Note that if your problem only occurs after multiple operations or under load etc, you probably need to script your test with the sftp CLI to replicate a similar use pattern
2. Create a minimal example script. The most important part of solving a problem is being able to reproduce it as simply as possible. Creating a script which can reproduce the issue with as few lines of code as possible is the first step. It also enables the code to be easily run by someone else in a different environment, which can help to eliminate environmental issues. Typically, if we can reproduce the issue, it is fixed within days (if not hours).
3. Create a script which uses just ssh2 and try to reproduce the issue. If the problem can be reproduced just using ssh2, it is either an ssh2 specific issue and needs to be logged with the maintainer of ssh2 or it is a local issue. If it turns out to be an issue specific to ssh2, the script will provide valuable information to the ssh2 maintainers and will usually result in faster resolution of the issue.

Scripts

This scripts in this directory are very simple scripts with minimal error handling and input validation. They are provided mainly as examples and not as polished or completed utilities for validation. Typically, you would use these scripts as a starting point and modify them to fit your purposes.

Most of these scripts use the dotenv library to manage authentication and configuration data. I use a number of different .env files to configure different test environments. This has two major advantages. It ensures I don’t have to change scripts when testing against different test environments and by adding the .env files to .gitignore and .npmignore, I can have additional confidence I’m unlikely to accidentally commit sensitive data to my git repository. If ou don’t want to use dotenv, comment out the lines relating to that library and add the config data to the scripts as hard coded values.