Add optional alias parameter to host config

[simonfelding]

this is useful for weird ssh proxies like cyberark PAM. Without this, it is difficult to identify the source of the output, as they all have the same hostname.

As a side effect, this also adds part of the future ~/.ssh/config parsing, which would be nice (as per https://github.com/ParallelSSH/parallel-ssh/issues/103). the openssh config differentiates between host and hostname.

I wrote this code that implements simple ssh config parsing with unix-like pattern matching.

    hosts = []
    host_config = []
    i = 0

    with open(Path.expanduser(Path('~/.ssh/config'))) as sshconfig:
        pattern = sys.argv[1].strip('"')
        for line in sshconfig:
            if line.startswith("Host "):
                host = line.split("Host ")[1].split('\n')[0]
                if fnmatch.fnmatch(host,pattern):
                    hostname = next(sshconfig).strip().split("HostName ")[1]
                    user = next(sshconfig).strip().split("User ")[1]
                    hosts.append({})
                    hosts[i]["hostname"] = hostname
                    hosts[i]["user"] = user
                    hosts[i]['alias'] = host
                    i = i+1
        if hosts == []:
            print(f"No hosts matched by pattern {pattern}")
            exit(1)
        for host in hosts:
            host_config.append(HostConfig(user=host['user'], password=os.environ['SSHPASS']))

[simonfelding]

I'm not entirely sure how to fix the test errors but it should be trivial :) Edit: It was trivial, but I'm an idiot. Now it works :)

[codecov[bot]]

Codecov Report

Merging #355 (5b1be0e) into master (cd9836d) will increase coverage by 0.31%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #355      +/-   ##
==========================================
+ Coverage   99.19%   99.50%   +0.31%     
==========================================
  Files          18       18              
  Lines        1606     1613       +7     
==========================================
+ Hits         1593     1605      +12     
+ Misses         13        8       -5     

Impacted Files	Coverage Δ
pssh/clients/native/parallel.py	100.00% <ø> (ø)
pssh/clients/ssh/parallel.py	100.00% <ø> (ø)
pssh/clients/ssh/single.py	99.30% <ø> (+0.69%)	:arrow_up:
pssh/clients/base/parallel.py	99.14% <100.00%> (+0.43%)	:arrow_up:
pssh/clients/base/single.py	99.24% <100.00%> (+0.50%)	:arrow_up:
pssh/clients/native/single.py	100.00% <100.00%> (+0.28%)	:arrow_up:
pssh/config.py	100.00% <100.00%> (ø)
pssh/output.py	100.00% <100.00%> (ø)
... and 2 more

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[pkittenis]

Hi there,

Thanks for the interest and the PR.

This looks like useful functionality, and your code snippet above is a good first step for config parsing too. That one might be worth a separate PR if you're interested in making one.

I left some comments on the code.

[simonfelding]

Thank you! I'll make a seperate PR for parsing a ssh config file when this one gets pulled to master :) It would be useful indeed.

I don't see any comments on the code, did you use the review function on github or what?

[simonfelding]

Removed all the references to alias in parallel configs as per your review. I made a new single client test and it works as expected now :)

It throws an error in the host config test but I think it's actually supposed to. Shouldn't clients that fail still return parameters like alias when stop_on_errors=False?

I'm not entirely sure where in the code to fix this, maybe you can help me out here? :)

Edit: Fixed it :)

[pkittenis]

Looks good, thank you again for the PR.

Made a small change to docstrings and accepted types for alias to only accept str types as aliases, not int, to be in line with SSH conventions.

[simonfelding]

Brilliant! I'll commit a ssh config parser in a new PR. Thank you for the pleasant collaboration 😁