Wait.UntilPortsAreAvailable throws exception if the container doesn't have bash

[jdelucaa]

Describe the bug
When building a container with Wait.UntilPortsAreAvailable, I get an expection when starting the container:

Docker.DotNet.DockerApiException: 'Docker API responded with status code=BadRequest, response={"message":"OCI runtime exec failed: exec failed: container_linux.go:346: starting container process caused "exec: \"/bin/bash\": stat /bin/bash: no such file or directory": unknown"}

This is because my container doesn't have bash installed, only sh or other implementation of shell..

To Reproduce
Steps to reproduce the behavior:

var fhirServerContainerBuilder = new TestcontainersBuilder<TestcontainersContainer>()
        .WithImage("conceptant/hapi-fhir")
        .WithPortBinding(8080, true)
        .WithCleanUp(true)
        .WithWaitStrategy(Wait.UntilPortsAreAvailable(8080));

      using (var fhirServerContainer = fhirServerContainerBuilder.Build())
      {
        await fhirServerContainer.StartAsync();
      }

Expected behavior
The commands used to verify the availability of the ports should support other shells.

Screenshots
Not necessary

Desktop (please complete the following information):

• Linux container
• Docker for Windows version 19.03.5, build 633a0ea

Additional context
I did the following changes to the code that solved the problem

In WaitUntilBashCommandsAreCompleted.cs changed from /bin/bash to bin/sh - because sh will point to the actual implementation of the shell ( bash, dash, etc.. ), I think it'll work for most cases.

The expcetion was gone with that change, but the thread got stucked somewhere, I figured there was something wrong with the command used in WaitUntilPortsAreAvailable.cs, for some reason that command doesn't work in my container, it says the directory does not exist, so I changed the line 8 from timeout 15 bash -c \"echo > /dev/tcp/localhost/8080\" to a boolean expression with some ways to try and check if the port is available (like the testcontainers-java version does): true && (cat /proc/net/tcp{{,6}} | awk '{{print $2}}' | grep -i :{port} || nc -vz -w 1 localhost {port} || /bin/bash -c '</dev/tcp/localhost/{port}');

Those changes saved my day... let me know if you think it's a good solution to open a PR to fix the issue.

[HofmeisterAn]

@jdelucaa thanks for your effort, you're right. Of course, we're supposed to follow the standard, especially if we don't need any bash specific implementations.

I think it's a good idea to switch to sh and I would love to see a PR. I'm not sure the command covers all cases, but we will see if the unit tests succeed.

We should probably rename WaitUntilBashCommandsAreCompleted too and replace /bin/bash with /bin/sh in the unit tests. What do you think?

If you need any help, let me know.

[jdelucaa]

PR #179

[HofmeisterAn]

@jdelucaa I'll check #180 and #181 and probably release a new minor version after that. Until then you could use 1.1.0-beta.20200108.2. FYI: You should check our Git config email address. It seems like the address is not connected to your GitHub account. You would like to use a private address anyway for public commits: https://help.github.com/assets/images/help/settings/email_privacy.png.