[2.0.x] Does not install on alpine anymore - missing dependencies

### Description

Describe your issue here.

### What type of issue is this? (place an `x` in one of the `[ ]`)
- [x] bug
- [ ] enhancement (feature request)
- [ ] question
- [ ] documentation related
- [ ] testing related
- [ ] discussion

### Requirements (place an `x` in each of the `[ ]`)
* [x] I've read and understood the [Contributing guidelines](https://github.com/slackapi/python-slackclient/blob/master/.github/contributing.md) and have done my best effort to follow them.
* [x] I've read and agree to the [Code of Conduct](https://slackhq.github.io/code-of-conduct).
* [x] I've searched for any related issues and avoided creating a duplicate issue.

---

### Bug Report

Filling out the following details about bugs will help us solve your issue sooner.

#### Reproducible in:

slackclient version: 2.0.1 and 2.0.0

python version: 3.7.3-alpine / 3.7.2-alpine / 3.6.8-alpine

OS version(s): linux alpine docker image

#### Steps to reproduce:

1. Create the following files:

requirements.txt:
slackclient==2.0.0

echobot.py:
import slack

Dockerfile
FROM python:3.7.3-alpine
WORKDIR /app
ADD . /app
RUN pip install --upgrade pip
RUN pip install -r requirements.txt
CMD ["python", "echobot.py"]

2. Run the command:
docker build -t staticdev/k8s-python-slackbot:0.1.0 -f Dockerfile .

#### Expected result:

A successful image creation as in github.com/staticdev/k8s-python-slackbot (this works with versions 1.x)

#### Actual result:

I got a pip error installing slackclient:

```
Step 5/6 : RUN pip install -r requirements.txt
 ---> Running in d5d4f90d8f5a
Collecting slackclient==2.0.1 (from -r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/90/85/e2a43f04f79dec82ee86eb4cd19108d8a49721d732942ac8e14450357167/slackclient-2.0.1-py2.py3-none-any.whl
Collecting aiodns>1.0 (from slackclient==2.0.1->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/da/01/8f2d49b441573fd2478833bdba91cf0b853b4c750a1fbb9e98de1b94bb22/aiodns-2.0.0-py2.py3-none-any.whl
Collecting aiohttp>3.5.2 (from slackclient==2.0.1->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/0f/58/c8b83f999da3b13e66249ea32f325be923791c0c10aee6cf16002a3effc1/aiohttp-3.5.4.tar.gz (1.1MB)
  Installing build dependencies: started
  Installing build dependencies: finished with status 'done'
  Getting requirements to build wheel: started
  Getting requirements to build wheel: finished with status 'done'
    Preparing wheel metadata: started
    Preparing wheel metadata: finished with status 'done'
Collecting pycares>=3.0.0 (from aiodns>1.0->slackclient==2.0.1->-r requirements.txt (line 1))
  Downloading https://files.pythonhosted.org/packages/85/de/cd46a73e43e206a6ad1e9cf9cc893c3ed1b21caf57f1e0a8d9a119d290eb/pycares-3.0.0.tar.gz (211kB)
    ERROR: Complete output from command python setup.py egg_info:
    ERROR: 
        No working compiler found, or bogus compiler options passed to
        the compiler from Python's standard "distutils" module.  See
        the error messages above.  Likely, the problem is not related
        to CFFI but generic to the setup.py of any Python package that
        tries to compile C code.  (Hints: on OS/X 10.8, for errors about
        -mno-fused-madd see http://stackoverflow.com/questions/22313407/
        Otherwise, see https://wiki.python.org/moin/CompLangPython or
        the IRC channel #python on irc.freenode.net.)
    
        Trying to continue anyway.  If you are trying to install CFFI from
        a build done in a different context, you can ignore this warning.
    
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/distutils/unixccompiler.py", line 118, in _compile
        extra_postargs)
      File "/usr/local/lib/python3.7/distutils/ccompiler.py", line 909, in spawn
        spawn(cmd, dry_run=self.dry_run)
      File "/usr/local/lib/python3.7/distutils/spawn.py", line 36, in spawn
        _spawn_posix(cmd, search_path, dry_run=dry_run)
      File "/usr/local/lib/python3.7/distutils/spawn.py", line 159, in _spawn_posix
        % (cmd, exit_status))
    distutils.errors.DistutilsExecError: command 'gcc' failed with exit status 1
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/distutils/core.py", line 148, in setup
        dist.run_commands()
      File "/usr/local/lib/python3.7/distutils/dist.py", line 966, in run_commands
        self.run_command(cmd)
      File "/usr/local/lib/python3.7/distutils/dist.py", line 985, in run_command
        cmd_obj.run()
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/bdist_egg.py", line 172, in run
        cmd = self.call_command('install_lib', warn_dir=0)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/bdist_egg.py", line 158, in call_command
        self.run_command(cmdname)
      File "/usr/local/lib/python3.7/distutils/cmd.py", line 313, in run_command
        self.distribution.run_command(command)
      File "/usr/local/lib/python3.7/distutils/dist.py", line 985, in run_command
        cmd_obj.run()
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/install_lib.py", line 11, in run
        self.build()
      File "/usr/local/lib/python3.7/distutils/command/install_lib.py", line 107, in build
        self.run_command('build_ext')
      File "/usr/local/lib/python3.7/distutils/cmd.py", line 313, in run_command
        self.distribution.run_command(command)
      File "/usr/local/lib/python3.7/distutils/dist.py", line 985, in run_command
        cmd_obj.run()
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/build_ext.py", line 78, in run
        _build_ext.run(self)
      File "/usr/local/lib/python3.7/distutils/command/build_ext.py", line 340, in run
        self.build_extensions()
      File "/usr/local/lib/python3.7/distutils/command/build_ext.py", line 449, in build_extensions
        self._build_extensions_serial()
      File "/usr/local/lib/python3.7/distutils/command/build_ext.py", line 474, in _build_extensions_serial
        self.build_extension(ext)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/build_ext.py", line 199, in build_extension
        _build_ext.build_extension(self, ext)
      File "/usr/local/lib/python3.7/distutils/command/build_ext.py", line 534, in build_extension
        depends=ext.depends)
      File "/usr/local/lib/python3.7/distutils/ccompiler.py", line 574, in compile
        self._compile(obj, src, ext, cc_args, extra_postargs, pp_opts)
      File "/usr/local/lib/python3.7/distutils/unixccompiler.py", line 120, in _compile
        raise CompileError(msg)
    distutils.errors.CompileError: command 'gcc' failed with exit status 1
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 154, in save_modules
        yield saved
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 195, in setup_context
        yield
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 250, in run_setup
        _execfile(setup_script, ns)
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 45, in _execfile
        exec(code, globals, locals)
      File "/tmp/easy_install-crxph_g3/cffi-1.12.3/setup.py", line 248, in <module>
      File "/usr/local/lib/python3.7/site-packages/setuptools/__init__.py", line 145, in setup
        return distutils.core.setup(**attrs)
      File "/usr/local/lib/python3.7/distutils/core.py", line 163, in setup
        raise SystemExit("error: " + str(msg))
    SystemExit: error: command 'gcc' failed with exit status 1
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 1144, in run_setup
        run_setup(setup_script, args)
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 253, in run_setup
        raise
      File "/usr/local/lib/python3.7/contextlib.py", line 130, in __exit__
        self.gen.throw(type, value, traceback)
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 195, in setup_context
        yield
      File "/usr/local/lib/python3.7/contextlib.py", line 130, in __exit__
        self.gen.throw(type, value, traceback)
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 166, in save_modules
        saved_exc.resume()
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 141, in resume
        six.reraise(type, exc, self._tb)
      File "/usr/local/lib/python3.7/site-packages/setuptools/_vendor/six.py", line 685, in reraise
        raise value.with_traceback(tb)
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 154, in save_modules
        yield saved
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 195, in setup_context
        yield
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 250, in run_setup
        _execfile(setup_script, ns)
      File "/usr/local/lib/python3.7/site-packages/setuptools/sandbox.py", line 45, in _execfile
        exec(code, globals, locals)
      File "/tmp/easy_install-crxph_g3/cffi-1.12.3/setup.py", line 248, in <module>
      File "/usr/local/lib/python3.7/site-packages/setuptools/__init__.py", line 145, in setup
        return distutils.core.setup(**attrs)
      File "/usr/local/lib/python3.7/distutils/core.py", line 163, in setup
        raise SystemExit("error: " + str(msg))
    SystemExit: error: command 'gcc' failed with exit status 1
    
    During handling of the above exception, another exception occurred:
    
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-w9661i00/pycares/setup.py", line 45, in <module>
        zip_safe         = False
      File "/usr/local/lib/python3.7/site-packages/setuptools/__init__.py", line 144, in setup
        _install_setup_requires(attrs)
      File "/usr/local/lib/python3.7/site-packages/setuptools/__init__.py", line 139, in _install_setup_requires
        dist.fetch_build_eggs(dist.setup_requires)
      File "/usr/local/lib/python3.7/site-packages/setuptools/dist.py", line 717, in fetch_build_eggs
        replace_conflicting=True,
      File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 782, in resolve
        replace_conflicting=replace_conflicting
      File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 1065, in best_match
        return self.obtain(req, installer)
      File "/usr/local/lib/python3.7/site-packages/pkg_resources/__init__.py", line 1077, in obtain
        return installer(requirement)
      File "/usr/local/lib/python3.7/site-packages/setuptools/dist.py", line 784, in fetch_build_egg
        return cmd.easy_install(req)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 679, in easy_install
        return self.install_item(spec, dist.location, tmpdir, deps)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 705, in install_item
        dists = self.install_eggs(spec, download, tmpdir)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 890, in install_eggs
        return self.build_and_install(setup_script, setup_base)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 1158, in build_and_install
        self.run_setup(setup_script, setup_base, args)
      File "/usr/local/lib/python3.7/site-packages/setuptools/command/easy_install.py", line 1146, in run_setup
        raise DistutilsError("Setup script exited with %s" % (v.args[0],))
    distutils.errors.DistutilsError: Setup script exited with error: command 'gcc' failed with exit status 1
    ----------------------------------------
ERROR: Command "python setup.py egg_info" failed with error code 1 in /tmp/pip-install-w9661i00/pycares/
```

#### Attachments:

No need. Log above.

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[2.0.x] Does not install on alpine anymore - missing dependencies #433

Description

What type of issue is this? (place an `x` in one of the `[ ]`)

Requirements (place an `x` in each of the `[ ]`)

Bug Report

Reproducible in:

Steps to reproduce:

Expected result:

Actual result:

Attachments:

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

[2.0.x] Does not install on alpine anymore - missing dependencies #433

Description

Description

What type of issue is this? (place an x in one of the [ ])

Requirements (place an x in each of the [ ])

Bug Report

Reproducible in:

Steps to reproduce:

Expected result:

Actual result:

Attachments:

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions

What type of issue is this? (place an `x` in one of the `[ ]`)

Requirements (place an `x` in each of the `[ ]`)