Single binary executables (#1330)

* Single binary executables / DEB packages.

* Attach single binary executables to the releases

httpie/manager/compat.py

@@ -0,0 +1,69 @@
+import sys
+import shutil
+import subprocess
+
+from contextlib import suppress
+from typing import List, Optional
+from httpie.compat import is_frozen
+
+
+class PipError(Exception):
+    """An exception that occurs when pip exits with an error status code."""
+
+    def __init__(self, stdout, stderr):
+        self.stdout = stdout
+        self.stderr = stderr
+
+
+def _discover_system_pip() -> List[str]:
+    # When we are running inside of a frozen binary, we need the system
+    # pip to install plugins since there is no way for us to execute any
+    # code outside of the HTTPie.
+    #
+    # We explicitly depend on system pip, so the SystemError should not
+    # be executed (except for broken installations).
+    def _check_pip_version(pip_location: Optional[str]) -> bool:
+        if not pip_location:
+            return False
+
+        with suppress(subprocess.CalledProcessError):
+            stdout = subprocess.check_output([pip_location, "--version"], text=True)
+            return "python 3" in stdout
+
+    targets = [
+        "pip",
+        "pip3"
+    ]
+    for target in targets:
+        pip_location = shutil.which(target)
+        if _check_pip_version(pip_location):
+            return pip_location
+
+    raise SystemError("Couldn't find 'pip' executable. Please ensure that pip in your system is available.")
+
+
+def _run_pip_subprocess(pip_executable: List[str], args: List[str]) -> bytes:
+    import subprocess
+
+    cmd = [*pip_executable, *args]
+    try:
+        process = subprocess.run(
+            cmd,
+            check=True,
+            shell=False,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE
+        )
+    except subprocess.CalledProcessError as error:
+        raise PipError(error.stdout, error.stderr) from error
+    else:
+        return process.stdout
+
+
+def run_pip(args: List[str]) -> bytes:
+    if is_frozen:
+        pip_executable = [_discover_system_pip()]
+    else:
+        pip_executable = [sys.executable, '-m', 'pip']
+
+    return _run_pip_subprocess(pip_executable, args)