Setup users host env for local instance support

- Setup flow controller in setup.py
- Define common method in base_task_runner.py
- Required package installer in host_setup_runner.py
- Host env configuration in host_setup_runner.py

Bug: 110388133
Test: ./run_tests.sh, m acloud && acloud setup.
Change-Id: Id8b988149d606553d31dfb466e0ae14883513553
diff --git a/setup/setup_common.py b/setup/setup_common.py
new file mode 100644
index 0000000..497027e
--- /dev/null
+++ b/setup/setup_common.py
@@ -0,0 +1,141 @@
+#!/usr/bin/env python
+#
+# Copyright 2018 - The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Common code used by acloud setup tools."""
+
+from __future__ import print_function
+import logging
+import re
+import subprocess
+
+from acloud import errors
+
+logger = logging.getLogger(__name__)
+
+PKG_INSTALL_CMD = "sudo apt-get --assume-yes install %s"
+APT_CHECK_CMD = "apt-cache policy %s"
+_INSTALLED_RE = re.compile(r"(.*\s*Installed:)(?P<installed_ver>.*\s?)")
+_CANDIDATE_RE = re.compile(r"(.*\s*Candidate:)(?P<candidate_ver>.*\s?)")
+
+
+def CheckCmdOutput(cmd, print_cmd=True, **kwargs):
+    """Helper function to run subprocess.check_output.
+
+    This function will return the command output for parsing the result and will
+    raise Error if command return code was non-zero.
+
+    Args:
+        cmd: String, the cmd string.
+        print_cmd: True to print cmd to stdout.
+        kwargs: Other option args to subprocess.
+
+    Returns:
+        Return cmd output as a byte string.
+        If the return code was non-zero it raises a CalledProcessError.
+    """
+    if print_cmd:
+        print("Run command: %s" % cmd)
+
+    logger.debug("Run command: %s", cmd)
+    return subprocess.check_output(cmd, **kwargs)
+
+
+def InstallPackage(pkg):
+    """Install package.
+
+    Args:
+        pkg: String, the name of package.
+
+    Raises:
+        PackageInstallError: package is not installed.
+    """
+    try:
+        print(CheckCmdOutput(PKG_INSTALL_CMD % pkg,
+                             shell=True,
+                             stderr=subprocess.STDOUT))
+    except subprocess.CalledProcessError as cpe:
+        logger.error("Package install for %s failed: %s", pkg, cpe.output)
+        raise errors.PackageInstallError(
+            "Could not install package [" + pkg + "], :" + str(cpe.output))
+
+    if not PackageInstalled(pkg, compare_version=False):
+        raise errors.PackageInstallError(
+            "Package was not detected as installed after installation [" +
+            pkg + "]")
+
+
+def PackageInstalled(pkg_name, compare_version=True):
+    """Check if the package is installed or not.
+
+    This method will validate that the specified package is installed
+    (via apt cache policy) and check if the installed version is up-to-date.
+
+    Args:
+        pkg_name: String, the package name.
+        compare_version: Boolean, True to compare version.
+
+    Returns:
+        True if package is installed.and False if not installed or
+        the pre-installed package is not the same version as the repo candidate
+        version.
+
+    Raises:
+        UnableToLocatePkgOnRepositoryError: Unable to locate package on repository.
+    """
+    try:
+        pkg_info = CheckCmdOutput(
+            APT_CHECK_CMD % pkg_name,
+            print_cmd=False,
+            shell=True,
+            stderr=subprocess.STDOUT)
+
+        logger.debug("Check package install status")
+        logger.debug(pkg_info)
+    except subprocess.CalledProcessError as error:
+        # Unable locate package name on repository.
+        raise errors.UnableToLocatePkgOnRepositoryError(
+            "Could not find package [" + pkg_name + "] on repository, :" +
+            str(error.output) + ", have you forgotten to run 'apt update'?")
+
+    installed_ver = None
+    candidate_ver = None
+    for line in pkg_info.splitlines():
+        match = _INSTALLED_RE.match(line)
+        if match:
+            installed_ver = match.group("installed_ver").strip()
+            continue
+        match = _CANDIDATE_RE.match(line)
+        if match:
+            candidate_ver = match.group("candidate_ver").strip()
+            continue
+
+    # package isn't installed
+    if installed_ver == "(none)":
+        logger.debug("Package is not installed, status is (none)")
+        return False
+    # couldn't find the package
+    if not (installed_ver and candidate_ver):
+        logger.debug("Version info not found [installed: %s ,candidate: %s]",
+                     installed_ver,
+                     candidate_ver)
+        return False
+    # installed package is old and we care about the version.
+    if compare_version and installed_ver != candidate_ver:
+        logger.debug("Package %s version at %s, expected %s",
+                     pkg_name,
+                     installed_ver,
+                     candidate_ver)
+        return False
+    return True