Add environment check on startup

Use an environment check function to test if the env is
configured for running subiquity.

Signed-off-by: Ryan Harper <ryan.harper@canonical.com>

bin/subiquity-tui

@@ -18,10 +18,11 @@ import argparse
 import sys
 import logging
 import signal
-from subiquity.log import setup_logger
+from subiquity.log import setup_logger, LOGFILE
 from subiquity import __version__ as VERSION
 from subiquity.core import Controller as Subiquity
 from subiquity.ui.frame import SubiquityUI
+from subiquity.utils import environment_check
 
 
 def parse_options(argv):
@@ -55,10 +56,15 @@ def main():
 
     signal.signal(signal.SIGINT, control_c_handler)
 
+    env_ok = environment_check()
+    if env_ok is False:
+        print('Failed environment check.  Check {} for errors.'.format(LOGFILE))
+        return 1
+
     ui = SubiquityUI()
 
     subiquity_interface = Subiquity(ui, opts)
     subiquity_interface.run()
 
 if __name__ == '__main__':
-    main()
+    sys.exit(main())

subiquity/log.py

@@ -17,10 +17,10 @@ import logging
 import os
 from logging.handlers import TimedRotatingFileHandler
 
-
-def setup_logger(name=__name__):
 LOGDIR = "logs"
 LOGFILE = os.path.join(LOGDIR, "debug.log")
+
+def setup_logger(name=__name__):
     if not os.path.isdir(LOGDIR):
         os.makedirs(LOGDIR)
     log = TimedRotatingFileHandler(LOGFILE,

subiquity/utils.py

@@ -18,11 +18,85 @@ import errno
 import logging
 import os
 import random
+import yaml
 from subprocess import Popen, PIPE
 from subiquity.async import Async
 
 log = logging.getLogger("subiquity.utils")
 SYS_CLASS_NET = "/sys/class/net/"
+ENVIRONMENT_CHECK = '''
+checks:
+    read:
+        file:
+            - /var/log/syslog
+    write:
+        directory:
+            - /tmp
+    mount:
+        directory:
+            - /proc
+            - /sys
+    exec:
+        file:
+            - /sbin/hdparm
+            - /usr/bin/curtin
+'''
+
+def environment_check(check=ENVIRONMENT_CHECK):
+    ''' Check the environment to ensure subiquity can run without issues.
+    '''
+    log.info('Checking environment for installer requirements...')
+    def is_file(x):
+        return os.path.isfile(x)
+
+    def is_directory(x):
+        return os.path.isdir(x)
+
+    def is_mount(x):
+        return os.path.ismount(x)
+
+    def is_writable(x):
+        return os.access(x, os.W_OK)
+
+    def is_readable(x):
+        return os.access(x, os.R_OK)
+
+    def is_executable(x):
+        return os.access(x, os.X_OK)
+
+    check_map = {
+        'read': is_readable,
+        'write': is_writable,
+        'exec': is_executable,
+        'file': is_file,
+        'directory': is_directory,
+        'mount': is_mount,
+    }
+
+    checks = yaml.safe_load(check).get('checks', None)
+    if not checks:
+        log.error('Invalid environment check configuration')
+        return False
+
+    env_ok = True
+    for check_type in [c for c in checks
+                       if c in ['read', 'write', 'mount', 'exec']]:
+        for ftype, items in checks[check_type].items():
+            for i in items:
+                if not os.path.exists(i):
+                    log.error('FAIL: {} is not found on the filesystem'.format(i))
+                    env_ok = False
+                    continue
+                if check_map[ftype](i) is False:
+                    log.error('FAIL: {} is NOT of type: {}'.format(i, ftype))
+                    env_ok = False
+                    continue
+                if check_map[check_type](i) is False:
+                    log.error('FAIL: {} does NOT have required attr: {}'.format(i,
+                              check_type))
+                    env_ok = False
+
+    return env_ok
 
 
 def run_command_async(cmd, timeout=None):