Stop requiring /usr/local/bin links for glean.sh

Since Ic16f134fe34293bb68e7c632dd320f523366320d simple-init has
installed glean into a virtualenv.  Despite this, it still needs to
setup a range of global symlinks (in /usr/local/bin) so glean can
blindly call "glean" or "glean.sh".

This means that glean installation isn't actually stand-alone.  Unless
simple-init sets up these global symlinks the glean install doesn't
work.  This makes it very annoying to try and update the way the
scripts are working, because we have to merge changes into simple-init
as well.

We can make the installation self-consistent by using the install
tool.  The init scripts call glean.sh -- we can find the full path to
glean.sh using pkg_resources and write that into the files.

glean.sh wants to call the python tool "glean".  This is slightly
harder, because at runtime the script doesn't really know how to
invoke this (i.e. in a virtualenv, it should call
/path/to/virtualenv/bin/glean).  To allow for this, write a sibling
file next to "glean.sh" to invoke glean with the interpreter the
install is running under patched in.  This way, glean.sh can call this
wrapper relative to itself and get the right thing.  Add a __main__ to
allow glean to be called like this, and update the glean.sh script.

Change-Id: I1adfecf0d5c53648ee857be502216fd8d6cc5e16

glean/__main__.py

@@ -0,0 +1,26 @@
+# Copyright (c) 2021 Ian Wienand <iwienand@redhat.com>
+#
+# 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.
+
+import sys
+
+from glean.cmd import main
+
+rc = 1
+try:
+    main()
+    rc = 0
+except Exception as e:
+    print('Error: %s' % e, file=sys.stderr)
+sys.exit(rc)

glean/init/glean.conf

@@ -11,4 +11,4 @@ start on starting networking
 
 task
 
-exec /usr/local/bin/glean.sh %%EXTRA_ARGS%%
+exec %%GLEANSH_PATH%%/glean.sh %%EXTRA_ARGS%%

glean/init/glean.init

@@ -12,7 +12,7 @@
 
 NAME=glean
 INIT_NAME=/etc/init.d/${NAME}
-SCRIPT_NAME=/usr/local/bin/${NAME}.sh
+SCRIPT_NAME=%%GLEANSH_PATH%%/${NAME}.sh
 
 [ -x $SCRIPT_NAME ] || exit 0
 

glean/init/glean.sh

@@ -19,6 +19,10 @@ set -o pipefail
 
 PATH=/usr/local/bin:/bin:/sbin:/usr/bin:/usr/sbin
 
+# python-glean is installed alongside us and runs glean (the python
+# tool that actually does stuff).
+_GLEAN_PATH=$(dirname "$0")
+
 # NOTE(mnaser): Depending on the cloud, it may have `vfat` config drive which
 #               comes with a capitalized label rather than all lowercase.
 CONFIG_DRIVE_LABEL=""
@@ -47,7 +51,7 @@ if [ -n "$CONFIG_DRIVE_LABEL" ]; then
     else
         mount -o mode=0700 "${BLOCKDEV}" /mnt/config || true
     fi
-    glean --ssh --hostname $@
+    $_GLEAN_PATH/python-glean --ssh --hostname $@
 else
-    glean $@
+    $_GLEAN_PATH/python-glean $@
 fi

glean/init/python-glean.template

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+%%INTERP%% -m glean $@

glean/install.py

@@ -16,6 +16,7 @@
 import argparse
 import logging
 import os
+import pkg_resources
 import subprocess
 import sys
 
@@ -23,15 +24,13 @@ log = logging.getLogger("glean-install")
 
 
 def _find_gleansh_path():
-    # the "glean.sh" file is installed in /usr/bin/ on Fedora, and
-    # /usr/local/bin on Ubuntu/Debian thanks to differences in pip and
-    # where it likes to put scripts.
-    if os.path.exists("/usr/local/bin/glean.sh"):
-        return "/usr/local/bin"
-    if os.path.exists("/usr/bin/glean.sh"):
-        return "/usr/bin"
-    log.error("Unable to find glean.sh!")
-    sys.exit(1)
+    # glean.sh is a script installed by setup.cfg as a sibling to this
+    # script
+    p = pkg_resources.resource_filename(__name__, "init")
+    if not os.path.exists(os.path.join(p, "glean.sh")):
+        log.error("Unable to find glean.sh!")
+        sys.exit(1)
+    return p
 
 
 def install(source_file, target_file, mode='0755', replacements=dict()):
@@ -106,6 +105,13 @@ def main():
     else:
         logging.basicConfig(level=logging.INFO)
 
+    # Write the path of the currently executing interpreter into a
+    # file alongside glean.sh.  This means glean.sh can call the
+    # sibling python-glean and know that it's using the glean we
+    # installed, even in a virtualenv etc.
+    install('python-glean.template', os.path.join(p, 'python-glean'),
+            mode='0755', replacements={'INTERP': sys.executable})
+
     # needs to go first because gentoo can have systemd along side openrc
     if os.path.exists('/etc/gentoo-release'):
         log.info('installing openrc services')
@@ -171,13 +177,19 @@ def main():
     elif os.path.exists('/etc/init'):
         log.info("Installing upstart services")
         install('glean.conf', '/etc/init/glean.conf',
-                replacements={'EXTRA_ARGS': extra_args})
+                replacements={
+                    'GLEANSH_PATH': p,
+                    'EXTRA_ARGS': extra_args
+                })
     elif os.path.exists('/sbin/rc-update'):
         subprocess.call(['rc-update', 'add', 'glean', 'boot'])
     else:
         log.info("Installing sysv services")
         install('glean.init', '/etc/init.d/glean',
-                replacements={'EXTRA_ARGS': extra_args})
+                replacements={
+                    'GLEANSH_PATH': p,
+                    'EXTRA_ARGS': extra_args
+                })
         os.system('update-rc.d glean defaults')
 
 

setup.cfg

@@ -24,10 +24,6 @@ console_scripts =
     glean = glean.cmd:main
     glean-install = glean.install:main
 
-[files]
-scripts =
-    glean/init/glean.sh
-
 [build_sphinx]
 source-dir = doc/source
 build-dir = doc/build