helloworld: Move helloweb program to component/helloweb

This

- better illustrates what components do (provide building recipes for
  programs) and what software do (gather components and provide recipes
  for instances).

- illustrates how to build the software properly - usually we build
  eggs or scripts with zc.recipe.egg:* , not generate python programs via
  jinja2 templating. Because when installing via egg, it is possible to
  import other installed eggs relatively straghtforward, and for jinja2
  way it is hard to do.

The helloweb program itself is moved into newly introduced helloweb.git
repository and, as almost all other software, becomes separate from
slapos.git .

/cc @jerome

component/helloweb/buildout.cfg

+# helloweb - programs to say hello to the Web in various languages
+[buildout]
+extends =
+  ../git/buildout.cfg
+
+parts =
+  helloweb
+
+
+# repository with examples
+[helloweb-repository]
+recipe  = slapos.recipe.build:gitclone
+git-executable = ${git:location}/bin/git
+repository = https://lab.nexedi.com/nexedi/helloweb.git
+revision = 88d517131e75929f79a4d36de4124dab4521614a
+location = ${buildout:parts-directory}/helloweb
+
+
+[helloweb-egg]
+recipe  = zc.recipe.egg:develop
+egg     = helloweb
+setup   = ${helloweb-repository:location}/python/
+
+[helloweb]
+recipe  = zc.recipe.egg:scripts
+eggs    = ${helloweb-egg:egg}
+scripts = helloweb

software/helloworld/helloweb.in

-#!{{ python_executable }}
-"""Simple web-server that says "Hello World" for every path
-
-helloweb [--logfile <logfile>] <bind-ip> <bind-port> ...
-"""
-
-import sys
-import time
-import argparse
-from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer
-from socket import AF_INET6
-
-
-class WebHello(BaseHTTPRequestHandler):
-
-    def do_GET(self):
-        self.send_response(200) # ok
-        self.send_header("Content-type", "text/plain")
-        self.end_headers()
-
-        print >>self.wfile, \
-            "Hello %s at `%s`  ; %s" % (
-                ' '.join(self.server.webhello_argv) or 'world',
-                self.path, time.asctime())
-
-
-class HTTPServerV6(HTTPServer):
-    address_family = AF_INET6
-
-def main():
-    parser = argparse.ArgumentParser()
-    parser.add_argument('--logfile', dest='logfile')
-    parser.add_argument('bind_ip')
-    parser.add_argument('bind_port', type=int)
-    parser.add_argument('argv_extra', metavar='...', nargs=argparse.REMAINDER)
-
-    args = parser.parse_args()
-
-    # HTTPServer logs to sys.stderr - override it if we have --logfile
-    if args.logfile:
-        f = open(args.logfile, 'a', buffering=1)
-        sys.stderr = f
-
-    print >>sys.stderr, '* %s helloweb starting at %s' % (
-        time.asctime(), (args.bind_ip, args.bind_port))
-
-    # TODO autodetect ipv6/ipv4
-    httpd = HTTPServerV6( (args.bind_ip, args.bind_port), WebHello)
-    httpd.webhello_argv = args.argv_extra
-    httpd.serve_forever()
-
-if __name__ == '__main__':
-    main()

software/helloworld/instance.cfg.in

@@ -81,7 +81,7 @@ logfile = $${directory:log}/helloweb.log
 # This recipe will try to "exec" the command-line after separating parameters.
 recipe = slapos.cookbook:wrapper
 command-line =
-    ${helloweb-bin:rendered} --logfile $${helloweb:logfile}
+    ${buildout:bin-directory}/helloweb --logfile $${helloweb:logfile}
         $${:ipv6} $${:port} $${instance-parameter:configuration.name}
 # Put this shell script in the "etc/service" directory. Each executable of this
 # repository will be started and monitored by supervisord. If a service

software/helloworld/software.cfg

@@ -6,10 +6,10 @@ extends =
   ../../stack/slapos.cfg
 # Extend here component profiles, like openssl, apache, mariadb, curl...
 # Or/and extend a stack (lamp, tomcat) that does most of the work for you
-# In this example we don't need anything more than python which is provided by
-# above stack/slapos.cfg
+# In this example we extend from helloweb component.
 # ../../component/component1/buildout.cfg
 # ../../component/component2/buildout.cfg
+  ../../component/helloweb/buildout.cfg
 
 parts =
 # Call installation of slapos.cookbook egg defined in stack/slapos.cfg (needed
@@ -19,8 +19,8 @@ parts =
 # instance
   instance-profile
 
-# "build" python program (install + correct shebang for our python)
-  helloweb-bin
+# build helloweb program
+  helloweb
 
 
 # Download instance.cfg.in (buildout profile used to deployment of instance),
@@ -31,23 +31,5 @@ recipe = slapos.recipe.template
 url = ${:_profile_base_location_}/instance.cfg.in
 output = ${buildout:directory}/instance.cfg
 # MD5 checksum can be skipped for development (easier to develop), but must be filled for production
-md5sum = 1861b47bcc4dc61751857193303c8bef
+md5sum = 38243467b23a9abfa728bd4d30ab51ad
 mode = 0644
-
-
-# install helloweb with correct python_executable
-[helloweb-bin]
-recipe = slapos.recipe.template:jinja2
-filename = helloweb
-md5sum = 2cfa80eba8cadea3e9cad64db2e3f536
-template = ${:_profile_base_location_}/${:filename}.in
-rendered = ${buildout:bin-directory}/${:filename}
-mode = 0755
-# XXX python_executable should be ${${buildout:python}:executable}
-#     but buildout cannot support such indirection.
-#
-# in real-cases, python software is usually installed with zc.recipe.egg
-# which cares about correctly specifiing python interpreter for
-# entry-points automatically.
-context =
-    raw python_executable ${buildout:executable}