add startup service and script to apply jinja template

apply_templates.py

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+import os, re, sys
+from jinja2 import Environment, FileSystemLoader, select_autoescape
+
+"""
+Apply Default Values to Jinja Templates
+"""
+
+TEMPLATE_FILES= ['service/apollo.service.j2']
+REAL_FILES = [t[:-3] for t in TEMPLATE_FILES]
+
+# Should existing files be overwritten
+OVERWRITE = False
+
+REQ_ENV_VARS = [
+    'APOLLO_PATH',  # path to the apollo repo
+    'APOLLO_USER',  # the user to run the service as
+]
+
+def usage():
+    print(sys.argv[0], "usage:")
+    print("")
+    print("You must define the following environment variables")
+    print("to render the Jinja templates:")
+    for env_var in REQ_ENV_VARS:
+        print(" "*4,env_var)
+
+for env_var in REQ_ENV_VARS:
+    if env_var not in os.environ:
+        usage()
+        raise Exception(f"Error: required env var not defined: {env_var}")
+
+for template_file, real_file in zip(TEMPLATE_FILES, REAL_FILES):
+    template_dir = os.path.basepath(template_file)
+    env = Environment(loader=FileSystemLoader(template_dir))
+    render_kwargs = {}
+    for env_var in REQ_ENV_VARS:
+        render_kwargs[env_var.lower()] = os.environ[env_var]
+    content = env.get_template(template_file).render(**render_kwargs)
+
+
+# Write to file
+if os.path.exists(rfile) and not OVERWRITE:
+    raise Exception("Error: file %s already exists!"%(rfile))
+else:
+    with open(rfile,'w') as f:
+        f.write(content)
+

service/Readme.md

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+# uptime service
+
+Directory containing files useful for creating a bot startup service
+(on Linux, of course).
+
+## Jinja Template
+
+This directory contains a Jinja template for a systemd service
+called `apollo.service` that can be installed to run on startup.
+The Jinja template contains one parameter that is the location of
+the uptime repo on disk.
+
+To render the template using a user-sepcified path:
+
+* Edit `render_template.py` to specify path of uptime repo
+* Run `render_template.py` to create `apollo.service`
+
+## Virtual Environment
+
+To run the startup service, you must first create a virtualenv
+in the `vp/` folder of the `uptime` repo. To do this, run this
+command from the `uptime` repo:
+
+```
+virtualenv -p python3.6 vp && source vp/bin/activate'
+```
+
+Now install the required software:
+
+```
+pip install -r requirements.txt
+```
+
+Now the python exeutable at `{{ apollo_path }}/vp/bin/python` will
+have the necessary libraries installed and can be used by the
+service script.
+
+

service/apollo.service.j2

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+[Unit]
+Description=apollo space junk twitter bot
+
+[Service]
+Restart=always
+User={{ apollo_user }}
+Group=wheel
+ExecStart={{ apollo_path }}/vp/bin/python -u {{ apollo_path }}/bot/ApolloBotFlock.py
+ExecStop=/usr/bin/killall {{ apollo_path }}/vp/bin/python
+
+[Install]
+WantedBy=default.target
+
+