diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..ce32f24
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,4 @@
+.github
+.travis.yml
+build*
+*.env
diff --git a/Dockerfile b/Dockerfile
index 02cdc08..289d7bb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -16,7 +16,11 @@ RUN apk add --no-cache \
       postgresql-dev \
       wget
 
-RUN pip install gunicorn
+RUN pip install \
+# gunicorn is used for launching netbox
+      gunicorn \
+# ruamel is used in startup_scripts
+      ruamel.yaml
 
 WORKDIR /opt
 
@@ -31,11 +35,14 @@ RUN pip install -r requirements.txt
 COPY docker/configuration.docker.py /opt/netbox/netbox/netbox/configuration.py
 COPY docker/gunicorn_config.py /opt/netbox/
 COPY docker/nginx.conf /etc/netbox-nginx/nginx.conf
+COPY docker/docker-entrypoint.sh docker-entrypoint.sh
+COPY startup_scripts/ /opt/netbox/startup_scripts/
+COPY initializers/ /opt/netbox/initializers/
+COPY configuration/configuration.py /etc/netbox/configuration.py
 
 WORKDIR /opt/netbox/netbox
 
-COPY docker/docker-entrypoint.sh /docker-entrypoint.sh
-ENTRYPOINT [ "/docker-entrypoint.sh" ]
+ENTRYPOINT [ "/opt/netbox/docker-entrypoint.sh" ]
 
 VOLUME ["/etc/netbox-nginx/"]
 
diff --git a/README.md b/README.md
index 478dbe4..0390dc2 100644
--- a/README.md
+++ b/README.md
@@ -66,11 +66,11 @@ For example defining `ALLOWED_HOSTS=localhost ::1 127.0.0.1` would allows access
 
 [compose-env]: https://docs.docker.com/compose/environment-variables/
 
-### Custom Initialisation Code (e.g. Automatically Setting Up Custom Fields)
+### Custom Initialization Code (e.g. Automatically Setting Up Custom Fields)
 
-When using `docker-compose`, all the python scripts present in `docker/startup_scripts` will automatically be executed after the application boots in the context of `./manage.py`.
+When using `docker-compose`, all the python scripts present in `/opt/netbox/startup_scripts` will automatically be executed after the application boots in the context of `./manage.py`.
 
-That mechanism can be used for many things, and in particular to load Netbox custom fields:
+That mechanism can be used for many things, e.g. to create Netbox custom fields:
 
 ```python
 # docker/startup_scripts/load_custom_fields.py
@@ -94,12 +94,54 @@ if created:
   my_custom_field.obj_type.add(device_type)
 ```
 
+#### Initializers
+
+Initializers are built-in startup scripts for defining Netbox custom fields, groups and users.
+All you need to do is to mount you own `initializers` folder ([see `docker-compose.yml`][netbox-docker-compose]).
+Look at the [`initializers` folder][netbox-docker-initializers] to learn how the files must look like.
+
+Here's an example for defining a custom field:
+
+```yaml
+# initializers/custom_fields.yml
+text_field:
+  type: text
+  label: Custom Text
+  description: Enter text in a text field.
+  required: false
+  filterable: true
+  weight: 0
+  on_objects:
+  - dcim.models.Device
+  - dcim.models.Rack
+  - ipam.models.IPAddress
+  - ipam.models.Prefix
+  - tenancy.models.Tenant
+  - virtualization.models.VirtualMachine
+```
+
+[netbox-docker-initializers]: https://github.com/ninech/netbox-docker/tree/master/initializers
+[netbox-docker-compose]: https://github.com/ninech/netbox-docker/blob/master/docker-compose.yml
+
+#### Custom Docker Image
+
+You can also build your own Netbox Docker image containing your own startup scripts, custom fields, users and groups
+like this:
+
+```
+ARG VERSION=latest
+FROM ninech/netbox:$VERSION
+
+COPY startup_scripts/ /opt/netbox/startup_scripts/
+COPY initializers/ /opt/netbox/initializers/
+```
+
 ### Production
 
 The default settings are optimized for (local) development environments.
 You should therefore adjust the configuration for production setups, at least the following variables:
 
-* `ALLOWED_HOSTS`: Add all URLs that lead to your netbox instance.
+* `ALLOWED_HOSTS`: Add all URLs that lead to your Netbox instance.
 * `DB_*`: Use a persistent database.
 * `EMAIL_*`: Use your own mailserver.
 * `MAX_PAGE_SIZE`: Use the recommended default of 1000.
@@ -109,7 +151,7 @@ You should therefore adjust the configuration for production setups, at least th
 
 You may run this image in a cluster such as Docker Swarm, Kubernetes or OpenShift, but this is advanced level.
 
-In this case, we encourage you to statically configure Netbox by starting from [Netbox's example config file][default-config], and mounting it into your container using the mechanism provided by your container platform (i.e. [Docker Swarm configs][swarm-config], [Kubernetes ConfigMap][k8s-config], [OpenShift ConfigMaps][openshift-config]).
+In this case, we encourage you to statically configure Netbox by starting from [Netbox's example config file][default-config], and mounting it into your container in the directory `/etc/netbox/` using the mechanism provided by your container platform (i.e. [Docker Swarm configs][swarm-config], [Kubernetes ConfigMap][k8s-config], [OpenShift ConfigMaps][openshift-config]).
 
 But if you rather continue to configure your application through environment variables, you may continue to use [the built-in configuration file][docker-config].
 We discourage storing secrets in environment variables, as environment variable are passed on to all sub-processes and may leak easily into other systems, e.g. error collecting tools that often collect all environment variables whenever an error occurs.
diff --git a/configuration/configuration.py b/configuration/configuration.py
new file mode 100644
index 0000000..5eba733
--- /dev/null
+++ b/configuration/configuration.py
@@ -0,0 +1,156 @@
+import os
+import socket
+
+# For reference see http://netbox.readthedocs.io/en/latest/configuration/mandatory-settings/
+# Based on https://github.com/digitalocean/netbox/blob/develop/netbox/netbox/configuration.example.py
+
+# Read secret from file
+def read_secret(secret_name):
+    try:
+        f = open('/run/secrets/' + secret_name, 'r', encoding='utf-8')
+    except EnvironmentError:
+        return ''
+    else:
+        with f:
+            return f.readline().strip()
+
+BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+#########################
+#                       #
+#   Required settings   #
+#                       #
+#########################
+
+# This is a list of valid fully-qualified domain names (FQDNs) for the NetBox server. NetBox will not permit write
+# access to the server via any other hostnames. The first FQDN in the list will be treated as the preferred name.
+#
+# Example: ALLOWED_HOSTS = ['netbox.example.com', 'netbox.internal.local']
+ALLOWED_HOSTS = os.environ.get('ALLOWED_HOSTS', socket.gethostname()).split(' ')
+
+# PostgreSQL database configuration.
+DATABASE = {
+    'NAME': os.environ.get('DB_NAME', 'netbox'),         # Database name
+    'USER': os.environ.get('DB_USER', ''),               # PostgreSQL username
+    'PASSWORD': os.environ.get('DB_PASSWORD', read_secret('db_password')),
+                                                         # PostgreSQL password
+    'HOST': os.environ.get('DB_HOST', 'localhost'),      # Database server
+    'PORT': os.environ.get('DB_PORT', ''),               # Database port (leave blank for default)
+}
+
+# This key is used for secure generation of random numbers and strings. It must never be exposed outside of this file.
+# For optimal security, SECRET_KEY should be at least 50 characters in length and contain a mix of letters, numbers, and
+# symbols. NetBox will not run without this defined. For more information, see
+# https://docs.djangoproject.com/en/dev/ref/settings/#std:setting-SECRET_KEY
+SECRET_KEY = os.environ.get('SECRET_KEY', read_secret('secret_key'))
+
+#########################
+#                       #
+#   Optional settings   #
+#                       #
+#########################
+
+# Specify one or more name and email address tuples representing NetBox administrators. These people will be notified of
+# application errors (assuming correct email settings are provided).
+ADMINS = [
+    # ['John Doe', 'jdoe@example.com'],
+]
+
+# Optionally display a persistent banner at the top and/or bottom of every page. HTML is allowed. To display the same
+# content in both banners, define BANNER_TOP and set BANNER_BOTTOM = BANNER_TOP.
+BANNER_TOP = os.environ.get('BANNER_TOP', '')
+BANNER_BOTTOM = os.environ.get('BANNER_BOTTOM', '')
+
+# Text to include on the login page above the login form. HTML is allowed.
+BANNER_LOGIN = os.environ.get('BANNER_LOGIN', '')
+
+# Base URL path if accessing NetBox within a directory. For example, if installed at http://example.com/netbox/, set:
+# BASE_PATH = 'netbox/'
+BASE_PATH = os.environ.get('BASE_PATH', '')
+
+# API Cross-Origin Resource Sharing (CORS) settings. If CORS_ORIGIN_ALLOW_ALL is set to True, all origins will be
+# allowed. Otherwise, define a list of allowed origins using either CORS_ORIGIN_WHITELIST or
+# CORS_ORIGIN_REGEX_WHITELIST. For more information, see https://github.com/ottoyiu/django-cors-headers
+CORS_ORIGIN_ALLOW_ALL = os.environ.get('CORS_ORIGIN_ALLOW_ALL', False)
+CORS_ORIGIN_WHITELIST = os.environ.get('CORS_ORIGIN_WHITELIST', '').split(' ')
+CORS_ORIGIN_REGEX_WHITELIST = [
+    # r'^(https?://)?(\w+\.)?example\.com$',
+]
+
+# Set to True to enable server debugging. WARNING: Debugging introduces a substantial performance penalty and may reveal
+# sensitive information about your installation. Only enable debugging while performing testing. Never enable debugging
+# on a production system.
+DEBUG = os.environ.get('DEBUG', False)
+
+# Email settings
+EMAIL = {
+    'SERVER': os.environ.get('EMAIL_SERVER', 'localhost'),
+    'PORT': int(os.environ.get('EMAIL_PORT', 25)),
+    'USERNAME': os.environ.get('EMAIL_USERNAME', ''),
+    'PASSWORD': os.environ.get('EMAIL_PASSWORD', read_secret('email_password')),
+    'TIMEOUT': int(os.environ.get('EMAIL_TIMEOUT', 10)),  # seconds
+    'FROM_EMAIL': os.environ.get('EMAIL_FROM', ''),
+}
+
+# Enforcement of unique IP space can be toggled on a per-VRF basis.
+# To enforce unique IP space within the global table (all prefixes and IP addresses not assigned to a VRF),
+# set ENFORCE_GLOBAL_UNIQUE to True.
+ENFORCE_GLOBAL_UNIQUE = os.environ.get('ENFORCE_GLOBAL_UNIQUE', False)
+
+# Enable custom logging. Please see the Django documentation for detailed guidance on configuring custom logs:
+#   https://docs.djangoproject.com/en/1.11/topics/logging/
+LOGGING = {}
+
+# Setting this to True will permit only authenticated users to access any part of NetBox. By default, anonymous users
+# are permitted to access most data in NetBox (excluding secrets) but not make any changes.
+LOGIN_REQUIRED = os.environ.get('LOGIN_REQUIRED', False)
+
+# Base URL path if accessing NetBox within a directory. For example, if installed at http://example.com/netbox/, set:
+# BASE_PATH = 'netbox/'
+BASE_PATH = os.environ.get('BASE_PATH', '')
+
+# Setting this to True will display a "maintenance mode" banner at the top of every page.
+MAINTENANCE_MODE = os.environ.get('MAINTENANCE_MODE', False)
+
+# An API consumer can request an arbitrary number of objects =by appending the "limit" parameter to the URL (e.g.
+# "?limit=1000"). This setting defines the maximum limit. Setting it to 0 or None will allow an API consumer to request
+# all objects by specifying "?limit=0".
+MAX_PAGE_SIZE = int(os.environ.get('MAX_PAGE_SIZE', 1000))
+
+# The file path where uploaded media such as image attachments are stored. A trailing slash is not needed. Note that
+# the default value of this setting is derived from the installed location.
+MEDIA_ROOT = os.environ.get('MEDIA_ROOT', os.path.join(BASE_DIR, 'media'))
+
+# Credentials that NetBox will use to access live devices.
+NAPALM_USERNAME = os.environ.get('NAPALM_USERNAME', '')
+NAPALM_PASSWORD = os.environ.get('NAPALM_PASSWORD', read_secret('napalm_password'))
+
+# NAPALM timeout (in seconds). (Default: 30)
+NAPALM_TIMEOUT = int(os.environ.get('NAPALM_TIMEOUT', 30))
+
+# NAPALM optional arguments (see http://napalm.readthedocs.io/en/latest/support/#optional-arguments). Arguments must
+# be provided as a dictionary.
+NAPALM_ARGS = {}
+
+# Determine how many objects to display per page within a list. (Default: 50)
+PAGINATE_COUNT = int(os.environ.get('PAGINATE_COUNT', 50))
+
+# When determining the primary IP address for a device, IPv6 is preferred over IPv4 by default. Set this to True to
+# prefer IPv4 instead.
+PREFER_IPV4 = os.environ.get('PREFER_IPV4', False)
+
+# The file path where custom reports will be stored. A trailing slash is not needed. Note that the default value of
+# this setting is derived from the installed location.
+REPORTS_ROOT = os.environ.get('REPORTS_ROOT', os.path.join(BASE_DIR, 'reports'))
+
+# Time zone (default: UTC)
+TIME_ZONE = os.environ.get('TIME_ZONE', 'UTC')
+
+# Date/time formatting. See the following link for supported formats:
+# https://docs.djangoproject.com/en/dev/ref/templates/builtins/#date
+DATE_FORMAT = os.environ.get('DATE_FORMAT', 'N j, Y')
+SHORT_DATE_FORMAT = os.environ.get('SHORT_DATE_FORMAT', 'Y-m-d')
+TIME_FORMAT = os.environ.get('TIME_FORMAT', 'g:i a')
+SHORT_TIME_FORMAT = os.environ.get('SHORT_TIME_FORMAT', 'H:i:s')
+DATETIME_FORMAT = os.environ.get('DATETIME_FORMAT', 'N j, Y g:i a')
+SHORT_DATETIME_FORMAT = os.environ.get('SHORT_DATETIME_FORMAT', 'Y-m-d H:i')
diff --git a/docker-compose.test.yml b/docker-compose.test.yml
index 9177dd2..158defc 100644
--- a/docker-compose.test.yml
+++ b/docker-compose.test.yml
@@ -9,11 +9,13 @@ services:
       depends_on:
       - postgres
       env_file: netbox.env
+      volumes:
+      - ./configuration:/etc/netbox:ro
       command:
       - ./manage.py
       - test
     postgres:
-      image: postgres:9.6-alpine
+      image: postgres:10.2-alpine
       env_file: postgres.env
 volumes:
   netbox-static-files:
diff --git a/docker-compose.yml b/docker-compose.yml
index 34e4572..71735a8 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -10,23 +10,25 @@ services:
         - postgres
         env_file: netbox.env
         volumes:
-        - ./docker/startup_scripts:/opt/netbox/netbox/startup_scripts
+        - ./startup_scripts:/opt/netbox/startup_scripts:ro
+        - ./initializers:/opt/netbox/initializers:ro
+        - ./configuration:/etc/netbox:ro
         - netbox-nginx-config:/etc/netbox-nginx/
         - netbox-static-files:/opt/netbox/netbox/static
         - netbox-media-files:/opt/netbox/netbox/media
         - netbox-report-files:/opt/netbox/netbox/reports
     nginx:
-        image: nginx:1.11-alpine
+        image: nginx:1.13-alpine
         command: nginx -g 'daemon off;' -c /etc/netbox-nginx/nginx.conf
         depends_on:
         - netbox
         ports:
         - 8080
         volumes:
-        - netbox-static-files:/opt/netbox/netbox/static
-        - netbox-nginx-config:/etc/netbox-nginx/
+        - netbox-static-files:/opt/netbox/netbox/static:ro
+        - netbox-nginx-config:/etc/netbox-nginx/:ro
     postgres:
-        image: postgres:9.6-alpine
+        image: postgres:10.2-alpine
         env_file: postgres.env
         volumes:
         - netbox-postgres-data:/var/lib/postgresql/data
diff --git a/docker/configuration.docker.py b/docker/configuration.docker.py
index 5eba733..fbca950 100644
--- a/docker/configuration.docker.py
+++ b/docker/configuration.docker.py
@@ -1,156 +1,10 @@
-import os
-import socket
+import importlib.util
+import sys
 
-# For reference see http://netbox.readthedocs.io/en/latest/configuration/mandatory-settings/
-# Based on https://github.com/digitalocean/netbox/blob/develop/netbox/netbox/configuration.example.py
-
-# Read secret from file
-def read_secret(secret_name):
-    try:
-        f = open('/run/secrets/' + secret_name, 'r', encoding='utf-8')
-    except EnvironmentError:
-        return ''
-    else:
-        with f:
-            return f.readline().strip()
-
-BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
-
-#########################
-#                       #
-#   Required settings   #
-#                       #
-#########################
-
-# This is a list of valid fully-qualified domain names (FQDNs) for the NetBox server. NetBox will not permit write
-# access to the server via any other hostnames. The first FQDN in the list will be treated as the preferred name.
-#
-# Example: ALLOWED_HOSTS = ['netbox.example.com', 'netbox.internal.local']
-ALLOWED_HOSTS = os.environ.get('ALLOWED_HOSTS', socket.gethostname()).split(' ')
-
-# PostgreSQL database configuration.
-DATABASE = {
-    'NAME': os.environ.get('DB_NAME', 'netbox'),         # Database name
-    'USER': os.environ.get('DB_USER', ''),               # PostgreSQL username
-    'PASSWORD': os.environ.get('DB_PASSWORD', read_secret('db_password')),
-                                                         # PostgreSQL password
-    'HOST': os.environ.get('DB_HOST', 'localhost'),      # Database server
-    'PORT': os.environ.get('DB_PORT', ''),               # Database port (leave blank for default)
-}
-
-# This key is used for secure generation of random numbers and strings. It must never be exposed outside of this file.
-# For optimal security, SECRET_KEY should be at least 50 characters in length and contain a mix of letters, numbers, and
-# symbols. NetBox will not run without this defined. For more information, see
-# https://docs.djangoproject.com/en/dev/ref/settings/#std:setting-SECRET_KEY
-SECRET_KEY = os.environ.get('SECRET_KEY', read_secret('secret_key'))
-
-#########################
-#                       #
-#   Optional settings   #
-#                       #
-#########################
-
-# Specify one or more name and email address tuples representing NetBox administrators. These people will be notified of
-# application errors (assuming correct email settings are provided).
-ADMINS = [
-    # ['John Doe', 'jdoe@example.com'],
-]
-
-# Optionally display a persistent banner at the top and/or bottom of every page. HTML is allowed. To display the same
-# content in both banners, define BANNER_TOP and set BANNER_BOTTOM = BANNER_TOP.
-BANNER_TOP = os.environ.get('BANNER_TOP', '')
-BANNER_BOTTOM = os.environ.get('BANNER_BOTTOM', '')
-
-# Text to include on the login page above the login form. HTML is allowed.
-BANNER_LOGIN = os.environ.get('BANNER_LOGIN', '')
-
-# Base URL path if accessing NetBox within a directory. For example, if installed at http://example.com/netbox/, set:
-# BASE_PATH = 'netbox/'
-BASE_PATH = os.environ.get('BASE_PATH', '')
-
-# API Cross-Origin Resource Sharing (CORS) settings. If CORS_ORIGIN_ALLOW_ALL is set to True, all origins will be
-# allowed. Otherwise, define a list of allowed origins using either CORS_ORIGIN_WHITELIST or
-# CORS_ORIGIN_REGEX_WHITELIST. For more information, see https://github.com/ottoyiu/django-cors-headers
-CORS_ORIGIN_ALLOW_ALL = os.environ.get('CORS_ORIGIN_ALLOW_ALL', False)
-CORS_ORIGIN_WHITELIST = os.environ.get('CORS_ORIGIN_WHITELIST', '').split(' ')
-CORS_ORIGIN_REGEX_WHITELIST = [
-    # r'^(https?://)?(\w+\.)?example\.com$',
-]
-
-# Set to True to enable server debugging. WARNING: Debugging introduces a substantial performance penalty and may reveal
-# sensitive information about your installation. Only enable debugging while performing testing. Never enable debugging
-# on a production system.
-DEBUG = os.environ.get('DEBUG', False)
-
-# Email settings
-EMAIL = {
-    'SERVER': os.environ.get('EMAIL_SERVER', 'localhost'),
-    'PORT': int(os.environ.get('EMAIL_PORT', 25)),
-    'USERNAME': os.environ.get('EMAIL_USERNAME', ''),
-    'PASSWORD': os.environ.get('EMAIL_PASSWORD', read_secret('email_password')),
-    'TIMEOUT': int(os.environ.get('EMAIL_TIMEOUT', 10)),  # seconds
-    'FROM_EMAIL': os.environ.get('EMAIL_FROM', ''),
-}
-
-# Enforcement of unique IP space can be toggled on a per-VRF basis.
-# To enforce unique IP space within the global table (all prefixes and IP addresses not assigned to a VRF),
-# set ENFORCE_GLOBAL_UNIQUE to True.
-ENFORCE_GLOBAL_UNIQUE = os.environ.get('ENFORCE_GLOBAL_UNIQUE', False)
-
-# Enable custom logging. Please see the Django documentation for detailed guidance on configuring custom logs:
-#   https://docs.djangoproject.com/en/1.11/topics/logging/
-LOGGING = {}
-
-# Setting this to True will permit only authenticated users to access any part of NetBox. By default, anonymous users
-# are permitted to access most data in NetBox (excluding secrets) but not make any changes.
-LOGIN_REQUIRED = os.environ.get('LOGIN_REQUIRED', False)
-
-# Base URL path if accessing NetBox within a directory. For example, if installed at http://example.com/netbox/, set:
-# BASE_PATH = 'netbox/'
-BASE_PATH = os.environ.get('BASE_PATH', '')
-
-# Setting this to True will display a "maintenance mode" banner at the top of every page.
-MAINTENANCE_MODE = os.environ.get('MAINTENANCE_MODE', False)
-
-# An API consumer can request an arbitrary number of objects =by appending the "limit" parameter to the URL (e.g.
-# "?limit=1000"). This setting defines the maximum limit. Setting it to 0 or None will allow an API consumer to request
-# all objects by specifying "?limit=0".
-MAX_PAGE_SIZE = int(os.environ.get('MAX_PAGE_SIZE', 1000))
-
-# The file path where uploaded media such as image attachments are stored. A trailing slash is not needed. Note that
-# the default value of this setting is derived from the installed location.
-MEDIA_ROOT = os.environ.get('MEDIA_ROOT', os.path.join(BASE_DIR, 'media'))
-
-# Credentials that NetBox will use to access live devices.
-NAPALM_USERNAME = os.environ.get('NAPALM_USERNAME', '')
-NAPALM_PASSWORD = os.environ.get('NAPALM_PASSWORD', read_secret('napalm_password'))
-
-# NAPALM timeout (in seconds). (Default: 30)
-NAPALM_TIMEOUT = int(os.environ.get('NAPALM_TIMEOUT', 30))
-
-# NAPALM optional arguments (see http://napalm.readthedocs.io/en/latest/support/#optional-arguments). Arguments must
-# be provided as a dictionary.
-NAPALM_ARGS = {}
-
-# Determine how many objects to display per page within a list. (Default: 50)
-PAGINATE_COUNT = int(os.environ.get('PAGINATE_COUNT', 50))
-
-# When determining the primary IP address for a device, IPv6 is preferred over IPv4 by default. Set this to True to
-# prefer IPv4 instead.
-PREFER_IPV4 = os.environ.get('PREFER_IPV4', False)
-
-# The file path where custom reports will be stored. A trailing slash is not needed. Note that the default value of
-# this setting is derived from the installed location.
-REPORTS_ROOT = os.environ.get('REPORTS_ROOT', os.path.join(BASE_DIR, 'reports'))
-
-# Time zone (default: UTC)
-TIME_ZONE = os.environ.get('TIME_ZONE', 'UTC')
-
-# Date/time formatting. See the following link for supported formats:
-# https://docs.djangoproject.com/en/dev/ref/templates/builtins/#date
-DATE_FORMAT = os.environ.get('DATE_FORMAT', 'N j, Y')
-SHORT_DATE_FORMAT = os.environ.get('SHORT_DATE_FORMAT', 'Y-m-d')
-TIME_FORMAT = os.environ.get('TIME_FORMAT', 'g:i a')
-SHORT_TIME_FORMAT = os.environ.get('SHORT_TIME_FORMAT', 'H:i:s')
-DATETIME_FORMAT = os.environ.get('DATETIME_FORMAT', 'N j, Y g:i a')
-SHORT_DATETIME_FORMAT = os.environ.get('SHORT_DATETIME_FORMAT', 'Y-m-d H:i')
+try:
+  spec = importlib.util.spec_from_file_location('configuration', '/etc/netbox/configuration.py')
+  module = importlib.util.module_from_spec(spec)
+  spec.loader.exec_module(module)
+  sys.modules['netbox.configuration'] = module
+except:
+  raise ImportError('')
diff --git a/docker/docker-entrypoint.sh b/docker/docker-entrypoint.sh
index ff22cad..bcf418f 100755
--- a/docker/docker-entrypoint.sh
+++ b/docker/docker-entrypoint.sh
@@ -39,7 +39,8 @@ if not User.objects.filter(username='${SUPERUSER_NAME}'):
     Token.objects.create(user=u, key='${SUPERUSER_API_TOKEN}')
 END
 
-for script in $(ls startup_scripts/*.py 2> /dev/null); do
+for script in /opt/netbox/startup_scripts/*.py; do
+  echo "⚙️ Executing '$script'"
   ./manage.py shell --plain < "${script}"
 done
 
@@ -48,5 +49,6 @@ done
 
 echo "✅ Initialisation is done."
 
-# launch whatever is passed by docker via RUN
+# launch whatever is passed by docker
+# (i.e. the RUN instruction in the Dockerfile)
 exec ${@}
diff --git a/docker/gunicorn_config.py b/docker/gunicorn_config.py
index 65f4b89..059e394 100644
--- a/docker/gunicorn_config.py
+++ b/docker/gunicorn_config.py
@@ -2,7 +2,6 @@ command = '/usr/bin/gunicorn'
 pythonpath = '/opt/netbox/netbox'
 bind = '0.0.0.0:8001'
 workers = 3
-user = 'root'
 errorlog = '-'
 accesslog = '-'
 capture_output = False
diff --git a/docker/startup_scripts/.gitkeep b/docker/startup_scripts/.gitkeep
deleted file mode 100644
index e69de29..0000000
diff --git a/initializers/custom_fields.yml b/initializers/custom_fields.yml
new file mode 100644
index 0000000..ccde9a0
--- /dev/null
+++ b/initializers/custom_fields.yml
@@ -0,0 +1,66 @@
+# text_field:
+#   type: text
+#   label: Custom Text
+#   description: Enter text in a text field.
+#   required: false
+#   filterable: true
+#   weight: 0
+#   on_objects:
+#   - dcim.models.Device
+#   - dcim.models.Rack
+#   - ipam.models.IPAddress
+#   - ipam.models.Prefix
+#   - tenancy.models.Tenant
+#   - virtualization.models.VirtualMachine
+# integer_field:
+#   type: integer
+#   label: Custom Number
+#   description: Enter numbers into an integer field.
+#   required: true
+#   filterable: true
+#   weight: 10
+#   on_objects:
+#   - tenancy.models.Tenant
+# selection_field:
+#   type: selection
+#   label: Choose between items
+#   required: false
+#   filterable: true
+#   weight: 30
+#   on_objects:
+#   - dcim.models.Device
+#   choices:
+#   - value: First Item
+#     weight: 10
+#   - value: Second Item
+#     weight: 20
+#   - value: Third Item
+#     weight: 30
+#   - value: Fifth Item
+#     weight: 50
+#   - value: Fourth Item
+#     weight: 40
+# boolean_field:
+#   type: boolean
+#   label: Yes Or No?
+#   required: true
+#   filterable: true
+#   default: "false" # important: but "false" in quotes!
+#   weight: 90
+#   on_objects:
+#   - dcim.models.Device
+# url_field:
+#   type: url
+#   label: Hyperlink
+#   description: Link to something nice.
+#   required: true
+#   filterable: false
+#   on_objects:
+#   - tenancy.models.Tenant
+# date_field:
+#   type: date
+#   label: Important Date
+#   required: false
+#   filterable: false
+#   on_objects:
+#   - dcim.models.Device
diff --git a/initializers/groups.yml b/initializers/groups.yml
new file mode 100644
index 0000000..1f4a5a7
--- /dev/null
+++ b/initializers/groups.yml
@@ -0,0 +1,9 @@
+# applications:
+#   users:
+#   - technical_user
+# readers:
+#   users:
+#   - reader
+# writers:
+#   users:
+#   - writer
diff --git a/initializers/users.yml b/initializers/users.yml
new file mode 100644
index 0000000..ed57fef
--- /dev/null
+++ b/initializers/users.yml
@@ -0,0 +1,6 @@
+# technical_user:
+#   api_token: 0123456789technicaluser789abcdef01234567 # must be looooong!
+# reader:
+#   password: reader
+# writer:
+#   password: writer
diff --git a/startup_scripts/00_users.py b/startup_scripts/00_users.py
new file mode 100644
index 0000000..1db0ebe
--- /dev/null
+++ b/startup_scripts/00_users.py
@@ -0,0 +1,20 @@
+from django.contrib.auth.models import Group, User
+from users.models import Token
+
+from ruamel.yaml import YAML
+
+with open('/opt/netbox/initializers/users.yml', 'r') as stream:
+  yaml=YAML(typ='safe')
+  users = yaml.load(stream)
+
+  if users is not None:
+    for username, user_details in users.items():
+      if not User.objects.filter(username=username):
+        user = User.objects.create_user(
+          username = username,
+          password = user_details.get('password', 0) or User.objects.make_random_password)
+
+        print("👤 Created user ",username)
+
+        if user_details.get('api_token', 0):
+          Token.objects.create(user=user, key=user_details['api_token'])
diff --git a/startup_scripts/10_groups.py b/startup_scripts/10_groups.py
new file mode 100644
index 0000000..7932874
--- /dev/null
+++ b/startup_scripts/10_groups.py
@@ -0,0 +1,19 @@
+from django.contrib.auth.models import Group, User
+from ruamel.yaml import YAML
+
+with open('/opt/netbox/initializers/groups.yml', 'r') as stream:
+  yaml=YAML(typ='safe')
+  groups = yaml.load(stream)
+
+  if groups is not None:
+    for groupname, group_details in groups.items():
+      group, created = Group.objects.get_or_create(name=groupname)
+
+      if created:
+        print("👥 Created group", groupname)
+
+      for username in group_details['users']:
+        user = User.objects.get(username=username)
+
+        if user:
+          user.groups.add(group)
diff --git a/startup_scripts/20_custom_fields.py b/startup_scripts/20_custom_fields.py
new file mode 100644
index 0000000..5c40e37
--- /dev/null
+++ b/startup_scripts/20_custom_fields.py
@@ -0,0 +1,68 @@
+from extras.constants import CF_TYPE_TEXT, CF_TYPE_INTEGER, CF_TYPE_BOOLEAN, CF_TYPE_DATE, CF_TYPE_URL, CF_TYPE_SELECT
+from extras.models import CustomField, CustomFieldChoice
+
+from ruamel.yaml import YAML
+
+text_to_fields = {
+  'boolean': CF_TYPE_BOOLEAN,
+  'date': CF_TYPE_DATE,
+  'integer': CF_TYPE_INTEGER,
+  'selection': CF_TYPE_SELECT,
+  'text': CF_TYPE_TEXT,
+  'url': CF_TYPE_URL,
+}
+
+def get_class_for_class_path(class_path):
+  import importlib
+  from django.contrib.contenttypes.models import ContentType
+
+  module_name, class_name = class_path.rsplit(".", 1)
+  module = importlib.import_module(module_name)
+  clazz = getattr(module, class_name)
+  return ContentType.objects.get_for_model(clazz)
+
+with open('/opt/netbox/initializers/custom_fields.yml', 'r') as stream:
+  yaml = YAML(typ='safe')
+  customfields = yaml.load(stream)
+
+  if customfields is not None:
+    for cf_name, cf_details in customfields.items():
+      custom_field, created = CustomField.objects.get_or_create(name = cf_name)
+
+      if created:
+        if cf_details.get('default', 0):
+          custom_field.default = cf_details['default']
+
+        if cf_details.get('description', 0):
+          custom_field.description = cf_details['description']
+
+        if cf_details.get('filterable', 0):
+          custom_field.is_filterables = cf_details['filterable']
+
+        if cf_details.get('label', 0):
+          custom_field.label = cf_details['label']
+
+        for object_type in cf_details.get('on_objects', []):
+          custom_field.obj_type.add(get_class_for_class_path(object_type))
+
+        if cf_details.get('required', 0):
+          custom_field.required = cf_details['required']
+
+        if cf_details.get('type', 0):
+          custom_field.type = text_to_fields[cf_details['type']]
+
+        if cf_details.get('weight', 0):
+          custom_field.weight = cf_details['weight']
+
+        custom_field.save()
+
+        for choice_details in cf_details.get('choices', []):
+          choice = CustomFieldChoice.objects.create(
+            field=custom_field,
+            value=choice_details['value'])
+
+          if choice_details.get('weight', 0):
+            choice.weight = choice_details['weight']
+            choice.save()
+
+        print("🔧 Created custom field", cf_name)