diff --git a/addons/cetmix_tower_server/models/constants.py b/addons/cetmix_tower_server/models/constants.py
new file mode 100644
index 0000000..a0f121e
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+++ b/addons/cetmix_tower_server/models/constants.py
@@ -0,0 +1,125 @@
+from odoo import _
+
+# ***
+# This file is used to define commonly used constants
+# ***
+
+# Returned when a general error occurs
+GENERAL_ERROR = -100
+
+# Returned when a resource is not found
+NOT_FOUND = -101
+
+# -- SSH
+
+# Returned when an SSH connection error occurs
+SSH_CONNECTION_ERROR = 503
+
+# -- Command: -200 > -299
+
+# Returned when trying to execute another instance of a command on the same server
+# and this command doesn't allow parallel run
+ANOTHER_COMMAND_RUNNING = -201
+
+# Returned when no runner is found for command action
+NO_COMMAND_RUNNER_FOUND = -202
+
+# Returned when the command failed to execute due to a python code execution error
+PYTHON_COMMAND_ERROR = -203
+
+# Returned when the command failed to execute because the condition was not met
+PLAN_LINE_CONDITION_CHECK_FAILED = -205
+
+# Returned when the command timed out
+COMMAND_TIMED_OUT = -206
+COMMAND_TIMED_OUT_MESSAGE = _("Command timed out and was terminated")
+
+# Returned when the command is not compatible with the server
+COMMAND_NOT_COMPATIBLE_WITH_SERVER = -207
+
+# Returned when the command was stopped by user
+COMMAND_STOPPED = -208
+
+# -- Plan: -300 > -399
+
+# Returned when trying to execute another instance of a flightplan on the same server
+# and this flightplan doesn't allow parallel run
+ANOTHER_PLAN_RUNNING = -301
+
+# Returned when trying to start plan without lines
+PLAN_IS_EMPTY = -302
+
+# Returned when a plan tries to parse a command log record which doesn't have
+# a valid plan reference in it
+PLAN_NOT_ASSIGNED = -303
+
+# Returned when a plan tries to parse a command log record which doesn't have
+# a valid plan line reference in it
+PLAN_LINE_NOT_ASSIGNED = -304
+
+# Returned when any of the commands in the plan is not compatible with the server
+PLAN_NOT_COMPATIBLE_WITH_SERVER = -306
+
+# Returned when the flight plan was stopped by user
+PLAN_STOPPED = -308
+
+# -- File: -400 > -499
+
+# Returned when the file could not be created on the server
+FILE_CREATION_FAILED = -400
+
+# Returned when the file could not be uploaded to the server
+FILE_UPLOAD_FAILED = -401
+
+# Returned when the file could not be downloaded from the server
+FILE_DOWNLOAD_FAILED = -402
+
+# -- Default values
+
+# Default Python code used in Python code command
+DEFAULT_PYTHON_CODE = _(
+    """# Please refer to the 'Help' tab and documentation for more information.
+#
+# You can return command result in the 'result' variable which is a dictionary:
+#   result = {"exit_code": 0, "message": "Some message"}
+#   default value is {"exit_code": 0, "message": None}
+"""  # noqa: E501
+)
+
+
+# Default Python code help displayed in the "Help" tab
+DEFAULT_PYTHON_CODE_HELP = _(
+    """
+<h3>Help with Python expressions</h3>
+<div style="margin-bottom: 10px;">
+    <p>
+        Each Python code command returns the <code>result</code> value which is a dictionary.
+        <br>There are two keys in the dictionary:
+        <ul>
+    <li><code>exit_code</code>: Integer. Exit code of the command. "0" means success, any other value means failure. Default value is "0".</li>
+    <li><code>message</code>: String. Message to be logged. Default value is "None".</li>
+</ul>
+You can also access the <code>custom_values</code> dictionary that contains custom values provided to the command or flight plan.
+Custom values can be modified, thus can be used to pass data between commands in a flight plan.
+Please keep in mind that custom values are persistent only between commands in a flight plan and are not saved to the database.
+<br/>
+Here is an example of a python code command:
+
+<code style='white-space: pre-wrap'>
+    server_name = server.name
+    build_name = custom_values.get("build_name")
+    if build_name:
+        result = {"exit_code": 0, "message": "Build name for " + server_name + " is " + build_name}
+    else:
+        result = {"exit_code": 0, "message": "No build name provided for " + server_name}
+    custom_values["build_name"] = "New build name"
+</code>
+</p>
+<br>
+Please refer to the <a href="https://cetmix.com/tower/documentation/command/#python-code-commands" target="_blank">official documentation</a> for more information and examples.
+</div>
+<p
+>Various fields may use Python code or Python expressions. The
+    following variables can be used:</p>
+"""  # noqa: E501
+)