Documentation updates
Minor corrections and update of the remote debugging guide. Change-Id: I0d08aaf4f02f5575f1a68b65ebc16aafad8a0270
This commit is contained in:
Tom Weininger
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@ -28,11 +28,12 @@ Note that this does not mean we are against having vendors develop products
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which can replace some of the components within Octavia. (For example, the
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Octavia VM images might be replaced by a vendor's proprietary VM image.)
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Rather, it means that:
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* The reference implementation should always be open source and unencumbered.
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* We are typically not interested in making design compromises in order to work
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with a vendor's proprietary product. If a vendor wants to develop a component
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for Octavia, then the vendor should bend to Octavia's needs, not the other
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way around.
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with a vendor's proprietary product. If a vendor wants to develop a component
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for Octavia, then the vendor should bend to Octavia's needs, not the other
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way around.
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Octavia is a load balancer for large operators
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----------------------------------------------
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@ -61,6 +61,7 @@ either additional knowledge about the state of other components in the Octavia
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system, advanced logic behind decisions, or otherwise a high degree of
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intelligence should be done by centralized components (ex. controllers) within
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the Octavia system. Examples of this might include:
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* Generating haproxy configuration files
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* Managing the lifecycle of Octavia amphorae
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* Moving a loadbalancer instance from one Octavia amphora to another.
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@ -68,6 +69,7 @@ the Octavia system. Examples of this might include:
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On the other hand, tasks done extremely often, or which entail a significant
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load on the system should be pushed as far out to the most horizontally
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scalable components as possible. Examples of this might include:
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* Serving actual client requests to end-users (ie. running haproxy)
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* Monitoring pool members for failure and sending notifications about this
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* Processing log files
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@ -27,45 +27,124 @@ Prerequisites
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Setup
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=====
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Ensure your OpenStack and IDE environments have the PyDev or ptvsd library
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installed.
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Both PyCharm Professional edition and Visual Studio Code offer remote debugging
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features that can be used for debugging Octavia components.
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If you're using PyCharm, you can find it in
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*/path/to/pycharm/debug-eggs/pycharm-debug.egg* (Python 2) and
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*/path/to/pycharm/debug-eggs/pycharm-debug-py3k.egg* (Python 3). Copy that file
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into your OpenStack host and install the library in your Python path:
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.. note:: Before running a new Octavia process you should
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make sure that processes of that component are no longer running.
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You can use ``ps aux`` in order to verify that.
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::
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PyCharm
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-------
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$ sudo easy_install pycharm-debug.egg
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.. note:: Remote debugging is a *PyCharm Professional* feature.
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If using Visual Studio Code, simply install ptvsd in both environments:
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PyCharm offers two ways of debugging remotely [1]_. In general, the
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"through a remote interpreter" approach is more convenient and should
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be preferred.
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On the other hand, the "Python debug server" approach is the only
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one that works for debugging the API component (because of uWSGI).
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Therefore, this guide will explain both approaches.
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::
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Using a remote interpreter
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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$ pip install ptvsd
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First, configure a remote interpreter for the VM as documented in [2]_.
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Adding a deployment configuration with correct path mappings allows
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PyCharm to upload local changes to the remote host automatically.
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Create a remote debugging configuration in your IDE. In PyCharm, go to *Run ->
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Edit Configurations -> Python Remote Debug*. The local host name refers to the
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local machine you're running your IDE from and it must be one reachable by your
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OpenStack environment. The port can be any available port (e.g. 5678). If the
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code on the OpenStack and PyCharm hosts is on different paths (likely), define
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a path mapping in the remote debug configuration.
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Then, create a new *Run/Debug Configuration* by selecting
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*Run -> Edit Configurations...* in the menu bar.
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Add a new configuration and make sure
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*Module name* is selected instead of *Script path*. Enter the module name of
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the Octavia component you want to debug, for instance
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``octavia.cmd.octavia_worker``. Additionally, add
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``--config-file /etc/octavia/octavia.conf`` to *Parameters*.
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Then check whether the right remote Python interpreter
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is selected. After you confirm the settings by clicking *OK* you should be
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able to run/debug the Octavia component with that new run configuration.
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Invoke the debug configuration (*Run -> Debug... -> (config name)*). PyCharm
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will begin listening on the specified host and port.
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Using a Python debug server
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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As mentioned above the "remote interpreter" approach does not work with
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*Octavia-API* because that process is managed by uWSGI. Here the
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Python debug server approach [3]_ needs to be used. You will need to
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install the ``pydevd-pycharm`` via ``pip`` as shown when creating the run/debug
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configuration. However, it is not necessary to modify the Python code
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in any way because Octavia code is already set up for it to work.
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Export *DEBUGGER_TYPE*, *DEBUGGER_HOST* and *DEBUGGER_PORT* (host and port of
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the system running the IDE, respectively), and start the Octavia service you
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want to debug. It is recommended to run only one uWSGI process/controller
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worker. For example, to debug the Octavia Worker service:
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::
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want to debug. For example, to debug the Octavia API service::
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$ export DEBUGGER_TYPE=pydev
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$ export DEBUGGER_HOST=192.168.121.1
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$ export DEBUGGER_PORT=5678
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$ /usr/bin/octavia-worker --config-file /etc/octavia/octavia.conf
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$ uwsgi --ini /etc/octavia/octavia-uwsgi.ini
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.. note:: You must run the Octavia/uWSGI command directly. Starting it
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via ``systemctl`` will not work with the debug server.
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Visual Studio Code
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------------------
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While PyCharm synchronizes local changes with
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the remote host, Code will work on the remote environment directly
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through a SSH tunnel. That means that you don't even need to have
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source code on your local machine in order to debug code on the remote.
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Detail information about remote debugging over SSH can be found
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in the official Visual Studio Code documentation [4]_.
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This guide will focus on the essential steps only.
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Using the remote development extension pack
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.. note:: This approach will not work with the Octavia API component
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because that component is managed by uWSGI.
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After installing the *Visual Studio Code Remote Development Extension Pack*
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[5]_ you need to open the *Remote Explorer* view and connect to the
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SSH target. This will open a new window and on the bottom left of that window
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you should see *SSH:* followed by the SSH host name. In the *Explorer*
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view you can then choose to either clone a repository or open an
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existing folder on the remote. For instance when working with
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devstack you might want to open */opt/stack* or */opt/stack/octavia*.
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Next, you should configure the *launch.json*, which contains the run
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configurations. Use the following template and adjust it to your needs::
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{
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// Use IntelliSense to learn about possible attributes.
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// Hover to view descriptions of existing attributes.
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// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
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"version": "0.2.0",
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"configurations": [
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{
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"name": "Octavia Worker",
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"type": "python",
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"request": "launch",
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"module": "octavia.cmd.octavia_worker",
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"args": ["--config-file", "/etc/octavia/octavia.conf"],
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"justMyCode": true
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}
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]
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}
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Make sure that the correct Python interpreter is selected in the status bar.
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In a devstack environment the global Python interpreter */usr/bin/python3*
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should be the correct one. Now you can start debugging by pressing *F5*.
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.. note:: When running this the first time Visual Studio Code might ask you
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to install the Python debugger extension on the remote, which you must
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do. Simply follow the steps shown in the IDE.
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Using ptvsd
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~~~~~~~~~~~
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.. warning:: ptvsd has been deprecated and replaced by debugpy. However, debugpy doesn't seem
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work with uWSGI processes. The information in this section might be outdated.
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Another example is debugging the Octavia API service with the ptvsd debugger:
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@ -80,3 +159,23 @@ The service will connect to your IDE, at which point remote debugging is
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active. Resume the program on the debugger to continue with the initialization
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of the service. At this point, the service should be operational and you can
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start debugging.
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Troubleshooting
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===============
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Remote process does not connect with local PyCharm debug server
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---------------------------------------------------------------
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#. Check if the debug server is still running
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#. Check if the values of the exported *DEBUGGER_* variables above are correct.
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#. Check if the remote machine can reach the port of the debug server::
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$ nc -zvw10 $DEBUGGER_HOST $DEBUGGER_PORT
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If it cannot connect, the connection may be blocked by a firewall.
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.. [1] https://www.jetbrains.com/help/pycharm/remote-debugging-with-product.html
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.. [2] https://www.jetbrains.com/help/pycharm/remote-debugging-with-product.html#remote-interpreter
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.. [3] https://www.jetbrains.com/help/pycharm/remote-debugging-with-product.html#remote-debug-config
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.. [4] https://code.visualstudio.com/docs/remote/ssh
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.. [5] https://marketplace.visualstudio.com/items?itemName=ms-vscode-remote.vscode-remote-extensionpack
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@ -30,7 +30,7 @@ Octavia accomplishes its delivery of load balancing services by managing a
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fleet of virtual machines, containers, or bare metal servers—collectively known
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as *amphorae*\— which it spins up on demand. This on-demand, horizontal scaling
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feature differentiates Octavia from other load balancing solutions, thereby
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making Octavia truly suited "for the cloud."
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making Octavia truly suited "for the cloud".
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Where Octavia fits into the OpenStack ecosystem
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-----------------------------------------------
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