Merge "ETCD health research: test plan"
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.. _ETCD_health_tests:
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==============================
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ETCD health research test plan
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==============================
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:status: **ready**
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:version: 1.0
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:Abstract:
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This document is a test plan for ETCD health research that should
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determine a process of getting the dependency between Kubernetes
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cluster under load and ETCD cluster health state.
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Test Plan
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=========
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We should obtain the test results by collecting crucial system
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metrics that provided natively by ETCD/Kubernetes API, compare and
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normalize them and plot dependency graphs.
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Test Environment
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----------------
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Preparation
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^^^^^^^^^^^
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1.
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Monitoring system must be set up and working, basing on the
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`Monitoring`_ methodology documentation.
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2.
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K8S cluster should be deployed using `Kargo`_ on top of the
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430 nodes with preinstalled Ubuntu Xenial.
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3.
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On the one of the K8S master we should check/install the
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following packages/tools:
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.. table:: Software to be installed
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+--------------+---------+-----------------------------------+
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| package name | version | source |
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+==============+=========+===================================+
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| `curl`_ | latest | Ubuntu xenial universe repository |
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+--------------+---------+-----------------------------------+
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| `jq`_ | latest | Ubuntu xenial universe repository |
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+--------------+---------+-----------------------------------+
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| `paste`_ | latest | Ubuntu xenial universe repository |
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+--------------+---------+-----------------------------------+
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| `MMM`_ | latest | GitHub |
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+--------------+---------+-----------------------------------+
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| `Hoseproxy`_ | latest | Github |
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+--------------+---------+-----------------------------------+
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Environment description
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^^^^^^^^^^^^^^^^^^^^^^^
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Test results MUST include a description of the environment used. The following
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items should be included:
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- **Hardware configuration of each server.** If virtual machines are used then
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both physical and virtual hardware should be fully documented.
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An example format is given below:
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.. table:: Description of server hardware
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+-------+----------------+-------+-------+
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|server |name | | |
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| +----------------+-------+-------+
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| |role | | |
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| +----------------+-------+-------+
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| |vendor,model | | |
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| +----------------+-------+-------+
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| |operating_system| | |
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+-------+----------------+-------+-------+
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|CPU |vendor,model | | |
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| +----------------+-------+-------+
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| |processor_count | | |
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| +----------------+-------+-------+
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| |core_count | | |
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| +----------------+-------+-------+
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| |frequency_MHz | | |
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+-------+----------------+-------+-------+
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|RAM |vendor,model | | |
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| +----------------+-------+-------+
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| |amount_MB | | |
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+-------+----------------+-------+-------+
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|NETWORK|interface_name | | |
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| +----------------+-------+-------+
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| |vendor,model | | |
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| +----------------+-------+-------+
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| |bandwidth | | |
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+-------+----------------+-------+-------+
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|STORAGE|dev_name | | |
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| +----------------+-------+-------+
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| |vendor,model | | |
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| +----------------+-------+-------+
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| |SSD/HDD | | |
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| +----------------+-------+-------+
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| |size | | |
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+-------+----------------+-------+-------+
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- **Configuration of hardware network switches.** The configuration file from
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the switch can be downloaded and attached.
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- **Network scheme.** The plan should show how all hardware is connected and
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how the components communicate. All ethernet/fibrechannel and VLAN channels
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should be included. Each interface of every hardware component should be
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matched with the corresponding L2 channel and IP address.
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Test Cases
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----------
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Description
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^^^^^^^^^^^
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There are two specific cases that should be conducted.
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1.
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Load K8S with as much big as possible number of pods per each node.
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Stop when either of K8S or ETCD degrades or existing limits are reached.
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2.
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Load K8S with as much big as possible number of services.
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Stop when either of K8S or ETCD degrades or existing limits are reached.
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List of performance metrics
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^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Basing on `CoreOS ETCD`_ documentation, we collected a list of key metrics
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that define ETCD cluster health state:
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.. table:: List of performance metrics
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+------------------------------------------------------------+------------------------------------------+
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| Metrics | Short description |
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+============================================================+==========================================+
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| || Resident memory size in bytes. |
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| process_resident_memory_bytes || |
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| || |
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+------------------------------------------------------------+------------------------------------------+
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| || The total latency distributions of save |
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| etcd_debugging_snap_save_total_duration_seconds_bucket || called by snapshot. |
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| || |
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+------------------------------------------------------------+------------------------------------------+
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| || The latency distributions of commit |
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| etcd_disk_backend_commit_duration_seconds_bucket || called by backend. |
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| || |
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+------------------------------------------------------------+------------------------------------------+
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| || Counter of handle failures of requests |
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| etcd_http_failed_total || (non-watches), by method (GET/PUT etc.) |
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| || and code (400, 500 etc.). |
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+------------------------------------------------------------+------------------------------------------+
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| || The total number of bytes received/sent |
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| etcd_network_peer_(received|sent)_bytes_total || from/to peers. |
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| || |
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+------------------------------------------------------------+------------------------------------------+
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| || Current number of proposals pending/ |
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| etcd_server_proposals_(pending|committed|applied|failed) || committed/applied/failed. |
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| || |
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+------------------------------------------------------------+------------------------------------------+
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K8S-sided metrics should only define total number of pods/services in the cluster
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for each moment of time within testing period.
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Collecting metrics
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^^^^^^^^^^^^^^^^^^
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Each required metric could be gathered through `Prometheus API`_ using
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curl and jq to extract json objects and strip off extra data. For
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example, let say we need to get `<metric_a>` values within period
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starting from `<start>` and finishing at `<stop>` with a time step
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= `<step>`. Prometheus IP address is `<prometheus_server>`. Resulted
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query will look like:
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.. code:: bash
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curl -q 'http://<prometheus_server>/api/v1/query_range?query=<metric_a>&start=<start>&end=<end>&step=<step>'
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Plotting 'K8S vs ETCD dependency'
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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After obtaining metrics for each case, we need to make plots showing
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dependency between K8S pods/services number and corresponding metric.
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It's better to merge collected metrics in two csv files (for each case)
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in order to make plots easily using third-party instruments like
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`Google sheets`_ or `Plotly`_.
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Reports
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=======
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Resulted report page:
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* :ref:`Results_of_the_ETCD_health_tests`
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.. references:
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.. _Kargo: https://github.com/kubernetes-incubator/kargo.git
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.. _Monitoring: https://docs.openstack.org/developer/performance-docs/methodologies/monitoring/index.html
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.. _curl: https://curl.haxx.se/
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.. _jq: https://stedolan.github.io/jq/
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.. _paste: https://linux.die.net/man/1/paste
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.. _MMM: https://github.com/AleksandrNull/MMM
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.. _Hoseproxy: https://github.com/ivan4th/hoseproxy
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.. _CoreOS ETCD: https://coreos.com/etcd/docs/latest/metrics.html
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.. _Prometheus API: https://prometheus.io/docs/querying/api/
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.. _Google sheets: https://docs.google.com/spreadsheets/
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.. _Plotly: https://plot.ly/
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@ -17,6 +17,7 @@ Contents
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kargo_deploy_performance
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performance_and_scaling
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API_latency
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etcd
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.. raw:: pdf
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@ -8,7 +8,7 @@ Results of the ETCD health tests
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:Abstract:
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This piece of art includes the results of the ETCD tests made
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basing on the _ETCD_health_tests plan.
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basing on the :ref:`ETCD_health_tests`.
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Our goal was to research how many Kubernetes items (pods and services)
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could be spawned in terms of ETCD. We figured out which ETCD metrics
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are crucial and collected them under appropriate (pods or services)
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