.. _topotests: Topotests ========= Topotests is a suite of topology tests for FRR built on top of micronet. Installation and Setup ---------------------- Topotests run under python3. Additionally, for ExaBGP (which is used in some of the BGP tests) an older python2 version (and the python2 version of ``pip``) must be installed. Tested with Ubuntu 20.04,Ubuntu 18.04, and Debian 11. Instructions are the same for all setups (i.e. ExaBGP is only used for BGP tests). Installing Topotest Requirements ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. code:: shell apt-get install gdb apt-get install iproute2 apt-get install net-tools apt-get install python3-pip python3 -m pip install wheel python3 -m pip install 'pytest>=6.2.4' python3 -m pip install 'pytest-xdist>=2.3.0' python3 -m pip install 'scapy>=2.4.5' python3 -m pip install xmltodict # Use python2 pip to install older ExaBGP python2 -m pip install 'exabgp<4.0.0' useradd -d /var/run/exabgp/ -s /bin/false exabgp # To enable the gRPC topotest install: python3 -m pip install grpcio grpcio-tools Enable Coredumps """""""""""""""" Optional, will give better output. .. code:: shell disable apport (which move core files) Set ``enabled=0`` in ``/etc/default/apport``. Next, update security limits by changing :file:`/etc/security/limits.conf` to:: # * soft core unlimited root soft core unlimited * hard core unlimited root hard core unlimited Reboot for options to take effect. SNMP Utilities Installation """"""""""""""""""""""""""" To run SNMP test you need to install SNMP utilities and MIBs. Unfortunately there are some errors in the upstream MIBS which need to be patched up. The following steps will get you there on Ubuntu 20.04. .. code:: shell apt install libsnmp-dev apt install snmpd snmp apt install snmp-mibs-downloader download-mibs wget http://www.iana.org/assignments/ianaippmmetricsregistry-mib/ianaippmmetricsregistry-mib -O /usr/share/snmp/mibs/iana/IANA-IPPM-METRICS-REGISTRY-MIB wget http://pastebin.com/raw.php?i=p3QyuXzZ -O /usr/share/snmp/mibs/ietf/SNMPv2-PDU wget http://pastebin.com/raw.php?i=gG7j8nyk -O /usr/share/snmp/mibs/ietf/IPATM-IPMC-MIB edit /etc/snmp/snmp.conf to look like this # As the snmp packages come without MIB files due to license reasons, loading # of MIBs is disabled by default. If you added the MIBs you can reenable # loading them by commenting out the following line. mibs +ALL FRR Installation ^^^^^^^^^^^^^^^^ FRR needs to be installed separately. It is assume to be configured like the standard Ubuntu Packages: - Binaries in :file:`/usr/lib/frr` - State Directory :file:`/var/run/frr` - Running under user ``frr``, group ``frr`` - vtygroup: ``frrvty`` - config directory: :file:`/etc/frr` - For FRR Packages, install the dbg package as well for coredump decoding No FRR config needs to be done and no FRR daemons should be run ahead of the test. They are all started as part of the test. Manual FRR build """""""""""""""" If you prefer to manually build FRR, then use the following suggested config: .. code:: shell ./configure \ --prefix=/usr \ --localstatedir=/var/run/frr \ --sbindir=/usr/lib/frr \ --sysconfdir=/etc/frr \ --enable-vtysh \ --enable-pimd \ --enable-sharpd \ --enable-multipath=64 \ --enable-user=frr \ --enable-group=frr \ --enable-vty-group=frrvty \ --enable-snmp=agentx \ --with-pkg-extra-version=-my-manual-build And create ``frr`` user and ``frrvty`` group as follows: .. code:: shell addgroup --system --gid 92 frr addgroup --system --gid 85 frrvty adduser --system --ingroup frr --home /var/run/frr/ \ --gecos "FRRouting suite" --shell /bin/false frr usermod -G frrvty frr Executing Tests --------------- Configure your sudo environment ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Topotests must be run as root. Normally this will be accomplished through the use of the ``sudo`` command. In order for topotests to be able to open new windows (either XTerm or byobu/screen/tmux windows) certain environment variables must be passed through the sudo command. One way to do this is to specify the ``-E`` flag to ``sudo``. This will carry over most if not all your environment variables include ``PATH``. For example: .. code:: shell sudo -E python3 -m pytest -s -v If you do not wish to use ``-E`` (e.g., to avoid ``sudo`` inheriting ``PATH``) you can modify your `/etc/sudoers` config file to specifically pass the environment variables required by topotests. Add the following commands to your ``/etc/sudoers`` config file. .. code:: shell Defaults env_keep="TMUX" Defaults env_keep+="TMUX_PANE" Defaults env_keep+="STY" Defaults env_keep+="DISPLAY" If there was already an ``env_keep`` configuration there be sure to use the ``+=`` rather than ``=`` on the first line above as well. Execute all tests in distributed test mode ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. code:: shell sudo -E pytest -s -v -nauto --dist=loadfile The above command must be executed from inside the topotests directory. All test\_\* scripts in subdirectories are detected and executed (unless disabled in ``pytest.ini`` file). Pytest will execute up to N tests in parallel where N is based on the number of cores on the host. Analyze Test Results (``analyze.py``) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ By default router and execution logs are saved in ``/tmp/topotests`` and an XML results file is saved in ``/tmp/topotests.xml``. An analysis tool ``analyze.py`` is provided to archive and analyze these results after the run completes. After the test run completes one should pick an archive directory to store the results in and pass this value to ``analyze.py``. On first execution the results are copied to that directory from ``/tmp``, and subsequent runs use that directory for analyzing the results. Below is an example of this which also shows the default behavior which is to display all failed and errored tests in the run. .. code:: shell ~/frr/tests/topotests# ./analyze.py -Ar run-save bgp_multiview_topo1/test_bgp_multiview_topo1.py::test_bgp_converge ospf_basic_functionality/test_ospf_lan.py::test_ospf_lan_tc1_p0 bgp_gr_functionality_topo2/test_bgp_gr_functionality_topo2.py::test_BGP_GR_10_p2 bgp_multiview_topo1/test_bgp_multiview_topo1.py::test_bgp_routingTable Here we see that 4 tests have failed. We an dig deeper by displaying the captured logs and errors. First let's redisplay the results enumerated by adding the ``-E`` flag .. code:: shell ~/frr/tests/topotests# ./analyze.py -Ar run-save -E 0 bgp_multiview_topo1/test_bgp_multiview_topo1.py::test_bgp_converge 1 ospf_basic_functionality/test_ospf_lan.py::test_ospf_lan_tc1_p0 2 bgp_gr_functionality_topo2/test_bgp_gr_functionality_topo2.py::test_BGP_GR_10_p2 3 bgp_multiview_topo1/test_bgp_multiview_topo1.py::test_bgp_routingTable Now to look at the error message for a failed test we use ``-T N`` where N is the number of the test we are interested in along with ``--errmsg`` option. .. code:: shell ~/frr/tests/topotests# ./analyze.py -Ar run-save -T0 --errmsg bgp_multiview_topo1/test_bgp_multiview_topo1.py::test_bgp_converge: AssertionError: BGP did not converge: IPv4 Unicast Summary (VIEW 1): BGP router identifier 172.30.1.1, local AS number 100 vrf-id -1 BGP table version 1 RIB entries 1, using 184 bytes of memory Peers 3, using 2169 KiB of memory Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd PfxSnt Desc 172.16.1.1 4 65001 0 0 0 0 0 never Connect 0 N/A 172.16.1.2 4 65002 0 0 0 0 0 never Connect 0 N/A 172.16.1.5 4 65005 0 0 0 0 0 never Connect 0 N/A Total number of neighbors 3 assert False Now to look at the full text of the error for a failed test we use ``-T N`` where N is the number of the test we are interested in along with ``--errtext`` option. .. code:: shell ~/frr/tests/topotests# ./analyze.py -Ar run-save -T0 --errtext bgp_multiview_topo1/test_bgp_multiview_topo1.py::test_bgp_converge: def test_bgp_converge(): "Check for BGP converged on all peers and BGP views" global fatal_error global net [...] else: # Bail out with error if a router fails to converge bgpStatus = net["r%s" % i].cmd('vtysh -c "show ip bgp view %s summary"' % view) > assert False, "BGP did not converge:\n%s" % bgpStatus E AssertionError: BGP did not converge: E E IPv4 Unicast Summary (VIEW 1): E BGP router identifier 172.30.1.1, local AS number 100 vrf-id -1 [...] E Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd PfxSnt Desc E 172.16.1.1 4 65001 0 0 0 0 0 never Connect 0 N/A E 172.16.1.2 4 65002 0 0 0 0 0 never Connect 0 N/A [...] To look at the full capture for a test including the stdout and stderr which includes full debug logs, just use the ``-T N`` option without the ``--errmsg`` or ``--errtext`` options. .. code:: shell ~/frr/tests/topotests# ./analyze.py -Ar run-save -T0 @classname: bgp_multiview_topo1.test_bgp_multiview_topo1 @name: test_bgp_converge @time: 141.401 @message: AssertionError: BGP did not converge: [...] system-out: --------------------------------- Captured Log --------------------------------- 2021-08-09 02:55:06,581 DEBUG: lib.micronet_compat.topo: Topo(unnamed): Creating 2021-08-09 02:55:06,581 DEBUG: lib.micronet_compat.topo: Topo(unnamed): addHost r1 [...] 2021-08-09 02:57:16,932 DEBUG: topolog.r1: LinuxNamespace(r1): cmd_status("['/bin/bash', '-c', 'vtysh -c "show ip bgp view 1 summary" 2> /dev/null | grep ^[0-9] | grep -vP " 11\\s+(\\d+)"']", kwargs: {'encoding': 'utf-8', 'stdout': -1, 'stderr': -2, 'shell': False}) 2021-08-09 02:57:22,290 DEBUG: topolog.r1: LinuxNamespace(r1): cmd_status("['/bin/bash', '-c', 'vtysh -c "show ip bgp view 1 summary" 2> /dev/null | grep ^[0-9] | grep -vP " 11\\s+(\\d+)"']", kwargs: {'encoding': 'utf-8', 'stdout': -1, 'stderr': -2, 'shell': False}) 2021-08-09 02:57:27,636 DEBUG: topolog.r1: LinuxNamespace(r1): cmd_status("['/bin/bash', '-c', 'vtysh -c "show ip bgp view 1 summary"']", kwargs: {'encoding': 'utf-8', 'stdout': -1, 'stderr': -2, 'shell': False}) --------------------------------- Captured Out --------------------------------- system-err: --------------------------------- Captured Err --------------------------------- Execute single test ^^^^^^^^^^^^^^^^^^^ .. code:: shell cd test_to_be_run ./test_to_be_run.py For example, and assuming you are inside the frr directory: .. code:: shell cd tests/topotests/bgp_l3vpn_to_bgp_vrf ./test_bgp_l3vpn_to_bgp_vrf.py For further options, refer to pytest documentation. Test will set exit code which can be used with ``git bisect``. For the simulated topology, see the description in the python file. StdErr log from daemos after exit ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ To enable the reporting of any messages seen on StdErr after the daemons exit, the following env variable can be set:: export TOPOTESTS_CHECK_STDERR=Yes (The value doesn't matter at this time. The check is whether the env variable exists or not.) There is no pass/fail on this reporting; the Output will be reported to the console. Collect Memory Leak Information ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ FRR processes can report unfreed memory allocations upon exit. To enable the reporting of memory leaks, define an environment variable ``TOPOTESTS_CHECK_MEMLEAK`` with the file prefix, i.e.:: export TOPOTESTS_CHECK_MEMLEAK="/home/mydir/memleak_" This will enable the check and output to console and the writing of the information to files with the given prefix (followed by testname), ie :file:`/home/mydir/memcheck_test_bgp_multiview_topo1.txt` in case of a memory leak. Running Topotests with AddressSanitizer ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Topotests can be run with AddressSanitizer. It requires GCC 4.8 or newer. (Ubuntu 16.04 as suggested here is fine with GCC 5 as default). For more information on AddressSanitizer, see https://github.com/google/sanitizers/wiki/AddressSanitizer. The checks are done automatically in the library call of ``checkRouterRunning`` (ie at beginning of tests when there is a check for all daemons running). No changes or extra configuration for topotests is required beside compiling the suite with AddressSanitizer enabled. If a daemon crashed, then the errorlog is checked for AddressSanitizer output. If found, then this is added with context (calling test) to :file:`/tmp/AddressSanitizer.txt` in Markdown compatible format. Compiling for GCC AddressSanitizer requires to use ``gcc`` as a linker as well (instead of ``ld``). Here is a suggest way to compile frr with AddressSanitizer for ``master`` branch: .. code:: shell git clone https://github.com/FRRouting/frr.git cd frr ./bootstrap.sh ./configure \ --enable-address-sanitizer \ --prefix=/usr/lib/frr --sysconfdir=/etc/frr \ --localstatedir=/var/run/frr \ --sbindir=/usr/lib/frr --bindir=/usr/lib/frr \ --with-moduledir=/usr/lib/frr/modules \ --enable-multipath=0 --enable-rtadv \ --enable-tcp-zebra --enable-fpm --enable-pimd \ --enable-sharpd make sudo make install # Create symlink for vtysh, so topotest finds it in /usr/lib/frr sudo ln -s /usr/lib/frr/vtysh /usr/bin/ and create ``frr`` user and ``frrvty`` group as shown above. Debugging Topotest Failures ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Install and run tests inside ``tmux`` or ``byobu`` for best results. ``XTerm`` is also fully supported. GNU ``screen`` can be used in most situations; however, it does not work as well with launching ``vtysh`` or shell on error. For the below debugging options which launch programs or CLIs, topotest should be run within ``tmux`` (or ``screen``)_, as ``gdb``, the shell or ``vtysh`` will be launched using that windowing program, otherwise ``xterm`` will be attempted to launch the given programs. NOTE: you must run the topotest (pytest) such that your DISPLAY, STY or TMUX environment variables are carried over. You can do this by passing the ``-E`` flag to ``sudo`` or you can modify your ``/etc/sudoers`` config to automatically pass that environment variable through to the ``sudo`` environment. .. _screen: https://www.gnu.org/software/screen/ .. _tmux: https://github.com/tmux/tmux/wiki Spawning Debugging CLI, ``vtysh`` or Shells on Routers on Test Failure """""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" One can have a debugging CLI invoked on test failures by specifying the ``--cli-on-error`` CLI option as shown in the example below. .. code:: shell sudo -E pytest --cli-on-error all-protocol-startup The debugging CLI can run shell or vtysh commands on any combination of routers It can also open shells or vtysh in their own windows for any combination of routers. This is usually the most useful option when debugging failures. Here is the help command from within a CLI launched on error: .. code:: shell test_bgp_multiview_topo1/test_bgp_routingTable> help Commands: help :: this help sh [hosts] :: execute on term [hosts] :: open shell terminals for hosts vtysh [hosts] :: open vtysh terminals for hosts [hosts] :: execute vtysh-command on hosts test_bgp_multiview_topo1/test_bgp_routingTable> r1 show int br ------ Host: r1 ------ Interface Status VRF Addresses --------- ------ --- --------- erspan0 down default gre0 down default gretap0 down default lo up default r1-eth0 up default 172.16.1.254/24 r1-stub up default 172.20.0.1/28 ---------------------- test_bgp_multiview_topo1/test_bgp_routingTable> Additionally, one can have ``vtysh`` or a shell launched on all routers when a test fails. To launch the given process on each router after a test failure specify one of ``--shell-on-error`` or ``--vtysh-on-error``. Spawning ``vtysh`` or Shells on Routers """"""""""""""""""""""""""""""""""""""" Topotest can automatically launch a shell or ``vtysh`` for any or all routers in a test. This is enabled by specifying 1 of 2 CLI arguments ``--shell`` or ``--vtysh``. Both of these options can be set to a single router value, multiple comma-seperated values, or ``all``. When either of these options are specified topotest will pause after setup and each test to allow for inspection of the router state. Here's an example of launching ``vtysh`` on routers ``rt1`` and ``rt2``. .. code:: shell sudo -E pytest --vtysh=rt1,rt2 all-protocol-startup Debugging with GDB """""""""""""""""" Topotest can automatically launch any daemon with ``gdb``, possibly setting breakpoints for any test run. This is enabled by specifying 1 or 2 CLI arguments ``--gdb-routers`` and ``--gdb-daemons``. Additionally ``--gdb-breakpoints`` can be used to automatically set breakpoints in the launched ``gdb`` processes. Each of these options can be set to a single value, multiple comma-seperated values, or ``all``. If ``--gdb-routers`` is empty but ``--gdb_daemons`` is set then the given daemons will be launched in ``gdb`` on all routers in the test. Likewise if ``--gdb_routers`` is set, but ``--gdb_daemons`` is empty then all daemons on the given routers will be launched in ``gdb``. Here's an example of launching ``zebra`` and ``bgpd`` inside ``gdb`` on router ``r1`` with a breakpoint set on ``nb_config_diff`` .. code:: shell sudo -E pytest --gdb-routers=r1 \ --gdb-daemons=bgpd,zebra \ --gdb-breakpoints=nb_config_diff \ all-protocol-startup Detecting Memleaks with Valgrind """""""""""""""""""""""""""""""" Topotest can automatically launch all daemons with ``valgrind`` to check for memleaks. This is enabled by specifying 1 or 2 CLI arguments. ``--valgrind-memleaks`` will enable general memleak detection, and ``--valgrind-extra`` enables extra functionality including generating a suppression file. The suppression file ``tools/valgrind.supp`` is used when memleak detection is enabled. .. code:: shell sudo -E pytest --valgrind-memleaks all-protocol-startup .. _topotests_docker: Running Tests with Docker ------------------------- There is a Docker image which allows to run topotests. Quickstart ^^^^^^^^^^ If you have Docker installed, you can run the topotests in Docker. The easiest way to do this, is to use the make targets from this repository. Your current user needs to have access to the Docker daemon. Alternatively you can run these commands as root. .. code:: console make topotests This command will pull the most recent topotests image from Dockerhub, compile FRR inside of it, and run the topotests. Advanced Usage ^^^^^^^^^^^^^^ Internally, the topotests make target uses a shell script to pull the image and spawn the Docker container. There are several environment variables which can be used to modify the behavior of the script, these can be listed by calling it with ``-h``: .. code:: console ./tests/topotests/docker/frr-topotests.sh -h For example, a volume is used to cache build artifacts between multiple runs of the image. If you need to force a complete recompile, you can set ``TOPOTEST_CLEAN``: .. code:: console TOPOTEST_CLEAN=1 ./tests/topotests/docker/frr-topotests.sh By default, ``frr-topotests.sh`` will build frr and run pytest. If you append arguments and the first one starts with ``/`` or ``./``, they will replace the call to pytest. If the appended arguments do not match this patttern, they will be provided to pytest as arguments. So, to run a specific test with more verbose logging: .. code:: console ./tests/topotests/docker/frr-topotests.sh -vv -s all-protocol-startup/test_all_protocol_startup.py And to compile FRR but drop into a shell instead of running pytest: .. code:: console ./tests/topotests/docker/frr-topotests.sh /bin/bash Development ^^^^^^^^^^^ The Docker image just includes all the components to run the topotests, but not the topotests themselves. So if you just want to write tests and don't want to make changes to the environment provided by the Docker image. You don't need to build your own Docker image if you do not want to. When developing new tests, there is one caveat though: The startup script of the container will run a ``git-clean`` on its copy of the FRR tree to avoid any pollution of the container with build artefacts from the host. This will also result in your newly written tests being unavailable in the container unless at least added to the index with ``git-add``. If you do want to test changes to the Docker image, you can locally build the image and run the tests without pulling from the registry using the following commands: .. code:: console make topotests-build TOPOTEST_PULL=0 make topotests .. _topotests-guidelines: Guidelines ---------- Executing Tests ^^^^^^^^^^^^^^^ To run the whole suite of tests the following commands must be executed at the top level directory of topotest: .. code:: shell $ # Change to the top level directory of topotests. $ cd path/to/topotests $ # Tests must be run as root, since micronet requires it. $ sudo -E pytest In order to run a specific test, you can use the following command: .. code:: shell $ # running a specific topology $ sudo -E pytest ospf-topo1/ $ # or inside the test folder $ cd ospf-topo1 $ sudo -E pytest # to run all tests inside the directory $ sudo -E pytest test_ospf_topo1.py # to run a specific test $ # or outside the test folder $ cd .. $ sudo -E pytest ospf-topo1/test_ospf_topo1.py # to run a specific one The output of the tested daemons will be available at the temporary folder of your machine: .. code:: shell $ ls /tmp/topotest/ospf-topo1.test_ospf-topo1/r1 ... zebra.err # zebra stderr output zebra.log # zebra log file zebra.out # zebra stdout output ... You can also run memory leak tests to get reports: .. code:: shell $ # Set the environment variable to apply to a specific test... $ sudo -E env TOPOTESTS_CHECK_MEMLEAK="/tmp/memleak_report_" pytest ospf-topo1/test_ospf_topo1.py $ # ...or apply to all tests adding this line to the configuration file $ echo 'memleak_path = /tmp/memleak_report_' >> pytest.ini $ # You can also use your editor $ $EDITOR pytest.ini $ # After running tests you should see your files: $ ls /tmp/memleak_report_* memleak_report_test_ospf_topo1.txt Writing a New Test ^^^^^^^^^^^^^^^^^^ This section will guide you in all recommended steps to produce a standard topology test. This is the recommended test writing routine: - Write a topology (Graphviz recommended) - Obtain configuration files - Write the test itself - Format the new code using `black `_ - Create a Pull Request Some things to keep in mind: - BGP tests MUST use generous convergence timeouts - you must ensure that any test involving BGP uses a convergence timeout of at least 130 seconds. - Topotests are run on a range of Linux versions: if your test requires some OS-specific capability (like mpls support, or vrf support), there are test functions available in the libraries that will help you determine whether your test should run or be skipped. - Avoid including unstable data in your test: don't rely on link-local addresses or ifindex values, for example, because these can change from run to run. - Using sleep is almost never appropriate. As an example: if the test resets the peers in BGP, the test should look for the peers re-converging instead of just sleeping an arbitrary amount of time and continuing on. See ``verify_bgp_convergence`` as a good example of this. In particular look at it's use of the ``@retry`` decorator. If you are having troubles figuring out what to look for, please do not be afraid to ask. - Don't duplicate effort. There exists many protocol utility functions that can be found in their eponymous module under ``tests/topotests/lib/`` (e.g., ``ospf.py``) Topotest File Hierarchy """"""""""""""""""""""" Before starting to write any tests one must know the file hierarchy. The repository hierarchy looks like this: .. code:: shell $ cd path/to/topotest $ find ./* ... ./README.md # repository read me ./GUIDELINES.md # this file ./conftest.py # test hooks - pytest related functions ./example-test # example test folder ./example-test/__init__.py # python package marker - must always exist. ./example-test/test_template.jpg # generated topology picture - see next section ./example-test/test_template.dot # Graphviz dot file ./example-test/test_template.py # the topology plus the test ... ./ospf-topo1 # the ospf topology test ./ospf-topo1/r1 # router 1 configuration files ./ospf-topo1/r1/zebra.conf # zebra configuration file ./ospf-topo1/r1/ospfd.conf # ospf configuration file ./ospf-topo1/r1/ospfroute.txt # 'show ip ospf' output reference file # removed other for shortness sake ... ./lib # shared test/topology functions ./lib/topogen.py # topogen implementation ./lib/topotest.py # topotest implementation Guidelines for creating/editing topotest: - New topologies that don't fit the existing directories should create its own - Always remember to add the ``__init__.py`` to new folders, this makes auto complete engines and pylint happy - Router (Quagga/FRR) specific code should go on topotest.py - Generic/repeated router actions should have an abstraction in topogen.TopoRouter. - Generic/repeated non-router code should go to topotest.py - pytest related code should go to conftest.py (e.g. specialized asserts) Defining the Topology """"""""""""""""""""" The first step to write a new test is to define the topology. This step can be done in many ways, but the recommended is to use Graphviz to generate a drawing of the topology. It allows us to see the topology graphically and to see the names of equipment, links and addresses. Here is an example of Graphviz dot file that generates the template topology :file:`tests/topotests/example-test/test_template.dot` (the inlined code might get outdated, please see the linked file):: graph template { label="template"; # Routers r1 [ shape=doubleoctagon, label="r1", fillcolor="#f08080", style=filled, ]; r2 [ shape=doubleoctagon, label="r2", fillcolor="#f08080", style=filled, ]; # Switches s1 [ shape=oval, label="s1\n192.168.0.0/24", fillcolor="#d0e0d0", style=filled, ]; s2 [ shape=oval, label="s2\n192.168.1.0/24", fillcolor="#d0e0d0", style=filled, ]; # Connections r1 -- s1 [label="eth0\n.1"]; r1 -- s2 [label="eth1\n.100"]; r2 -- s2 [label="eth0\n.1"]; } Here is the produced graph: .. graphviz:: graph template { label="template"; # Routers r1 [ shape=doubleoctagon, label="r1", fillcolor="#f08080", style=filled, ]; r2 [ shape=doubleoctagon, label="r2", fillcolor="#f08080", style=filled, ]; # Switches s1 [ shape=oval, label="s1\n192.168.0.0/24", fillcolor="#d0e0d0", style=filled, ]; s2 [ shape=oval, label="s2\n192.168.1.0/24", fillcolor="#d0e0d0", style=filled, ]; # Connections r1 -- s1 [label="eth0\n.1"]; r1 -- s2 [label="eth1\n.100"]; r2 -- s2 [label="eth0\n.1"]; } Generating / Obtaining Configuration Files """""""""""""""""""""""""""""""""""""""""" In order to get the configuration files or command output for each router, we need to run the topology and execute commands in ``vtysh``. The quickest way to achieve that is writing the topology building code and running the topology. To bootstrap your test topology, do the following steps: - Copy the template test .. code:: shell $ mkdir new-topo/ $ touch new-topo/__init__.py $ cp example-test/test_template.py new-topo/test_new_topo.py - Modify the template according to your dot file Here is the template topology described in the previous section in python code: .. code:: py topodef = { "s1": "r1" "s2": ("r1", "r2") } If more specialized topology definitions, or router initialization arguments are required a build function can be used instead of a dictionary: .. code:: py def build_topo(tgen): "Build function" # Create 2 routers for routern in range(1, 3): tgen.add_router("r{}".format(routern)) # Create a switch with just one router connected to it to simulate a # empty network. switch = tgen.add_switch("s1") switch.add_link(tgen.gears["r1"]) # Create a connection between r1 and r2 switch = tgen.add_switch("s2") switch.add_link(tgen.gears["r1"]) switch.add_link(tgen.gears["r2"]) - Run the topology Topogen allows us to run the topology without running any tests, you can do that using the following example commands: .. code:: shell $ # Running your bootstraped topology $ sudo -E pytest -s --topology-only new-topo/test_new_topo.py $ # Running the test_template.py topology $ sudo -E pytest -s --topology-only example-test/test_template.py $ # Running the ospf_topo1.py topology $ sudo -E pytest -s --topology-only ospf-topo1/test_ospf_topo1.py Parameters explanation: .. program:: pytest .. option:: -s Actives input/output capture. If this is not specified a new window will be opened for the interactive CLI, otherwise it will be activated inline. .. option:: --topology-only Don't run any tests, just build the topology. After executing the commands above, you should get the following terminal output: .. code:: shell frr/tests/topotests# sudo -E pytest -s --topology-only ospf_topo1/test_ospf_topo1.py ============================= test session starts ============================== platform linux -- Python 3.9.2, pytest-6.2.4, py-1.10.0, pluggy-0.13.1 rootdir: /home/chopps/w/frr/tests/topotests, configfile: pytest.ini plugins: forked-1.3.0, xdist-2.3.0 collected 11 items [...] unet> The last line shows us that we are now using the CLI (Command Line Interface), from here you can call your router ``vtysh`` or even bash. Here's the help text: .. code:: shell unet> help Commands: help :: this help sh [hosts] :: execute on term [hosts] :: open shell terminals for hosts vtysh [hosts] :: open vtysh terminals for hosts [hosts] :: execute vtysh-command on hosts Here are some commands example: .. code:: shell unet> sh r1 ping 10.0.3.1 PING 10.0.3.1 (10.0.3.1) 56(84) bytes of data. 64 bytes from 10.0.3.1: icmp_seq=1 ttl=64 time=0.576 ms 64 bytes from 10.0.3.1: icmp_seq=2 ttl=64 time=0.083 ms 64 bytes from 10.0.3.1: icmp_seq=3 ttl=64 time=0.088 ms ^C --- 10.0.3.1 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 1998ms rtt min/avg/max/mdev = 0.083/0.249/0.576/0.231 ms unet> r1 show run Building configuration... Current configuration: ! frr version 8.1-dev-my-manual-build frr defaults traditional hostname r1 log file /tmp/topotests/ospf_topo1.test_ospf_topo1/r1/zebra.log [...] end unet> show daemons ------ Host: r1 ------ zebra ospfd ospf6d staticd ------- End: r1 ------ ------ Host: r2 ------ zebra ospfd ospf6d staticd ------- End: r2 ------ ------ Host: r3 ------ zebra ospfd ospf6d staticd ------- End: r3 ------ ------ Host: r4 ------ zebra ospfd ospf6d staticd ------- End: r4 ------ After you successfully configured your topology, you can obtain the configuration files (per-daemon) using the following commands: .. code:: shell unet> sh r3 vtysh -d ospfd Hello, this is FRRouting (version 3.1-devrzalamena-build). Copyright 1996-2005 Kunihiro Ishiguro, et al. r1# show running-config Building configuration... Current configuration: ! frr version 3.1-devrzalamena-build frr defaults traditional no service integrated-vtysh-config ! log file ospfd.log ! router ospf ospf router-id 10.0.255.3 redistribute kernel redistribute connected redistribute static network 10.0.3.0/24 area 0 network 10.0.10.0/24 area 0 network 172.16.0.0/24 area 1 ! line vty ! end r1# You can also login to the node specified by nsenter using bash, etc. A pid file for each node will be created in the relevant test dir. You can run scripts inside the node, or use vtysh's or feature. .. code:: shell [unet shell] # cd tests/topotests/srv6_locator # ./test_srv6_locator.py --topology-only unet> r1 show segment-routing srv6 locator Locator: Name ID Prefix Status -------------------- ------- ------------------------ ------- loc1 1 2001:db8:1:1::/64 Up loc2 2 2001:db8:2:2::/64 Up [Another shell] # nsenter -a -t $(cat /tmp/topotests/srv6_locator.test_srv6_locator/r1.pid) bash --norc # vtysh r1# r1 show segment-routing srv6 locator Locator: Name ID Prefix Status -------------------- ------- ------------------------ ------- loc1 1 2001:db8:1:1::/64 Up loc2 2 2001:db8:2:2::/64 Up Writing Tests """"""""""""" Test topologies should always be bootstrapped from :file:`tests/topotests/example_test/test_template.py` because it contains important boilerplate code that can't be avoided, like: Example: .. code:: py # For all routers arrange for: # - starting zebra using config file from /zebra.conf # - starting ospfd using an empty config file. for rname, router in router_list.items(): router.load_config(TopoRouter.RD_ZEBRA, "zebra.conf") router.load_config(TopoRouter.RD_OSPF) - The topology definition or build function .. code:: py topodef = { "s1": ("r1", "r2"), "s2": ("r2", "r3") } def build_topo(tgen): # topology build code ... - pytest setup/teardown fixture to start the topology and supply ``tgen`` argument to tests. .. code:: py @pytest.fixture(scope="module") def tgen(request): "Setup/Teardown the environment and provide tgen argument to tests" tgen = Topogen(topodef, module.__name__) # or tgen = Topogen(build_topo, module.__name__) ... # Start and configure the router daemons tgen.start_router() # Provide tgen as argument to each test function yield tgen # Teardown after last test runs tgen.stop_topology() Requirements: - Directory name for a new topotest must not contain hyphen (``-``) characters. To separate words, use underscores (``_``). For example, ``tests/topotests/bgp_new_example``. - Test code should always be declared inside functions that begin with the ``test_`` prefix. Functions beginning with different prefixes will not be run by pytest. - Configuration files and long output commands should go into separated files inside folders named after the equipment. - Tests must be able to run without any interaction. To make sure your test conforms with this, run it without the :option:`-s` parameter. - Use `black `_ code formatter before creating a pull request. This ensures we have a unified code style. - Mark test modules with pytest markers depending on the daemons used during the tests (see :ref:`topotests-markers`) - Always use IPv4 :rfc:`5737` (``192.0.2.0/24``, ``198.51.100.0/24``, ``203.0.113.0/24``) and IPv6 :rfc:`3849` (``2001:db8::/32``) ranges reserved for documentation. Tips: - Keep results in stack variables, so people inspecting code with ``pdb`` can easily print their values. Don't do this: .. code:: py assert foobar(router1, router2) Do this instead: .. code:: py result = foobar(router1, router2) assert result - Use ``assert`` messages to indicate where the test failed. Example: .. code:: py for router in router_list: # ... assert condition, 'Router "{}" condition failed'.format(router.name) Debugging Execution ^^^^^^^^^^^^^^^^^^^ The most effective ways to inspect topology tests are: - Run pytest with ``--pdb`` option. This option will cause a pdb shell to appear when an assertion fails Example: ``pytest -s --pdb ospf-topo1/test_ospf_topo1.py`` - Set a breakpoint in the test code with ``pdb`` Example: .. code:: py # Add the pdb import at the beginning of the file import pdb # ... # Add a breakpoint where you think the problem is def test_bla(): # ... pdb.set_trace() # ... The `Python Debugger `__ (pdb) shell allows us to run many useful operations like: - Setting breaking point on file/function/conditions (e.g. ``break``, ``condition``) - Inspecting variables (e.g. ``p`` (print), ``pp`` (pretty print)) - Running python code .. tip:: The TopoGear (equipment abstraction class) implements the ``__str__`` method that allows the user to inspect equipment information. Example of pdb usage: .. code:: shell > /media/sf_src/topotests/ospf-topo1/test_ospf_topo1.py(121)test_ospf_convergence() -> for rnum in range(1, 5): (Pdb) help Documented commands (type help ): ======================================== EOF bt cont enable jump pp run unt a c continue exit l q s until alias cl d h list quit step up args clear debug help n r tbreak w b commands disable ignore next restart u whatis break condition down j p return unalias where Miscellaneous help topics: ========================== exec pdb Undocumented commands: ====================== retval rv (Pdb) list 116 title2="Expected output") 117 118 def test_ospf_convergence(): 119 "Test OSPF daemon convergence" 120 pdb.set_trace() 121 -> for rnum in range(1, 5): 122 router = 'r{}'.format(rnum) 123 124 # Load expected results from the command 125 reffile = os.path.join(CWD, '{}/ospfroute.txt'.format(router)) 126 expected = open(reffile).read() (Pdb) step > /media/sf_src/topotests/ospf-topo1/test_ospf_topo1.py(122)test_ospf_convergence() -> router = 'r{}'.format(rnum) (Pdb) step > /media/sf_src/topotests/ospf-topo1/test_ospf_topo1.py(125)test_ospf_convergence() -> reffile = os.path.join(CWD, '{}/ospfroute.txt'.format(router)) (Pdb) print rnum 1 (Pdb) print router r1 (Pdb) tgen = get_topogen() (Pdb) pp tgen.gears[router] (Pdb) pp str(tgen.gears[router]) 'TopoGear"s1-eth0","r1-eth1"<->"s3-eth0"]> TopoRouter<>' (Pdb) l 125 120 pdb.set_trace() 121 for rnum in range(1, 5): 122 router = 'r{}'.format(rnum) 123 124 # Load expected results from the command 125 -> reffile = os.path.join(CWD, '{}/ospfroute.txt'.format(router)) 126 expected = open(reffile).read() 127 128 # Run test function until we get an result. Wait at most 60 seconds. 129 test_func = partial(compare_show_ip_ospf, router, expected) 130 result, diff = topotest.run_and_expect(test_func, '', (Pdb) router1 = tgen.gears[router] (Pdb) router1.vtysh_cmd('show ip ospf route') '============ OSPF network routing table ============\r\nN 10.0.1.0/24 [10] area: 0.0.0.0\r\n directly attached to r1-eth0\r\nN 10.0.2.0/24 [20] area: 0.0.0.0\r\n via 10.0.3.3, r1-eth1\r\nN 10.0.3.0/24 [10] area: 0.0.0.0\r\n directly attached to r1-eth1\r\nN 10.0.10.0/24 [20] area: 0.0.0.0\r\n via 10.0.3.1, r1-eth1\r\nN IA 172.16.0.0/24 [20] area: 0.0.0.0\r\n via 10.0.3.1, r1-eth1\r\nN IA 172.16.1.0/24 [30] area: 0.0.0.0\r\n via 10.0.3.1, r1-eth1\r\n\r\n============ OSPF router routing table =============\r\nR 10.0.255.2 [10] area: 0.0.0.0, ASBR\r\n via 10.0.3.3, r1-eth1\r\nR 10.0.255.3 [10] area: 0.0.0.0, ABR, ASBR\r\n via 10.0.3.1, r1-eth1\r\nR 10.0.255.4 IA [20] area: 0.0.0.0, ASBR\r\n via 10.0.3.1, r1-eth1\r\n\r\n============ OSPF external routing table ===========\r\n\r\n\r\n' (Pdb) tgen.cli() unet> To enable more debug messages in other Topogen subsystems, more logging messages can be displayed by modifying the test configuration file ``pytest.ini``: .. code:: ini [topogen] # Change the default verbosity line from 'info'... #verbosity = info # ...to 'debug' verbosity = debug Instructions for use, write or debug topologies can be found in :ref:`topotests-guidelines`. To learn/remember common code snippets see :ref:`topotests-snippets`. Before creating a new topology, make sure that there isn't one already that does what you need. If nothing is similar, then you may create a new topology, preferably, using the newest template (:file:`tests/topotests/example-test/test_template.py`). .. include:: topotests-markers.rst .. include:: topotests-snippets.rst License ------- All the configs and scripts are licensed under a ISC-style license. See Python scripts for details.