botanist is a tool used by the infrastructure to set up the bot environment before running tests. It handles setting some environment variables used by the other tools it invokes and also handles the initial starting up of the target(s) it will run the tests on.
botanist currently has three subcommands, two of which are planned for deprecation:
run botanist run is the main subcommand which is used by most of the builders run by the infrastructure. It takes a device config and image manifest and starts up the corresponding target in the device config. It also takes a command to run after starting up the targets. Usually this will be testrunner which takes in a test manifest containing the tests to run.
qemu botanist qemu is used to run bringup tests on QEMU. It starts a QEMU instance with a config it constructs from the command arguments and waits for it to complete. The required arguments are -type which specifies what type of emulator to run (qemu or aemu), and -qemu-dir which points to a directory containing the qemu binaries. It writes the test results to a MinFS image provided by the -minfs flag.
zedboot botanist zedboot is used to run bringup tests on physical devices. It paves the device and polls for a summary.json to be produced that contains the results to the tests that were run. This summary.json follows the runtests.TestSummary schema.
qemu and zedboot are both used for bringup tests. They take in an image manifest and various args to define the device config and where to output results. The positional arguments are used as extra command-line arguments to pass to the kernel.
The infrastructure writes a runcmds script which contains a list of all the tests it wants to run and embeds this into the zbi image used to boot the target. It then calls one of these subcommands with a command line argument that specifies to run the runcmds script on boot. After botanist starts up the target, it waits until it gets a signal that the tests are completed.