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e7cfc0865a
Using a debugger with the kata runtime is complicated, but it can be done and can be very useful. This commits provides a helper script that simplifies it, and updates the developper's documentation to explain how to use it. Signed-off-by: Julien Ropé <jrope@redhat.com>
102 lines
3.1 KiB
Bash
Executable File
102 lines
3.1 KiB
Bash
Executable File
#!/bin/bash
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#
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# Copyright (c) 2024 Red Hat, Inc.
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#
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# SPDX-License-Identifier: Apache-2.0
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#
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# This script allows debugging the GO kata shim using Delve.
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# It will start the delve debugger in a way where it runs the program and waits
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# for connections from your client interface (dlv commandline, vscode, etc).
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#
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# You need to configure crio or containerd to use this script in place of the
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# regular kata shim binary.
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# For cri-o, that would be in the runtime configuration, under
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# /etc/crio/crio.conf.d/
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#
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# Use this for quick-testing the shim binary without a debugger
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#NO_DEBUG=1
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# Edit this to point to the actual shim binary that needs to be debugged
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# Make sure you build it with the following flags:
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# -gcflags=all=-N -l
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SHIM_BINARY=/go/src/github.com/kata-containers/kata-containers/src/runtime/__debug_bin
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DLV_PORT=12345
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# Edit the following to make sure dlv is in the PATH
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export PATH=/usr/local/go/bin/:$PATH
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# The shim can be called multiple times for the same container.
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# If it is already running, subsequent calls just return the socket address that
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# crio/containerd need to connect to.
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# This is useful for recovery, if crio/contaienrd is restarted and loses context.
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#
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# We usually don't want to debug those additional calls while we're already
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# debugging the actual server process.
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# To avoid running additional debuggers and blocking on them, we use a lock file.
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LOCK_FILE=/tmp/shim_debug.lock
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if [ -e $LOCK_FILE ]; then
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NO_DEBUG=1
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fi
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# crio can try to call the shim with the "features" or "--version" parameters
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# to get capabilities from the runtime (assuming it's an OCI compatible runtime).
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# No need to debug that, so just run the regular shim.
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case "$1" in
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"features" | "--version")
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NO_DEBUG=1
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;;
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esac
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if [ "$NO_DEBUG" == "1" ]; then
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$SHIM_BINARY "$@"
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exit $?
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fi
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# dlv commandline
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#
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# --headless: dlv run as a server, waiting for a connection
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#
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# --listen: port to listen to
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#
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# --accept-multiclient: allow multiple dlv client connections
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# Allows having both a commandline and a GUI
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#
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# -r: have the output of the shim redirected to a separate file.
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# This script will retrieve the output and return it to the
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# caller, while letting dlv run in the background for debugging.
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#
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# -- $@ => give the shim all the parameters this script was given
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#
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SHIMOUTPUT=$(mktemp /tmp/shim_output_XXXXXX)
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cat > $LOCK_FILE << EOF
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#!/bin/bash
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dlv exec ${SHIM_BINARY} --headless --listen=:$DLV_PORT --accept-multiclient -r stdout:$SHIMOUTPUT -r stderr:$SHIMOUTPUT -- "\$@"
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rm $LOCK_FILE
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EOF
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chmod +x $LOCK_FILE
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# We're starting dlv as a background task, so that it continues to run while
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# this script returns, letting the caller resume its execution.
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#
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# We're redirecting the outputs of dlv itself to a separate file so that the
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# only output the caller will have is the one from this script, giving it the
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# address of the socket to connect to.
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#
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${LOCK_FILE} "$@" > /tmp/dlv_output 2>&1 &
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# wait for the output file of the shim process to be filled with the address.
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while [ ! -s $SHIMOUTPUT ]; do
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sleep 1
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done
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# write the adress to stdout
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cat $SHIMOUTPUT
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exit 0
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