feat: Add debugging setup for vscode #465
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In order to use the debugger, you should Run any build as usual, but use
substitute `debug/debug.sh` for `docker` in a docker invocation. The
script uses "pgrep" and "socat", as such they are required to run the
script. Example:
```
./debug/debug.sh -f /tmp/moby-runc.yml --target=azlinux3/container --output=type=docker,name=hello:world .
```
Then, connect to the debugging setup using this `launch.json` config in
vscode. You need the go plugin installed:
```json
{
// Use IntelliSense to learn about possible attributes.
// Hover to view descriptions of existing attributes.
// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
"version": "0.2.0",
"configurations": [
{
"name": "Connect to server",
"type": "go",
"request": "attach",
"mode": "remote",
"port": 30157,
"host": "127.0.0.1",
"apiVersion": 2
}
]
}
```
Signed-off-by: Peter Engelbert <[email protected]>
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| FROM --platform=${BUILDPLATFORM} mcr.microsoft.com/oss/go/microsoft/golang:1.22@sha256:9e5243001d0f43d6e1c556a0ce8eedc1bc80eb37b5210036b289d2c601bc08b6 AS go | |||
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Can we unify the dockerfiles and pass the debug in as a build-arg?
if [ "${DEBUG}" = "1" ]; then
extra_flags=...
fi
go build ${extra_fiags} ...
cmd/frontend/debug.go
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| } | ||
| }() | ||
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| s, cancel := signal.NotifyContext(ctx, syscall.SIGCONT) |
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I wonder if instead of using a signal here, if we can look at /proc/self/status: https://man7.org/linux/man-pages/man5/proc_pid_status.5.html
There should be a field called TracerPid which would be non-zero when being traced.
IF this works, there'd be no need to interact with the process at all other than to have dlv attach to it.
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This works!
Out of curiosity, how did you know this / find it out?
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I just looked up if there was a way to check if a process is being traced.
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Another limitation here is that this probably won't work on Docker Desktop for Mac. it might work on DD for Windows if the Daemon is running in WSL. Not sure how to get around this, but it's a pretty big limitation. |
Signed-off-by: Peter Engelbert <[email protected]>
Also add `set -eux` Signed-off-by: Peter Engelbert <[email protected]>
| set -x | ||
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| socat_logfile="$(mktemp)" | ||
| socat -v UNIX:"/proc/${pid}/root/dlv.sock" TCP-LISTEN:30157,reuseaddr,fork 2>"$socat_logfile" |
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@cpuguy83 can you think of a better way to connect vscode to the dlv instance running in the container? This isn't very portable. The vscode launch.json can't do much dynamically in the way of finding the port, so we need the port to be consistent across runs.
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| tracerPid = end | ||
| break | ||
| } |
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Maybe a short sleep here, like 100ms?
| tracerPid = end | ||
| break | ||
| } | ||
| } |
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Need to check s.Err() after the scan loop finishes.
cmd/frontend/debug.go
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| } | ||
| }() | ||
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| s, cancel := signal.NotifyContext(ctx, syscall.SIGCONT) |
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I just looked up if there was a way to check if a process is being traced.
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| tracerPid := "0" | ||
| for tracerPid == "0" { | ||
| b, err := os.Open("/proc/self/status") |
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Should we ensure the file gets closed? i.e. defer b.Close()
In order to use the debugger, you should Run any build as usual, but use substitute
debug/debug.shfordockerin a docker invocation. The script usespgrepandsocat, as such they are required to run the script. Example:Note, in some cases you may need to do the following if the frontend panics:
Then, connect to the debugging setup using this
launch.jsonconfig in vscode. You need the go plugin installed:{ // Use IntelliSense to learn about possible attributes. // Hover to view descriptions of existing attributes. // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387 "version": "0.2.0", "configurations": [ { "name": "Connect to server", "type": "go", "request": "attach", "mode": "remote", "port": 30157, "host": "127.0.0.1", "apiVersion": 2 } ] }What this PR does / why we need it:
Which issue(s) this PR fixes (optional, using
fixes #<issue number>(, fixes #<issue_number>, ...)format, will close the issue(s) when the PR gets merged):Fixes #
Special notes for your reviewer: