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Debugging Go code using VS Code
You can manually install delve as per the Installation Instructions.
Based on how you install delve it will either end up in your PATH
or GOPATH/bin
.
If dlv
binary is in your GOPATH/bin
and this GOPATH is not set as an environment variable, then make sure your PATH points to this GOPATH/bin
so that the Go extension can find the dlv
binary.
The below settings are used by the debugger
-
go.gopath
. See GOPATH in VS Code -
go.inferGopath
. See GOPATH in VS Code -
go.delveConfig
-
useApiV1
: Controls whether the version of delve apis to be used when launching the delve headless server -
dlvLoadConfig
: The configuration passed to delve. Controls various features of delve
-
Some common cases where you might want to tweak the configurations passed to delve
- Use the latest v2 apis
- Change the default cap of 64 on string and array length when inspecting variables in the debug viewlet.
- Evaluate variables that are nested when inspecting them in the debug viewlet.
Once delve is installed, you can either press F5
or go to the Code debug viewlet and select the configuration gear.
You will now see a launch.json
file created for your workspace, which will contain the configurations for debugging. By default, there would be a single configuration as below:
{
"version": "0.2.0",
"configurations": [
{
"name": "Launch",
"type": "go",
"request": "launch",
"mode": "debug",
"remotePath": "",
"port": 2345,
"host": "127.0.0.1",
"program": "${fileDirname}",
"env": {},
"args": [],
"showLog": true
}
]
}
Ignore remotePath
, host
and port
if you are not remote debugging.
The program
option is mandatory.
- This can refer to a package folder to debug, or a file within that folder.
- This should be a full path and not relative.
- Use
${workspaceFolder}
to debug package at the root of the workspace that is opened in VS Code - Use
${file}
to debug the current file.
The mode
parameter can be set to:
-
debug
to compile the contents of the program folder and launch under the debugger. [default] -
test
to debug tests in the program folder. To debug a single test, pass-test.run
and the Test name as args. Additionally, you can pass-test.v
to get verbose output as well. -
exec
to run a pre-built binary specified in program, for example"program":"${workspaceRoot}/mybin"
. -
remote
to attach to a remote headless Delve server. You must manually run Delve on the remote machine, and provide the additionalremotePath
,host
andport
debug configuration options pointing at the remote machine.
If your build needs build tags (e.g. go build -tags whatever_tag
), then add the parameter buildFlags
with the content "-tags whatever_tag"
.
In version 0.6.66 or lesser of the Go extension, the debugger cannot read your settings. It figures out the GOPATH from either the environment variables or from the path provided in the program
option. If you have set multiple GOPATHs in the go.gopath
setting, pass the same in the env
option of the launch.json
as an environment variable.
As of 0.6.67 version, the debugger will inherit the GOPATH from settings. Run Go: Current GOPATH
command to see the GOPATH being used by the Go extension and the debugger.
As of 0.6.54 version of the Go extension, you can now make use of snippets while editing the launch.json file. Type "Go" and you will get debug configuration snippets for debugging current file/package, a test function etc.
Set showLog
attribute in your debug configuration to true
. You will see logs in the debug console from delve.
Set trace
attribute in your debug configuration to verbose
. You will see logs in the debug console from the Go extension's debug adapter. These logs will be saved to a file whose path will be printed at the beginning in the debug console.
If you want to dig deeper and debug the debugger using source code of this extension, read building-and-debugging-the-extension
To remote debug using VS Code, you must first run a headless Delve server on the target machine. For example:
$ dlv debug --headless --listen=:2345 --log
Any arguments that you want to pass to the program you are debugging must be passed to this Delve server that runs on the target machine. For example:
$ dlv debug --headless --listen=:2345 --log -- -myArg=123
Note: Do not pass the flag
–api-version=2
to dlv. The Go extension doesn't support v2 of delve APIs yet.
Then, create a remote debug configuration in VS Code launch.json
.
{
"name": "Remote",
"type": "go",
"request": "launch",
"mode": "remote",
"remotePath": "${workspaceRoot}",
"port": 2345,
"host": "127.0.0.1",
"program": "${workspaceRoot}",
"env": {}
}
When you launch the debugger with this new Remote
target selected, VS Code will send debugging
commands to the dlv
server you started previously instead of launching it's own dlv
instance against your app.
The above example runs both the headless dlv
server and the VS Code debugger locally on the same machine. For an
example of running these on different hosts, see the example of debugging a process running in a docker host at https://github.com/lukehoban/webapp-go/tree/debugging.
Like the error message says, the extension cannot find dlv
. Remember, the debug adapter cannot read the VS Code settings.
Solution: Add the location where dlv is installed to your PATH. You can find this location by running which dlv
or where dlv
The debugger is not using the right GOPATH. This shouldn't happen, if it does, log a bug.
Solution: Until the bug you logged is resolved, the work around is to add the GOPATH as an env var in the env
property in the launch.json
file.
You have dlv
running just fine from command line, but VS Code gives this access related error.
This can happen if the extension is trying to run the dlv
binary from a wrong location.
The Go extension first tries to find dlv
in your $GOPATH/bin and then in your $PATH.
Solution: Run which dlv
in the command line. If this doesn't match your GOPATH/bin
, then delete the dlv
file in
your GOPATH/bin
You may see this in the debug console, while trying to run in the test
mode. This happens when the program
attribute points to a folder with no test files.
Solution: Ensure that the program
attribute points to the folder that contains the test files you want to run.
This usually happens in OSX due to signing issues. See the discussions in please see #717, #269 and derekparker/delve/357
Solution: You may have to uninstall dlv and install it manually as per instructions
This error can show up for Mac users using delve of version 0.12.2 or above. Not sure why, but doing a xcode-select --install
has solved the problem for users who have seen this issue.
Check the version of delve api being used in the remote delve process. v2 is not yet supported in the Go extension. So if you have –api-version=2
being passed to dlv
, remove that flag and try again