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debugging
The Go extension allows you to launch or attach to Go programs for debugging.You can inspect variables and stacks, set breakpoints, and do other debuggingactivities usingVS Code’s Debugging UI.
These debugging features are possible by usingDelve, the Go debugger.
Previously, the Go extension communicated with Delve through a custom debugadaptor program (legacy
mode). SinceDelve
's native debug adapter implementationis available, the Go extension is transitioning to deprecate the legacy debugadapter in favor of direct communication with Delve viaDAP.
📣We are happy to announce that the newdlv-dap
mode of Delveintegration is enabled forlocaldebugging by default. Forremotedebugging it is the default inpre-release versions and is available with stable builds on demand with"debugAdapter": "dlv-dap"
attribute inlaunch.json
orsettings.json
!
Many features and settings described in this document may be available only withthe newdlv-dap
mode. For troubleshooting and configuring the legacy debugadapter, seethe legacy debug adapter documentation.
Open a file to debug (eitherpackage main
source file or the test file) in theeditor, and select theRun and Debug
button fromthe Run view.Alternatively, you can start debugging usingStart Debugging (F5)
command fromthe Run menu orfromthe Command Palette(Linux/Windows: Ctrl+Shift+P, Mac: ⇧+⌘+P).
If you already have launch configurations for the project(.vscode/launch.json
), the Run view will display the configuration list tochoose from.
When no configuration is configured yet (no.vscode/launch.json
file), theextension will choose a default configuration based on the file open in theeditor.
❗ When you start debugging forthe first time or if thedlv
executable on your system is too old to supportDAP, the Go extension may ask to install or update Delve. Follow theinstructions to install it, and then start the debugging session again.
To learn more about debugging in Go, watchGo: Writing and debugging fast, reliable, and efficient software.
Review theFeatures section for an overview ofthe Go Extension's debug UI and available features.
Delve’s native DAP implementationis under active development. Take advantage of the most recent features and bugfixes by installing the latest version ofdlv
using theGo:Install/Update
Tools command from the Command Palette (Linux/Windows:Ctrl
+Shift
+P
, Mac:Command
+Shift
+P
). The command will showdlv
inthe tool list.
Oncedlv
is installed on your system, the extension will prompt you for updatewhenever installing a newer version is necessary. You can set thego.toolsManagement.autoUpdate
setting so the extension can updatedlv
automatically for you.
If you need to installdlv
manually outside of VS Code, follow the instructioninManually installingdlv
. An exampleof a situation where manual installation might be needed is if you are buildinga dev container with the necessary tools preinstalled, or installingdlv
builtfrom the tree head.
Note: The extension still uses the legacy debug adapter for remote debugging.
If you need to use the legacy debug adapter for local debugging (legacy
mode)by default, add the following in your VSCode settings.
"go.delveConfig": {"debugAdapter":"legacy", }
Whenmode
is set toremote
you must explicitly setdebugAdapter
todlv-dap
to override the legacy adapter default.
If you want to switch tolegacy
for only a subset of your launchconfigurations, you can usethedebugAdapter
attribute to switch between"dlv-dap"
and"legacy"
mode.
If you chose to switch to legacy because of bugs or limitations in the new debugadapter,open an issueto help us improve.
For general debugging features such as inspecting variables, settingbreakpoints, and other activities that aren't language-dependent, reviewVS Code debugging.
When you need more than the default debugging setup, you can create a launchconfiguration file for the project.
To create a configuration file:
- In thethe Run view,click "create a launch.json file"
- ChooseGo: Launch Package from the debug configuration drop-down menu. VSCode will create a
launch.json
file in a .vscode folder in your workspace(project root folder) or in youruser settingsorworkspace settings.
If you already have alaunch.json
for your project, you can open it using theCommand PaletteOpen launch.json command.
To add a new configuration to an existinglaunch.json
file:
- Open your
launch.json
file using the Command PaletteOpen launch.jsoncommand. - Click theAdd Configuration button to invoke the snippet IntelliSense.
There are many configuration attributes (seethe Launch.json attributes section). IntelliSense inVS Code’slaunch.json
editor will help you navigate available options anddocumentation.
To launch and debug your project, selectRun >Start Debugging (F5).
The launch feature uses alaunch
request type configuration in yourlaunch.json
file. Itsprogram
attribute needs to be the absolute path toeither the Go file, or folder containing the main package or test file. In thismode, the Go extension will start the debug session by building and launchingthe program. The launched program will be terminated when the debug sessionends.
- Supported modes
debug
: build and debug a main packagetest
: build and debug a testexec
: debug a precompiled binary- The binary must be built with
go build -gcflags=all="-N -l"
to disableinlining and optimizations that can interfere with debugging.
- The binary must be built with
auto
: automatically choose betweendebug
andtest
depending on theopen file
port
attribute to thelaunch configuration. VS Code will connect to the external user-specifieddlv dap
server athost:port
and launch the target there.
For remote debugging, theprogram
attribute must point to the absolute path tothe package or binary to debug in the remote host’s file system even whensubstitutePath
is specified.
You can use this configuration to attach to a running process or a running debugsession.
- Supported modes
local
: attaches to a local process.- The binary must be built with
go build -gcflags=all="-N -l"
to disableinlining and optimizations that can interfere with debugging.
- The binary must be built with
remote
: attaches to an in-progress debug session run by an externalserver.
You can debug an already running program using thelocal
mode typeconfiguration. The Go extension will startdlv dap
and configure it to attachto the specified process. Users can select the process to debug with one of thefollowing options:
- Specifying the numeric process id (PID) with the
processId
attribute. - Specifying the target program name in the
processId
attribute. If there aremultiple processes matching the specified program name, the extension willshow the list of matching processes at the start of the debug session. - Specifying
0
in theprocessId
attribute and selecting the process from thedrop-down menu at the start of the debug session.
NOTE: For remote debugging, add theport
attribute tothe launch configuration. VS Code will connect to the external user-specifieddlv dap
server athost:port
and attach to the target there.See"remote debugging" for more details).
You can connect to an already running remote debug session using theremote
mode. Specify optionalhost
and requiredport
for the externaldlv --headless
server that already took program or process id details ascommand-line arguments. See"Remote Debugging" for moredetails).
When you end an attach debug session, the debug UI allows you to choose to:
- [DEFAULT] Disconnect: disconnect the client and:
local
: leave the target process running (dlv terminates).remote
: let dlv decide if it can continue running (--accept-multiclient
mode only); if so, the target will stay in halted or running state it was inat disconnect.dlv debug/test/exec
: terminate the target process if dlv terminates.dlv attach
: leave the target process running even if dlv terminates.
- Stop: stop the attached server and the target process.
Once a debug session starts, the Debug toolbar will appear on the top of theeditor.
The available commands are:
- Continue / Pause F5
- Step Over (aka
next
in Delve) F10 - Step Into (aka
step
in Delve) F11 - Step Out (aka
stepout
in Delve) Shift+F11 or ⇧F11 - Restart (currently this is "Stop + Start") Ctrl+Shift+F5 or ⇧⌘F5
- Stop (terminate the debugee. Available in Launch request) Shift+F5 or ⇧F5
- Disconnect (detach from the debugee. Available only in Attach request)Shift+F5 or ⇧F5
- Terminate (terminate the debugee. Available only in Attach request)Alt+Shift+F5 or ⌥⇧F5
SeeVS Code’s Debug Documentation on Breakpointsto get familiar with VS Code’s UI. The Go debugger supports multiple ways toconfigure breakpoints.
- Breakpoints: you can set breakpoints by clicking on the editor margin orusing F9 on the current line. If the breakpoints can’t be set by Delve, VSCode will show the failure reason and grey out the dot.
- Conditional breakpoints: you can specify breakpoint conditions (similar toDelve’s
condition
command).- Expression condition: takes a boolean expression.
- Hit count: supports comparison operators (
>
,>=
,<
,<=
,==
,!=
)with an integer value.% n
form means we should stop at the breakpointwhen the hitcount is a multiple ofn
.
- Function Breakpoints: breakpoints can be set based on function names.Press the + button in the BREAKPOINTS section header and enter the location inthe form of
<function>[:<line>]
. This sets the breakpoint in theline
inside thefunction
. The full syntax forfunction
is<package>.(*<receiver type>).<function_name>
as specified inDelve’s location spec.Function breakpoints are shown with a red triangle in the BREAKPOINTS section.
- Logpoints: alogpoint isa variant of breakpoint that does not 'break', but instead logs a message toDEBUG CONSOLE and continues execution. Expressions within
{}
areinterpolated. For the list of acceptable expressions and syntax, seeDelve's documentation.
You can inspect variables in the VARIABLES section of the Run view or byhovering over their source in the editor. Variable values and expressionevaluation are relative to the selected stack frame in the CALL section.
By default, the VARIABLES section hides global variables, and shows only localvariables and function arguments. However, you can still inspect globalvariables from the DEBUG CONSOLE panel. If you prefer to have the VARIABLESsection show global variables, set theshowGlobalVariables
attribute in thelaunch.json
configuration, or set it in thego.delveConfig
setting.
When you select a variable and right click from the VARIABLES section, thecontext menu will present shortcuts to features such as:
Set Value
: you can set/modify simple string, numeric, pointer values. Usingcomposite literals, or memory allocation is not supported.Copy Value
: this copies the value in clipboard.Copy as Expression
: this is useful when you need to query from the REPL inthe DEBUG CONSOLE panel.Add to Watch
: this will automatically add the expression to the WATCHsection.
Shadowed variables will be marked with()
.
dlv-dap
modeuses a different approach. It takes advantage of the interactive UI features toprovide on-demand loading of individual variables, paging of arrays, slices andmaps and increased string limits depending on the context. We continue toexplore additional interactive features to balance performance and usability ofvariable loading and look forward to your feedback.
You can inspect variables and evaluate expressions from the DEBUG CONSOLE paneltoo. Acceptable expressions are either
- A validDelve expression,or
call <function_call_expression>
to call functions.
Variables and expressions accepted in DEBUG CONSOLE can be also registered inthe Run view’s WATCH section, so they can be evaluated automatically as youdebug. The "Add to Watch" feature from the VARIABLES section is convenient whenyou want to register interesting variables.
Hover over variables in editors during debugging shows the value of thevariable. For this feature, VS Code extracts the variable expression and makes arequest to the debugger to evaluate the expression. Delve evaluates theexpression relative to the highlighted stack frame chosen in the CALL STACK. Bydefault, that is the current top-most frame.
- VS Code heuristically determines the variable expression without fullunderstanding of the scope & the currently selected frame. Delve tries toevaluate the provided expression in the selected frame. As a result, hoverover variables outside the selected frame’s function may present incorrectinformation.
You can inspect all goroutines and their stacks in the CALL STACK section. TheCALL STACK section UI allows switching between goroutines or selecting adifferent stack frame. As a different stack frame or different goroutine isselected, the scope shown in the VARIABLE section will be updated for the newlyselected stack frame, and the expressions in the WATCH section will beautomatically reevaluated relative to the newly selected stack frame.
- Goroutine stacks are annotated with their internal goroutine IDs.
- The current goroutine is marked with
*
. If multiple goroutines stop (e.g.hit breakpoints) concurrently, Delve will pick one randomly. There also mightnot be a current goroutine (e.g. deadlock, pause or internal breakpoint hitby a system thread not running a goroutine). - If you click a goroutine call stack from the CALL STACK section, thegoroutine isselected.
- You can select a frame of the selected goroutine. The VARIABLE and WATCHsections will be updated accordingly and the cursor in the editor will bemoved to the corresponding location in the source code.
- Runtime stack frames are deemphasized (greyed out or collapsed).
- Thread IDs are shown for scheduled goroutines.
- Stop reason. It’s possible that there are multiple reasons goroutines werestopped, but currently only one reason is presented.
- File name and line number of the frame.
- You can trigger a debug action with the selected goroutine. Note: Resuming orstopping only a single goroutine (Go Issue25578,31132) is currently notsupported, so the action will cause all the goroutines to get activated orpaused.
- Function name of the frame.
When the program stops due to exception, panic, or bad access error, the CALLSTACK shows the stop reason and the editor highlights the source location withmore details.
DEBUG CONSOLE accepts commands that allow users to dynamically inspect/changedebug configuration, or inspect the list of source code compiled in the debuggedbinary. Usedlv help
anddlv config -list
from the DEBUG CONSOLE panel tosee the list of supported commands and dynamically adjustable settings.
There are many attributes that you can adjust in the launch and attach debugconfiguration. The following general attributes are mandatory for all launchconfigurations.
name
: the name of your configuration as it appears in the drop-down in theRun view.type
: the debugging type VS Code uses to decide which debugging extensionshould be used. Always leave this set to"go"
.request
:launch
orattach
.
Here is the list of attributes specific to Go debugging.
Property | Launch | Attach |
---|---|---|
args | Command line arguments passed to the debugged program. (Default: [] ) | n/a |
asRoot | (Experimental) Debug with elevated permissions (on Unix). It requiresintegrated orexternal console modes and is ignored in remote debugging.(Default: false ) | (Experimental) Debug with elevated permissions (on Unix). This requiresintegrated orexternal console modes and is ignored in remote debugging.(Default: false ) |
backend | Backend used by delve. Maps todlv 's--backend flag.Allowed Values: | same as Launch |
buildFlags | Build flags, to be passed to the Go compiler. Maps to dlv's--build-flags flag.(Default: [] ) | n/a |
console | (Experimental) Where to launch the debugger and the debug target: internal console, integrated terminal, or external terminal. It is ignored in remote debugging. Allowed Values: | (Experimental) Where to launch the debugger: internal console, integrated terminal, or external terminal. This does not affect tty of the running program. It is ignored in remote debugging. Allowed Values: |
coreFilePath | Path to the core dump file to open. For use on 'core' mode only (Default: "" ) | n/a |
cwd | Workspace relative or absolute path to the working directory of the program being debugged if a non-empty value is specified. Theprogram folder is used as the working directory ifcwd is omitted or empty.(Default: "" ) | Workspace relative or absolute path to the working directory of the program being debugged. Default is the current workspace. (Default: "${workspaceFolder}" ) |
debugAdapter | Select which debug adapter to use with this launch configuration. Allowed Values: | same as Launch |
dlvFlags | Extra flags fordlv . Seedlv help for the full list of supported. Flags such as--log-output ,--log ,--log-dest ,--api-version ,--output ,--backend already have corresponding properties in the debug configuration, and flags such as--listen and--headless are used internally. If they are specified indlvFlags , they may be ignored or cause an error. | same as Launch |
env | Environment variables passed to the launched debuggee program. Format as string key:value pairs. Merged withenvFile andgo.toolsEnvVars with precedenceenv >envFile >go.toolsEnvVars . | n/a |
envFile | Absolute path to a file containing environment variable definitions, formatted as string key=value pairs. Multiple files can be specified by provided an array of absolute paths. Merged withenv andgo.toolsEnvVars with precedenceenv >envFile >go.toolsEnvVars . | n/a |
hideSystemGoroutines | Boolean value to indicate whether system goroutines should be hidden from call stack view. (Default: false ) | same as Launch |
host | When applied to remote-attach configurations, will look for "dlv ... --headless --listen=:" server started externally. In dlv-dap mode this will apply to all other configurations as well. The extension will try to connect to an external server started with "dlv dap --listen=:" to ask it to launch/attach to the target process. (Default: "127.0.0.1" ) | When applied to remote-attach configurations, will look for "dlv ... --headless --listen=:" server started externally. In dlv-dap mode, this will apply to all other configurations as well. The extension will try to connect to an external server started with "dlv dap --listen=:" to ask it to launch/attach to the target process. (Default: "127.0.0.1" ) |
logDest | dlv's--log-dest flag. Seedlv log for details. Number argument is not allowed. Supported only indlv-dap mode, and on Linux and Mac OS. | dlv's--log-dest flag. Seedlv log for details. Number argument is not allowed. Supported only indlv-dap mode and on Linux and Mac OS. |
logOutput | Comma separated list of components that should produce debug output. Maps to dlv's--log-output flag. Checkdlv log for details.Allowed Values: | same as Launch |
mode | One ofauto ,debug ,test ,exec ,replay ,core . Inauto mode, the extension will choose eitherdebug ortest depending on active editor window.Allowed Values: | Indicates local or remote debugging. Local is similar to thedlv attach command, remote - todlv connect Allowed Values: |
output | Output path for the binary of the debugee. (Default: "debug" ) | n/a |
port | When applied to remote-attach configurations, will look for "dlv ... --headless --listen=:" server started externally. In dlv-dap mode this will apply to all other configurations as well. The extension will try to connect to an external server started with "dlv dap --listen=:" to ask it to launch/attach to the target process. (Default: 2345 ) | When applied to remote-attach configurations, will look for "dlv ... --headless --listen=:" server started externally. In dlv-dap mode, this will apply to all other configurations as well. The extension will try to connect to an external server started with "dlv dap --listen=:" to ask it to launch/attach to the target process. (Default: 2345 ) |
processId | n/a | Option 1: Use process picker to select a process to attach, or Process ID as integer. Allowed Values: Option 2: Attach to a process by name. If more than one process matches the name, use the process picker to select a process. Option 3: The numeric ID of the process to be debugged. If 0, use the process picker to select a process. |
program | Path to the program folder (or any go file within that folder) when indebug ortest mode, and to the pre-built binary file to debug inexec mode. If it is not an absolute path, the extension interprets it as a workspace relative path.(Default: "${workspaceFolder}" ) | n/a |
remotePath | n/a | (Deprecated)UsesubstitutePath instead.The path to the source code on the remote machine, when the remote path is different from the local machine. If specified, becomes the first entry in substitutePath. Not supported with dlv-dap .(Default: "" ) |
showGlobalVariables | Boolean value to indicate whether global package variables should be shown in the variables pane or not. (Default: false ) | same as Launch |
showLog | Show log output from the delve debugger. Maps to dlv's--log flag.(Default: false ) | same as Launch |
showRegisters | Boolean value to indicate whether register variables should be shown in the variables pane or not. (Default: false ) | same as Launch |
stackTraceDepth | Maximum depth of stack trace collected from Delve. (Default: 50 ) | same as Launch |
stopOnEntry | Automatically stop program after launch. (Default: false ) | Automatically stop program after attach. (Default: false ) |
substitutePath | An array of mappings from a local path (editor) to the remote path (debugee). This setting is useful when working in a file system with symbolic links, running remote debugging, or debugging an executable compiled externally. The debug adapter will replace the local path with the remote path in all of the calls.
| An array of mappings from a local path (editor) to the remote path (debugee). This setting is useful when working in a file system with symbolic links, running remote debugging, or debugging an executable compiled externally. The debug adapter will replace the local path with the remote path in all of the calls. Overridden byremotePath .
|
trace | Various levels of logging shown in the debug console & 'Go Debug' output channel. When using thelegacy debug adapter, the logs will also be written to a file if it is set to a value other thanerror .Allowed Values: | same as Launch |
traceDirPath | Directory in which the record trace is located or to be created for a new output trace. For use on 'replay' mode only (Default: "" ) | n/a |
dlv dap
process's working directory, butfrom which directory the extension spawns thedlv dap
process is animplementation detail. Thus, usethe VS Code variables substitutionto ensure consistent expansion of paths. VS Code will resolve the variablesinside strings inlaunch.json
before passing the configuration to the Goextension anddlv dap
. For example,${workspaceFolder}
will be replaced withthe absolute path to the workspace root folder. When appropriate, the Goextension will resolve relative paths or home directory (~) before sending theconfiguration todlv dap
.
Since the debugger and go compiler use the actual filenames, extra configurationis required to debug symlinked directories. Use thesubstitutePath
property totell thedebugAdapter
how to properly translate the paths. For example, ifyour project lives in/path/to/actual/helloWorld
, but the project is open invscode under the linked folder/link/to/helloWorld
, you can add the followingto your config to set breakpoints in the files in/link/to/helloWorld
:
{"name":"Launch with symlinks","type":"go","request":"launch","mode":"debug","program":"/path/to/actual/helloWorld","substitutePath": [ {"from":"/link/to/helloWorld","to":"/path/to/actual/helloWorld" } ]}
You can adjust the default value of the following configuration properties usinggo.delveConfig
settings. These default values are useful when you choose torun a debug session without the launch configuration set inlaunch.json
. Forexample, debug sessions started using theDebug Test
code lenses use theadjusted values from these settings.
go.delveConfig
debugAdapter
: Controls which debug adapter to use (default:legacy
).Select ‘dlv-dap’.showGlobalVariables
: Show global variables in the Debug view (default:false
).substitutePath
: Path mappings to apply to get from a path in the editor toa path in the compiled program (default:[]
).
dlvLoadConfig
setting? Delve debugger imposes variable loadinglimits to avoid loading too many variables at once and negatively impactingdebugging latency. The legacy adapter supporteddlvLoadConfig
to adjust theselimits for the duration of the session. The user therefore had to come up with aone-size-fits-all limit if the default behavior was not satisfactory.dlv-dap
mode uses a different approach as described inthe Data Inspection section. If this setting is configuredanddlv-dap
mode is used, the extension will show a warning prompt now. If thecurrent variable loading behavior and internal limits are not working for you,pleaseopen an issue and shareyour feedback.
VS Code implements a generic, language-agnostic debugger UI based onDebug Adapter Protocol(DAP), an abstract protocol for communicating with debugger backend. Previously,the Go extension used an intermediary typescript program (legacy debug adapter)to launch Delve and adapt Delve to DAP. Withthe new, native DAP implementation in Delve,the intermediary program is no longer necessary, and efficient and tightintegration with Delve becomes possible.
For information on debugging using the legacy debug adapter, please see the oldDebugging Documentation. Note that many new or enhanced featuresdiscussed in this document may not be available with the legacy debug adapter.
The Go extension anddlv
started as a subprocess of the extension do not haveaccess totty
. The Go extension captures and forwards STDOUT/STDERR of thedebug program to VS Code, so they can appear inDEBUG OUTPUT
panel. But thisarrangement does not handle STDIN.
When the target program needs to read from STDIN or access terminals (tty
),use the"console"
launch option that controls where thedlv
debugger and thetarget process run:
integratedTerminal
for the terminal inside VS CodeexternalTerminal
for the terminal outside VS Code
The Go extension delegates interaction with terminals to VS Codeusing Debug Adapter Protocol'sRunInTerminal
functionality.For configuring VS Code's terminal related behavior, see VS Code'sdocumentation.
In order to run and debug a program or a package test running as root, thedebugger (dlv
) must run with root privilege, too. You can start the debugsession with root privilege utilizing the"asRoot"
AND"console"
launchoptions. This is currently supported only on Linux and Mac.
WhenasRoot
is true, the Go extension will use thesudo
command to rundlv
. Sincesudo
may ask you to enter password, the debug session needsterminal access so set"console": "integratedTerminal"
or"console": "externalTerminal"
in the launch configuration.
For example, the following launch configuration will startmyprogram
and debugit by runningsudo dlv dap
command in the integrated terminal.
{"name":"Launch as Root","request":"launch","mode":"exec","asRoot":true,"program":"${workspaceRoot}/myprogram","console":"integratedTerminal",...}
TheasRoot
setting can be used withauto
/test
/debug
launch modes thatbuild the target binary to debug. That means thego
command will beinvoked as root to compile the binary, too. This can cause issues:
- by default,
sudo
does not preserve the user's current environment variables(see documentations about sudo's--preserve-env
option). For example,PATH
or library paths required for build may be different. - Go environment variable settings usually associated in the home directory aredifferent.
- Module/build caches used during build as root may be different from the cachesused in your normal build. If they are the same, you may encounter permissionerrors due to cache data written to the caches as root.
Instead, you can arrange theexec
launch mode to work with a pre-launchtask.
First, configure a debug build task to compile the target binary.
In.vscode/tasks.json
:
{..."tasks": [ {"label":"go: build (debug)","type":"shell","command":"go","args": ["build","-gcflags=all=-N -l","-o","${fileDirname}/__debug_bin" ],"options": {"cwd":"${fileDirname}" },... } ]}
The-gcflags=all=-N -l
flag tells thego build
command to preserve the debuginformation. The-o
flag causes the compiled binary to be placed in"${fileDirname}/__debug_bin"
. Extra build flags and environment variablesused for build should be configured here asargs
oroptions
'senv
settings.
It might be useful to add__debug_bin
to your.gitignore
to avoid debuggingbinaries getting checked-in into your repository.
Then, configure the launch config to run the task before starting debugging.
In.vscode/launch.json
:
..."configurations": [ {"name":"Launch Package as root","type":"go","request":"launch","mode":"exec","asRoot":true,"console":"integratedTerminal","program":"${fileDirname}/__debug_bin","preLaunchTask":"go: build (debug)", } ]
Settings (args
,cwd
,env
, ...) configured in the abovelaunch.json
willonly apply whenrunning the compiled binary, not when building the binary.
To debug package tests as root add the following launch and task configurations.
In.vscode/tasks.json
:
..."tasks": [ {... }, {"label":"go test (debug)","type":"shell","command":"go","args": ["test","-c","-o","${fileDirname}/__debug_bin" ],"options": {"cwd":"${fileDirname}", },... } ]
In.vscode/launch.json
:
..."configurations": [ {... }, {"name":"Debug Package Test as root","type":"go","request":"launch","mode":"exec","asRoot":true,"program":"${fileDirname}/__debug_bin","cwd":"${fileDirname}","console":"integratedTerminal","preLaunchTask":"go test (debug)" } ]
On rare occasions, you may want to installdlv
by yourself instead of lettingthe extension handle its installation.
First, find where the Go extension finds tools. Likeother tools the extension uses, the Go extension searches thedlv
executable from${GOPATH}/bin
,${GOBIN}
and${PATH}
(orPath
inWindows). So, installdlv
in the directory. The easiest way to check the toolinstallation location the Go extension uses is currently by running theGo: Locate Configured Go Tools
command from the command palette (⇧+⌘+P orCtrl+Shift+P).
If your Go version is 1.16 or newer:
GOBIN=<dir_to_install_dlv> go install github.com/go-delve/delve/cmd/dlv@latest
If your Go version is older than 1.16:
cd $(mktemp -d)GO111MODULE=on GOBIN=<dir_to_install_dlv> go get github.com/go-delve/delve/cmd/dlv@latest
You can choose to install a different version ofdlv
by specifying a specificcommit hash, a branch name (e.g.master
), or a released version instead oflatest
. For more details about manual installation, seeDelve's documentation.
If you want to explicitly specify the location of the delve binary, use thego.alternateTools
setting:
"go.alternateTools":{"dlv":"<absolute path to your dlv binary>"}
If you are able to use theRemote Developmentextensions and VS Code’s universalremote development capabilities,that is the recommended way to debug Go programs remotely. Check outGetting startedsection andRemote tutorialsto learn more.
Remote debugging is the debug mode commonly used to work with a debugger andtarget running on a remote machine or a container. In spite of its name, it canalso be used on a local machine with server started in an external terminal(e.g. to support entering stdin into the server's terminal window).
With the introduction ofdlv dap
users now have two options for remote (i.e.external) debugging.
In this mode the user must first manually start adlv --headless
server listening athost:port
while specifying the target program todebug/test/exec or a process to attach to on the command-line. Aremote attach configuration is then used to connect to the debuggerwith a running target.
Theheadless dlv servercan now be used with both"debugAdapter": "legacy"
(default value) and"debugAdapter": "dlv-dap"
(with Delve v1.7.3 or newer) as well as Delve'scommand-line interfaceviadlv connect
. The--accept-multiclient
flag makes this a multi-use serverthat persists onDisconnect
from a client and allows repeated connections fromany of the aforementioned clients. A combination of--accept-multiclient --continue
flags can be used to resume process executionon start-up. Please seedlv --help
anddlv [command] --help
for dlv'scommand-line options.
We encourage you to give the newly added"debugAdapter": "dlv-dap"
support atry and tolet us know of any issues. Ifyou need to use thelegacy
mode, please also see thelegacy remote debugging documentation.
For example, start external headless server:
dlv debug /path/to/program/ --headless --listen=:12345 # also add as needed: --accept-multiclient --continue
Connect to it with a remote attach configuration in yourlaunch.json
:
{"name":"Connect to external session","type":"go","debugAdapter":"dlv-dap",// `legacy` by default"request":"attach","mode":"remote","port":12345,"host":"127.0.0.1",// can skip for localhost"substitutePath":[{"from":"${workspaceFolder}","to":"/path/to/remote/workspace"}, ...]}
In this mode the user must first manually start adlv dap
serverlistening athost:port
and then specify the target program vialaunch orattach client config with a"port"
attribute.Instead of starting a new local server, the Go extension will tell VS Code toconnect to the server specified byhost:port
attributes and then send arequest with the target to debug. This option provides the flexibility of easilyadapting local configurations to connect to external servers, but
When usinglaunch
mode, theprogram
attribute must point to the absolutepath of the package or binary to debug in the remote host’s file system evenwhensubstitutePath
is specified. When usingattach
mode outside of localhost, you need to specify theprocessId
in the config sincethe processId resolution feature cannot gather information aboutprocesses running remotely.
Start adlv dap
server ready to accept a client request to launch or attach toa target process:
dlv dap --listen=:12345
Use the followinglaunch
configuration to telldlv
to execute a binaryprecompiled withgo build -gcflags=all="-N -l"
:
{"name":"Connect and launch","type":"go","debugAdapter":"dlv-dap",// the default"request":"launch","port":12345,"host":"127.0.0.1",// can skip for localhost"mode":"exec","program":"/absolute/path/to/remote/workspace/program/executable","substitutePath":[{"from":"${workspaceFolder}","to":"/path/to/remote/workspace"}, ...]}
Or have the binary compiled bydlv dap
by modifying the above configuration touse:
"mode":"debug","program":"/absolute/path/to/remote/workspace/package",
- Unlike
dlv --headless
above,dlv dap
does not support--accept-multiclient
or--continue
flags, which means after a debugsession ends, thedlv dap
process will always exit. - If you use
debug
ortest
modelaunch
requests, Delve builds the targetbinary. Delve tries to build the target from the directory where thedlv
process is running, so make sure to run thedlv
command from the directoryyou would run thego build
orgo test
command.
Sometimes you might like to launch the program for debugging outside of VS Code(e.g. as a workaround of the missingconsole
support to enter stdin via anexternal terminal or separate target's output from debug session logging). Thereare currently two options:
- Compile and run the target program from the external terminal and usethe "attach" configuration.
- Run the debug server from the external terminal with
--listen=:<port>
andhave VS Code connect to it usingport
in your launch configuration (see"Remote Debugging" for more details)
The suggestions below are intended to help you troubleshoot any problems youencounter. If you are unable to resolve the issue, please take a look at thecurrent known debugging issuesorreport a new issue.
- Read documentation andFAQs. Also check theDelve FAQin case the problem is mentioned there.
- Check your
launch.json
configuration. Often error messages appearing in theDEBUG CONSOLE panel reveal issues. - Update Delve (
dlv
) to pick up most recent bug fixes. Followthe instruction. - Check if you can reproduce the issue with
dlv
, the command line tool fromthe integrated terminal. If it's reproducible whenusingdlv
, take a look at theDelve project issue tracker. - Capturelogs and inspect them.
- Look at theexisting debugging issuesif similar issues were reported.
- If none of these solve your problem, pleaseopen a new issue.
The legacy adapter useddlvLoadConfig
as one-time session-wide setting tooverride dlv's conservative default variable loading limits, intended to protecttool's performance. The new debug adapter is taking a different approach withon-demand loading of composite data and updated string limits, relaxed wheninteracting with individual strings. In particular, if the new default limit of512, applied to all string values in the variables pane, is not sufficient, youcan take advantage of a larger limit of 4096 with one of the following:
- Hover over the variable in the source code
Copy as Expression
to query the string via REPL in the DEBUG CONSOLE panelCopy Value
to clipboard
Pleaseopen an issue if thisis not sufficient for your use case or if you have any additional feedback.
When stepping through a program on a particular goroutine, the debugger willmake sure that the step is completed, even when interrupted by events on adifferent goroutine. If a breakpoint is hit on a different goroutine, the debugadapter will stop the program execution to allow you to inspect the state, eventhough the step request is still active.
If you attempt to make another step request you will get aninvalid command
error.
UseContinue
to resume program execution.
If you do not want the step request to be interrupted, you can disable allbreakpoints from VS Code from the context menu in theBreakpoints
view.
Check the "BREAKPOINTS" section in the debug view and see if the breakpoints aregreyed outwhen your debug session is active. SettingstopOnEntry
is a great way to pauseexecution at the start toverify breakpoints are set correctly. Orenable logging and see ifsetBreakpoints
requestssucceeded with all the breakpointsverified.
This problem often occurs when the source location used in compiling thedebugged program and the workspace directory VS Code uses are different. Commonculprits are remote debugging where the program is built in the remote location,use of symbolic links, or use of-trimpath
build flags. In this case,configure thesubstitutePath
attribute in your launch configuration.
If you are using-trimpath
to build your program, you need to add entries to substitutepath to let the debugger know how to map the package paths that are compiled in thebinary to the files that you are looking at in the editor.
Here are some tips for configuring substitutePath. This assumes that your program is using module mode, which is the default.
One rule that you will need will map your main module. The mapping will map"from"
the file path to the directory containing the module,"to"
the module path.
You will also need to create a similar mapping for all dependencies. These include modulesin the module cache, vendored modules, and the standard library.
"substitutePath": [// Main module. {"from":"${workspaceFolder}","to":"moduleName", },// Module cache paths. {"from":"${env:HOME}/go/pkg/mod/github.com","to":"github.com", }, {"from":"${env:HOME}/go/pkg/mod/golang.org","to":"golang.org", },...// Standard library paths.// This rule should come last since the empty "to" will match every path. {"from":"/path/to/local/goroot/pkg" ,"to":""} ],
Since rules are applied both from client to server and server to client,rules with an empty string will be applied toall paths that it sees, so evendependencies will be mapped to"/path/to/module"
.
We plan to make this easier in the future. Progress can be trackedin the issue trackergolang/vscode-go#1985.
Debug sessions started with the "debug test" CodeLens or the test UI does not use mylaunch.json
configuration
The "debug test" CodeLens and thetest UI donot use thelaunch.json
configuration(Issue 855). As a workaround,use thego.delveConfig
setting and thego.testFlags
setting. Please notethat these all apply to all debug sessions unless overwritten by a specificlaunch.json
configuration.
decoding dwarf section info at offset 0x0: too short
orcould not open debug info
error
These errors indicate that your binary was built with linker flags that strippedthe symbol table (-s
) or the DWARF debug information (-w
), making debuggingimpossible. If the binary is built while launching the session, make sure yourlaunch.json
configuration does not contain"buildFlags": "--ldflags '-s -w'"
. If you usedebug test
or Test Explorer,checkgo.buildFlags
insettings.json
. If the binary is built externally,check the command-line flags and do not usego run
. Unlikego build
,go run
passes-s -w
to the linker under the hood. If you try to attach tosuch a binary with a debugger, it will fail with one of the above errors (see GoIssue24833). Instead let dlv buildthe binary for you or usego build -gcflags=all="-N -l"
.
When you are having issues indlv-dap
mode, first check if the problems arereproducible after updatingdlv
and using the most recent version ofdlv
.It's possible that the problems are already fixed. You can also try to installdlv
at tree head. Follow the instruction forupdatingdlv
andupdating extension.
Please report issues inour issue tracker with thefollowing information.
go version
go version -m <path/to/dlv>
- VS Code and VS Code Go version (e.g.
code --version
) - Instructions to reproduce the issue (code snippets, your
launch.json
, screenshot) - DAP trace (Seethe instruction)
{"name":"Launch file","type":"go","trace":"verbose","showLog":true,"logOutput":"dap", ...}
ThelogOutput
andshowLog
attributes inlaunch.json
enable Delve-sidelogging (server-side) and DAP message tracing. Thetrace
attribute controlsthe verbosity of Go extension's side logging (client-side).
The logging will appear in theGo Debug
output channel (Command Palette ->"View: Toggle Output" -> Select "Go Debug" from the dropdown menu). By nature,debug logs may contain sensitive information. Please review the logs carefullybefore sharing debug logs.
The core part of Delve DAP implementation is in theservice/dap
package. Follow Delve project'scontribution guidelineto send PRs.
Code for integration with the Go extension is mostly insrc/goDebugFactory.ts
and tests are intest/integration/goDebug.test.ts
.Please take a look at VS Code Go project'scontribution guideline to learn about how to prepare a changeand send it for review.
For simple launch cases, build thedlv
binary, and configure"go.alternateTools"
setting.
"go.alternateTools":{"dlv":<path_to_your_dlv>}
dlv dap --listen=:12345 --log --log-output=dap
{"name":"Launch file","type":"go","request":"launch","debugAdapter":"dlv-dap", ..."port":12345}
✏️ Want to contribute to this wiki?
Updatethe source and send a PR.