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Add Bun runtime support for JavaScript actions #4126

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2fe31d9
Add Bun runtime support for JavaScript actions
polRk Nov 20, 2025
89314e8
Merge branch 'main' into main
polRk Nov 28, 2025
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19 changes: 18 additions & 1 deletion src/Misc/externals.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,9 @@ NODE_ALPINE_URL=https://github.com/actions/alpine_nodejs/releases/download
NODE20_VERSION="20.19.5"
NODE24_VERSION="24.11.1"

BUN_URL=https://github.com/oven-sh/bun/releases/download
BUN_VERSION="1.3.2"

get_abs_path() {
# exploits the fact that pwd will print abs path when no args
echo "$(cd "$(dirname "$1")" && pwd)/$(basename "$1")"
Expand Down Expand Up @@ -142,18 +145,26 @@ if [[ "$PACKAGERUNTIME" == "win-x64" || "$PACKAGERUNTIME" == "win-x86" ]]; then
acquireExternalTool "$NODE_URL/v${NODE20_VERSION}/$PACKAGERUNTIME/node.lib" node20/bin
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/$PACKAGERUNTIME/node.exe" node24/bin
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/$PACKAGERUNTIME/node.lib" node24/bin

# Note: Bun is only available for Windows x64, not for win-x86 (32-bit Windows)
if [[ "$PACKAGERUNTIME" == "win-x64" ]]; then
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-windows-x64.zip" bun/bin fix_nested_dir
fi

if [[ "$PRECACHE" != "" ]]; then
acquireExternalTool "https://github.com/microsoft/vswhere/releases/download/2.6.7/vswhere.exe" vswhere
fi
fi

# Download the external tools only for Windows.
# Download the external tools only for Windows ARM64.
# Note: Bun doesn't have official Windows ARM64 release yet, so we skip it for now.
if [[ "$PACKAGERUNTIME" == "win-arm64" ]]; then
# todo: replace these with official release when available
acquireExternalTool "$NODE_URL/v${NODE20_VERSION}/$PACKAGERUNTIME/node.exe" node20/bin
acquireExternalTool "$NODE_URL/v${NODE20_VERSION}/$PACKAGERUNTIME/node.lib" node20/bin
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/$PACKAGERUNTIME/node.exe" node24/bin
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/$PACKAGERUNTIME/node.lib" node24/bin

if [[ "$PRECACHE" != "" ]]; then
acquireExternalTool "https://github.com/microsoft/vswhere/releases/download/2.6.7/vswhere.exe" vswhere
fi
Expand All @@ -163,12 +174,14 @@ fi
if [[ "$PACKAGERUNTIME" == "osx-x64" ]]; then
acquireExternalTool "$NODE_URL/v${NODE20_VERSION}/node-v${NODE20_VERSION}-darwin-x64.tar.gz" node20 fix_nested_dir
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/node-v${NODE24_VERSION}-darwin-x64.tar.gz" node24 fix_nested_dir
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-darwin-x64.zip" bun/bin fix_nested_dir
fi

if [[ "$PACKAGERUNTIME" == "osx-arm64" ]]; then
# node.js v12 doesn't support macOS on arm64.
acquireExternalTool "$NODE_URL/v${NODE20_VERSION}/node-v${NODE20_VERSION}-darwin-arm64.tar.gz" node20 fix_nested_dir
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/node-v${NODE24_VERSION}-darwin-arm64.tar.gz" node24 fix_nested_dir
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-darwin-aarch64.zip" bun/bin fix_nested_dir
fi

# Download the external tools for Linux PACKAGERUNTIMEs.
Expand All @@ -177,11 +190,15 @@ if [[ "$PACKAGERUNTIME" == "linux-x64" ]]; then
acquireExternalTool "$NODE_ALPINE_URL/v${NODE20_VERSION}/node-v${NODE20_VERSION}-alpine-x64.tar.gz" node20_alpine
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/node-v${NODE24_VERSION}-linux-x64.tar.gz" node24 fix_nested_dir
acquireExternalTool "$NODE_ALPINE_URL/v${NODE24_VERSION}/node-v${NODE24_VERSION}-alpine-x64.tar.gz" node24_alpine
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-linux-x64.zip" bun/bin fix_nested_dir
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-linux-x64-musl.zip" bun_alpine/bin fix_nested_dir
fi

if [[ "$PACKAGERUNTIME" == "linux-arm64" ]]; then
acquireExternalTool "$NODE_URL/v${NODE20_VERSION}/node-v${NODE20_VERSION}-linux-arm64.tar.gz" node20 fix_nested_dir
acquireExternalTool "$NODE_URL/v${NODE24_VERSION}/node-v${NODE24_VERSION}-linux-arm64.tar.gz" node24 fix_nested_dir
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-linux-aarch64.zip" bun/bin fix_nested_dir
acquireExternalTool "$BUN_URL/bun-v${BUN_VERSION}/bun-linux-aarch64-musl.zip" bun_alpine/bin fix_nested_dir
fi

if [[ "$PACKAGERUNTIME" == "linux-arm" ]]; then
Expand Down
7 changes: 4 additions & 3 deletions src/Runner.Common/Constants.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -173,19 +173,20 @@ public static class Features
public static readonly string SnapshotPreflightHostedRunnerCheck = "actions_snapshot_preflight_hosted_runner_check";
public static readonly string SnapshotPreflightImageGenPoolCheck = "actions_snapshot_preflight_image_gen_pool_check";
public static readonly string CompareWorkflowParser = "actions_runner_compare_workflow_parser";
public static readonly string AllowBunRuntime = "actions.runner.allowbunruntime";
}

// Node version migration related constants
public static class NodeMigration
{
// Node versions
public static readonly string Node20 = "node20";
public static readonly string Node24 = "node24";

// Environment variables for controlling node version selection
public static readonly string ForceNode24Variable = "FORCE_JAVASCRIPT_ACTIONS_TO_NODE24";
public static readonly string AllowUnsecureNodeVersionVariable = "ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION";

// Feature flags for controlling the migration phases
public static readonly string UseNode24ByDefaultFlag = "actions.runner.usenode24bydefault";
public static readonly string RequireNode24Flag = "actions.runner.requirenode24";
Expand Down
10 changes: 5 additions & 5 deletions src/Runner.Worker/ActionManifestManager.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ public ActionDefinitionDataNew Load(IExecutionContext executionContext, string m
ActionDefinitionDataNew actionDefinition = new();

// Clean up file name real quick
// Instead of using Regex which can be computationally expensive,
// Instead of using Regex which can be computationally expensive,
// we can just remove the # of characters from the fileName according to the length of the basePath
string basePath = HostContext.GetDirectory(WellKnownDirectory.Actions);
string fileRelativePath = manifestFile;
Expand Down Expand Up @@ -464,7 +464,8 @@ private ActionExecutionData ConvertRuns(
else if (string.Equals(usingToken.Value, "node12", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "node16", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "node20", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "node24", StringComparison.OrdinalIgnoreCase))
string.Equals(usingToken.Value, "node24", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "bun", StringComparison.OrdinalIgnoreCase))
{
if (string.IsNullOrEmpty(mainToken?.Value))
{
Expand Down Expand Up @@ -504,7 +505,7 @@ private ActionExecutionData ConvertRuns(
}
else
{
throw new ArgumentOutOfRangeException($"'using: {usingToken.Value}' is not supported, use 'docker', 'node12', 'node16', 'node20' or 'node24' instead.");
throw new ArgumentOutOfRangeException($"'using: {usingToken.Value}' is not supported, use 'docker', 'node12', 'node16', 'node20', 'node24' or 'bun' instead.");
}
}
else if (pluginToken != null)
Expand All @@ -515,7 +516,7 @@ private ActionExecutionData ConvertRuns(
};
}

throw new NotSupportedException("Missing 'using' value. 'using' requires 'composite', 'docker', 'node12', 'node16', 'node20' or 'node24'.");
throw new NotSupportedException("Missing 'using' value. 'using' requires 'composite', 'docker', 'node12', 'node16', 'node20', 'node24' or 'bun'.");
}

private void ConvertInputs(
Expand Down Expand Up @@ -600,4 +601,3 @@ public sealed class CompositeActionExecutionDataNew : ActionExecutionData
public MappingToken Outputs { get; set; }
}
}

10 changes: 5 additions & 5 deletions src/Runner.Worker/ActionManifestManagerLegacy.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -56,7 +56,7 @@ public ActionDefinitionData Load(IExecutionContext executionContext, string mani
ActionDefinitionData actionDefinition = new();

// Clean up file name real quick
// Instead of using Regex which can be computationally expensive,
// Instead of using Regex which can be computationally expensive,
// we can just remove the # of characters from the fileName according to the length of the basePath
string basePath = HostContext.GetDirectory(WellKnownDirectory.Actions);
string fileRelativePath = manifestFile;
Expand Down Expand Up @@ -451,7 +451,8 @@ private ActionExecutionData ConvertRuns(
else if (string.Equals(usingToken.Value, "node12", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "node16", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "node20", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "node24", StringComparison.OrdinalIgnoreCase))
string.Equals(usingToken.Value, "node24", StringComparison.OrdinalIgnoreCase) ||
string.Equals(usingToken.Value, "bun", StringComparison.OrdinalIgnoreCase))
{
if (string.IsNullOrEmpty(mainToken?.Value))
{
Expand Down Expand Up @@ -491,7 +492,7 @@ private ActionExecutionData ConvertRuns(
}
else
{
throw new ArgumentOutOfRangeException($"'using: {usingToken.Value}' is not supported, use 'docker', 'node12', 'node16', 'node20' or 'node24' instead.");
throw new ArgumentOutOfRangeException($"'using: {usingToken.Value}' is not supported, use 'docker', 'node12', 'node16', 'node20', 'node24' or 'bun' instead.");
}
}
else if (pluginToken != null)
Expand All @@ -502,7 +503,7 @@ private ActionExecutionData ConvertRuns(
};
}

throw new NotSupportedException("Missing 'using' value. 'using' requires 'composite', 'docker', 'node12', 'node16', 'node20' or 'node24'.");
throw new NotSupportedException("Missing 'using' value. 'using' requires 'composite', 'docker', 'node12', 'node16', 'node20', 'node24' or 'bun'.");
}

private void ConvertInputs(
Expand Down Expand Up @@ -543,4 +544,3 @@ private void ConvertInputs(
}
}
}

5 changes: 5 additions & 0 deletions src/Runner.Worker/FeatureManager.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,5 +16,10 @@ public static bool IsContainerActionRunnerTempEnabled(Variables variables)
{
return variables?.GetBoolean(Constants.Runner.Features.ContainerActionRunnerTemp) ?? false;
}

public static bool IsBunRuntimeEnabled(Variables variables)
{
return variables?.GetBoolean(Constants.Runner.Features.AllowBunRuntime) ?? false;
}
}
}
31 changes: 25 additions & 6 deletions src/Runner.Worker/Handlers/NodeScriptActionHandler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -110,11 +110,28 @@ public async Task RunAsync(ActionRunStage stage)
workingDirectory = HostContext.GetDirectory(WellKnownDirectory.Work);
}

var nodeRuntimeVersion = await StepHost.DetermineNodeRuntimeVersion(ExecutionContext, Data.NodeVersion);
ExecutionContext.StepTelemetry.Type = nodeRuntimeVersion;
string file = Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Externals), nodeRuntimeVersion, "bin", $"node{IOUtil.ExeExtension}");
string file;
bool isBun = string.Equals(Data.NodeVersion, "bun", StringComparison.OrdinalIgnoreCase);

// Format the arguments passed to node.
if (isBun)
{
if (!FeatureManager.IsBunRuntimeEnabled(ExecutionContext.Global.Variables))
{
throw new NotSupportedException($"Bun runtime is not enabled. Please enable the feature flag '{Constants.Runner.Features.AllowBunRuntime}' to use Bun runtime.");
}

var bunRuntimeVersion = await StepHost.DetermineBunRuntimeVersion(ExecutionContext);
ExecutionContext.StepTelemetry.Type = bunRuntimeVersion;
file = Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Externals), bunRuntimeVersion, "bin", $"bun{IOUtil.ExeExtension}");
}
else
{
var nodeRuntimeVersion = await StepHost.DetermineNodeRuntimeVersion(ExecutionContext, Data.NodeVersion);
ExecutionContext.StepTelemetry.Type = nodeRuntimeVersion;
file = Path.Combine(HostContext.GetDirectory(WellKnownDirectory.Externals), nodeRuntimeVersion, "bin", $"node{IOUtil.ExeExtension}");
}

// Format the arguments passed to node/bun.
// 1) Wrap the script file path in double quotes.
// 2) Escape double quotes within the script file path. Double-quote is a valid
// file name character on Linux.
Expand All @@ -128,7 +145,8 @@ public async Task RunAsync(ActionRunStage stage)
Encoding outputEncoding = null;
#endif

// Remove environment variable that may cause conflicts with the node within the runner.
// Remove environment variable that may cause conflicts with the node/bun within the runner.
// This applies to both Node.js and Bun to avoid conflicts with the runner's environment.
Environment.Remove("NODE_ICU_DATA"); // https://github.com/actions/runner/issues/795

using (var stdoutManager = new OutputManager(ExecutionContext, ActionCommandManager))
Expand Down Expand Up @@ -162,7 +180,8 @@ public async Task RunAsync(ActionRunStage stage)
else
{
var exitCode = await step;
ExecutionContext.Debug($"Node Action run completed with exit code {exitCode}");
string runtimeName = isBun ? "Bun" : "Node";
ExecutionContext.Debug($"{runtimeName} Action run completed with exit code {exitCode}");
if (exitCode != 0)
{
ExecutionContext.Result = TaskResult.Failed;
Expand Down
78 changes: 77 additions & 1 deletion src/Runner.Worker/Handlers/StepHost.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ public interface IStepHost : IRunnerService

Task<string> DetermineNodeRuntimeVersion(IExecutionContext executionContext, string preferredVersion);

Task<string> DetermineBunRuntimeVersion(IExecutionContext executionContext);

Task<int> ExecuteAsync(IExecutionContext context,
string workingDirectory,
string fileName,
Expand Down Expand Up @@ -64,10 +66,31 @@ public Task<string> DetermineNodeRuntimeVersion(IExecutionContext executionConte
{
executionContext.Warning(warningMessage);
}

return Task.FromResult(nodeVersion);
}

public Task<string> DetermineBunRuntimeVersion(IExecutionContext executionContext)
{
// Check platform compatibility for Bun runtime
if (Constants.Runner.PlatformArchitecture.Equals(Constants.Architecture.X86))
{
var os = Constants.Runner.Platform.ToString();
var msg = $"Bun runtime is not supported on {os} x86 (32-bit) platforms.";
throw new NotSupportedException(msg);
}

if (Constants.Runner.PlatformArchitecture.Equals(Constants.Architecture.Arm) &&
Constants.Runner.Platform.Equals(Constants.OSPlatform.Linux))
{
var msg = "Bun runtime is not supported on Linux ARM32 platforms.";
throw new NotSupportedException(msg);
}

// Bun runtime version is simply "bun"
return Task.FromResult("bun");
}

public async Task<int> ExecuteAsync(IExecutionContext context,
string workingDirectory,
string fileName,
Expand Down Expand Up @@ -183,6 +206,59 @@ public async Task<string> DetermineNodeRuntimeVersion(IExecutionContext executio
return nodeExternal;
}

public async Task<string> DetermineBunRuntimeVersion(IExecutionContext executionContext)
{
string bunExternal = "bun";

if (FeatureManager.IsContainerHooksEnabled(executionContext.Global.Variables))
{
if (Container.IsAlpine)
{
bunExternal = CheckPlatformForAlpineBunContainer(executionContext);
}
executionContext.Debug($"Running JavaScript Action with Bun runtime: {bunExternal}");
return bunExternal;
}

// Best effort to determine a compatible bun runtime
// Check if we're in an Alpine container
var osReleaseIdCmd = "sh -c \"cat /etc/*release | grep ^ID\"";
var dockerManager = HostContext.GetService<IDockerCommandManager>();

var output = new List<string>();
var execExitCode = await dockerManager.DockerExec(executionContext, Container.ContainerId, string.Empty, osReleaseIdCmd, output);
if (execExitCode == 0)
{
foreach (var line in output)
{
executionContext.Debug(line);
if (line.ToLower().Contains("alpine"))
{
bunExternal = CheckPlatformForAlpineBunContainer(executionContext);
return bunExternal;
}
}
}
executionContext.Debug($"Running JavaScript Action with Bun runtime: {bunExternal}");
return bunExternal;
}

private string CheckPlatformForAlpineBunContainer(IExecutionContext executionContext)
{
// Check for Alpine container compatibility
if (!Constants.Runner.PlatformArchitecture.Equals(Constants.Architecture.X64) &&
!Constants.Runner.PlatformArchitecture.Equals(Constants.Architecture.Arm64))
{
var os = Constants.Runner.Platform.ToString();
var arch = Constants.Runner.PlatformArchitecture.ToString();
var msg = $"Bun Actions in Alpine containers are only supported on x64 and ARM64 Linux runners. Detected {os} {arch}";
throw new NotSupportedException(msg);
}
string bunExternal = "bun_alpine";
executionContext.Debug($"Container distribution is alpine. Running JavaScript Action with Bun runtime: {bunExternal}");
return bunExternal;
}

public async Task<int> ExecuteAsync(IExecutionContext context,
string workingDirectory,
string fileName,
Expand Down
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