From 453c34afa3c4fd380f59742771558a47ff2f0a3c Mon Sep 17 00:00:00 2001
From: Brady Dowling <bradydowling@gmail.com>
Date: Fri, 23 Feb 2018 15:07:51 -0800
Subject: [PATCH] Allow debugger args to be passed to via environment variable
 (#307)

---
 README.md  | 12 ++++++++++++
 runtime.go | 27 +++++++++++++++++++++++----
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 65cfa319ed..b751efc03d 100644
--- a/README.md
+++ b/README.md
@@ -261,6 +261,18 @@ Unlike Node.JS and Java, Python requires you to enable remote debugging in your
 
 > Please note, due to a [open bug](https://github.com/Microsoft/vscode-python/issues/71) with Visual Studio Code, you may get a `Debug adapter process has terminated unexpectedly` error when attempting to debug Python applications with this IDE. Please track the [GitHub issue](https://github.com/Microsoft/vscode-python/issues/71) for updates.
 
+#### Passing Additional Runtime Debug Arguments
+
+To pass additional runtime arguments when debugging your function, use the environment variable `DEBUGGER_ARGUMENTS`. This will pass a string of arguments directly into the run command SAM Local uses to start your function.
+
+For example, if you want to load a debugger like iKPdb at runtime of your Python function, you could pass the following as `DEBUGGER_ARGUMENTS`: `-m ikpdb --ikpdb-port=5858 --ikpdb-working-directory=/var/task/ --ikpdb-client-working-directory=/myApp --ikpdb-address=0.0.0.0`. This would load iKPdb at runtime with the other arguments you've specified. In this case, your full SAM local command would be:
+
+```bash
+$ DEBUGGER_ARGUMENTS="-m ikpdb --ikpdb-port=5858 --ikpdb-working-directory=/var/task/ --ikpdb-client-working-directory=/myApp --ikpdb-address=0.0.0.0" echo {} | sam local invoke -d 5858 myFunction
+```
+
+You may pass debugger arguments to functions of all runtimes.
+
 ### Connecting to docker network
 Both `sam local invoke` and `sam local start-api` support connecting the create lambda docker containers to an existing docker network.
 
diff --git a/runtime.go b/runtime.go
index 91cb37c7c4..3131c2fa98 100644
--- a/runtime.go
+++ b/runtime.go
@@ -432,12 +432,17 @@ func (r *Runtime) getDebugEntrypoint() (overrides []string) {
 	if len(r.DebugPort) == 0 {
 		return
 	}
+	debuggerArgs := os.Getenv("DEBUGGER_ARGS")
+	debuggerArgsArray := strings.Split(debuggerArgs, " ")
 	switch r.Name {
 	// configs from: https://github.com/lambci/docker-lambda
 	// to which we add the extra debug mode options
 	case runtimeName.java8:
 		overrides = []string{
 			"/usr/bin/java",
+		}
+		overrides = append(overrides, debuggerArgsArray...)
+		overrides = append(overrides,
 			"-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,quiet=y,address=" + r.DebugPort,
 			"-XX:MaxHeapSize=1336935k",
 			"-XX:MaxMetaspaceSize=157286k",
@@ -447,10 +452,13 @@ func (r *Runtime) getDebugEntrypoint() (overrides []string) {
 			"-XX:-TieredCompilation",
 			"-jar",
 			"/var/runtime/lib/LambdaJavaRTEntry-1.0.jar",
-		}
+		)
 	case runtimeName.nodejs:
 		overrides = []string{
 			"/usr/bin/node",
+		}
+		overrides = append(overrides, debuggerArgsArray...)
+		overrides = append(overrides,
 			"--debug-brk=" + r.DebugPort,
 			"--nolazy",
 			"--max-old-space-size=1229",
@@ -458,10 +466,13 @@ func (r *Runtime) getDebugEntrypoint() (overrides []string) {
 			"--max-executable-size=153",
 			"--expose-gc",
 			"/var/runtime/node_modules/awslambda/bin/awslambda",
-		}
+		)
 	case runtimeName.nodejs43:
 		overrides = []string{
 			"/usr/local/lib64/node-v4.3.x/bin/node",
+		}
+		overrides = append(overrides, debuggerArgsArray...)
+		overrides = append(overrides,
 			"--debug-brk=" + r.DebugPort,
 			"--nolazy",
 			"--max-old-space-size=1229",
@@ -469,10 +480,13 @@ func (r *Runtime) getDebugEntrypoint() (overrides []string) {
 			"--max-executable-size=153",
 			"--expose-gc",
 			"/var/runtime/node_modules/awslambda/index.js",
-		}
+		)
 	case runtimeName.nodejs610:
 		overrides = []string{
 			"/var/lang/bin/node",
+		}
+		overrides = append(overrides, debuggerArgsArray...)
+		overrides = append(overrides,
 			"--debug-brk=" + r.DebugPort,
 			"--nolazy",
 			"--max-old-space-size=1229",
@@ -480,8 +494,13 @@ func (r *Runtime) getDebugEntrypoint() (overrides []string) {
 			"--max-executable-size=153",
 			"--expose-gc",
 			"/var/runtime/node_modules/awslambda/index.js",
+		)
+	case runtimeName.python27:
+		overrides = []string{
+			"/usr/bin/python2.7",
 		}
-		// TODO: also add debug mode for Python runtimes
+		overrides = append(overrides, debuggerArgsArray...)
+		overrides = append(overrides, "/var/runtime/awslambda/bootstrap.py")
 	}
 	return
 }