Panic just after Session was successfully started

[Kinjalrk2k]

The Problem

I'm trying to use session-manager-plugin to log into my ECS Fargate containers and I face the following issue:

Starting session with SessionId: ecs-execute-command-*****************
root@ip-***-***-***-***:/src# panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x18 pc=0x102584cec]

goroutine 1 [running]:
github.com/aws/session-manager-plugin/src/sessionmanagerplugin/session.glob..func2(0x140001a0340, {0x102980dd0, 0x140001d6760})
	/Users/kinjal/go/pkg/mod/github.com/aws/session-manager-plugin@v0.0.0-20230315220744-7b544e9f381d/src/sessionmanagerplugin/session/session.go:98 +0x5c
github.com/aws/session-manager-plugin/src/sessionmanagerplugin/session.(*Session).Execute(0x140001a0340, {0x102980dd0, 0x140001d6760})
	/Users/kinjal/go/pkg/mod/github.com/aws/session-manager-plugin@v0.0.0-20230315220744-7b544e9f381d/src/sessionmanagerplugin/session/session.go:233 +0x21c
github.com/wingsure-inc/sshing/sshing.EcsExec()
	/Users/kinjal/Desktop/DRIVE/WORK/sshing/sshing/aws.go:179 +0xa40
main.main()
	/Users/kinjal/Desktop/DRIVE/WORK/sshing/main.go:9 +0x1c
exit status 2

Sensitive information have been masked with ***

From the log line above, I can see that the session was successfully started. The line root@ip-***-***-***-***:/src# clearly depicts the same. I also confirmed through the Session Manager in AWS Console (https://ap-south-1.console.aws.amazon.com/systems-manager/session-manager/sessions?region=ap-south-1) that the sessions were started successfully. However as soon as the session is created, it panics somehow!

More information

I've setup the session in the following fashion:

var ssmSession session.Session
ssmSession.SessionId = *output.Session.SessionId
ssmSession.StreamUrl = *output.Session.StreamUrl
ssmSession.TokenValue = *output.Session.TokenValue
ssmSession.Endpoint = endpoint.URL
ssmSession.TargetId = fmt.Sprintf("ecs:%v_%v_%v", clusterName, taskId, containerRuntimeId)
ssmSession.ClientId = uuid.NewV4().String()
ssmSession.DataChannel = &datachannel.DataChannel{}
// ssmSession.SessionType = "NonInteractiveCommands"

log := log.Logger(true, ssmSession.ClientId)
err = ssmSession.Execute(log)
HandleErr(err)

The above code is inspired by this:

session-manager-plugin/src/sessionmanagerplugin/session/session.go

Lines 182 to 209 in 7b544e9

	clientId := uuid.NewV4().String()
	switch operationName {
	case StartSessionOperation:
	if err = json.Unmarshal(response, &startSessionOutput); err != nil {
	log.Errorf("Cannot perform start session: %v", err)
	fmt.Fprintf(out, "Cannot perform start session: %v\n", err)
	return
	}
	session.SessionId = *startSessionOutput.SessionId
	session.StreamUrl = *startSessionOutput.StreamUrl
	session.TokenValue = *startSessionOutput.TokenValue
	session.Endpoint = ssmEndpoint
	session.ClientId = clientId
	session.TargetId = target
	session.DataChannel = &datachannel.DataChannel{}
	default:
	fmt.Fprint(out, "Invalid Operation")
	return
	}
	if err = startSession(&session, log); err != nil {
	log.Errorf("Cannot perform start session: %v", err)
	fmt.Fprintf(out, "Cannot perform start session: %v\n", err)
	return
	}

AWS CLI

However, when I try to log into the container through aws-cli using this command, it works:

aws ecs execute-command --region <region> --cluster <cluster-name> --task <task-id> --container <container-name> --command "/bin/bash" --interactive

Digging into the aws-cli code, I find that it invokes session-manager-plugin as a subprocess rather than implementing it programmatically:
https://github.com/aws/aws-cli/blob/5218ac17b8141e1a15afed9e644904a6a1081b7d/awscli/customizations/ecs/executecommand.py#L103-L111

My Goal

I wish to log into my ECS Fargate containers programmatically! My goal is to reverse-engineer aws-cli and session-manager-plugin so that they work together

Any help would be appreciated. Thanks in advanced!

[mtolhurst]

I just ran into this same issue.

To solve it, add an import in on the session types that you require, similar to

session-manager-plugin/src/sessionmanagerplugin-main/main.go

Lines 21 to 22 in dbfa0bf

	_ "github.com/aws/session-manager-plugin/src/sessionmanagerplugin/session/portsession"
	_ "github.com/aws/session-manager-plugin/src/sessionmanagerplugin/session/shellsession"