Solve unordered container dependency problem

[ubhattacharjya]

Summary

This PR solves a problem of container ordering feature not working as expected when a container has multiple dependencies. This issue is mentioned in #2579 .

Implementation details

With unordered multiple dependencies - stuck as PENDING ❌

{
    "containerDefinitions": [
        {
            "command": [
                "cat",
                "123"
            ],
            "image": "alpine",
            "startTimeout": 10,
            "name": "exit1",
            "essential": false
        },
        {
            "image": "nginx",
            "startTimeout": 60,
            "dependsOn": [
                {
                    "containerName": "mysql",
                    "condition": "START"
                },
                {
                    "containerName": "exit1",
                    "condition": "SUCCESS"
                }
            ],
            "name": "nginx"
        },
        {
            "image": "mysql:5.7",
            "startTimeout": 30,
            "dependsOn": [
                {
                    "containerName": "exit1",
                    "condition": "SUCCESS"
                }
            ],
            "name": "mysql"
        }
    ],
    "memory": "100",
    "family": "reproduce-dependency-problem",
    "requiresCompatibilities": [
        "EC2"
    ],
    "cpu": "128"
}

With logically ordered multiple dependencies - task STOPPED as expected ✅

{
    "containerDefinitions": [
        {
            "command": [
                "cat",
                "123"
            ],
            "image": "alpine",
            "startTimeout": 10,
            "name": "exit1",
            "essential": false
        },
        {
            "image": "nginx",
            "startTimeout": 60,
            "dependsOn": [
                {
                    "containerName": "exit1",
                    "condition": "SUCCESS"
                },
                {
                    "containerName": "mysql",
                    "condition": "START"
                }
            ],
            "name": "nginx"
        },
        {
            "image": "mysql:5.7",
            "startTimeout": 30,
            "dependsOn": [
                {
                    "containerName": "exit1",
                    "condition": "SUCCESS"
                }
            ],
            "name": "mysql"
        }
    ],
    "memory": "100",
    "family": "reproduce-dependency-problem",
    "requiresCompatibilities": [
        "EC2"
    ],
    "cpu": "128"
}

Here, in the first task definiton, the task should have stopped much earlier, as exit1 has stopped unsuccessfully. But it was stuck in pending because the first mentioned dependency did not yet meet requirements.

This problem was happening because whenever a container was waiting on a dependency to resolve, instead of continuing to check for other dependencies, it would just return with error as dependency not resolved. This PR returns this error at the end of checking all dependencies. If we can fail faster, we will be able to do so after this fix.

Testing

Tested that the above mentioned tasks behaved as expected and both transitioned to STOPPED status

Description for the changelog

Bug: Fix the container ordering bug where the agent did not iterate through all the dependencies of a particular container

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[fierlion]

Can we add a test to cover this specific case?
(I could approve if you wanted to break such a test into a separate PR)

[ubhattacharjya]

Can we add a test to cover this specific case?
(I could approve if you wanted to break such a test into a separate PR)

Added integration test

[fierlion]

looks good. Thanks for adding the test here.