canonical/multipass

Handle yaml-cpp exceptions from a cloud-init config better

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#646 opened on Feb 28, 2019

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enhancementgood first issue

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Description

Currently, we just bubble up any yaml-cpp exceptions back to the client, but the error message is out of context of what is really wrong. For example, if a user creates a cloud-init config with incorrect yaml, an error could look like: launch failed: operator[] call on a scalar As can be seen, it's not clear where the error is.

We should catch the yaml-cpp exceptions and make it a more meaningful message to pass to the client and user.

Contributor guide

Research direction
Investigate the current error handling in cloud init config parsing in the Multipass codebase. Locate where yaml cpp exceptions are thrown and trace the path to where they are caught or propagated to the client. Then, implement a catch block for yaml cpp exceptions and rethrow with a more descriptive error message indicating which part of the config is malformed.
Tech stack
cpp
Domain
backendcli
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++CMake
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70