Config merge

[lakkeger]

Motivation

Config merging and respecting the original stack config is not something currently well supported in pulumi-local. To solve this issue, reported on this issue too, we'll introduce 3 different config strategies:

• overwrite strategy (current, default): this config option simply updates/overwrites the current config with the necessary changes we have to apply for LocalStack
• override (with dry-run): this config option temporarily creates a config file by merging the original stacks config with our recommended options and running pulumi commands with it. By setting dry-run, pulumi-local creates the config file then terminates without running the command.
• separation: copying the currently selected stack's config and creates a new separate stack (by default called localstack, however this is configurable with DEFAULT_STACK_NAME env variable)

If any of the config files we'd like to create exists we'll prompt for user input.

Additional options and features

• DRY_RUN: in cases when makes sense creates the config file but terminates after without modifying it, if it finds an already existing one it prompts the user.
• --non-interactive/NON_INTERACTIVE: the usage of the non-interactive flag is now allowed to suppress any pulumi-local prompts for user input.
• LOCAL_STACK_NAME: the name of the LocalStack stack/config file we create, depending on the strategy
• deactivate aws:accessKey and aws:secretKey options

Changes

• [x] add user prompt for existing stack configs
• [x] add logic for strategy selection
• [x] add merge strategy, by taking leverage of --config-file option of pulumi
• [x] add separate stack strategy by copying the currently selected stack's config and then change to it
• [x] deactivate AWS credentials in the config file
• [x] create tests for strategies