Feat/add currency conversion

[tim775]

No description provided.

[alikhajeh1]

LGTM - I added my suggestions. We should update https://www.infracost.io/docs/multi_project/report to include the currency in the JOSN output.

I'm not sure we need the "$ CAD" on every line as it clutters the output in the table and the HTML outputs:

Project: infracost/infracost/examples/terraform

 Name                                                          Monthly Qty  Unit                      Monthly Cost

 aws_instance.web_app
 ├─ Instance usage (Linux/UNIX, on-demand, m5.4xlarge)                 730  hours                        $0.00 CAD
 ├─ root_block_device
 │  └─ Storage (general purpose SSD, gp2)                               50  GB                           $0.00 CAD
 └─ ebs_block_device[0]
    ├─ Storage (provisioned IOPS SSD, io1)                           1,000  GB                           $0.00 CAD
    └─ Provisioned IOPS                                                800  IOPS                         $0.00 CAD

 aws_lambda_function.hello_world
 ├─ Requests                                            Monthly cost depends on usage: $0.00 CAD per 1M requests
 └─ Duration                                            Monthly cost depends on usage: $0.00 CAD per GB-seconds

 OVERALL TOTAL                                                                                           $0.00 CAD

How about we only include it in the OVERALL TOTAL, or maybe only in the headings: "Price (CAD)", "Hourly Cost (CAD)" and "Monthly Cost (CAD)"?

Project: infracost/infracost/examples/terraform

 Name                                                          Monthly Qty  Unit                      Monthly Cost (CAD)

 aws_instance.web_app
 ├─ Instance usage (Linux/UNIX, on-demand, m5.4xlarge)                 730  hours                        $0.00
 ├─ root_block_device
 │  └─ Storage (general purpose SSD, gp2)                               50  GB                           $0.00
 └─ ebs_block_device[0]
    ├─ Storage (provisioned IOPS SSD, io1)                           1,000  GB                           $0.00
    └─ Provisioned IOPS                                                800  IOPS                         $0.00

 aws_lambda_function.hello_world
 ├─ Requests                                            Monthly cost depends on usage: $0.00 per 1M requests
 └─ Duration                                            Monthly cost depends on usage: $0.00 per GB-seconds

 OVERALL TOTAL                                                                                           $0.00

For the diff output, we could include it in the project diff total:

Monthly cost change for infracost/infracost/examples/terraform
Amount:  $0.00 CAD ($0.00 -> $0.00)

[alikhajeh1]

Thanks @tim775 - this is looking awesome. The HTML format (./build/infracost breakdown --path examples/terraform --format html > test.html) doesn't show the currency code in the heading or overall total. We try to keep the formats consistent where possible but if that's not possible in this case, it's ok.

There seems to be a bug in the way infracost output handles currency: it uses the global config but assume the values in the JSON file were USD. Repro steps:

1. ./build/infracost configure set currency EUR
2. ./build/infracost breakdown --path examples/terraform --format json > test.json
3. test.json now holds values in EUR (overall total = 632.25)
4. ./build/infracost configure set currency GBP
5. ./build/infracost output --path test.json shows the same overall total (632.25) as step 3 but the table heading shows GBP.

Expected behavior: the simplest thing is probably to have infracost output use the currency in the JSON file (i.e. ignore the global config and the INFRACOST_CURRENCY env var). There might be users in large organizations with multiple currencies, where the JSON file was generated with currency A, and users want currency B - we don't need to handle that.