Add '-group-by' flag to compute aggregated disk usage

[fedordikarev]

Draft on how "Group by" functionality could be added.

Example output:

> unused -gcp.project dev-project -group-by kubernetes.io/created-for/pvc/namespace
PROVIDER  GROUP_BY                         TYPE    SIZE_GB
GCP       agent-smoke-test                 ssd     30
GCP       default                          hdd     941
GCP       preview                          ssd     120
GCP       NONE                             ssd     1000
GCP       ge-logs                          hdd     5
...

> unused -gcp.project dev-project -group-by zone
PROVIDER  GROUP_BY       TYPE    SIZE_GB
GCP       us-central1-a  ssd     56370
GCP       us-central1-a  hdd     4340
GCP       us-central1-b  ssd     10528
GCP       us-central1-f  ssd     6188
GCP       us-central1-f  hdd     451
GCP       us-central1-b  hdd     1150

[inkel]

I like the idea, and the implementation looks good. Can you past the output of the table in the PR description?

[inkel]

Thanks for the example! It made it far easier to understand the changes. I've left some comments, tho, which I'd love to discuss. I created a different thread for each one so it's easier to discuss.

[inkel]

I'm not sure GROUP_BY is clear enough as a column header. I'd love to have the value passed by the user for the -group-by flag, although I'm not sure how would that look in the case of something like kubernetes.io/created-for/pvc/namespace for instance.

[fedordikarev]

I have doubts here as well and can't find good enough solution for column name.
Tag names are long and also confusing when I tried to use them.

I have 3 ideas:

• add comment about grouping tag when run with -v flag and use GROUP_BY_TAG as column name

  Grouping by 'kubernetes.io/created-for/pvc/namespace' tag.
  PROVIDER  GROUP_BY_TAG    TYPE    DISKS_COUNT  TOTAL_SIZE_GB
  GCP       redis-test      ssd     3            9
  

• print group-by name as column

  PROVIDER  kubernetes.io/created-for/pvc/namespace  TYPE    DISKS_COUNT  TOTAL_SIZE_GB
  GCP       redis-test                               ssd     3            9
  

• print upcased group-by name

  PROVIDER  KUBERNETES.IO/CREATED-FOR/PVC/NAMESPACE  TYPE    DISKS_COUNT  TOTAL_SIZE_GB
  GCP       redis-test                               ssd     3            9
  

what do you think?

[inkel]

I think I like the second option the better. It's definitely a hard question to answer 🤔

[inkel]

Left a few more comments, mostly aesthetic.

[fedordikarev]

thanks @inkel , addressed all your comments :)

[inkel]

Love it! Thanks!