From toml to toml

[dangra]

Change Summary

What and Why: While adding gpus to [[vm]] section, I found that BurntSushi/toml lib serializes zero values of integer fields even if omitempty tag is set for the struct field.

Sounds like a minor thing, but it is very awkward for fly.toml files created by fly launch whose [[vm]] section looks like:

[[vm]]
size = "shared-cpu-1x"
memory_mb  = 1024
gpus = 0

How: Unfortunately BurntSushi won't fix it and suggests using an integer pointer (*int instead of int), so the other alternative was to switch to https://github.com/pelletier/go-toml that works like we expect and claims to be more encoding/json alike.

As a big plus, this PR adds a test case to ensure reading a toml file and writing it back generates an equal configuration without missing sections nor new ones.

Related to:

• Multi-GPU support #3199
• Encode: support json.Number type pelletier/go-toml#923
• Encode: support pointers to embedded structs pelletier/go-toml#924

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Documentation

• Fresh Produce
• In superfly/docs, or asked for help from docs team
• n/a

[billyb2]

banger pr 👍🏾