Go format string has numbers and special characters in map index?

Question

When I run podman inspect I can get to a map[...] with --format. But indexing through it seems to be impossible.

$ podman run -d -p 1234:1234 --name evanrox alpine:3 sleep 360

$ podman inspect evanrox --format '{{ .NetworkSettings.Ports }}'
map[1234/tcp:[{ 1234}]]

However, these don't work,

--format '{{ .NetworkSettings.Ports.1234/tcp }}'
--format '{{ .NetworkSettings.Ports."1234/tcp" }}'
--format '{{ .NetworkSettings.Ports.[1234/tcp] }}'
--format '{{ .NetworkSettings.Ports.["1234/tcp"] }}'

I don't write Go. What's the right syntax?

Answer 1

index(obj, idx1, [idx2..])

You can index into a map with index,

index Returns the result of indexing its first argument by the following arguments. Thus index x 1 2 3 is, in Go syntax, x[1][2][3]. Each indexed item must be a map, slice, or array.

So in my case, I did

--format '{{ index .NetworkSettings.Ports "1234/tcp" }}'