docker build --secret does not support dst

[briandealwis]

Our Docker builder's secret object takes a dst field (#4731), but it is not supported by docker build --secret: that field is actually specified from within the Dockerfile.

Expected behavior

Using a filled in secret should succeed:

secret:
    id: npmrc
    src: "/Users/bdealwis/.npmrc"
    dst: /app/npmrc

Actual behavior

$ skaffold build
Starting build...
Building [skaffold-example]...
could not parse secrets: [id=npmrc,src=/Users/bdealwis/.npmrc,dst=/app/npmrc]: unexpected key 'dst' in 'dst=/app/npmrc'
running build: exit status 1

$ docker build --secret id=npmrc,src=$HOME/.npmrc,dst=/app/npmrc .
could not parse secrets: [id=npmrc,src=/Users/bdealwis/.npmrc,dst=/app/npmrc]: unexpected key 'dst' in 'dst=/app/npmrc'

Information

• Skaffold version: 1.23.0