Support additional request header fields for HTTP sources, "Accept" and
"User-Agent" as a start.
The "Accept" header is required in some cases and some servers may vary
the response body based on the header value.
The "User-Agent" header may be useful in custom frontends and
potentially other cases.
- llb: Add `llb.Header` and `HTTPInfo.Header` to allow `client/llb`
users to set these header fields on HTTP sources. The argument to
`llb.Header` is a struct to effectively limit header fields to a
subset.
- llb: Define and flag new `source.http.header` capability when
`llb.Header` is used.
- solver: Define new `http.header.` source attribute prefix. Giving
each header field its own attribute (opposed to JSON encoding the
header struct) will allow source policy to make assertions on
individual header fields.
- source/http: Parse `http.header.` attributes into a sorted slice and
include them in cache key digest.
- source/http: Set request headers accordingly.
Signed-off-by: Dan Duvall <dduvall@wikimedia.org>
Support authentication for HTTP sources.
- llb: Define general `llb.AuthOption` interface composed of
`HTTPOption` and `GitOption`.
- llb: Refactor `llb.AuthHeaderSecret` to return an `llb.AuthOption` so
it may be used with both `llb.Git` and `llb.HTTP`.
- llb: Define `HTTPInfo.AuthHeaderSecret`.
- llb: Define and flag new `source.http.auth` capability when
`HTTPInfo.AuthHeaderSecret` is set.
- solver: Define new `http.auth` source attribute.
- source/http: If an `http.auth` attribute is specified, resolve a
secret named by its value and set the "Authorization" request header.
Signed-off-by: Dan Duvall <dduvall@wikimedia.org>
Sources are a pretty neat extension point, except there are a few code
paths that hard-code against each type. This moves code around and
adjusts interfaces so that Source implementations are self-contained and
merely need to be registered with the source.Manager.
Signed-off-by: Alex Suraci <suraci.alex@gmail.com>
