Help: HTTP datasource do a HEAD call first?

[MaxenceG2M]

Hi,

I'd like to use gomplate with the discogs API as datasource. Each call fails in a 405 status:

$ gomplate -d discogs=https://api.discogs.com/releases/249504 -i 'Album ID: {{ (ds "discogs").id }}' -H "ip=User-Agent: curl"
Album ID: 23:44:12 ERR  err="renderTemplate: failed to render template <arg>: template: <arg>:1:14: executing \"<arg>\" at <ds \"discogs\">: error calling ds: couldn't read datasource 'discogs' (https://api.discogs.com/releases/249504): stat (url: \"https://api.discogs.com/\", name: \"releases/249504\"): http GET failed with status 405"
$ gomplate --context discogs=https://api.discogs.com/releases/249504 -i 'Album ID: {{ .discogs.id }}'
23:51:09 ERR  err="couldn't read datasource 'discogs' (https://api.discogs.com/releases/249504): stat (url: \"https://api.discogs.com/\", name: \"releases/249504\"): http GET failed with status 405"

The same curl call success without problems:

$ curl -XGET https://api.discogs.com/releases/249504 -H 'User-Agent: curl'
{"id":249504,"status":"Accepted","year":1987,"resource_url":"https://api.discogs.com/releases/249504","uri":"https://www.discogs.com/release/249504-Rick-Astley-Never-Gonna-Give-You-Up", ........}

To try to understand why this doesn't work, I simply started a http server with (with nothing, just for debug) and call it. Then, I can see an "HEAD" call on each execution:

$ python3 -m http.server
Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) ...
---> Doing first call with datasource:  gomplate -d discogs=http://localhost:8000/ -i 'Album ID: {{ (ds "discogs").id }}'
127.0.0.1 - - [03/Feb/2025 23:49:17] "HEAD / HTTP/1.1" 200 -
127.0.0.1 - - [03/Feb/2025 23:49:17] "GET / HTTP/1.1" 200 -
---> Doing a second call with context: gomplate --context discogs=http://localhost:8000/test -i 'Album ID: {{ .discogs.id }}'
127.0.0.1 - - [03/Feb/2025 23:50:20] code 404, message File not found
127.0.0.1 - - [03/Feb/2025 23:50:20] "HEAD /test HTTP/1.1" 404 -

Indeed, when I call discogs with HEAD method I'm getting a 405:

$ curl -I https://api.discogs.com/releases/249508
HTTP/2 405
date: Mon, 03 Feb 2025 23:01:34 GMT
content-type: application/json
content-length: 32
allow: GET
strict-transport-security: max-age=15552000
x-discogs-ratelimit: 25
x-discogs-ratelimit-remaining: 22
x-discogs-ratelimit-used: 3
cf-cache-status: DYNAMIC
set-cookie: __cf_bm=4F.sXkQpYyugMP6Dp4xPzEXbx__012liQRmjtBaLEiE-1738623694-1.0.1.1-1ETVTuoP7LhR72sw1ZU3DKDHAkZLfSlcoxLNz3OJswVp4gZZigYmSd7HHyOiLS5JRbQDZI.qGatsE9UH0W81hQ; path=/; expires=Mon, 03-Feb-25 23:31:34 GMT; domain=.discogs.com; HttpOnly; Secure; SameSite=None
server: cloudflare
cf-ray: 90c60b2c1da7700b-CDG
alt-svc: h3=":443"; ma=86400

Is this behavior known? Is there any way to avoid this call?

Thank for your help :)