caddyserver
Can we make reverse proxy response available in templates
This is in response to my question here on the community forum.
Can we add a feature where the response to a reverse proxy can be made available to or passed as argument(s) to templates?
:9000
reverse_proxy 127.0.0.1:3000 {
handle_response {
templates
try_files posts.html
file_server
}
}
And if the response from the 127.0.0.1:3000 application is:
[
{
"id": 1,
"title": "Post 1"
},
{
"id": 2,
"title": "Post 2"
},
{
"id": 3,
"title": "Post 4"
},
]
Being able to do something like this:
<!DOCTYPE html>
<html>
<body>
<main>
<div class="post-container">
{{range $field, $val := .Res.Body}}
<p id={{$val.id}}>{{$val.title}}</p>
{{end}}
</div>
</main>
</body>
</html>
Hmm. I think you'd be better off by responding with HTML that has JS fetch() calls to get the JSON, and render that however you need with JS.
Or, write a separate backend endpoint that renders HTML from the the JSON with an actual programming language.
There's a bunch of pieces in play here that make this tricky to implement, and I'm afraid it'll add undue complexity to the system:
- Response may be huge, making it available in templates would mean reading it all and buffering it into memory
- Making the data available in templates could require some complex pipework
- The response may not necessarily be JSON, decoding it to make it available in an map, and probably not handle other kinds of responses seems weird
Yeah, this'll definitely require buffering the response. Maybe if it was explicitly enabled in config (up to a max size, I dunno?) that would be one easy way to do it. For example, "Enabling this option always reads the response from the backend up to a certain size and then sets these placeholders/variables, etc."
FYI, this should be closer to being possible to implement now that we have a copy_response handler in handle_response routes (as of v2.5.0-beta.1).
Parsing the response is a whole other thing though, and likely best left to plugins once #4568 is done as well.
@mindon you'll need to elaborate. What's your config? What behaviour are you seeing? What does it look like when you make a request with curl -v?
@mindon you'll need to elaborate. What's your config? What behaviour are you seeing? What does it look like when you make a request with
curl -v?
curl -v works fine, the issue pattern is encode zstd gzip → reverse_proxy → templates
remove encode zstd gzip from target server or the templates from current server deliminates the 500 error
https://github.com/caddyserver/caddy/issues/4819
here's a simple config
{
debug
auto_https off
}
:8081 {
encode zstd gzip
root * ./hello
route /world/* {
uri strip_prefix /world
header X-Real-IP {http.request.remote}
reverse_proxy 127.0.0.1:8080
}
file_server
templates
}
:8080 {
encode zstd gzip
root * ./world
file_server
templates
}
@francislavoie a simple case is proxy target output something like "{{}}", then caddy app with templates will surely 500 error
That seems off-topic from what this issue is about @mindon.
The feature request here is about being able to write the proxy response from within a template, with handle_response. Your config doesn't do that.
@byoungdale Please see #4871 where I've implemented this functionality. It's a little rough around the edges still, but it should work.
If you want to parse JSON, simply use the fromJSON or mustFromJSON function: https://masterminds.github.io/sprig/defaults.html#fromjson-mustfromjson