Switch to POST if the URI is too long

[ggrossetie]

When using very large Vega specification file (when data is embed in the file), the public instance of Kroki can return the following error "414 Request-URI Too Large nginx/1.14.0 (Ubuntu)".

I think we should use a POST request to avoid this error if the URI is longer than 4096.

See: yuzutech/kroki-go#11

[eshepelyuk]

@Mogztter why not use POST by default if kroki server supports this ?

[ggrossetie]

My main concern is corporate proxy/firewall. I believe that it's more likely that a POST request will be blocked than a GET request but maybe that's not a good enough reason.

In one of my previous job the corporate proxy was a nightmare so I might be biased 😂

[eshepelyuk]

Hey, lets introduce an attribute for this ?
Called kroki-http-method - with following values

• get - means always use GET
• post - means always use POST
• adaptive - try to use GET, unless query string length is less than 4096 bytes, then fall back to POST

For instance, we wilk use local kroki and we would like to force POST always

[ggrossetie]

That's a good idea 👍

[ggrossetie]

There are several challenges we need to address.

When using the option "inline" we delegate all the work to Asciidoctor.js (ie. read the image data from the specified URI and generate a data URI). In this case, Asciidoctor.js will use a GET request to read the image data from the specified URI... 😞

Another issue is that we are currently using the Virtual File System to read the image data from the specified URI but if we want to use a POST request then we need to explicitly use an HTTP client.

[ggrossetie]

It's actually possible to set the target as a data-uri: asciidoctor/asciidoctor#3657 (comment) 🎉

[eshepelyuk]

@Mogztter although issue is closed, the README is not updated :((

[ggrossetie]

Indeed it was automatically closed when I merged the pull request, reopening 😉

[ggrossetie]

README updated!
I think we can close now? @eshepelyuk any objection?

[eshepelyuk]

@Mogztter plz close