Mattermost-server: Link previews are not generated on supported sites (wikipedia, github,...)

[raphael0202]

Summary

Link previews are not generated on supported sites (wikipedia, github,...)

Steps to reproduce

Using last version of Mattermost (3.2.0). Create several new messages on a public channel with the following content:
https://en.wikipedia.org/wiki/ISO_8601 or
https://github.com/leedo/noembed/commit/87fc1b3a439d9ccd724b331e32223cad289eb6a1

Expected behavior

A preview of the link should be generated thanks to https://noembed.com/, as this pull request https://github.com/mattermost/platform/pull/1352 was merged into master

Observed behavior

No preview is generated.

[lfbrock]

Hi @raphael0202, can you go to Account Settings > Advanced > Preview Pre-release features, and check that "Show experimental previews of link content, when available" is enabled?

The link previews for websites have some issues so they're not turned on by default. We have a ticket here to update how they work: https://mattermost.atlassian.net/browse/PLT-1835

[jasonblais]

Thanks again @raphael0202 for the report -- the link preview should appear after going to Account Settings > Advanced > Preview Pre-release features, and enabling "Show experimental previews of link content, when available".

Closing, given link previews aren't enabled by default as described above.

However, if you find they don't work after enabling, please reopen the issue.

[raphael0202]

Thanks for your responses, enabling link previews in settings does the trick.

[marcocevoli]

I have "Show experimental previews of link content, when available" enabled but links (Wikipedia) are not shown. I only see an empty box under the link.

[jasonblais]

Thanks @marcocevoli, the current implementation supports websites that use Open Graph data.

I believe Wikipedia doesn't use it, which would be why the link preview isn't generated.

[marcocevoli]

Thanks, jasonblais. Then, it would make more sense that no box appeared, like with other links. This is what I get, instead: http://i.imgur.com/cyL4Ghv.png

[jasonblais]

Ah, that issue was fixed in Mattermost v3.7 and later. You can upgrade Mattermost to the latest version here: https://about.mattermost.com/download/

[gokceneraslan]

That's not working in my mattermost instance (v4.2) and there is no experimental option about it either. Any comments?

[gokceneraslan]

Ah ok it needs to be enabled in System console as well.