Reuse OAuth2 Token with Mattermost?

[oculos]

Hi,

We use OIDC on Nextcloud so that our users have SSO.

Our Mattermost instance also uses that solution.

Would it be possible to create a seamless integration between the two, since the user already is logged in both and the token is there?

[janepie]

Thanks for suggesting this! This sounds like a good idea and we could use the obtained token to try a log-in to Mattermost, but I doubt Mattermost will accept an OIDC ID/access token as valid authentication. You could maybe ask on their side.

In the other direction, it is already possible. Nextcloud accepts OIDC tokens as bearer tokens in API requests. It is supported by user_oidc. So if both services use the same client, Mattermost can use an ID/access token to authenticate against Nextclouds API.

[oculos]

Mattermost does support oidc on its enterprise version.

On 2025-02-06 14:26, janepie wrote: Thanks for suggesting this! This sounds like a good idea and we could use the obtained token to try a log-in to Mattermost, but I doubt Mattermost will accept an OIDC ID/access token as valid authentication. You could maybe ask on their side. In the other direction, it is already possible. Nextcloud accepts OIDC tokens as bearer tokens in API requests. It is supported by user_oidc. So if both services use the same client, Mattermost can use an ID/access token to authenticate against Nextclouds API. -- Reply to this email directly, view it on GitHub [1], or unsubscribe [2]. You are receiving this because you authored the thread.Message ID: ***@***.***>

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[julien-nc]

@oculos Mattermost supporting user login via Oidc does not mean that it will accept Oidc id/access tokens as valid authentication when receiving API requests.