1 files changed, 28 insertions, 0 deletions
diff --git a/doc/integration/mattermost/gitlab-mattermost.msc b/doc/integration/mattermost/gitlab-mattermost.msc
new file mode 100644
index 00000000000..f6d4bf7aa68
--- /dev/null
+++ b/doc/integration/mattermost/gitlab-mattermost.msc
@@ -0,0 +1,28 @@
+msc {
+  # Use https://mscgen.js.org or mscgen to convert this into PNG
+  hscale="1.5",
+  wordwraparcs=on;
+
+  user [ label="User", textbgcolor="blue", textcolor="white" ],
+  mattermost [ label="Mattermost", textbgcolor="red", textcolor="white"],
+  gitlab [ label="GitLab", textbgcolor="indigo", textcolor="white"];
+
+  user=>mattermost [label="GET https://mm.domain.com"];
+  mattermost note gitlab [label="Obtain access code", textcolor="green"];
+  mattermost=>gitlab [label="GET https://gitlab.domain.com/oauth/authorize", textcolor="indigo"];
+  gitlab rbox user [label="GitLab user logs in (if necessary)"];
+  gitlab rbox gitlab [label="GitLab verifies client_id matches an OAuth application"];
+  gitlab=>user [label="GitLab asks user to authorize Mattermost OAuth app"];
+  user=>gitlab [label="User clicks 'Allow'"];
+  gitlab rbox gitlab [label="GitLab verifies redirect_uri matches list of valid URLs"];
+  gitlab=>user [label="302 Redirect: https://mm.domain.com/signup/gitlab/complete"];
+  user=>mattermost [label="GET https://mm.domain.com/signup/gitlab/complete", textcolor="red"];
+  mattermost note gitlab [label="Exchange access code for access token", textcolor="green"];
+  mattermost=>gitlab [label="POST http://gitlab.domain.com/oauth/token", textcolor="indigo"];
+  gitlab=>gitlab [label="Doorkeeper::TokensController#create"];
+  gitlab=>mattermost [label="Access token", textcolor="red"];
+  mattermost note gitlab [label="Mattermost looks up GitLab user", textcolor="green"];
+  mattermost=>gitlab [label="GET https://gitlab.domain.com/api/v4/user", textcolor="indigo"];
+  gitlab=>mattermost [label="User details", textcolor="red"];
+  mattermost=>user [label="Mattermost/GitLab user ready"];
+}