update ci configuration to send slack notifications on failure

Updates CI config file and adds a task to send notifications when a build fails on master or on any tag.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/12805

This requires an env. variable: CI_SLACK_WEBHOOK_URL to be set - that points to an incoming webhook generated by Slack.

Added 1 commit:

• 0e789124 - make build fail so we can test notifications...

Added 1 commit:

• 26ae450d - update gitlab ci config

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• 63a950a5 - testing build failure

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• 5fe354ef - refactored rake task and make build pass

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• 70f82cc5 - uncomment restriction to branches or tags

@ayufan A few questions on this one if you have some time:

• At the moment if CI_SLACK_WEBHOOK_URL is not defined, the notification shouldn't do anything hence there should be no error - let me know if need to do something else for preventing forks that do not push to our Gitlab to fail.

• I've been using #ci-test for testing the notifications. Would #development be the right channel to post this? Also, it might be a bit chatty looking at failures on https://gitlab.com/gitlab-org/gitlab-ce/commits/master, so it's something we need to take into account...

• TODO: I haven't added the env. variable the gitlab-ee as I don't have access to master there...

/cc @jacobvosmaer

Reassigned to @ayufan

@jameslopez We shouldn't add the rake task for it, since this is only used by us. Maybe it would be simpler to put the script in scripts/send_slack_notification.(sh|rb) and execute this?

I would suggest to add:

only:
- master@gitlab-org/gitlab-ce
- tags@gitlab-org/gitlab-ce
- master@gitlab-org/gitlab-ee
- tags@gitlab-org/gitlab-ee

This will prevent from executing the job on forks.

@ayufan good point! I will move it to scripts/, thanks!

Reassigned to @jameslopez

Added 1 commit:

• 0309e081 - removed slack task and added bash script instead. Updated gitlab-ci config file

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• 27a82b2f - typo to make build fail

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• ff4a1f72 - update with branch and tags restriction

@ayufan this is ready to be reviewed again.. Still need to update the channel and assign a milestone - should we make it 8.5?

Thanks!

Reassigned to @ayufan

LGTM

Please put "production" data and we can merge it :)

Added 1 commit:

• 8006d025 - default slack notification channel

@ayufan done! added #notifications as the default channel