How do I tell my waterfall JIRA project the order in which tasks need to be completed?

[Valerie Boudreau]

I've entered 12 tasks(issues) for my new project. They need to be done in order, my project is a waterfall project. Do I have to make each task a Blocker of the one before it to order my tasks? 

[Joshua DeClerck]

If you have JIRA Server, I'm pretty sure you can use the free Script Runner add-on for this. You might create a new kind of issue link, with the set "precedes" and "follows". Use these links to order your issues, where any issue that must be done before other issues "precedes" them.

Then, choose an appropriate transition in the issue type's workflow (Start Work, or whatever your equivalent is), and add a Condition to it. Choose the Script Condition option, and then a Custom Script Condition. You should then be able to imitate the example script here:

https://jamieechlin.atlassian.net/wiki/display/GRV/Conditions#Conditions-Alldependentissuesneedtoberesolved

Just change the LinkType value to whatever you called the link type you created. As-is, that script should prevent that workflow transition from being possible until all linked issues of that type are resolved.

I haven't personally tested this out, but if I had to set something up like you're describing, it's the first route I'd attempt.

-- Edit – 

Just saw all the Cloud tags on your original post, and realized this probably isn't helpful to you at all. =(

[Valerie Boudreau]

Yeah, we are on Cloud. I am very confused as to how JIRA talks about working for waterfall methodology but this requires an add-on.

[Deleted user]

How about using 1 parent issue then create sub-tasks for each milestone? I'm not really sure what restrictions you can do based on the cloud (what plugins available and how much customization can you do).

[Valerie Boudreau]

Then each of my projects would be a task and won't work when I bring them into JIRA Portfolio. Thank you though.