What goes first cover letter or resume?

Both.

That is, you should list your work experience, education, certifications and such in a general way in the resume. In the cover letter, you should highlight those of your qualifications that specifically match the job requirements.

This makes it easier on the HR person screening resumes to say "Yep, this matches our bullet points" and pass the resume on to the hiring manager. They may or may not pass along the cover letter as well, so this information should be in the resume as well.