You just need a solenoid water valve to let the timer control the water flow.

https://www.amazon.com/gp/aw/d/B00E1HXYQA/ref=mp_s_a_1_1?qid...

https://www.amazon.com/gp/aw/d/B00K0TKJCU/ref=mp_s_a_1_2?qid...

https://www.amazon.com/gp/aw/d/B006LYHG42/ref=mp_s_a_1_1?qid...

Doesn't this solenoid need 12V?

Yes (actually they say it works as low as 6V). You could, however, power it off a solar panel + battery enclosure so it's mostly set and forget.

A drip line with a timer? This is low-tech stuff that's been available for quite some time. Search for B013JPIJG4 on Amazon.

While you're shopping at amazon there are $25 class kits that come with a water filter, backflow preventer, and pressure regulator. That's what I have on my container garden.

Drip emitters are the kind of thing I should be 3-d printing but at $5 for 50 or whatever the going rate is...