Safe?

[aart]

It will take much more than those vertical 2x4's to carry the load of just the roof.

Yes.

You've already got a good start there with those large posts sticking up to attach the roof framing to.

 

[Blue Eager]

Yes.

Yes off to a good start. However, the vertical 2x4's should either be replaced by 4x4's or doubled up & set at 8' on center. The same 4x4 dimensional lumber is then used as horizontal beams that rest on top of the vertical posts, not on the sides. The rafters will then rest on top of the horizontal beams. The vertical posts on one side of the run should be place at least 4' higher than the opposing side to allow for snow melt. Having said that current shortages in lumber resulting in the highest prices in recent memory is another consideration.

The other option might be doubling up on the 2x4 hard wire (off-set), or using 2x4 hard wire as the base and attaching chicken wire to it. This method will allow for the current support to remain as is. I attached a couple of photos illustrating the two...