There is no objective answer like "1 km is ok but 2 km is too far" because that depends on the size and the individual fitness of your dog, and the terrain you're running on.
In general, dogs can cover long distances in a jogging tempo. The trot gait saves a lot of energy (compared to a sprint). You should gauge the reactions of your dog during and after a run.
- If he has to sprint to keep up with you, you're too fast. You can let him sprint during play or for short bursts, but it's not ideal to sprint log distances.
- If he runs in front of you, he still has energy. If he falls back or behind, he's exhausted and you need to stop.
- If he stops and lays down panting, he's utterly exhausted and you must give him time to rest before you can move him again, even if you're not home yet. Ideally this scenario wouldn't happen anyways.
- If he's very lethargic the day after your run, he's sore and needs shorter runs until his stamina improves.
- If he licks his paws hours or a day after the run, his joints hurt (maybe because the sidewalk is too hard) and you may want to look for a different route where he can run on grass.
Don't forget to offer fresh water after a run. If you increase the distances you run with him, you might have to increase his amount of food as well (at least slightly).