open tmp_cfgfil with w+ and fix seek

[lucasalvatore]

my environment:
python: 3.10.14
napalm: 5.0.0
napalm-srl: 1.0.5

Was testing basic config changes using this simple script:

from napalm import get_network_driver
import json
driver = get_network_driver("srl")
optional_args = {"gnmi_port": 6030,"skip_verify": True, "insecure": True,"encoding": "JSON_IETF"}
router = driver(hostname="mydevice",username="admin",password="xxxx",optional_args=optional_args)
router.open()
config = {
  "interface": [
    {
      "name": "ethernet-1/4/1",
      "admin-state": "enable",
      "vlan-tagging": True,
      "transceiver": {
        "forward-error-correction": "base-r"
      },
      "subinterface": [
        {
          "index": 0,
          "type": "bridged",
          "vlan": {
            "encap": {
              "untagged": {
              }
            }
          }
        }
      ]
    }
  ]
}

test = json.dumps(config)


print("trying to merge")
router.load_merge_candidate(config=test)
print("compare")
diff = router.compare_config()
print(f"diff is {diff}")
input("do you want to commit? ")
router.commit_config()
print("commit")
router.close()

Which results in these error:

ERROR:root:Error occurred in compare_config: not readable
Traceback (most recent call last):
  File "/Users/lsalvatore/git/napalm-srlinux/napalm_srl/srl.py", line 2187, in compare_config
    cand_config = json.load(self.tmp_cfgfile)
  File "/opt/homebrew/Cellar/[email protected]/3.10.14/Frameworks/Python.framework/Versions/3.10/lib/python3.10/json/__init__.py", line 293, in load
    return loads(fp.read(),
io.UnsupportedOperation: not readable

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/lsalvatore/git/network-automation/utilities/srl-napalm.py", line 38, in <module>
    diff = router.compare_config()
  File "/Users/lsalvatore/git/napalm-srlinux/napalm_srl/srl.py", line 2194, in compare_config
    raise CommandErrorException(e) from e
napalm.base.exceptions.CommandErrorException: not readable

i was able to fix this by opening tmp_cfgfile with w+ permissions

Also ran into a problem when doing the compare_config() before a commit. When that happens we need to reset the pointer back to the start of tmp_cfgfile so it can be read again, so thats what line 2299 is doing

Maybe better ways of solving this but it seems to work fine for me