Can't re-install captive-redirect snap after setting up a rule

[Victor gonzalez]

Story: once captive-redirect passed canonical tests on pi3 I removed the snap and tried to re-install it but it failed.

Environment:

latest candidate image on pi3
captive-redirect --candidate

Steps:

1. $ snap install captive-redirect --candidate
2. Set a new rule(i.e following canonical tests snap):
3. $ snap remove captive redirect
4. $ snap install captive redirect --candidate

Expected result: captive-redirect is installed

Current result:

$ sudo snap install captive-redirect --candidate
error: cannot perform the following tasks:
- Run configure hook of "captive-redirect" snap if present (run hook "configure": fork/exec /sbin/iptables: permission denied)

[Matteo Croce (teknoraver)]

After a few investigations I've noticed that snapd doesn't fully remove configuration after a remove:

# snap set captive-redirect active=true port=8080

# cat /var/snap/captive-redirect/common/config.json
{"active":true,"port":8080,"interfaces":null}

# grep -ro '{[^{]*8080[^}]*}' /var/lib/snapd/
/var/lib/snapd/state.json:{"active":true,"port":8080}
/var/lib/snapd/state.json:{"port":8080}
/var/lib/snapd/state.json:{"active":true,"port":8080}

# snap remove captive-redirect

# cat /var/snap/captive-redirect/common/config.json
cat: /var/snap/captive-redirect/common/config.json: No such file or directory

# grep -ro '{[^{]*8080[^}]*}' /var/lib/snapd/
/var/lib/snapd/state.json:{"active":true,"port":8080}
/var/lib/snapd/state.json:{"port":8080}
/var/lib/snapd/state.json:{"active":true,"port":8080}

Fortunately this will be fixed in the next version as a fix was already merged:

https://github.com/snapcore/snapd/pull/3052

[Jim Hodapp (jhodapp)]

@Victor: Given what Matteo discovered with snapd, do you want to wait and retest the captive-redirect snap when this snapd fix is in place?

[Victor gonzalez (victor-gonzalez-0)]

@jhodapp: sure, I'll take it once it's ready

[Alfie Huang (alfie073)]

Update info:

Test Platform: St.Louis (CID:201603-21474)
Snapd version: 2.24
captive-redirect version: Rev.27

Test Step:
1.Install captive-redirect
  $ snap install captive-redirect --candidate
2.Run the following manual test case.
3.After step2, remove captive-redirect
  $ snap remove captive-redirect
4.Re-install captive-redirect again.
  $ snap install captive-redirect --candidate

Result:
captive-redirect snap is installed completed. ---> PASS

[Jim Hodapp (jhodapp)]

Test results spreadsheet from AlfieHuang.