many: support 'system' nickname in interfaces #5080

bboozzoo · 2018-04-23T12:07:59Z

The series add support for system nickname in interface endpoints and commands. It is possible to connect/disconnect/list interfaces using system, eg:

$ snap interface opengl
name:    opengl
summary: allows access to OpenGL stack
plugs:
  - ohmygiraffe
slots:
  - system
$ diff -up <(snap interfaces core) <(snap interfaces system)
--- /proc/self/fd/11    2018-04-23 14:04:10.598886193 +0200
+++ /proc/self/fd/12    2018-04-23 14:04:10.598886193 +0200
@@ -11,7 +11,7 @@ Slot                       Plug
 :browser-support           -
 :camera                    -
 :classic-support           -
-:core-support              core:core-support-plug
+:core-support              system:core-support-plug
 :cups-control              -
 :dcdbas-control            -
 :desktop                   -
$ snap disconnect system:opengl
$ snap connect ohmygiraffe:opengl system

To preserve the API stability of snapd, the system nickname is silently accepted in operations that modify connections. However, endpoints that return connections/interfaces will not output system by default and instead use core. This is because the daemon cannot tell whether the client is aware of the nickname or not. For simplicity, snap will stransform core to system in snap interfaces output when system was passed in command line. snap interface OTOH uses system by default in its output.

When handling requests that act on something, make sure to accept snap nicknames seamlessly. When returning data on GET requests, do not apply the nicknames so as to not break the API stability. Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

codecov-io · 2018-04-24T11:44:40Z

Codecov Report

Merging #5080 into master will decrease coverage by <.01%.
The diff coverage is 86.66%.

@@            Coverage Diff             @@
##           master    #5080      +/-   ##
==========================================
- Coverage   79.01%   79.01%   -0.01%     
==========================================
  Files         488      489       +1     
  Lines       36477    36597     +120     
==========================================
+ Hits        28823    28917      +94     
- Misses       5369     5388      +19     
- Partials     2285     2292       +7

Impacted Files	Coverage Δ
cmd/snap/cmd_interfaces.go	`85.45% <100%> (+1.45%)`	⬆️
snap/info.go	`79.93% <100%> (+0.52%)`	⬆️
daemon/api.go	`75.83% <57.14%> (+0.18%)`	⬆️
cmd/snap/cmd_interface.go	`79.54% <75%> (ø)`	⬆️
cmd/snap/main.go	`59.47% <0%> (-3.34%)`	⬇️
overlord/ifacestate/handlers.go	`59.65% <0%> (-0.43%)`	⬇️
interfaces/ifacetest/backend.go	`0% <0%> (ø)`	⬆️
client/client.go	`79.32% <0%> (ø)`	⬆️
cmd/snap/cmd_sandbox_features.go	`86.66% <0%> (ø)`
... and 8 more

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stolowski

First pass.

stolowski · 2018-05-10T12:21:59Z

cmd/snap/cmd_interfaces.go

@@ -100,19 +121,20 @@ func (x *cmdInterfaces) Execute(args []string) error {
 		}
 		// The OS snap is special and enable abbreviated
 		// display syntax on the slot-side of the connection.
-		if slot.Snap == "core" || slot.Snap == "ubuntu-core" {
+		if slot.Snap == "core" || slot.Snap == "ubuntu-core" || slot.Snap == snap.Nickname("core") {


We have a growing number of places that do check like this, I wonder if it's time for a helper.

AFAICT this is the only place where all 3 options appear.

stolowski · 2018-05-10T12:39:27Z

cmd/snap/cmd_interfaces.go

+				ok = wantedSnap == slot.Connections[i].Snap
+				if !ok && wantedSnap == snap.Nickname(slot.Connections[i].Snap) {
+					askedWithNick = true
+					ok = true


I think the above checks could use a helper:
matches, askedWithNick := isWantedSnap(snapname)
and the helper would internaly check nickaname as well.

niemeyer

Looks reasonable. Just a few points:

niemeyer · 2018-05-10T19:13:18Z

cmd/snap/cmd_interfaces.go

 			fmt.Fprintf(w, ":%s\t", slot.Name)
 		} else {
-			fmt.Fprintf(w, "%s:%s\t", slot.Snap, slot.Name)
+			fmt.Fprintf(w, "%s:%s\t", maybeAsNickname(slot.Snap, askedWithNick), slot.Name)


Doesn't feel like we gain much from varying here based on the snap. Just feels more magic, which isn't necessarily good. In fact, the case for core, which is the system snap and the only nickname we care about right now, is already special case here in a custom branch right above. So the change seems to introduce extra complexity without much of a win. Plus, this whole command is a bit unfortunate.. we really need that "connections" command we discussed a few times.

So perhaps we should keep this simpler and more straightforward for now.

Are you suggesting I should drop maybeAsNickname() here, as well as where connections and unconnected plugs are printed or just this particular location?

We discussed this on IRC

niemeyer · 2018-05-10T19:15:27Z

daemon/api.go

@@ -1852,6 +1852,13 @@ func changeInterfaces(c *Command, r *http.Request, user *auth.UserState) Respons
 	st.Lock()
 	defer st.Unlock()

+	for i := range a.Plugs {
+		a.Plugs[i].Snap = systemCoreSnapUnalias(a.Plugs[i].Snap)


"alias" means something else in the snap world. Perhaps;

useSnapNick

dropSnapNick

niemeyer · 2018-05-10T19:16:51Z

snap/info.go

+
+// Nickname returns the nickname for given snap name. If there is none, returns
+// the original name.
+func Nickname(snapName string) string {


Isn't this the same function we have above? Can we use the same without cycles?

Also, perhaps similar to the above point:

snap.UseNick

snap.DropNick

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

zyga · 2018-05-14T17:36:53Z

# github.com/snapcore/snapd/daemon
daemon/api_test.go:4113:23: not enough arguments in call to repo.Connect
	have (interfaces.ConnRef)
	want (interfaces.ConnRef, map[string]interface {}, map[string]interface {}, interfaces.PolicyFunc)
daemon/api_test.go:4113:23: multiple-value repo.Connect() in single-value context

…faces-system

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

chipaca

Nice one.

bboozzoo · 2018-05-16T18:29:28Z

This is ready for re-review

mvo5

This looks nice! What I find interesting is that maybe we can use something like snap.UseNick,DropNick also for upcoming installs. The problem is somewhat similar.

There was a certain time span between canonical#5080 being last built and merging it, meanwhile some incompatible changes entered master. Update the tests to accomodate for API changes. Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

bboozzoo added 4 commits April 23, 2018 13:56

snap: helper for getting snap's nickname

0802d53

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

cmd/snap: handle 'system' nickname

c0a8e0e

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

tests/main/snap-interface: account for changes in snap interface output

4fd101b

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

stolowski reviewed May 10, 2018

View reviewed changes

niemeyer requested changes May 10, 2018

View reviewed changes

bboozzoo added 4 commits May 11, 2018 13:25

snap: introduce UseNick/DropNick helpers

1f09441

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

daemon: use snap.DropNick instead of local helpers

591c777

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

cmd/snap: use snap.DropNick/UseNick helpers

977d5f0

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

cmd/snap: simplify nickname handling in interfaces output

e9cc71e

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

bboozzoo added 2 commits May 14, 2018 19:48

Merge remote-tracking branch 'origin/master' into bboozzoo/snap-inter…

c87eafb

…faces-system

daemon: update test to accomodate changes in master

70b0589

Signed-off-by: Maciej Borzecki <maciej.zenon.borzecki@canonical.com>

chipaca approved these changes May 15, 2018

View reviewed changes

bboozzoo requested a review from niemeyer May 18, 2018 06:01

mvo5 approved these changes May 18, 2018

View reviewed changes

niemeyer approved these changes May 22, 2018

View reviewed changes

niemeyer merged commit 58a848f into canonical:master May 22, 2018

bboozzoo mentioned this pull request May 22, 2018

daemon: update unit tests to match current master #5186

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many: support 'system' nickname in interfaces #5080

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many: support 'system' nickname in interfaces #5080

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