Executing a snap binary from the Node snap distribution

[mortenpi]

I am running into a strange problem with the snap distribution of Node on Ubuntu 18.04. For some reason the child_process module is not able to exec other snap programs if they are started with the snap binary (including via the /snap/bin symlinks). To reproduce:

1. Install the hello and node snaps:

   sudo snap install hello
   sudo snap install node --classic --channel=8/stable

2. Run the hello command with child_process.exec:

   > chp = require("child_process")
   > chp.exec("hello -v", function(x,y,z){console.log(x,y,z);})
   

   With this setup I am getting the following error:

   > { Error: Command failed: hello -v
   
       at ChildProcess.exithandler (child_process.js:282:12)
       at ChildProcess.emit (events.js:182:13)
       at ChildProcess.EventEmitter.emit (domain.js:460:23)
       at maybeClose (internal/child_process.js:957:16)
       at Process.ChildProcess._handle.onexit (internal/child_process.js:246:5) killed: false, code: 1, signal: null, cmd: 'hello -v' } '' ''
   

   instead of seeing

   > null 'Hello, world!\n' ''
   

Additionally:

• Running non-snap commands seems to work fine (e.g. chp.exec("ls")
• If you give the full path to the snap binary, it works as expected:

  > chp.exec("/snap/hello/current/bin/hello", function(x,y,z){console.log(x,y,z);})
  > null 'Hello, world!\n' ''
  

• I tried both v8.11.1 and v11.0.0-nightly2018051220509ebee6 snap distributions -- both have the issue.
• Everything works as expected with the v8.11.1 64-bit Linux binaries from the Node.js website.

Versions:

$ snap version
snap    2.32.6
snapd   2.32.6
series  16
ubuntu  18.04
kernel  4.15.0-20-generic

[true0r]

I have similar problem. I spent a lot of time reading the code and debugging, figuring out what was happening in one of the npm modules.

$ snap version
snap    2.38+19.04
snapd   2.38+19.04
series  16
ubuntu  19.04
kernel  5.0.0-11-generic

$ node -v
v10.15.3

[ivoanjo]

I'm having exactly the same problem when using the aws cdk installed via the node snap: whenever it tries to exec() npm to perform some of the operations it uses it fails.

Example output:

anjoivo:~/workspaces/experiments/hellocdk$ cdk ls
[INFO] Scanning for projects...
...
Could not run version check due to error Command failed: npm view aws-cdk version

[xbao]

Ran into this too. Took me a while to figure out it was the snap layer where it was breaking. I don't know how to fix it, here's some more debugging info:

Running

NODE_DEBUG=CHILD_PROCESS node -e 'require("child_process").exec("/snap/bin/hello-world")'

gives:

CHILD_PROCESS 14802: spawn [ '/bin/sh', '-c', '/snap/bin/hello-world' ] { cwd: null,
  env: null,
  gid: undefined,
  uid: undefined,
  shell: true,
  windowsHide: false,
  windowsVerbatimArguments: false }

and generates a bunch of denies in /var/log/syslog:

Sep  2 14:07:02 pop-os kernel: [16630.420153] audit: type=1400 audit(1567390022.342:323): apparmor="DENIED" operation="file_inherit" profile="/snap/core/7396/usr/lib/snapd/snap-confine" pid=15086 comm="snap-confine" family="unix" sock_type="stream" protocol=0 requested_mask="send receive" denied_mask="send receive" addr=none peer_addr=none
Sep  2 14:07:02 pop-os kernel: [16630.420155] audit: type=1400 audit(1567390022.342:324): apparmor="DENIED" operation="file_inherit" profile="/snap/core/7396/usr/lib/snapd/snap-confine" pid=15086 comm="snap-confine" family="unix" sock_type="stream" protocol=0 requested_mask="send receive" denied_mask="send receive" addr=none peer_addr=none
Sep  2 14:07:02 pop-os kernel: [16630.420157] audit: type=1400 audit(1567390022.342:325): apparmor="DENIED" operation="file_inherit" profile="/snap/core/7396/usr/lib/snapd/snap-confine" pid=15086 comm="snap-confine" family="unix" sock_type="stream" protocol=0 requested_mask="send receive" denied_mask="send receive" addr=none peer_addr=none
Sep  2 14:07:02 pop-os kernel: [16630.420991] audit: type=1400 audit(1567390022.342:326): apparmor="DENIED" operation="open" profile="/snap/core/7396/usr/lib/snapd/snap-confine" name="/etc/pop-os/os-release" pid=15086 comm="snap-confine" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
Sep  2 14:07:02 pop-os kernel: [16630.422729] audit: type=1400 audit(1567390022.346:327): apparmor="DENIED" operation="file_inherit" profile="snap.hello-world.hello-world" name="/apparmor/.null" pid=15086 comm="snap-exec" requested_mask="wr" denied_mask="wr" fsuid=1000 ouid=0
Sep  2 14:07:02 pop-os kernel: [16630.422731] audit: type=1400 audit(1567390022.346:328): apparmor="DENIED" operation="file_inherit" profile="snap.hello-world.hello-world" name="/apparmor/.null" pid=15086 comm="snap-exec" requested_mask="wr" denied_mask="wr" fsuid=1000 ouid=0
Sep  2 14:07:02 pop-os kernel: [16630.422732] audit: type=1400 audit(1567390022.346:329): apparmor="DENIED" operation="file_inherit" profile="snap.hello-world.hello-world" name="/apparmor/.null" pid=15086 comm="snap-exec" requested_mask="wr" denied_mask="wr" fsuid=1000 ouid=0
Sep  2 14:07:02 pop-os kernel: [16630.423598] audit: type=1400 audit(1567390022.346:330): apparmor="DENIED" operation="open" profile="snap.hello-world.hello-world" name="/etc/pop-os/os-release" pid=15086 comm="snap-exec" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0

Running the command that's spawned by node manually works (prints out 'Hello World!') with two denies in /var/log/syslog:

Sep  2 14:08:04 pop-os kernel: [16692.778119] audit: type=1400 audit(1567390084.698:331): apparmor="DENIED" operation="open" profile="/snap/core/7396/usr/lib/snapd/snap-confine" name="/etc/pop-os/os-release" pid=15242 comm="snap-confine" requested_mask="r" denied_mask="r" fsuid=0 ouid=0
Sep  2 14:08:04 pop-os kernel: [16692.780559] audit: type=1400 audit(1567390084.702:332): apparmor="DENIED" operation="open" profile="snap.hello-world.hello-world" name="/etc/pop-os/os-release" pid=15242 comm="snap-exec" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0

I'm running Node 10.16.1 on Pop!_OS 19.04 (Ubuntu derivative), notes from node info --verbose snap:

notes:               
  private:           false
  confinement:       classic
  devmode:           false
  jailmode:          false
  trymode:           false
  enabled:           true
  broken:            false
  ignore-validation: false

[colonelchlorine]

Failing for me as well. Had to opt out of snap and found a way to install an up-to-date version of NodeJS, npm, npx via apt instead.

curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -
sudo apt-get install -y nodejs

[jdstrand]

FYI, this seems to be https://bugs.launchpad.net/snapd/+bug/1835805