`docker info --format` panic

[rumpl]

Description

The cli panics when I run docker info --format '{{.LoggingDriver}}' while the daemon is not running.

Steps to reproduce the issue:

1. stop the daemon
2. run docker info --format '{{.LoggingDriver}}'

Describe the results you received:

panic: reflect: indirection through nil pointer to embedded struct [recovered]
	panic: reflect: indirection through nil pointer to embedded struct

goroutine 1 [running]:
text/template.errRecover(0xc0007972e8)
	/usr/local/go/src/text/template/exec.go:169 +0x1c5
panic(0x10ec3d780, 0x10ef37608)
	/usr/local/go/src/runtime/panic.go:965 +0x1b9
reflect.Value.FieldByIndex(0x10edd5720, 0xc000a10100, 0x99, 0xc0007b8230, 0x2, 0x2, 0x0, 0x10efc66e8, 0x10ec3d780)
	/usr/local/go/src/reflect/value.go:889 +0x325
text/template.(*state).evalField(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0x7ff7b2c56537, 0xd, 0x10efb0300, 0xc000a143c0, 0xc000230120, 0x1, ...)
	/usr/local/go/src/text/template/exec.go:616 +0x4ed
text/template.(*state).evalFieldChain(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0x10edd5720, 0xc000a10100, 0x99, 0x10efb0300, 0xc000a143c0, 0xc000230110, ...)
	/usr/local/go/src/text/template/exec.go:569 +0x225
text/template.(*state).evalFieldNode(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0xc000a143c0, 0xc000230120, 0x1, 0x1, 0x10eccbe40, 0x10fd457b0, ...)
	/usr/local/go/src/text/template/exec.go:533 +0x113
text/template.(*state).evalCommand(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0xc000a14390, 0x10eccbe40, 0x10fd457b0, 0x99, 0xd0, 0xc0007b2820, ...)
	/usr/local/go/src/text/template/exec.go:461 +0x8f0
text/template.(*state).evalPipeline(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0xc000a16660, 0x10d8d91b6, 0xc0000c0378, 0xc000a100c0)
	/usr/local/go/src/text/template/exec.go:435 +0x125
text/template.(*state).walk(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0x10efb0108, 0xc000a143f0)
	/usr/local/go/src/text/template/exec.go:254 +0x38a
text/template.(*state).walk(0xc000797258, 0x10edd5720, 0xc000a10100, 0x99, 0x10efb03d8, 0xc000a14360)
	/usr/local/go/src/text/template/exec.go:263 +0x13c
text/template.(*Template).execute(0xc000a100c0, 0x10ef56bd8, 0xc00021b6e0, 0x10edd5720, 0xc000a10100, 0x0, 0x0)
	/usr/local/go/src/text/template/exec.go:217 +0x1c6
text/template.(*Template).Execute(...)
	/usr/local/go/src/text/template/exec.go:200
github.com/docker/cli/cli/command/system.formatInfo(0x10efc35a8, 0xc0004b0410, 0x0, 0xc0007a2010, 0x1, 0x1, 0xc0007aa000, 0x0, 0x0, 0x0, ...)
	/go/src/github.com/docker/cli/cli/command/system/info.go:511 +0x1fd
github.com/docker/cli/cli/command/system.runInfo(0xc0004238c0, 0x10efc35a8, 0xc0004b0410, 0xc00042c1f0, 0x0, 0x0)
	/go/src/github.com/docker/cli/cli/command/system/info.go:88 +0x3a5
github.com/docker/cli/cli/command/system.NewInfoCommand.func1(0xc0004238c0, 0xc0009ab300, 0x0, 0x2, 0x0, 0x0)
	/go/src/github.com/docker/cli/cli/command/system/info.go:54 +0x46
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).execute(0xc0004238c0, 0xc000427cf0, 0x2, 0x2, 0xc0004238c0, 0xc000427cf0)
	/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:850 +0x472
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0xc0001ea580, 0xc000427ce0, 0x3, 0x3)
	/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:958 +0x375
github.com/docker/cli/vendor/github.com/spf13/cobra.(*Command).Execute(...)
	/go/src/github.com/docker/cli/vendor/github.com/spf13/cobra/command.go:895
main.runDocker(0xc0004b0410, 0x10ef59138, 0xc000010020)
	/go/src/github.com/docker/cli/cmd/docker/docker.go:287 +0x1eb
main.main()
	/go/src/github.com/docker/cli/cmd/docker/docker.go:298 +0xfc

Describe the results you expected:

I would expect an error message saying that the engine is not running.

Additional information you deem important (e.g. issue happens only occasionally):

Output of docker version:

❯ docker version
Client:
 Cloud integration: v1.0.24
 Version:           20.10.14
 API version:       1.41
 Go version:        go1.16.15
 Git commit:        a224086
 Built:             Thu Mar 24 01:49:20 2022
 OS/Arch:           darwin/amd64
 Context:           default
 Experimental:      true

Server: Docker Desktop 4.8.0 (78653)
 Engine:
  Version:          20.10.14
  API version:      1.41 (minimum version 1.12)
  Go version:       go1.16.15
  Git commit:       87a90dc
  Built:            Thu Mar 24 01:46:14 2022
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          1.5.11
  GitCommit:        3df54a852345ae127d1fa3092b95168e4a88e2f8
 runc:
  Version:          1.0.3
  GitCommit:        v1.0.3-0-gf46b6ba
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

Output of docker info:

Client:
 Context:    default
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc., v0.8.2)
  compose: Docker Compose (Docker Inc., v2.5.0)
  sbom: View the packaged-based Software Bill Of Materials (SBOM) for an image (Anchore Inc., 0.6.0)
  scan: Docker Scan (Docker Inc., v0.17.0)

Server:
 Containers: 2
  Running: 2
  Paused: 0
  Stopped: 0
 Images: 20
 Server Version: 20.10.14
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Native Overlay Diff: true
  userxattr: false
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 io.containerd.runtime.v1.linux runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 3df54a852345ae127d1fa3092b95168e4a88e2f8
 runc version: v1.0.3-0-gf46b6ba
 init version: de40ad0
 Security Options:
  seccomp
   Profile: default
  cgroupns
 Kernel Version: 5.10.104-linuxkit
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 6
 Total Memory: 7.676GiB
 Name: docker-desktop
 ID: HTHB:QB5O:AI5F:CQLN:XY7W:5C4M:25BF:WXJK:ZE2O:XOKF:EKZC:A3EH
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 No Proxy: hubproxy.docker.internal
 Registry: https://index.docker.io/v1/
 Labels:
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5000
  127.0.0.0/8
 Live Restore Enabled: false

[thaJeztah]

Looks like master no longer panics, but some improvements could be made to handling (related to #3179);

docker -H tcp://127.0.0.1:2375 info --format '{{.LoggingDriver}}'

template: :1:2: executing "" at <.LoggingDriver>: reflect: indirection through nil pointer to embedded struct field Info

[thaJeztah]

opened #3594 for the above

[rumpl]

Closing since #3594 is merged

[thaJeztah]

The 20.10 branch would still have the issue, but (unless there's a very small fix) I think it's too minor of an issue to fix (nobody reported the issue in ~2 years, so I don't expect many to have run into this problem)