Calling inspect with a {{json .}} template doesn't unwrap the object

[ValentinParamonov]

Is this a BUG REPORT or FEATURE REQUEST? (leave only one on its own line)

/kind bug

Description

Steps to reproduce the issue:

1. Call podman inspect -f '{{json .}}' busybox

Describe the results you received:

A JSON array with a single object inside of it:

[
     {
          "Id": "bc01a3326866eedd68525a4d2d91d2cf86f9893db054601d6be524d5c9d03981",
          "Digest": "sha256:6bdd92bf5240be1b5f3bf71324f5e371fe59f0e153b27fa1f1620f78ba16963c",
          "RepoTags": [
               "docker.io/library/busybox:latest"
          ],
          "RepoDigests": [
               "docker.io/library/busybox@sha256:6bdd92bf5240be1b5f3bf71324f5e371fe59f0e153b27fa1f1620f78ba16963c",
               "docker.io/library/busybox@sha256:dacd1aa51e0b27c0e36c4981a7a8d9d8ec2c4a74bf125c0a44d0709497a522e9"
          ],
          "Parent": "",
          "Comment": "",
          "Created": "2022-10-26T06:30:33.794221299Z",
          "Config": {
               "Env": [
                    "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
               ],
               "Cmd": [
                    "sh"
               ]
          },
          "Version": "20.10.12",
          "Author": "",
          "Architecture": "amd64",
          "Os": "linux",
          "Size": 1464006,
          "VirtualSize": 1464006,
          "GraphDriver": {
               "Name": "overlay",
               "Data": {
                    "UpperDir": "/home/valentine/.local/share/containers/storage/overlay/0438ade5aeea533b00cd75095bec75fbc2b307bace4c89bb39b75d428637bcd8/diff",
                    "WorkDir": "/home/valentine/.local/share/containers/storage/overlay/0438ade5aeea533b00cd75095bec75fbc2b307bace4c89bb39b75d428637bcd8/work"
               }
          },
          "RootFS": {
               "Type": "layers",
               "Layers": [
                    "sha256:0438ade5aeea533b00cd75095bec75fbc2b307bace4c89bb39b75d428637bcd8"
               ]
          },
          "Labels": null,
          "Annotations": {},
          "ManifestType": "application/vnd.docker.distribution.manifest.v2+json",
          "User": "",
          "History": [
               {
                    "created": "2022-10-26T06:30:33.700079457Z",
                    "created_by": "/bin/sh -c #(nop) ADD file:5e991de3200129dc05c3130f7a64bebb5704486b4f773bfcaa6b13165d6c2416 in / "
               },
               {
                    "created": "2022-10-26T06:30:33.794221299Z",
                    "created_by": "/bin/sh -c #(nop)  CMD [\"sh\"]",
                    "empty_layer": true
               }
          ],
          "NamesHistory": [
               "docker.io/library/busybox:latest"
          ]
     }
]

Describe the results you expected:

I'd expect the output to be the same as docker's (not sure about the formatting, but the object should be unwrapped):

docker inspect -f '{{json .}}' busybox

produces

{"Id":"sha256:bc01a3326866eedd68525a4d2d91d2cf86f9893db054601d6be524d5c9d03981","RepoTags":["busybox:latest"],"RepoDigests":["busybox@sha256:6bdd92bf5240be1b5f3bf71324f5e371fe59f0e153b27fa1f1620f78ba16963c"],"Parent":"","Comment":"","Created":"2022-10-26T06:30:33.794221299Z","Container":"773c16077d49e716d62d584e90b21a0c0d5807680177b879bf28b6a1f997966c","ContainerConfig":{"Hostname":"773c16077d49","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"],"Cmd":["/bin/sh","-c","#(nop) ","CMD [\"sh\"]"],"Image":"sha256:bd903b2b2a1001a80d9d50f9c3d77c648184cc89bdb622b84d59790ff6ee1f40","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":{}},"DockerVersion":"20.10.12","Author":"","Config":{"Hostname":"","Domainname":"","User":"","AttachStdin":false,"AttachStdout":false,"AttachStderr":false,"Tty":false,"OpenStdin":false,"StdinOnce":false,"Env":["PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"],"Cmd":["sh"],"Image":"sha256:bd903b2b2a1001a80d9d50f9c3d77c648184cc89bdb622b84d59790ff6ee1f40","Volumes":null,"WorkingDir":"","Entrypoint":null,"OnBuild":null,"Labels":null},"Architecture":"amd64","Os":"linux","Size":1239772,"VirtualSize":1239772,"GraphDriver":{"Data":{"MergedDir":"/home/valentine/.docker/volumes/overlay2/6821b031fdaa32d2ebcb280213baab919f7e179d36fc4f8bb309ef46971f7102/merged","UpperDir":"/home/valentine/.docker/volumes/overlay2/6821b031fdaa32d2ebcb280213baab919f7e179d36fc4f8bb309ef46971f7102/diff","WorkDir":"/home/valentine/.docker/volumes/overlay2/6821b031fdaa32d2ebcb280213baab919f7e179d36fc4f8bb309ef46971f7102/work"},"Name":"overlay2"},"RootFS":{"Type":"layers","Layers":["sha256:0438ade5aeea533b00cd75095bec75fbc2b307bace4c89bb39b75d428637bcd8"]},"Metadata":{"LastTagTime":"0001-01-01T00:00:00Z"}}

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

Output of podman version:

Client:       Podman Engine
Version:      4.3.0
API Version:  4.3.0
Go Version:   go1.19.2
Git Commit:   ad42af94903ce4f3c3cd0693e4e17e4286bf094b-dirty
Built:        Thu Oct 20 00:09:30 2022
OS/Arch:      linux/amd64

Output of podman info:

host:
  arch: amd64
  buildahVersion: 1.28.0
  cgroupControllers:
  - memory
  - pids
  cgroupManager: systemd
  cgroupVersion: v2
  conmon:
    package: /usr/bin/conmon is owned by conmon 1:2.1.5-1
    path: /usr/bin/conmon
    version: 'conmon version 2.1.5, commit: c9f7f19eb82d5b8151fc3ba7fbbccf03fdcd0325'
  cpuUtilization:
    idlePercent: 96.93
    systemPercent: 0.43
    userPercent: 2.64
  cpus: 16
  distribution:
    distribution: arch
    version: unknown
  eventLogger: journald
  hostname: kame
  idMappings:
    gidmap:
    - container_id: 0
      host_id: 1001
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
    uidmap:
    - container_id: 0
      host_id: 1001
      size: 1
    - container_id: 1
      host_id: 100000
      size: 65536
  kernel: 6.0.7-arch1-1
  linkmode: dynamic
  logDriver: journald
  memFree: 26904285184
  memTotal: 67123310592
  networkBackend: netavark
  ociRuntime:
    name: crun
    package: /usr/bin/crun is owned by crun 1.6-1
    path: /usr/bin/crun
    version: |-
      crun version 1.6
      commit: 18cf2efbb8feb2b2f20e316520e0fd0b6c41ef4d
      spec: 1.0.0
      +SYSTEMD +SELINUX +APPARMOR +CAP +SECCOMP +EBPF +CRIU +YAJL
  os: linux
  remoteSocket:
    exists: true
    path: /run/user/1001/podman/podman.sock
  security:
    apparmorEnabled: false
    capabilities: CAP_CHOWN,CAP_DAC_OVERRIDE,CAP_FOWNER,CAP_FSETID,CAP_KILL,CAP_NET_BIND_SERVICE,CAP_SETFCAP,CAP_SETGID,CAP_SETPCAP,CAP_SETUID,CAP_SYS_CHROOT
    rootless: true
    seccompEnabled: true
    seccompProfilePath: /etc/containers/seccomp.json
    selinuxEnabled: false
  serviceIsRemote: false
  slirp4netns:
    executable: /usr/bin/slirp4netns
    package: /usr/bin/slirp4netns is owned by slirp4netns 1.2.0-1
    version: |-
      slirp4netns version 1.2.0
      commit: 656041d45cfca7a4176f6b7eed9e4fe6c11e8383
      libslirp: 4.7.0
      SLIRP_CONFIG_VERSION_MAX: 4
      libseccomp: 2.5.4
  swapFree: 68719472640
  swapTotal: 68719472640
  uptime: 11h 35m 41.00s (Approximately 0.46 days)
plugins:
  authorization: null
  log:
  - k8s-file
  - none
  - passthrough
  - journald
  network:
  - bridge
  - macvlan
  volume:
  - local
registries:
  search:
  - registry.fedoraproject.org
  - registry.access.redhat.com
  - registry.centos.org
  - docker.io
store:
  configFile: /home/valentine/.config/containers/storage.conf
  containerStore:
    number: 1
    paused: 0
    running: 1
    stopped: 0
  graphDriverName: overlay
  graphOptions: {}
  graphRoot: /home/valentine/.local/share/containers/storage
  graphRootAllocated: 442297745408
  graphRootUsed: 153486311424
  graphStatus:
    Backing Filesystem: btrfs
    Native Overlay Diff: "true"
    Supports d_type: "true"
    Using metacopy: "false"
  imageCopyTmpDir: /var/tmp
  imageStore:
    number: 49
  runRoot: /run/user/1001/containers
  volumePath: /home/valentine/.local/share/containers/storage/volumes
version:
  APIVersion: 4.3.0
  Built: 1666213770
  BuiltTime: Thu Oct 20 00:09:30 2022
  GitCommit: ad42af94903ce4f3c3cd0693e4e17e4286bf094b-dirty
  GoVersion: go1.19.2
  Os: linux
  OsArch: linux/amd64
  Version: 4.3.0

Package info (pacman -Q podman):

podman 4.3.0-1

Have you tested with the latest version of Podman and have you checked the Podman Troubleshooting Guide? (https://github.com/containers/podman/blob/main/troubleshooting.md)

Yes

[ValentinParamonov]

Basically, {{json .}} should be treated the same way as {{. | json}}.

[Luap99]

Yes currently {{json .}} is considered the same as json. As you noted this is not correct when the output is an array.
I take a look.

[frippe75]

Should I open a new issue or add to this?

The fix may have addressed the reported issue. But taking it a step further the podman-inspect man pages clearly have a few examples where using a JSON path type of a query allows limiting the out to what you really need.

$ docker network inspect -f '{{ json . }}' kind
Emulate Docker CLI using podman. Create /etc/containers/nodocker to quiet msg.
[
     {
          "name": "kind",
          "id": "751e7c3199a91d12c23af8d0a2ae1b710896259f8ff8e40515f3687431492919",
          "driver": "bridge",
          "network_interface": "podman1",
          "created": "2023-02-04T15:43:58.694036133+01:00",
          "subnets": [
               {
                    "subnet": "fc00:f853:ccd:e793::/64",
                    "gateway": "fc00:f853:ccd:e793::1"
               },
               {
                    "subnet": "10.89.0.0/24",
                    "gateway": "10.89.0.1"
               }
          ],
          "ipv6_enabled": true,
          "internal": false,
          "dns_enabled": true,
          "ipam_options": {
               "driver": "host-local"
          }
     }
]

I am then trying to target the name field.

$ docker network inspect -f '{{ json .name }}' kind
Error: inspecting object: printing inspect output: template: inspect:1:19: executing "inspect" at <.name>: can't evaluate field name in type interface {}

Running a similar command on a non podman host

docker inspect -f '{{ json . }}' host
{"Name":"host","Id":"08dccc8f8f27039b95a6e7bfa7611ac3590f5992e8637625249d1e772549cf64","Created":"2022-11-25T21:10:47.039558663+01:00","Scope":"local","Driver":"host","EnableIPv6":false,"IPAM":{"Driver":"default","Options":null,"Config":[]},"Internal":false,"Attachable":false,"Ingress":false,"ConfigFrom":{"Network":""},"ConfigOnly":false,"Containers":{},"Options":{},"Labels":{}}

Docker is not returning the output as an array of a single object with a document in that first element. Just a JSON doc, nothing more.

Targeting the "Name" works as expectred.

$ docker inspect -f '{{ json .Name }}' host
"host"

[rhatdan]

Yes new issue.