Inspecting a running container
Syntax#
- docker inspect [OPTIONS] CONTAINER|IMAGE [CONTAINER|IMAGE…]
Get container information
To get all the information for a container you can run:
docker inspect <container>Get specific information from a container
You can get an specific information from a container by running:
docker inspect -f '<format>' <container>For instance, you can get the Network Settings by running:
docker inspect -f '{{ .NetworkSettings }}' <container>You can also get just the IP address:
docker inspect -f '{{ .NetworkSettings.IPAddress }}' <container>The parameter -f means format and will receive a Go Template as input to format what is expected, but this won’t bring a beautiful return, so try:
docker inspect -f '{{ json .NetworkSettings }}' {{containerIdOrName}}the json keyword will bring the return as a JSON.
So to finish, a little tip is to use python in there to format the output JSON:
docker inspect -f '{{ json .NetworkSettings }}' <container> | python -mjson.toolAnd voila, you can query anything on the docker inspect and make it look pretty in your terminal.
It’s also possible to use a utility called ”jq” in order to help process docker inspect command output.
docker inspect -f '{{ json .NetworkSettings }}' aa1 | jq [.Gateway]The above command will return the following output:
[
"172.17.0.1"
]This output is actually a list containing one element. Sometimes, docker inspect displays a list of several elements, and you may want to refer to a specific element. For example, if Config.Env contains several elements, you can refer to the first element of this list using index:
docker inspect --format '{{ index (index .Config.Env) 0 }}' <container>The first element is indexed at zero, which means that the second element of this list is at index 1:
docker inspect --format '{{ index (index .Config.Env) 1 }}' <container>Using len it is possible to get the number of elements of the list:
docker inspect --format ‘{{ len .Config.Env }}’ <container>And using negative numbers, it’s possible to refer to the last element of the list:
docker inspect –format “{{ index .Config.Cmd $[$(docker inspect –format ‘{{ len .Config.Cmd }}’ <container>)-1]}}” <container>Some docker inspect information comes as a dictionary of key:value, here is an extract of a
docker inspectof a jess/spotify running container
"Config": {
"Hostname": "8255f4804dde",
"Domainname": "",
"User": "spotify",
"AttachStdin": false,
"AttachStdout": false,
"AttachStderr": false,
"Tty": false,
"OpenStdin": false,
"StdinOnce": false,
"Env": [
"DISPLAY=unix:0",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
"HOME=/home/spotify"
],
"Cmd": [
"-stylesheet=/home/spotify/spotify-override.css"
],
"Image": "jess/spotify",
"Volumes": null,
"WorkingDir": "/home/spotify",
"Entrypoint": [
"spotify"
],
"OnBuild": null,
"Labels": {}
},
so I an get the values of the whole Config section
docker inspect -f '{{.Config}}' 825
{8255f4804dde spotify false false false map[] false false false [DISPLAY=unix:0 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin HOME=/home/spotify] [-stylesheet=/home/spotify/spotify-override.css] false jess/spotify map[] /home/spotify [spotify] false [] map[] }
but also a single field, like the value of Config.Image
docker inspect -f '{{index (.Config) "Image" }}' 825
jess/spotify
or Config.Cmd
docker inspect -f '{{.Config.Cmd}}' 825
[-stylesheet=/home/spotify/spotify-override.css]
Inspect an image
Printing specific informations
Debugging the container logs using docker inspect
Examining stdout/stderr of a running container
docker logs --follow <containerid>This tails the output of the running container. This is useful if you did not set up a logging driver on the docker daemon.