Format command and log output
Docker supports Go templates which you can use to manipulate the output format of certain commands and log drivers.
Docker provides a set of basic functions to manipulate template elements.
All of these examples use the docker inspect
command, but many other CLI
commands have a --format
flag, and many of the CLI command references
include examples of customizing the output format.
Note
When using the
--format
flag, you need observe your shell environment. In a POSIX shell, you can run the following with a single quote:$ docker inspect --format '{{join .Args " , "}}'
Otherwise, in a Windows shell (for example, PowerShell), you need to use single quotes, but escape the double quotes inside the parameters as follows:
$ docker inspect --format '{{join .Args \" , \"}}'
join
join
concatenates a list of strings to create a single string.
It puts a separator between each element in the list.
$ docker inspect --format '{{join .Args " , "}}' container
table
table
specifies which fields you want to see its output.
$ docker image list --format "table {{.ID}}\t{{.Repository}}\t{{.Tag}}\t{{.Size}}"
json
json
encodes an element as a json string.
$ docker inspect --format '{{json .Mounts}}' container
lower
lower
transforms a string into its lowercase representation.
$ docker inspect --format "{{lower .Name}}" container
split
split
slices a string into a list of strings separated by a separator.
$ docker inspect --format '{{split .Image ":"}}' container
title
title
capitalizes the first character of a string.
$ docker inspect --format "{{title .Name}}" container
upper
upper
transforms a string into its uppercase representation.
$ docker inspect --format "{{upper .Name}}" container
println
println
prints each value on a new line.
$ docker inspect --format='{{range .NetworkSettings.Networks}}{{println .IPAddress}}{{end}}' container
Hint
To find out what data can be printed, show all content as json:
$ docker container ls --format='{{json .}}'