How to extract mapped ports from `docker ps`'s output

According to the docker man pages you could try this:

sudo docker ps --format "{{.Ports}}"

or if you also need ID:

sudo docker ps --format "{{.ID}}: {{.Ports}}"

It is not mentioned in the documentation, but to format output you have to use {{}}.

Quote from man docker-ps:

   --format="TEMPLATE"
      Pretty-print containers using a Go template.
      Valid placeholders:
         .ID - Container ID
         .Image - Image ID
         .Command - Quoted command
         .CreatedAt - Time when the container was created.
         .RunningFor - Elapsed time since the container was started.
         .Ports - Exposed ports.
         .Status - Container status.
         .Size - Container disk size.
         .Labels - All labels asigned to the container.
         .Label - Value of a specific label for this container. For example .Label "com.docker.swarm.cpu"

---

Docker 1.10.3

Nowadays, there are a few useful notes about {{}} braces in man docker-ps:

   --format="TEMPLATE"
      Pretty-print containers using a Go template.
      Valid placeholders:
         .ID - Container ID
         .Image - Image ID
         .Command - Quoted command
         .CreatedAt - Time when the container was created.
         .RunningFor - Elapsed time since the container was started.
         .Ports - Exposed ports.
         .Status - Container status.
         .Size - Container disk size.
         .Labels - All labels assigned to the container.
         .Label - Value of a specific label for this container. 
         For example {{.Label "com.docker.swarm.cpu"}}

Display containers with their commands
              # docker ps --format "{{.ID}}: {{.Command}}"
              a87ecb4f327c: /bin/sh -c #(nop) MA
              01946d9d34d8: /bin/sh -c #(nop) MA
              c1d3b0166030: /bin/sh -c yum -y up
              41d50ecd2f57: /bin/sh -c #(nop) MA

Display containers with their labels in a table
              # docker ps --format "table {{.ID}}\t{{.Labels}}"
              CONTAINER ID        LABELS
              a87ecb4f327c        com.docker.swarm.node=ubuntu,com.docker.swarm.storage=ssd
              01946d9d34d8
              c1d3b0166030        com.docker.swarm.node=debian,com.docker.swarm.cpu=6
              41d50ecd2f57        com.docker.swarm.node=fedora,com.docker.swarm.cpu=3,com.docker.swarm.storage=ssd

Display containers with their node label in a table
              # docker ps --format 'table {{.ID}}\t{{(.Label "com.docker.swarm.node")}}'
              CONTAINER ID        NODE
              a87ecb4f327c        ubuntu
              01946d9d34d8
              c1d3b0166030        debian
              41d50ecd2f57        fedora

Using Perl:

sudo docker ps | \
tail -n 1 | \
perl -lae '$,="\n";foreach(@F){/tcp,?$/&&push(@x,$_)};print(@x)'

• -l: enables automatic line-ending processing. It has two separate effects. First, it automatically chomps $/ (the input record separator) when used with -n or -p. Second, it assigns $\ (the output record separator) to have the value of octnum so that any print statements will have that separator added back on. If octnum is omitted, sets $\ to the current value of $/.
• -a: turns on autosplit mode when used with a -n or -p. An implicit split command to the @F array is done as the first thing inside the implicit while loop produced by the -n or -p.
• -e: may be used to enter one line of program.
• $,="\n": sets the output field separator to \n;
• foreach(@F){/tcp,?$/&&push(@x,$_)}: for each element of @F, if the element ends with tcp followed by an optional , adds the element at the end of @x;
• print(@x): prints each element of @x followed by the output field separator;

% cat in
29ba3137f3e2        java8/local:latest   "/bin/bash"         3 hours ago         Up 3 hours          foo/tcp, 0.0.0.0:8443->8443/tcp, 0.0.0.0:32783->5432/tcp, 0.0.0.0:32782->10523/tcp   DEMO-20151118124751
29ba3137f3e2        java8/local:latest   "/bin/bash"         3 hours ago         Up 3 hours          0.0.0.0:8080->8080/tcp, 0.0.0.0:8443->8443/tcp, 0.0.0.0:32783->5432/tcp, 0.0.0.0:32782->10523/tcp   DEMO-20151118124751
29ba3137f3e2        java8/local:latest   "/bin/bash"         3 hours ago         Up 3 hours          0.0.0.0:8080->8080/tcp, 0.0.0.0:8443->8443/tcp, 0.0.0.0:32783->5432/tcp, 0.0.0.0:32782->10523/tcp   DEMO-20151118124751
% tail -n 1 in | perl -lae '$,="\n";foreach(@F){/tcp,?$/&&push(@x,$_)};print(@x)'
0.0.0.0:8080->8080/tcp,
0.0.0.0:8443->8443/tcp,
0.0.0.0:32783->5432/tcp,
0.0.0.0:32782->10523/tcp

Using awk with the field delimiter {2,}. Why {2,}? the output of ps uses more than one space as separator between the columns. Means, we can use this as separator for the awk command.

awk -F" {2,}" '{print $6}'

or for your ps command

sudo docker ps | tail -n1 | awk -F" {2,}" '{print $6}'

or without tail

sudo docker ps | awk -F" {2,}" 'END {print $6}'

---

Sample output

% <<<'29ba3137f3e2        java8/local:latest   "/bin/bash"         3 hours ago         Up 3 hours          0.0.0.0:8080->8080/tcp, 0.0.0.0:8443->8443/tcp, 0.0.0.0:32783->5432/tcp, 0.0.0.0:32782->10523/tcp   DEMO-20151118124751' \
awk -F" {2,}" '{print $6}'
0.0.0.0:8080->8080/tcp, 0.0.0.0:8443->8443/tcp, 0.0.0.0:32783->5432/tcp, 0.0.0.0:32782->10523/tcp

or

% <<<'29ba3137f3e2        java8/local:latest   "/bin/bash"         3 hours ago         Up 3 hours          0.0.0.0:8080->8080/tcp, 0.0.0.0:8443->8443/tcp, 0.0.0.0:32783->5432/tcp, 0.0.0.0:32782->10523/tcp   DEMO-20151118124751' \
    awk -F" {2,}" '{print $6}' |\
    tr ' ' '\n'
0.0.0.0:8080->8080/tcp,
0.0.0.0:8443->8443/tcp,
0.0.0.0:32783->5432/tcp,
0.0.0.0:32782->10523/tcp