How can I find a Docker image with a specific tag in Docker registry on the Docker command line?

Solution 1:

When using CoreOS, jq is available to parse JSON data.

So like you were doing before, looking at library/centos:

$ curl -s -S 'https://registry.hub.docker.com/v2/repositories/library/centos/tags/' | jq '."results"[]["name"]' |sort
"6"
"6.7"
"centos5"
"centos5.11"
"centos6"
"centos6.6"
"centos6.7"
"centos7.0.1406"
"centos7.1.1503"
"latest"

The cleaner v2 API is available now, and that's what I'm using in the example. I will build a simple script docker_remote_tags:

#!/usr/bin/bash
curl -s -S "https://registry.hub.docker.com/v2/repositories/library/$@/tags/" | jq '."results"[]["name"]' |sort

Enables:

$ ./docker_remote_tags library/centos
"6"
"6.7"
"centos5"
"centos5.11"
"centos6"
"centos6.6"
"centos6.7"
"centos7.0.1406"
"centos7.1.1503"
"latest"

Reference:

jq: https://stedolan.github.io/jq/ | apt-get install jq

Solution 2:

I didn't like any of the solutions above because A) they required external libraries that I didn't have and didn't want to install. B) I didn't get all the pages.

The Docker API limits you to 100 items per request. This will loop over each "next" item and get them all (for Python it's seven pages; other may be more or less... It depends)

If you really want to spam yourself, remove | cut -d '-' -f 1 from the last line, and you will see absolutely everything.

url=https://registry.hub.docker.com/v2/repositories/library/redis/tags/?page_size=100 `# Initial url` ; \
( \
  while [ ! -z $url ]; do `# Keep looping until the variable url is empty` \
    >&2 echo -n "." `# Every iteration of the loop prints out a single dot to show progress as it got through all the pages (this is inline dot)` ; \
    content=$(curl -s $url | python -c 'import sys, json; data = json.load(sys.stdin); print(data.get("next", "") or ""); print("\n".join([x["name"] for x in data["results"]]))') `# Curl the URL and pipe the output to Python. Python will parse the JSON and print the very first line as the next URL (it will leave it blank if there are no more pages) then continue to loop over the results extracting only the name; all will be stored in a variable called content` ; \
    url=$(echo "$content" | head -n 1) `# Let's get the first line of content which contains the next URL for the loop to continue` ; \
    echo "$content" | tail -n +2 `# Print the content without the first line (yes +2 is counter intuitive)` ; \
  done; \
  >&2 echo `# Finally break the line of dots` ; \
) | cut -d '-' -f 1 | sort --version-sort | uniq;

Sample output:

$ url=https://registry.hub.docker.com/v2/repositories/library/redis/tags/?page_size=100 `#initial url` ; \
> ( \
>   while [ ! -z $url ]; do `#Keep looping until the variable url is empty` \
>     >&2 echo -n "." `#Every iteration of the loop prints out a single dot to show progress as it got through all the pages (this is inline dot)` ; \
>     content=$(curl -s $url | python -c 'import sys, json; data = json.load(sys.stdin); print(data.get("next", "") or ""); print("\n".join([x["name"] for x in data["results"]]))') `# Curl the URL and pipe the JSON to Python. Python will parse the JSON and print the very first line as the next URL (it will leave it blank if there are no more pages) then continue to loop over the results extracting only the name; all will be store in a variable called content` ; \
>     url=$(echo "$content" | head -n 1) `#Let's get the first line of content which contains the next URL for the loop to continue` ; \
>     echo "$content" | tail -n +2 `#Print the content with out the first line (yes +2 is counter intuitive)` ; \
>   done; \
>   >&2 echo `#Finally break the line of dots` ; \
> ) | cut -d '-' -f 1 | sort --version-sort | uniq;
...
2
2.6
2.6.17
2.8
2.8.6
2.8.7
2.8.8
2.8.9
2.8.10
2.8.11
2.8.12
2.8.13
2.8.14
2.8.15
2.8.16
2.8.17
2.8.18
2.8.19
2.8.20
2.8.21
2.8.22
2.8.23
3
3.0
3.0.0
3.0.1
3.0.2
3.0.3
3.0.4
3.0.5
3.0.6
3.0.7
3.0.504
3.2
3.2.0
3.2.1
3.2.2
3.2.3
3.2.4
3.2.5
3.2.6
3.2.7
3.2.8
3.2.9
3.2.10
3.2.11
3.2.100
4
4.0
4.0.0
4.0.1
4.0.2
4.0.4
4.0.5
4.0.6
4.0.7
4.0.8
32bit
alpine
latest
nanoserver
windowsservercore

If you want the bash_profile version:

function docker-tags () {
  name=$1
  # Initial URL
  url=https://registry.hub.docker.com/v2/repositories/library/$name/tags/?page_size=100
  (
    # Keep looping until the variable URL is empty
    while [ ! -z $url ]; do
      # Every iteration of the loop prints out a single dot to show progress as it got through all the pages (this is inline dot)
      >&2 echo -n "."
      # Curl the URL and pipe the output to Python. Python will parse the JSON and print the very first line as the next URL (it will leave it blank if there are no more pages)
      # then continue to loop over the results extracting only the name; all will be stored in a variable called content
      content=$(curl -s $url | python -c 'import sys, json; data = json.load(sys.stdin); print(data.get("next", "") or ""); print("\n".join([x["name"] for x in data["results"]]))')
      # Let's get the first line of content which contains the next URL for the loop to continue
      url=$(echo "$content" | head -n 1)
      # Print the content without the first line (yes +2 is counter intuitive)
      echo "$content" | tail -n +2
    done;
    # Finally break the line of dots
    >&2 echo
  ) | cut -d '-' -f 1 | sort --version-sort | uniq;
}

And simply call it: docker-tags redis

Sample output:

$ docker-tags redis
...
2
2.6
2.6.17
2.8

--trunc----

32bit
alpine
latest
nanoserver
windowsservercore

Solution 3:

As far as I know, the CLI does not allow searching/listing tags in a repository.

But if you know which tag you want, you can pull that explicitly by adding a colon and the image name: docker pull ubuntu:saucy

Solution 4:

This script (docker-show-repo-tags.sh) should work for any Docker enabled host that has curl, sed, grep, and sort. This was updated to reflect the fact the repository tag URLs changed.

#!/bin/sh
#
# Simple script that will display Docker repository tags
# using basic tools: curl, sed, grep, and sort.
#
# Usage:
#   $ docker-show-repo-tags.sh ubuntu centos
for Repo in $* ; do
    curl -sS "https://hub.docker.com/r/library/$Repo/tags/" | \
        sed -e $'s/"tags":/\\\n"tags":/g' -e $'s/\]/\\\n\]/g' | \
        grep '^"tags"' | \
        grep '"library"' | \
        sed -e $'s/,/,\\\n/g' -e 's/,//g' -e 's/"//g' | \
        grep -v 'library:' | \
        sort -fu | \
        sed -e "s/^/${Repo}:/"
done

This older version no longer works.

#!/bin/sh
# WARNING: This no long works!
# Simple script that will display Docker repository tags.
#
# Usage:
#   $ docker-show-repo-tags.sh ubuntu centos
for Repo in $* ; do
  curl -s -S "https://registry.hub.docker.com/v2/repositories/library/$Repo/tags/" | \
    sed -e $'s/,/,\\\n/g' -e $'s/\[/\\\[\n/g' | \
    grep '"name"' | \
    awk -F\" '{print $4;}' | \
    sort -fu | \
    sed -e "s/^/${Repo}:/"
done

This is the output for a simple example:

$ docker-show-repo-tags.sh centos | cat -n
     1    centos:5
     2    centos:5.11
     3    centos:6
     4    centos:6.10
     5    centos:6.6
     6    centos:6.7
     7    centos:6.8
     8    centos:6.9
     9    centos:7.0.1406
    10    centos:7.1.1503
    11    centos:7.2.1511
    12    centos:7.3.1611
    13    centos:7.4.1708
    14    centos:7.5.1804
    15    centos:centos5
    16    centos:centos5.11
    17    centos:centos6
    18    centos:centos6.10
    19    centos:centos6.6
    20    centos:centos6.7
    21    centos:centos6.8
    22    centos:centos6.9
    23    centos:centos7
    24    centos:centos7.0.1406
    25    centos:centos7.1.1503
    26    centos:centos7.2.1511
    27    centos:centos7.3.1611
    28    centos:centos7.4.1708
    29    centos:centos7.5.1804
    30    centos:latest

Solution 5:

I wrote a command line tool to simplify searching Docker Hub repository tags, available in my PyTools GitHub repository. It's simple to use with various command line switches, but most basically:

./dockerhub_show_tags.py repo1 repo2

It's even available as a Docker image and can take multiple repositories:

docker run harisekhon/pytools dockerhub_show_tags.py centos ubuntu

DockerHub

repo: centos
tags: 5.11
      6.6
      6.7
      7.0.1406
      7.1.1503
      centos5.11
      centos6.6
      centos6.7
      centos7.0.1406
      centos7.1.1503

repo: ubuntu
tags: latest
      14.04
      15.10
      16.04
      trusty
      trusty-20160503.1
      wily
      wily-20160503
      xenial
      xenial-20160503

If you want to embed it in scripts, use -q / --quiet to get just the tags, like normal Docker commands:

./dockerhub_show_tags.py centos -q
5.11
6.6
6.7
7.0.1406
7.1.1503
centos5.11
centos6.6
centos6.7
centos7.0.1406
centos7.1.1503