Find the tag of a Docker image having only the SHA256

get-docker-image-tag-by-sha.sh

#!/bin/bash

SHA256_HASH="5bb4faffc8b35e2702b2ffa78e982b979d7b66db29bd55b0c58de8fa745df661"

for i in {1..1000}
do
   echo "Looking into page: $i"

   curl "https://registry.hub.docker.com/v2/repositories/apache/superset/tags/?page=$i" \
    | jq '.results[] | select(.["images"][]["digest"] == "sha256:'${SHA256_HASH}'")'
done

To find your SHA256_HASH:

 docker images --digests

@ThomDietrich @aryehb Thank you for the contribution mates!

This is used more as a life-saver trick when you only have the sha256 and you need to find the tag pointing to that digest in the repo to fix it in your deployment manifests

Putting it together:

SHA256_HASH='5bb4faffc8b35e2702b2ffa78e982b979d7b66db29bd55b0c58de8fa745df661'
NAMESPACE='apache'
REPO_NAME='superset'

for i in {1..1000}; do 
    if [ $i -eq 100 ]; then
        echo -e "\e[35mSleeping for 7 seconds on page $i...\e[0m"
        sleep 7
    fi
    echo "Looking into page: $i"
    result=$(curl -s "https://registry.hub.docker.com/v2/repositories/$NAMESPACE/$REPO_NAME/tags/?page=$i" | jq -r ".results[] | select(.[\"images\"][][\"digest\"] == \"sha256:$hash\" or .digest == \"sha256:$SHA256_HASH\")") || break
    if [ ! -z "$result" ]; then
        echo "$result" | jq '.'
        break
    fi
done

For official images like https://hub.docker.com/_/node the namespace is "library".

Also, I think @Kyu meant for $hash to be $SHA256_HASH. Fixed:

#!/bin/bash

SHA256_HASH="5bb4faffc8b35e2702b2ffa78e982b979d7b66db29bd55b0c58de8fa745df661"
NAMESPACE='apache'
REPO_NAME='superset'

for i in {1..1000}; do 
    if [ $i -eq 100 ]; then
        echo -e "\e[35mSleeping for 7 seconds on page $i...\e[0m"
        sleep 7
    fi

    echo "Looking into page: $i"

    result=$(
        curl -s "https://registry.hub.docker.com/v2/repositories/$NAMESPACE/$REPO_NAME/tags/?page=$i" \
        | jq -r ".results[] | select(.[\"images\"][][\"digest\"] == \"sha256:$SHA256_HASH\" or .digest == \"sha256:$SHA256_HASH\")"
    ) || break

    if [ ! -z "$result" ]; then
        echo "$result" | jq '.'
        break
    fi
done

For the benefit of anyone else who happens to hit this, if what you have is the hash of a particular tag of a multi-arch image, this approach does not work.

Ha, the later iterations do work! It's the or .digest == [...] part which does the trick I think.

Anyway, for posterity, here's my iteration of the script, with simplistic command line argument handling, sleeping every 100 pages and adding the sha256: prefix if not given.

#!/bin/bash
set -eou pipefail

SHA256_HASH=""
IMAGE=""

while [[ $# -gt 0 ]]; do
  case "$1" in
  --hash)
    shift
    SHA256_HASH="$1"
    shift
    ;;
  --image)
    shift
    IMAGE="$1"
    shift
    ;;
  *)
    echo "Unknown argument \"$1\"" >&2
    echo "Usage: $0 --hash HASH --image REPO/IMAGE" >&2
    exit 1
    ;;
  esac
done

if [[ -z "$SHA256_HASH" || -z "$IMAGE" ]]; then
  echo "Usage: $0 --hash HASH --image REPO/IMAGE" >&2
  exit 1
fi

if [[ ! "${SHA256_HASH:0:7}" == "sha256:" ]]; then
  SHA256_HASH="sha256:${SHA256_HASH}"
fi

for i in {1..1000}; do
  if [[ $(expr $i % 100) -eq 0 ]]; then
    echo "Sleeping for 7 seconds on page $i..."
    sleep 7
  fi

  echo "Looking into page: $i"

  result=$(
    curl "https://registry.hub.docker.com/v2/repositories/$IMAGE/tags/?page=$i" |
      jq '.results[] | select(.["images"][]["digest"] == "'${SHA256_HASH}'" or .digest == "'${SHA256_HASH}'")'
  ) || break

  if [[ ! -z "$result" ]]; then
    echo "$result" | jq .
    break
  fi
done

Continuing the trend, this scripts automates both getting the hash and getting tags with the hash (no jq needed).

usage:

# if you have the digest:
docker_tag_pinner 'FROM electronuserland/builder:wine@sha256:8bb6fa0f99a00a5b845521910508958ebbb682b59221f0aa4b82102c22174164'
# if you don't:
docker_tag_pinner 'FROM electronuserland/builder:wine' 

Get deno
curl -fsSL https://deno.land/install.sh | sh

Script

#!/usr/bin/env -S deno run --allow-all
import $ from "https://esm.sh/@jsr/[email protected]/mod.ts"

//
// check arg
//
let fromStatment = Deno.args[0].trim()
// ex: fromStatment="docker.io/electronuserland/builder:wine@sha256:8bb6fa0f99a00a5b845521910508958ebbb682b59221f0aa4b82102c22174164"


//
// parse the FROM statement
//
// remove prefixy stuff
fromStatment = fromStatment.replace(/^FROM\s+/, "")
fromStatment = fromStatment.replace(/^docker\.io\//, "")
var [namespace, repo, tag] = fromStatment.split(/\/|:/g)
if (!tag) {
    tag = "latest"
}
if (!namespace || !repo) {
    console.error("Invalid FROM statement:", fromStatment)
    console.error("I'd usually expect an argument like:\n   FROM docker.io/electronuserland/builder:wine")
    console.error("OR:\n    FROM docker.io/electronuserland/builder:wine@sha256:8bb6fa0f99a00a5b845521910508958ebbb682b59221f0aa4b82102c22174164")
    Deno.exit(1)
}

if (tag.includes("@")) {
    var [tag, hashVersion] = tag.split("@")
}

//
// if digest missing get with `docker images --digests` 
//
try_again: while (true) {
    if (!hashVersion) {
        console.log(`trying to get the hash by running: docker images --digests --format '{{json .}}'`)
        const imagesText = await $`docker images --digests --format '{{json .}}'`.text()
        const rows = imagesText.split("\n").map(JSON.parse)
        const relevantRows = rows.filter((each) => each.Repository.includes(`${namespace}/${repo}`) && each.Tag === tag)
        if (relevantRows.length === 0) {
            // need to pull it
            if (confirm("No digest found for this image. Can I pull it to get the digest?")) {
                await $`docker pull ${namespace}/${repo}`
                continue try_again
            } else {
                console.error("No digest found for this image. Please provide the digest manually. (add @DIGEST_HASH to the end of the from statement)")
                Deno.exit(1)
            }
        }
        hashVersion = relevantRows[0].Digest
        console.log(`digest is: ${hashVersion}`)
    }
    break
}

hashVersion = hashVersion.replace(/^sha256:/, "")

//
// fetch the tag pages
//
let i = 0
while (true) {
    i++
    if (i % 100 === 0) {
        console.log(`\x1b[35mSleeping for 7 seconds on page ${i}...\x1b[0m`)
        await new Promise((resolve) => setTimeout(resolve, 7000))
    }
    
    console.log(`\x1b[35mLooking into page: ${i}\x1b[0m`)
    const url = `https://registry.hub.docker.com/v2/repositories/${namespace}/${repo}/tags/?page=${i}`

    const res = await fetch(url)
    if (!res.ok) {
        console.error(`Error fetching page ${i}: ${res.statusText}`)
        break
    }

    const data = await res.json()
    const results = data.results ?? []
    const matchesWithCorrectHash = results.filter((each) => each.digest === `sha256:${hashVersion}` || (each.images || []).some((each) => each.digest === `sha256:${hashVersion}`))
    const usefulMatches = matchesWithCorrectHash.filter(each=>each.name!=tag)
    if (usefulMatches.length > 0) {
        console.log(`Found ${usefulMatches.length} matches:`)
        for (const each of usefulMatches) {
            console.log(`    \x1b[34mFROM docker.io/${namespace}/${repo}:${each.name}\x1b[0m   # last updated: ${monthsAgo(each.last_updated)} months ago`)
        }
        if (confirm("\nThere could be more matches on other pages. Should I STOP here?")) {
            Deno.exit(0)
        }
    }
}

// helper function
function monthsAgo(dateString) {
    const pastDate = new Date(dateString)
    const today = new Date()

    let yearsDiff = today.getFullYear() - pastDate.getFullYear()
    let monthsDiff = today.getMonth() - pastDate.getMonth()

    let totalMonths = yearsDiff * 12 + monthsDiff

    // If the day of the month hasn't been reached yet, subtract one month
    if (today.getDate() < pastDate.getDate()) {
        totalMonths -= 1
    }

    return totalMonths
}