364 lines
12 KiB
Bash
Executable file
364 lines
12 KiB
Bash
Executable file
#!/usr/bin/env bash
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set -eo pipefail
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# hello-world latest ef872312fe1b 3 months ago 910 B
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# hello-world latest ef872312fe1bbc5e05aae626791a47ee9b032efa8f3bda39cc0be7b56bfe59b9 3 months ago 910 B
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# debian latest f6fab3b798be 10 weeks ago 85.1 MB
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# debian latest f6fab3b798be3174f45aa1eb731f8182705555f89c9026d8c1ef230cbf8301dd 10 weeks ago 85.1 MB
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# check if essential commands are in our PATH
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for cmd in curl jq go; do
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if ! command -v $cmd &> /dev/null; then
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echo >&2 "error: \"$cmd\" not found!"
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exit 1
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fi
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done
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usage() {
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echo "usage: $0 dir image[:tag][@digest] ..."
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echo " $0 /tmp/old-hello-world hello-world:latest@sha256:8be990ef2aeb16dbcb9271ddfe2610fa6658d13f6dfb8bc72074cc1ca36966a7"
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[ -z "$1" ] || exit "$1"
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}
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dir="$1" # dir for building tar in
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shift || usage 1 >&2
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if ! [ $# -gt 0 ] && [ "$dir" ]; then
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usage 2 >&2
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fi
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mkdir -p "$dir"
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# hacky workarounds for Bash 3 support (no associative arrays)
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images=()
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rm -f "$dir"/tags-*.tmp
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manifestJsonEntries=()
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doNotGenerateManifestJson=
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# repositories[busybox]='"latest": "...", "ubuntu-14.04": "..."'
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# bash v4 on Windows CI requires CRLF separator
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newlineIFS=$'\n'
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if [ "$(go env GOHOSTOS)" = 'windows' ]; then
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major=$(echo "${BASH_VERSION%%[^0.9]}" | cut -d. -f1)
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if [ "$major" -ge 4 ]; then
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newlineIFS=$'\r\n'
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fi
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fi
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registryBase='https://registry-1.docker.io'
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authBase='https://auth.docker.io'
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authService='registry.docker.io'
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# https://github.com/moby/moby/issues/33700
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fetch_blob() {
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local token="$1"
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shift
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local image="$1"
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shift
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local digest="$1"
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shift
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local targetFile="$1"
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shift
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local curlArgs=("$@")
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local curlHeaders
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curlHeaders="$(
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curl -S "${curlArgs[@]}" \
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-H "Authorization: Bearer $token" \
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"$registryBase/v2/$image/blobs/$digest" \
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-o "$targetFile" \
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-D-
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)"
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curlHeaders="$(echo "$curlHeaders" | tr -d '\r')"
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if grep -qE "^HTTP/[0-9].[0-9] 3" <<< "$curlHeaders"; then
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rm -f "$targetFile"
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local blobRedirect
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blobRedirect="$(echo "$curlHeaders" | awk -F ': ' 'tolower($1) == "location" { print $2; exit }')"
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if [ -z "$blobRedirect" ]; then
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echo >&2 "error: failed fetching '$image' blob '$digest'"
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echo "$curlHeaders" | head -1 >&2
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return 1
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fi
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curl -fSL "${curlArgs[@]}" \
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"$blobRedirect" \
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-o "$targetFile"
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fi
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}
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# handle 'application/vnd.docker.distribution.manifest.v2+json' manifest
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handle_single_manifest_v2() {
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local manifestJson="$1"
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shift
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local configDigest
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configDigest="$(echo "$manifestJson" | jq --raw-output '.config.digest')"
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local imageId="${configDigest#*:}" # strip off "sha256:"
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local configFile="$imageId.json"
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fetch_blob "$token" "$image" "$configDigest" "$dir/$configFile" -s
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local layersFs
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layersFs="$(echo "$manifestJson" | jq --raw-output --compact-output '.layers[]')"
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local IFS="$newlineIFS"
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local layers
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mapfile -t layers <<< "$layersFs"
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unset IFS
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echo "Downloading '$imageIdentifier' (${#layers[@]} layers)..."
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local layerId=
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local layerFiles=()
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for i in "${!layers[@]}"; do
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local layerMeta="${layers[$i]}"
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local layerMediaType
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layerMediaType="$(echo "$layerMeta" | jq --raw-output '.mediaType')"
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local layerDigest
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layerDigest="$(echo "$layerMeta" | jq --raw-output '.digest')"
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# save the previous layer's ID
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local parentId="$layerId"
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# create a new fake layer ID based on this layer's digest and the previous layer's fake ID
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layerId="$(echo "$parentId"$'\n'"$layerDigest" | sha256sum | cut -d' ' -f1)"
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# this accounts for the possibility that an image contains the same layer twice (and thus has a duplicate digest value)
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mkdir -p "$dir/$layerId"
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echo '1.0' > "$dir/$layerId/VERSION"
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if [ ! -s "$dir/$layerId/json" ]; then
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local parentJson
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parentJson="$(printf ', parent: "%s"' "$parentId")"
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local addJson
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addJson="$(printf '{ id: "%s"%s }' "$layerId" "${parentId:+$parentJson}")"
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# this starter JSON is taken directly from Docker's own "docker save" output for unimportant layers
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jq "$addJson + ." > "$dir/$layerId/json" <<- 'EOJSON'
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{
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"created": "0001-01-01T00:00:00Z",
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"container_config": {
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"Hostname": "",
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"Domainname": "",
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"User": "",
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"AttachStdin": false,
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"AttachStdout": false,
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"AttachStderr": false,
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"Tty": false,
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"OpenStdin": false,
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"StdinOnce": false,
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"Env": null,
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"Cmd": null,
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"Image": "",
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"Volumes": null,
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"WorkingDir": "",
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"Entrypoint": null,
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"OnBuild": null,
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"Labels": null
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}
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}
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EOJSON
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fi
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case "$layerMediaType" in
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application/vnd.docker.image.rootfs.diff.tar.gzip)
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local layerTar="$layerId/layer.tar"
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layerFiles=("${layerFiles[@]}" "$layerTar")
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# TODO figure out why "-C -" doesn't work here
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# "curl: (33) HTTP server doesn't seem to support byte ranges. Cannot resume."
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# "HTTP/1.1 416 Requested Range Not Satisfiable"
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if [ -f "$dir/$layerTar" ]; then
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# TODO hackpatch for no -C support :'(
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echo "skipping existing ${layerId:0:12}"
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continue
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fi
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local token
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token="$(curl -fsSL "$authBase/token?service=$authService&scope=repository:$image:pull" | jq --raw-output '.token')"
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fetch_blob "$token" "$image" "$layerDigest" "$dir/$layerTar" --progress-bar
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;;
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*)
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echo >&2 "error: unknown layer mediaType ($imageIdentifier, $layerDigest): '$layerMediaType'"
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exit 1
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;;
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esac
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done
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# change "$imageId" to be the ID of the last layer we added (needed for old-style "repositories" file which is created later -- specifically for older Docker daemons)
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imageId="$layerId"
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# munge the top layer image manifest to have the appropriate image configuration for older daemons
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local imageOldConfig
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imageOldConfig="$(jq --raw-output --compact-output '{ id: .id } + if .parent then { parent: .parent } else {} end' "$dir/$imageId/json")"
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jq --raw-output "$imageOldConfig + del(.history, .rootfs)" "$dir/$configFile" > "$dir/$imageId/json"
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local manifestJsonEntry
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manifestJsonEntry="$(
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echo '{}' | jq --raw-output '. + {
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Config: "'"$configFile"'",
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RepoTags: ["'"${image#library\/}:$tag"'"],
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Layers: '"$(echo '[]' | jq --raw-output ".$(for layerFile in "${layerFiles[@]}"; do echo " + [ \"$layerFile\" ]"; done)")"'
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}'
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)"
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manifestJsonEntries=("${manifestJsonEntries[@]}" "$manifestJsonEntry")
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}
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while [ $# -gt 0 ]; do
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imageTag="$1"
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shift
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image="${imageTag%%[:@]*}"
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imageTag="${imageTag#*:}"
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digest="${imageTag##*@}"
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tag="${imageTag%%@*}"
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# add prefix library if passed official image
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if [[ "$image" != *"/"* ]]; then
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image="library/$image"
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fi
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imageFile="${image//\//_}" # "/" can't be in filenames :)
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token="$(curl -fsSL "$authBase/token?service=$authService&scope=repository:$image:pull" | jq --raw-output '.token')"
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manifestJson="$(
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curl -fsSL \
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-H "Authorization: Bearer $token" \
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-H 'Accept: application/vnd.docker.distribution.manifest.v2+json' \
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-H 'Accept: application/vnd.docker.distribution.manifest.list.v2+json' \
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-H 'Accept: application/vnd.docker.distribution.manifest.v1+json' \
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"$registryBase/v2/$image/manifests/$digest"
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)"
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if [ "${manifestJson:0:1}" != '{' ]; then
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echo >&2 "error: /v2/$image/manifests/$digest returned something unexpected:"
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echo >&2 " $manifestJson"
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exit 1
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fi
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imageIdentifier="$image:$tag@$digest"
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schemaVersion="$(echo "$manifestJson" | jq --raw-output '.schemaVersion')"
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case "$schemaVersion" in
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2)
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mediaType="$(echo "$manifestJson" | jq --raw-output '.mediaType')"
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case "$mediaType" in
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application/vnd.docker.distribution.manifest.v2+json)
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handle_single_manifest_v2 "$manifestJson"
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;;
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application/vnd.docker.distribution.manifest.list.v2+json)
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layersFs="$(echo "$manifestJson" | jq --raw-output --compact-output '.manifests[]')"
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IFS="$newlineIFS"
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mapfile -t layers <<< "$layersFs"
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unset IFS
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found=""
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# parse first level multi-arch manifest
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for i in "${!layers[@]}"; do
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layerMeta="${layers[$i]}"
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maniArch="$(echo "$layerMeta" | jq --raw-output '.platform.architecture')"
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if [ "$maniArch" = "$(go env GOARCH)" ]; then
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digest="$(echo "$layerMeta" | jq --raw-output '.digest')"
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# get second level single manifest
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submanifestJson="$(
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curl -fsSL \
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-H "Authorization: Bearer $token" \
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-H 'Accept: application/vnd.docker.distribution.manifest.v2+json' \
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-H 'Accept: application/vnd.docker.distribution.manifest.list.v2+json' \
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-H 'Accept: application/vnd.docker.distribution.manifest.v1+json' \
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"$registryBase/v2/$image/manifests/$digest"
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)"
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handle_single_manifest_v2 "$submanifestJson"
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found="found"
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break
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fi
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done
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if [ -z "$found" ]; then
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echo >&2 "error: manifest for $maniArch is not found"
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exit 1
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fi
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;;
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*)
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echo >&2 "error: unknown manifest mediaType ($imageIdentifier): '$mediaType'"
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exit 1
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;;
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esac
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;;
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1)
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if [ -z "$doNotGenerateManifestJson" ]; then
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echo >&2 "warning: '$imageIdentifier' uses schemaVersion '$schemaVersion'"
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echo >&2 " this script cannot (currently) recreate the 'image config' to put in a 'manifest.json' (thus any schemaVersion 2+ images will be imported in the old way, and their 'docker history' will suffer)"
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echo >&2
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doNotGenerateManifestJson=1
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fi
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layersFs="$(echo "$manifestJson" | jq --raw-output '.fsLayers | .[] | .blobSum')"
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IFS="$newlineIFS"
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mapfile -t layers <<< "$layersFs"
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unset IFS
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history="$(echo "$manifestJson" | jq '.history | [.[] | .v1Compatibility]')"
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imageId="$(echo "$history" | jq --raw-output '.[0]' | jq --raw-output '.id')"
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echo "Downloading '$imageIdentifier' (${#layers[@]} layers)..."
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for i in "${!layers[@]}"; do
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imageJson="$(echo "$history" | jq --raw-output ".[${i}]")"
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layerId="$(echo "$imageJson" | jq --raw-output '.id')"
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imageLayer="${layers[$i]}"
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mkdir -p "$dir/$layerId"
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echo '1.0' > "$dir/$layerId/VERSION"
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echo "$imageJson" > "$dir/$layerId/json"
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# TODO figure out why "-C -" doesn't work here
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# "curl: (33) HTTP server doesn't seem to support byte ranges. Cannot resume."
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# "HTTP/1.1 416 Requested Range Not Satisfiable"
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if [ -f "$dir/$layerId/layer.tar" ]; then
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# TODO hackpatch for no -C support :'(
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echo "skipping existing ${layerId:0:12}"
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continue
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fi
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token="$(curl -fsSL "$authBase/token?service=$authService&scope=repository:$image:pull" | jq --raw-output '.token')"
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fetch_blob "$token" "$image" "$imageLayer" "$dir/$layerId/layer.tar" --progress-bar
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done
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;;
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*)
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echo >&2 "error: unknown manifest schemaVersion ($imageIdentifier): '$schemaVersion'"
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exit 1
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;;
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esac
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echo
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if [ -s "$dir/tags-$imageFile.tmp" ]; then
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echo -n ', ' >> "$dir/tags-$imageFile.tmp"
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else
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images=("${images[@]}" "$image")
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fi
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echo -n '"'"$tag"'": "'"$imageId"'"' >> "$dir/tags-$imageFile.tmp"
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done
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echo -n '{' > "$dir/repositories"
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firstImage=1
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for image in "${images[@]}"; do
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imageFile="${image//\//_}" # "/" can't be in filenames :)
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image="${image#library\/}"
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[ "$firstImage" ] || echo -n ',' >> "$dir/repositories"
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firstImage=
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echo -n $'\n\t' >> "$dir/repositories"
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echo -n '"'"$image"'": { '"$(cat "$dir/tags-$imageFile.tmp")"' }' >> "$dir/repositories"
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done
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echo -n $'\n}\n' >> "$dir/repositories"
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rm -f "$dir"/tags-*.tmp
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if [ -z "$doNotGenerateManifestJson" ] && [ "${#manifestJsonEntries[@]}" -gt 0 ]; then
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echo '[]' | jq --raw-output ".$(for entry in "${manifestJsonEntries[@]}"; do echo " + [ $entry ]"; done)" > "$dir/manifest.json"
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else
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rm -f "$dir/manifest.json"
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fi
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echo "Download of images into '$dir' complete."
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echo "Use something like the following to load the result into a Docker daemon:"
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echo " tar -cC '$dir' . | docker load"
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