download-docker-info.ps1

download-docker-info.ps1

param(
    [Parameter(Mandatory=$true)]$image,
    $tag = "latest",
    $registry = "registry.hub.docker.com",
    $outputFolder = "C:\temp\dockerStuff"
)

try {
    invoke-restmethod "https://$registry/v2/$image/manifests/$tag"
} catch {
    $match = [regex]::Matches($_.Exception.Response.Headers['WWW-Authenticate'], 'Bearer([ ,](?<name>[^=]+)="(?<value>[^"]+)")+')
    $keys = @{}
    $names = $match.groups | ? 'name' -eq 'name' | % captures
    $values = $match.groups | ? 'name' -eq 'value' | % captures
    0..$($names.count-1) | % { $keys[$names[$_].value] = $values[$_].value}
    $keys

    $url = $keys['realm'] + "?service=" + $keys["service"] + "&scope=" + $keys["scope"]
    echo $url

    $cred = Get-Credential
    $token = invoke-restmethod $url -UseBasicParsing -Headers @{
        "Authorization" = "Basic $([convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes($cred.GetNetworkCredential().UserName + ":" + $cred.GetNetworkCredential().Password)))"
    } | % token
    $token
}

$manifest = Invoke-WebRequest "https://$registry/v2/$image/manifests/$tag" -UseBasicParsing -Headers @{
    "Authorization" = "Bearer $token"
    "Accept" = @(
        "application/vnd.oci.image.index.v1+json",
        "application/vnd.docker.distribution.manifest.v1+prettyjws",
        "application/json",
        "application/vnd.oci.image.manifest.v1+json",
        "application/vnd.docker.distribution.manifest.v2+json",
        "application/vnd.docker.distribution.manifest.list.v2+json"
    ) -join ","
}

[System.text.encoding]::ASCII.getString($manifest.content) | convertfrom-json | convertto-json -depth 20
$manifest.headers
$manifestListDigest = $manifest.headers.'Docker-Content-Digest'
$manifestList = Invoke-WebRequest "https://$registry/v2/$image/manifests/$manifestListDigest" -UseBasicParsing -Headers @{
    "Authorization" = "Bearer $token"
}
$manifestList.headers
if ($manifestList.headers['Content-Type'] -eq "application/vnd.docker.distribution.manifest.v2+json") {
    $manifest = [System.text.encoding]::ASCII.getString($manifestList.content) | convertfrom-json
} else {
    throw "Unkown response type (maybe a list) for tag manifest"
}
$manifest | convertto-json -depth 20

rm -recurse -force $outputFolder
mkdir $outputFolder
$configDigest = $manifest.config.digest
[System.Text.Encoding]::UTF8.getString($(Invoke-WebRequest "https://$registry/v2/$image/blobs/$configDigest" -Headers @{
    "Authorization" = "Bearer $token"
}).content) | convertfrom-json | convertto-json -depth 20 > "$outputFolder\config.json"
0..$($manifest.layers.count-1) | % {
    $blobDigest = $manifest.layers[$_].digest
    Invoke-WebRequest "https://$registry/v2/$image/blobs/$blobDigest" -Headers @{
        "Authorization" = "Bearer $token"
    } -outfile "$outputFolder\layer$_.tar.gz"
}