fix: migrate DockerHub tag check from V1 to V2 API (#281)

The DockerHub V1 API (index.docker.io/v1) has been decommissioned and
returns 410 Gone. This caused docker_tag_exists checks to always fail,
meaning builds never detected already-published images and rebuilt them
unnecessarily (~30 min wasted per duplicate build).

Migrate all 10 workflow files (6 Linux curl, 4 Windows PowerShell) to
use the V2 API (hub.docker.com/v2) which returns 200 for existing tags
and 404 for missing ones.

This will significantly speed up the retry queue by skipping
already-published images instead of rebuilding them.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: frostebite

.github/workflows/new-ubuntu-base-image-requested.yml

@@ -60,9 +60,9 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Check if image does not already exist
         run: |
-          # Source: https://stackoverflow.com/a/39731444/3593896
+          # DockerHub V2 API (V1 was decommissioned, returns 410 Gone)
           function docker_tag_exists() {
-            curl --silent -f -lSL https://index.docker.io/v1/repositories/$1/tags/$2 > /dev/null
+            curl --silent -f -lSL https://hub.docker.com/v2/repositories/$1/tags/$2 > /dev/null
           }
 
           if docker_tag_exists unityci/base ubuntu-${{ github.event.client_payload.repoVersionFull }} ; then

.github/workflows/new-ubuntu-hub-image-requested.yml

@@ -60,9 +60,9 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Check if image does not already exist
         run: |
-          # Source: https://stackoverflow.com/a/39731444/3593896
+          # DockerHub V2 API (V1 was decommissioned, returns 410 Gone)
           function docker_tag_exists() {
-            curl --silent -f -lSL https://index.docker.io/v1/repositories/$1/tags/$2 > /dev/null
+            curl --silent -f -lSL https://hub.docker.com/v2/repositories/$1/tags/$2 > /dev/null
           }
 
           if docker_tag_exists unityci/hub ubuntu-${{ github.event.client_payload.repoVersionFull }} ; then

.github/workflows/new-ubuntu-legacy-editor-image-requested.yml

@@ -74,9 +74,9 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Check if image does not already exist
         run: |
-          # Source: https://stackoverflow.com/a/39731444/3593896
+          # DockerHub V2 API (V1 was decommissioned, returns 410 Gone)
           function docker_tag_exists() {
-            curl --silent -f -lSL https://index.docker.io/v1/repositories/$1/tags/$2 > /dev/null
+            curl --silent -f -lSL https://hub.docker.com/v2/repositories/$1/tags/$2 > /dev/null
           }
 
           if docker_tag_exists unityci/editor ubuntu-${{ github.event.client_payload.editorVersion }}-${{ matrix.targetPlatform }}-${{ github.event.client_payload.repoVersionFull }} ; then

.github/workflows/new-ubuntu-post-2019-2-editor-image-requested.yml

@@ -74,9 +74,9 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Check if image does not already exist
         run: |
-          # Source: https://stackoverflow.com/a/39731444/3593896
+          # DockerHub V2 API (V1 was decommissioned, returns 410 Gone)
           function docker_tag_exists() {
-            curl --silent -f -lSL https://index.docker.io/v1/repositories/$1/tags/$2 > /dev/null
+            curl --silent -f -lSL https://hub.docker.com/v2/repositories/$1/tags/$2 > /dev/null
           }
 
           if docker_tag_exists unityci/editor ubuntu-${{ github.event.client_payload.editorVersion }}-${{ matrix.targetPlatform }}-${{ github.event.client_payload.repoVersionFull }} ; then

.github/workflows/new-windows-base-image-requested.yml

@@ -122,7 +122,7 @@ jobs:
             param([string] $Repository, [string] $Tag)
 
             Try {
-              Invoke-RestMethod "https://index.docker.io/v1/repositories/$Repository/tags/$Tag"
+              Invoke-RestMethod "https://hub.docker.com/v2/repositories/$Repository/tags/$Tag"
             } Catch {} # Assume image does not exist on erroneous response
 
             return $?

.github/workflows/new-windows-hub-image-requested.yml

@@ -122,7 +122,7 @@ jobs:
             param([string] $Repository, [string] $Tag)
 
             Try {
-              Invoke-RestMethod "https://index.docker.io/v1/repositories/$Repository/tags/$Tag"
+              Invoke-RestMethod "https://hub.docker.com/v2/repositories/$Repository/tags/$Tag"
             } Catch {} # Assume image does not exist on erroneous response
 
             return $?

.github/workflows/new-windows-legacy-editor-image-requested.yml

@@ -141,7 +141,7 @@ jobs:
             param([string] $Repository, [string] $Tag)
 
             Try {
-              Invoke-RestMethod "https://index.docker.io/v1/repositories/$Repository/tags/$Tag"
+              Invoke-RestMethod "https://hub.docker.com/v2/repositories/$Repository/tags/$Tag"
             } Catch {} # Assume image does not exist on erroneous response
 
             return $?

.github/workflows/new-windows-post-2019-2-editor-image-requested.yml

@@ -148,7 +148,7 @@ jobs:
             param([string] $Repository, [string] $Tag)
 
             Try {
-              Invoke-RestMethod "https://index.docker.io/v1/repositories/$Repository/tags/$Tag"
+              Invoke-RestMethod "https://hub.docker.com/v2/repositories/$Repository/tags/$Tag"
             } Catch {} # Assume image does not exist on erroneous response
 
             return $?

.github/workflows/retry-ubuntu-editor-image-requested.yml

@@ -56,9 +56,9 @@ jobs:
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Check if image does not already exist
         run: |
-          # Source: https://stackoverflow.com/a/39731444/3593896
+          # DockerHub V2 API (V1 was decommissioned, returns 410 Gone)
           function docker_tag_exists() {
-            curl --silent -f -lSL https://index.docker.io/v1/repositories/$1/tags/$2 > /dev/null
+            curl --silent -f -lSL https://hub.docker.com/v2/repositories/$1/tags/$2 > /dev/null
           }
 
           if docker_tag_exists unityci/editor ubuntu-${{ github.event.client_payload.editorVersion }}-${{ github.event.client_payload.targetPlatform }}-${{ github.event.client_payload.repoVersionFull }} ; then

.github/workflows/retry-windows-editor-image-requested.yml

@@ -81,7 +81,7 @@ jobs:
             param([string] $Repository, [string] $Tag)
 
             Try {
-              Invoke-RestMethod "https://index.docker.io/v1/repositories/$Repository/tags/$Tag"
+              Invoke-RestMethod "https://hub.docker.com/v2/repositories/$Repository/tags/$Tag"
             } Catch {} # Assume image does not exist on erroneous response
 
             return $?