Use specific Android NDK version in CI builds. (#12350)

Current builds use a NDK version that happens to be on the build machine. The build machine environment may change in ways that are outside of our control.
This change installs a specific version of NDK (the current LTS version 25.0.8775105) and uses it.

tools/ci_build/github/azure-pipelines/android-x86_64-crosscompile-ci-pipeline.yml

@@ -23,6 +23,8 @@ jobs:
   - script: sudo apt-get update -y && sudo apt-get install -y coreutils ninja-build
     displayName: Install coreutils and ninja
 
+  - template: "templates/use-android-ndk.yml"
+
   - script: /bin/bash tools/ci_build/github/android/setup_gradle_wrapper.sh $(pwd)
     displayName: Setup gradle wrapper to use gradle 6.8.3
 
@@ -35,12 +37,8 @@ jobs:
     displayName: Build Host Protoc
 
   - script: |
-      export ANDROID_SDK_ROOT=/usr/local/lib/android/sdk
-      export ANDROID_HOME=/usr/local/lib/android/sdk
-      export ANDROID_NDK_HOME=/usr/local/lib/android/sdk/ndk-bundle
-      export ANDROID_NDK_ROOT=/usr/local/lib/android/sdk/ndk-bundle
       env | grep ANDROID
-    displayName: Set Android ENVs
+    displayName: View Android ENVs
 
   # Start switching to jdk 11 after the Android Emulator is started
   # since Android SDK manager requires java 8
@@ -116,6 +114,13 @@ jobs:
         artifact: 'CPUBuildOutput'
         path: $(Build.SourcesDirectory)
 
+    - task: UsePythonVersion@0
+      displayName: Use Python $(pythonVersion)
+      inputs:
+        versionSpec: $(pythonVersion)
+
+    - template: "templates/use-android-ndk.yml"
+
     - script: /bin/bash tools/ci_build/github/android/setup_gradle_wrapper.sh $(pwd)
       displayName: Setup gradle wrapper to use gradle 6.8.3
 
@@ -173,6 +178,8 @@ jobs:
   - script: sudo apt-get update -y && sudo apt-get install -y coreutils ninja-build
     displayName: Install coreutils and ninja
 
+  - template: "templates/use-android-ndk.yml"
+
   - script: /bin/bash tools/ci_build/github/android/setup_gradle_wrapper.sh $(pwd)
     displayName: Setup gradle wrapper to use gradle 6.8.3
 
@@ -185,12 +192,8 @@ jobs:
     displayName: Build Host Protoc
 
   - script: |
-      export ANDROID_SDK_ROOT=/usr/local/lib/android/sdk
-      export ANDROID_HOME=/usr/local/lib/android/sdk
-      export ANDROID_NDK_HOME=/usr/local/lib/android/sdk/ndk-bundle
-      export ANDROID_NDK_ROOT=/usr/local/lib/android/sdk/ndk-bundle
       env | grep ANDROID
-    displayName: set Android ENVs
+    displayName: View Android ENVs
 
   # Start switching to jdk 11 after the Android Emulator is started since Android SDK manager requires java 8
   - task: JavaToolInstaller@0
@@ -272,6 +275,8 @@ jobs:
       inputs:
         versionSpec: $(pythonVersion)
 
+    - template: "templates/use-android-ndk.yml"
+
     - script: /bin/bash tools/ci_build/github/android/setup_gradle_wrapper.sh $(pwd)
       displayName: Setup gradle wrapper to use gradle 6.8.3
 
@@ -350,6 +355,8 @@ jobs:
       inputs:
         versionSpec: $(pythonVersion)
 
+    - template: "templates/use-android-ndk.yml"
+
     - script: /bin/bash tools/ci_build/github/android/setup_gradle_wrapper.sh $(pwd)
       displayName: Setup gradle wrapper to use gradle 6.8.3
 

tools/ci_build/github/azure-pipelines/templates/android-java-api-aar-test.yml

@@ -37,6 +37,8 @@ jobs:
       artifactName: '${{parameters.artifactName}}'
       targetPath: '$(Build.BinariesDirectory)/final-android-aar'
 
+  - template: use-android-ndk.yml
+
   - script: /bin/bash tools/ci_build/github/android/setup_gradle_wrapper.sh $(Build.SourcesDirectory)
     displayName: Setup gradle wrapper to use gradle 6.8.3
 

tools/ci_build/github/azure-pipelines/templates/android-java-api-aar.yml

@@ -72,6 +72,8 @@ jobs:
       DockerBuildArgs: "--build-arg BUILD_UID=$( id -u )"
       Repository: onnxruntimecpubuild
 
+  - template: use-android-ndk.yml
+
   - task: CmdLine@2
     displayName: Build Android AAR Packages
     inputs:

tools/ci_build/github/azure-pipelines/templates/use-android-ndk.yml

@@ -0,0 +1,30 @@
+# Installs the Android NDK and sets environment variables ANDROID_NDK_HOME and ANDROID_NDK_ROOT to refer to it.
+
+  parameters:
+  - name: AndroidNdkVersion
+    type: string
+    default: "25.0.8775105"  # LTS version
+
+  steps:
+  - bash: |
+      set -e
+
+      "${ANDROID_SDK_ROOT}/cmdline-tools/latest/bin/sdkmanager" --install "ndk;${{ parameters.AndroidNdkVersion }}"
+
+      NDK_PATH="${ANDROID_SDK_ROOT}/ndk/${{ parameters.AndroidNdkVersion }}"
+      if [[ ! -d "${NDK_PATH}" ]]; then
+        echo "NDK directory is not in expected location: ${NDK_PATH}"
+        exit 1
+      fi
+
+      set_var() {
+        local VAR_NAME=${1:?}
+        local VAR_VALUE=${2:?}
+        echo "##vso[task.setvariable variable=${VAR_NAME}]${VAR_VALUE}"
+        echo "${VAR_NAME}: ${VAR_VALUE}"
+      }
+
+      set_var "ANDROID_NDK_HOME" "${NDK_PATH}"
+      set_var "ANDROID_NDK_ROOT" "${NDK_PATH}"
+
+    displayName: Use Android NDK ${{ parameters.AndroidNdkVersion }}