source-build: read base image from SBOM

STONEBLD-2607 When the BASE_IMAGES param is empty, fall back to reading the base image from the SBOM of the BINARY_IMAGE. This removes the source-build task's dependency on the BASE_IMAGES_DIGESTS result, finally allowing us to stop returning this result from build tasks. Signed-off-by: Adam Cmiel <[email protected]>
konflux-ci · Jul 12, 2024 · f00fdae · f00fdae
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diff --git a/task/source-build-oci-ta/0.1/README.md b/task/source-build-oci-ta/0.1/README.md
@@ -5,7 +5,7 @@ Source image build.
 ## Parameters
 |name|description|default value|required|
 |---|---|---|---|
-|BASE_IMAGES|Base images used to build the binary image. Each image per line in the same order of FROM instructions specified in a multistage Dockerfile. Default to an empty string, which means to skip handling a base image.|""|false|
+|BASE_IMAGES|By default, the task inspects the SBOM of the binary image to find the base image. With this parameter, you can override that behavior and pass the base image directly. The value should be a newline-separated list of images, in the same order as the FROM instructions specified in a multistage Dockerfile.|""|false|
 |BINARY_IMAGE|Binary image name from which to generate the source image name.||true|
 |CACHI2_ARTIFACT|The Trusted Artifact URI pointing to the artifact with the prefetched dependencies.|""|false|
 |SOURCE_ARTIFACT|The Trusted Artifact URI pointing to the artifact with the application source code.||true|

diff --git a/task/source-build-oci-ta/0.1/source-build-oci-ta.yaml b/task/source-build-oci-ta/0.1/source-build-oci-ta.yaml
@@ -12,10 +12,11 @@ spec:
   description: Source image build.
   params:
     - name: BASE_IMAGES
-      description: Base images used to build the binary image. Each image
-        per line in the same order of FROM instructions specified in a multistage
-        Dockerfile. Default to an empty string, which means to skip handling
-        a base image.
+      description: By default, the task inspects the SBOM of the binary image
+        to find the base image. With this parameter, you can override that
+        behavior and pass the base image directly. The value should be a newline-separated
+        list of images, in the same order as the FROM instructions specified
+        in a multistage Dockerfile.
       type: string
       default: ""
     - name: BINARY_IMAGE
@@ -42,6 +43,11 @@ spec:
     - name: workdir
       emptyDir: {}
   stepTemplate:
+    env:
+      - name: BASE_IMAGES_FILE
+        value: /var/source-build/base-images.txt
+      - name: BINARY_IMAGE
+        value: $(params.BINARY_IMAGE)
     volumeMounts:
       - mountPath: /var/workdir
         name: workdir
@@ -52,16 +58,63 @@ spec:
         - use
         - $(params.SOURCE_ARTIFACT)=/var/workdir/source
         - $(params.CACHI2_ARTIFACT)=/var/workdir/cachi2
+    - name: get-base-images
+      image: quay.io/konflux-ci/appstudio-utils:ab6b0b8e40e440158e7288c73aff1cf83a2cc8a9@sha256:24179f0efd06c65d16868c2d7eb82573cce8e43533de6cea14fec3b7446e0b14
+      env:
+        - name: BASE_IMAGES
+          value: $(params.BASE_IMAGES)
+      script: |
+        #!/usr/bin/env bash
+        set -euo pipefail
+
+        if [[ -n "$BASE_IMAGES" ]]; then
+            echo "BASE_IMAGES param received:"
+            printf "%s" "$BASE_IMAGES" | tee "$BASE_IMAGES_FILE"
+            exit
+        fi
+
+        echo "BASE_IMAGES param is empty, inspecting the SBOM instead"
+
+        raw_inspect=$(skopeo inspect --raw "docker://$BINARY_IMAGE")
+        if manifest_digest=$(jq -e -r '.manifests[0].digest' <<<"$raw_inspect"); then
+            # The BINARY_IMAGE is an index image, each manifest in the list has its own SBOM.
+            # We're gonna assume the base images are the same or similar enough in all the SBOMs.
+            # How would we even handle a build where each manifest in the list is built from different base images?
+            echo "BINARY_IMAGE ($BINARY_IMAGE) is a manifest list, picking an arbitrary image from the list"
+            image_without_digest=${BINARY_IMAGE%@*}
+            image_without_tag=${image_without_digest%:*}
+            image=${image_without_tag}@${manifest_digest}
+        else
+            # The image is a single manifest
+            image=$BINARY_IMAGE
+        fi
+
+        for i in {1..5}; do
+            echo "Downloading SBOM for $image (attempt $i)"
+            sbom=$(cosign download sbom "$image") && break
+            [[ "$i" -lt 5 ]] && sleep 1
+        done
+
+        if [[ -z "$sbom" ]]; then
+            echo "Failed to download SBOM after 5 attempts"
+            exit 1
+        fi
+
+        echo -n "Extracting base images from SBOM"
+        echo " (looking for .formulation[].components[] with 'konflux:container:is_base_image' property)"
+        jq -r '
+            .formulation[]?
+            | .components[]?
+            | select(any(.properties[]?; .name == "konflux:container:is_base_image"))
+            | (.purl | capture("^pkg:oci/.*?@(?<digest>.*?:[a-f0-9]*)")) as $matched
+            | .name + "@" + $matched.digest
+        ' <<<"$sbom"  | tee "$BASE_IMAGES_FILE"
     - name: build
       image: quay.io/konflux-ci/source-container-build:9ad131acf5154d2f280b7b46a1abc543952d325c@sha256:94271c32e4578208ac90308695d2b625d4e932d65f0cdd116b200c39228f5ece
       workingDir: /var/workdir
       env:
-        - name: BINARY_IMAGE
-          value: $(params.BINARY_IMAGE)
         - name: SOURCE_DIR
           value: /var/workdir/source
-        - name: BASE_IMAGES
-          value: $(params.BASE_IMAGES)
         - name: RESULT_FILE
           value: $(results.BUILD_RESULT.path)
         - name: CACHI2_ARTIFACTS_DIR
@@ -92,7 +145,7 @@ spec:
           --output-binary-image "$BINARY_IMAGE" \
           --workspace /var/workdir \
           --source-dir "$SOURCE_DIR" \
-          --base-images "$BASE_IMAGES" \
+          --base-images "$(cat "$BASE_IMAGES_FILE")" \
           --write-result-to "$RESULT_FILE" \
           --cachi2-artifacts-dir "$CACHI2_ARTIFACTS_DIR" \
           --registry-allowlist="$registry_allowlist"

diff --git a/task/source-build/0.1/README.md b/task/source-build/0.1/README.md
@@ -6,7 +6,7 @@ Source image build.
 |name|description|default value|required|
 |---|---|---|---|
 |BINARY_IMAGE|Binary image name from which to generate the source image name.||true|
-|BASE_IMAGES|Base images used to build the binary image. Each image per line in the same order of FROM instructions specified in a multistage Dockerfile. Default to an empty string, which means to skip handling a base image.|""|false|
+|BASE_IMAGES|By default, the task inspects the SBOM of the binary image to find the base image. With this parameter, you can override that behavior and pass the base image directly. The value should be a newline-separated list of images, in the same order as the FROM instructions specified in a multistage Dockerfile.|""|false|
 
 ## Results
 |name|description|

diff --git a/task/source-build/0.1/source-build.yaml b/task/source-build/0.1/source-build.yaml
@@ -16,9 +16,10 @@ spec:
       type: string
     - name: BASE_IMAGES
       description: >-
-        Base images used to build the binary image. Each image per line in the same order of FROM
-        instructions specified in a multistage Dockerfile. Default to an empty string, which means
-        to skip handling a base image.
+        By default, the task inspects the SBOM of the binary image to find the base image.
+        With this parameter, you can override that behavior and pass the base image directly.
+        The value should be a newline-separated list of images, in the same order as the FROM
+        instructions specified in a multistage Dockerfile.
       type: string
       default: ""
   results:
@@ -34,7 +35,69 @@ spec:
   volumes:
     - name: source-build-work-place
       emptyDir: {}
+  stepTemplate:
+    env:
+      - name: BINARY_IMAGE
+        value: "$(params.BINARY_IMAGE)"
+      - name: BASE_IMAGES_FILE
+        value: /var/source-build/base-images.txt
+    volumeMounts:
+      - name: source-build-work-place
+        mountPath: /var/source-build
   steps:
+    - name: get-base-images
+      image: quay.io/konflux-ci/appstudio-utils:ab6b0b8e40e440158e7288c73aff1cf83a2cc8a9@sha256:24179f0efd06c65d16868c2d7eb82573cce8e43533de6cea14fec3b7446e0b14
+      env:
+        - name: BASE_IMAGES
+          value: "$(params.BASE_IMAGES)"
+      script: |
+        #!/usr/bin/env bash
+        set -euo pipefail
+
+        if [[ -n "$BASE_IMAGES" ]]; then
+            echo "BASE_IMAGES param received:"
+            printf "%s" "$BASE_IMAGES" | tee "$BASE_IMAGES_FILE"
+            exit
+        fi
+
+        echo "BASE_IMAGES param is empty, inspecting the SBOM instead"
+
+        raw_inspect=$(skopeo inspect --raw "docker://$BINARY_IMAGE")
+        if manifest_digest=$(jq -e -r '.manifests[0].digest' <<< "$raw_inspect"); then
+            # The BINARY_IMAGE is an index image, each manifest in the list has its own SBOM.
+            # We're gonna assume the base images are the same or similar enough in all the SBOMs.
+            # How would we even handle a build where each manifest in the list is built from different base images?
+            echo "BINARY_IMAGE ($BINARY_IMAGE) is a manifest list, picking an arbitrary image from the list"
+            image_without_digest=${BINARY_IMAGE%@*}
+            image_without_tag=${image_without_digest%:*}
+            image=${image_without_tag}@${manifest_digest}
+        else
+            # The image is a single manifest
+            image=$BINARY_IMAGE
+        fi
+
+
+        for i in {1..5}; do
+            echo "Downloading SBOM for $image (attempt $i)"
+            sbom=$(cosign download sbom "$image") && break
+            [[ "$i" -lt 5 ]] && sleep 1
+        done
+
+        if [[ -z "$sbom" ]]; then
+            echo "Failed to download SBOM after 5 attempts"
+            exit 1
+        fi
+
+        echo -n "Extracting base images from SBOM"
+        echo " (looking for .formulation[].components[] with 'konflux:container:is_base_image' property)"
+        jq -r '
+            .formulation[]?
+            | .components[]?
+            | select(any(.properties[]?; .name == "konflux:container:is_base_image"))
+            | (.purl | capture("^pkg:oci/.*?@(?<digest>.*?:[a-f0-9]*)")) as $matched
+            | .name + "@" + $matched.digest
+        ' <<< "$sbom" | tee "$BASE_IMAGES_FILE"
+
     - name: build
       image: quay.io/konflux-ci/source-container-build:9ad131acf5154d2f280b7b46a1abc543952d325c@sha256:94271c32e4578208ac90308695d2b625d4e932d65f0cdd116b200c39228f5ece
       # per https://kubernetes.io/docs/concepts/containers/images/#imagepullpolicy-defaulting
@@ -51,16 +114,9 @@ spec:
         capabilities:
           add:
             - SETFCAP
-      volumeMounts:
-        - name: source-build-work-place
-          mountPath: /var/source-build
       env:
-        - name: BINARY_IMAGE
-          value: "$(params.BINARY_IMAGE)"
         - name: SOURCE_DIR
           value: "$(workspaces.workspace.path)/source"
-        - name: BASE_IMAGES
-          value: "$(params.BASE_IMAGES)"
         - name: RESULT_FILE
           value: "$(results.BUILD_RESULT.path)"
         - name: CACHI2_ARTIFACTS_DIR
@@ -91,7 +147,7 @@ spec:
           --output-binary-image "$BINARY_IMAGE" \
           --workspace /var/source-build \
           --source-dir "$SOURCE_DIR" \
-          --base-images "$BASE_IMAGES" \
+          --base-images "$(cat "$BASE_IMAGES_FILE")" \
           --write-result-to "$RESULT_FILE" \
           --cachi2-artifacts-dir "$CACHI2_ARTIFACTS_DIR" \
           --registry-allowlist="$registry_allowlist"