Simplify caching example in author guide

Work out the gremlins in the caching example. We now cache only the layer creating the runtime. Signed-off-by: Aidan Delaney <[email protected]>
buildpacks · Nov 17, 2023 · 1c48fc5 · 1c48fc5
1 parent 58fe15d
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diff --git a/content/docs/buildpack-author-guide/create-buildpack/adding-bill-of-materials.md b/content/docs/buildpack-author-guide/create-buildpack/adding-bill-of-materials.md
@@ -123,29 +123,29 @@ plan=$3
 node_js_layer="${layersdir}"/node-js
 mkdir -p "${node_js_layer}"
 
-# ======= MODIFIED =======
 # 3. DOWNLOAD node-js
-node_js_version=$(cat "$plan" | yj -t | jq -r '.entries[] | select(.name == "node-js") | .metadata.version') || "18.18.1"
-node_js_url=https://nodejs.org/dist/v18.18.1/node-v${node_js_version}-linux-x64.tar.xz
-remote_nodejs_version=$(cat "${layersdir}/node-js.toml" 2> /dev/null | yj -t | jq -r .metadata.nodejs-version 2>/dev/null || echo 'NOT FOUND')
+default_node_js_version="18.18.1"
+node_js_version=$(cat "$plan" | yj -t | jq -r '.entries[] | select(.name == "node-js") | .metadata.version' || echo ${default_node_js_version})
+node_js_url=https://nodejs.org/dist/v${node_js_version}/node-v${node_js_version}-linux-x64.tar.xz
+remote_nodejs_version=$(cat "${layersdir}/node-js.toml" 2> /dev/null | yj -t | jq -r .metadata.nodejs_version 2>/dev/null || echo 'NOT FOUND')
 if [[ "${node_js_url}" != *"${remote_nodejs_version}"* ]] ; then
     echo "-----> Downloading and extracting NodeJS"
-    node_js_url=https://nodejs.org/dist/v18.18.1/node-v18.18.1-linux-x64.tar.xz
     wget -q -O - "${node_js_url}" | tar -xJf - --strip-components 1 -C "${node_js_layer}"
-    cat >> "${layersdir}/node-js.toml" << EOL
-[metadata]
-nodejs-version = "${node_js_version}"
-EOL
 else
     echo "-----> Reusing NodeJS"
 fi
 
 # 4. MAKE node-js AVAILABLE DURING LAUNCH and CACHE the LAYER
-echo -e '[types]\ncache = true\nlaunch = true' > "${layersdir}/node-js.toml"
+    cat > "${layersdir}/node-js.toml" << EOL
+[types]
+cache = true
+launch = true
+[metadata]
+nodejs_version = "${node_js_version}"
+EOL
 
-# ========== ADDED ===========
 # 5. SET DEFAULT START COMMAND
-cat > "${layersdir}/launch.toml" << EOL
+cat >> "${layersdir}/launch.toml" << EOL
 [[processes]]
 type = "web"
 command = "node app.js"
@@ -154,8 +154,8 @@ EOL
 
 # ========== ADDED ===========
 # 6. ADD A SBOM
-node-jsbom="${layersdir}/node-js.sbom.cdx.json"
-cat >> ${node-jsbom} << EOL
+node_jsbom="${layersdir}/node-js.sbom.cdx.json"
+cat >> ${node_jsbom} << EOL
 {
   "bomFormat": "CycloneDX",
   "specVersion": "1.4",

diff --git a/content/docs/buildpack-author-guide/create-buildpack/caching.md b/content/docs/buildpack-author-guide/create-buildpack/caching.md
@@ -81,7 +81,7 @@ Reusing layer 'examples/node-js:node-js'
 
 ## Caching dependencies
 
-Now, let's implement the caching logic.  We need to record the version of the NodeJS runtime that is used in a build.  On subsequent builds, the caching logic will detect the current requested NodeJS version and restore the previous layer from the cache if the current requested NodeJS version matches the previous NodeJS runtime version.
+Now, let's implement the caching logic.  We need to record the version of the NodeJS runtime that is used in a build.  On subsequent builds, the caching logic will detect if the NodeJS version is the same as the version in the cached layer.  We restore the previous layer from the cache if the current requested NodeJS version matches the previous NodeJS runtime version.
 
 <!-- test:file=node-js-buildpack/bin/build -->
 ```
@@ -97,27 +97,30 @@ layersdir=$1
 node_js_layer="${layersdir}"/node-js
 mkdir -p "${node_js_layer}"
 
+# ======= MODIFIED =======
 # 3. DOWNLOAD node-js
-node_js_url=https://nodejs.org/dist/v18.18.1/node-v18.18.1-linux-x64.tar.xz
-remote_nodejs_version=$(cat "${layersdir}/node-js.toml" 2> /dev/null | yj -t | jq -r .metadata.nodejs-version 2>/dev/null || echo 'NOT FOUND')
-if [[ "${node_js_url}" != *"${remote_nodejs_version}"* ]] ; then
+node_js_version="18.18.1"
+node_js_url=https://nodejs.org/dist/v${node_js_version}/node-v${node_js_version}-linux-x64.tar.xz
+cached_nodejs_version=$(cat "${layersdir}/node-js.toml" 2> /dev/null | yj -t | jq -r .metadata.nodejs_version 2>/dev/null || echo 'NOT FOUND')
+if [[ "${node_js_url}" != *"${cached_nodejs_version}"* ]] ; then
     echo "-----> Downloading and extracting NodeJS"
-    node_js_url=https://nodejs.org/dist/v18.18.1/node-v18.18.1-linux-x64.tar.xz
     wget -q -O - "${node_js_url}" | tar -xJf - --strip-components 1 -C "${node_js_layer}"
-    cat >> "${layersdir}/node-js.toml" << EOL
-[metadata]
-nodejs-version = "18.18.1"
-EOL
 else
     echo "-----> Reusing NodeJS"
 fi
 
+# ======= MODIFIED =======
 # 4. MAKE node-js AVAILABLE DURING LAUNCH and CACHE the LAYER
-echo -e '[types]\ncache = true\nlaunch = true' > "${layersdir}/node-js.toml"
+    cat > "${layersdir}/node-js.toml" << EOL
+[types]
+cache = true
+launch = true
+[metadata]
+nodejs_version = "${node_js_version}"
+EOL
 
-# ========== ADDED ===========
 # 5. SET DEFAULT START COMMAND
-cat > "${layersdir}/launch.toml" << EOL
+cat >> "${layersdir}/launch.toml" << EOL
 [[processes]]
 type = "web"
 command = "node app.js"
@@ -140,7 +143,7 @@ you will see the new caching logic at work during the `BUILDING` phase:
 ===> BUILDING
 ...
 ---> NodeJS Buildpack
----> Reusing node-js
+---> Reusing NodeJS
 ```
 
 Next, let's see how buildpack users may be able to provide configuration to the buildpack.

diff --git a/...ent/docs/buildpack-author-guide/create-buildpack/make-buildpack-configurable.md b/...ent/docs/buildpack-author-guide/create-buildpack/make-buildpack-configurable.md
@@ -57,27 +57,29 @@ mkdir -p "${node_js_layer}"
 
 # ======= MODIFIED =======
 # 3. DOWNLOAD node-js
-node_js_version=$(cat "$plan" | yj -t | jq -r '.entries[] | select(.name == "node-js") | .metadata.version') || "18.18.1"
-node_js_url=https://nodejs.org/dist/v18.18.1/node-v${node_js_version}-linux-x64.tar.xz
-remote_nodejs_version=$(cat "${layersdir}/node-js.toml" 2> /dev/null | yj -t | jq -r .metadata.nodejs-version 2>/dev/null || echo 'NOT FOUND')
+default_node_js_version="18.18.1"
+node_js_version=$(cat "$plan" | yj -t | jq -r '.entries[] | select(.name == "node-js") | .metadata.version' || echo ${default_node_js_version})
+node_js_url=https://nodejs.org/dist/v${node_js_version}/node-v${node_js_version}-linux-x64.tar.xz
+remote_nodejs_version=$(cat "${layersdir}/node-js.toml" 2> /dev/null | yj -t | jq -r .metadata.nodejs_version 2>/dev/null || echo 'NOT FOUND')
 if [[ "${node_js_url}" != *"${remote_nodejs_version}"* ]] ; then
     echo "-----> Downloading and extracting NodeJS"
-    node_js_url=https://nodejs.org/dist/v18.18.1/node-v18.18.1-linux-x64.tar.xz
     wget -q -O - "${node_js_url}" | tar -xJf - --strip-components 1 -C "${node_js_layer}"
-    cat >> "${layersdir}/node-js.toml" << EOL
-[metadata]
-nodejs-version = "${node_js_version}"
-EOL
 else
     echo "-----> Reusing NodeJS"
 fi
 
 # 4. MAKE node-js AVAILABLE DURING LAUNCH and CACHE the LAYER
-echo -e '[types]\ncache = true\nlaunch = true' > "${layersdir}/node-js.toml"
+    cat > "${layersdir}/node-js.toml" << EOL
+[types]
+cache = true
+launch = true
+[metadata]
+nodejs_version = "${node_js_version}"
+EOL
 
 # ========== ADDED ===========
 # 5. SET DEFAULT START COMMAND
-cat > "${layersdir}/launch.toml" << EOL
+cat >> "${layersdir}/launch.toml" << EOL
 [[processes]]
 type = "web"
 command = "node app.js"

diff --git a/.../docs/buildpack-author-guide/create-buildpack/specify-multiple-process-types.md b/.../docs/buildpack-author-guide/create-buildpack/specify-multiple-process-types.md
@@ -50,7 +50,10 @@ node_js_url=https://nodejs.org/dist/v18.18.1/node-v18.18.1-linux-x64.tar.xz
 wget -q -O - "$node_js_url" | tar -xJf - --strip-components 1 -C "${node_js_layer}"
 
 # 4. MAKE node-js AVAILABLE DURING LAUNCH
-echo -e '[types]\nlaunch = true' > "${layersdir}/node-js.toml"
+    cat > "${layersdir}/node-js.toml" << EOL
+[types]
+launch = true
+EOL
 
 # ========== MODIFIED ===========
 # 5. SET DEFAULT START COMMAND