improving readme

README.md

@@ -16,7 +16,7 @@ With the MetaBuildpack, you can easily describe what assets and processes are ne
 - [x] Caching
 - [ ] Bill of materials (sbom)
 - [x] Launch configuration
-- [ ] Tracing of Pipeline (in progress)
+- [-] Tracing of Pipeline (in progress)
 - [x] Published builder image and stack with tool included (docker.io/atgracey/metabuildpackbase:latest)
 - [ ] Automated stack builds
 - - [ ] x86_64
@@ -26,8 +26,83 @@ With the MetaBuildpack, you can easily describe what assets and processes are ne
 
 ## How to use
 
-Full story to be written when I can. See ./testing/runtest.sh for clues. 
+I'm building a stack that anyone can use: 
 
+```
+[stack]
+id = "opensuse.stack.leap15.3"
+run-image = "registry.opensuse.org/home/atgracey/opensuse_leap_15.3/cnbp_run:latest"
+build-image = "docker.io/atgracey/metabuildpackbuild:latest" 
+``` 
+Note: I'll be moving the build image to registry.opensuse.org as soon as I get the rust code built there as well.
 
-To use the program, run 
-`cargo run -- --phase build -f ./noop-spec.json  -e /tmp/env/ -p /tmp/plan.json -l /tmp/`
+
+You can use this inside your detect and build bash scripts with: 
+
+```
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+env_dir="$1/env"
+plan_path="$2"
+
+/usr/local/bin/metabuildpack --phase detect -b $CNB_BUILDPACK_DIR -f $CNB_BUILDPACK_DIR/spec.json -e $env_dir -p $plan_path
+exit $?
+```
+
+and 
+
+```
+#!/usr/bin/env bash
+
+set -euo pipefail
+layers_dir="$1"
+env_dir="$2/env"
+plan_path="$3"
+
+/usr/local/bin/metabuildpack --phase build -b $CNB_BUILDPACK_DIR -f $CNB_BUILDPACK_DIR/spec.json -e $env_dir -p $plan_path -l $layers_dir
+
+exit $?
+```
+
+
+With those scripts in place, the last part is to write a spec file.
+
+I wrote this one to install node in an airgapped manner. 
+
+Note: I'm adding comments that will break copy and paste!
+
+```
+{
+  "name":"nodejs-bins", # name used to log and trace correctly 
+  "layers":[{ 
+    "name":"nodebin", # layers can be used to cache files across builds, expose files to the published image, or expose files to later buildpacks 
+    "cache": true,
+    "launch": true,
+    "build": true
+  }],
+  "environment":[{ # This allows us to set variables in a more dynamic way, if a value is passed in to the build process by the end user, it will superscede what's defined here. 
+    "key": "PATH",
+    "default": "{{env.PATH}}:{{layers_dir}}/nodebin/node-v17.0.1-linux-x64/bin/"
+  }], 
+  "detect": { # You can decide whether to run or not based on existence of files or the result of a script.
+    "exists": [{
+      "path": "./package.json"
+    }],
+    "scripts": [] 
+  },
+  "build":[{ # When building, you can pull files from other places, from a set of files provided in the buildpack itself, and run scripts. 
+    "remote": [],
+    "local": [],
+    "scripts": [{
+      "command": "tar -xf {{buildpack_dir}}/assets/node.tar.xz -C {{layers_dir}}/nodebin/"
+    }]
+  }],
+  "process":"{{layers_dir}}/nodebin/node-v17.0.1-linux-x64/bin/node index.js" # You can also set the default command the published container will run
+}
+```
+
+
+
+A reference set of buildpacks can be found at: https://github.com/agracey/buildpack_example