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[Platform API] - Add Execution Environment definition #416

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jkutner merged 5 commits into from
Nov 13, 2025
Merged

[Platform API] - Add Execution Environment definition #416

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Add Execution Environment
jjbustamante May 7, 2025
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formatting issue
jjbustamante May 7, 2025
0312eab
Fixing review comments from Natalie
jjbustamante May 14, 2025
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1. ✅ Added CNB_EXEC_ENV to the restorer phase - The environment vari…
jjbustamante Jun 3, 2025
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Merge branch 'main' into jjbustamante/0134-execution-env-platform
jkutner Nov 13, 2025
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16 changes: 14 additions & 2 deletions platform.md
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Original file line number Diff line number Diff line change
Expand Up @@ -130,6 +130,8 @@ A **launcher layer** refers to a layer in the app OCI image containing the **lau

The **launcher** refers to a lifecycle executable packaged in the **app image** for the purpose of executing processes at runtime.

An **execution environment** refers to the context in which an application is intended to run. Standard values include "production", "test", and "development". Production is the default if not specified.

An **image extension** refers to software compliant with the [Image Extension Interface Specification](image_extension.md). Image extensions participate in detection and execute before the buildpack build process.

A **stack** (deprecated, see [deprecations](#deprecations)) is a contract, implemented by a **build image** and **run image**, that guarantees properties of the **build environment** and **app image**.
Expand Down Expand Up @@ -400,6 +402,7 @@ Usage:
| `<app>` | `CNB_APP_DIR` | `/workspace` | Path to application directory |
| `<build-config>` | `CNB_BUILD_CONFIG_DIR` | `/cnb/build-config` | Path to build config directory |
| `<buildpacks>` | `CNB_BUILDPACKS_DIR` | `/cnb/buildpacks` | Path to buildpacks directory (see [Buildpacks Directory Layout](#buildpacks-directory-layout)) |
| `<exec-env>` | `CNB_EXEC_ENV` | `production` | Target execution environment. Standard values: "production", "test", "development". |
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@natalieparellano natalieparellano May 9, 2025

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This all seems fine to me, but I'm looking at this comment from the RFC and I don't see that specified anywhere. Are we expecting the lifecycle to skip over buildpacks or groups that don't match the current environment?

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@jkutner jkutner May 15, 2025

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yes. the question is if we want to skip an entire group if one of the buildpack doesn't match the env. We need @hone to chime in there

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@jjbustamante jjbustamante Jun 3, 2025

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@jkutner @hone @natalieparellano here is a proposal

- When `CNB_EXEC_ENV` is set and differs from a previous build's execution environment:
  - The lifecycle SHALL skip buildpacks that do not support the current execution environment
  - If all buildpacks in a group are skipped due to execution environment mismatch, the lifecycle SHALL continue to the next group in the order
  - The lifecycle SHOULD NOT restore layers from previous builds with different execution environments

Or do we want to skip the entire group?

| `<extensions>`^ | `CNB_EXTENSIONS_DIR` | `/cnb/extensions` | Path to image extensions directory (see [Image Extensions Directory Layout](#image-extensions-directory-layout) |
| `<generated>`^ | `CNB_GENERATED_DIR` | `<layers>/generated` | Path to output directory for generated Dockerfiles |
| `<group>` | `CNB_GROUP_PATH` | `<layers>/group.toml` | Path to output group definition |
Expand Down Expand Up @@ -656,6 +659,7 @@ Usage:
| `<app>` | `CNB_APP_DIR` | `/workspace` | Path to application directory |
| `<build-config>` | `CNB_BUILD_CONFIG_DIR` | `/cnb/build-config` | Path to build config directory |
| `<buildpacks>` | `CNB_BUILDPACKS_DIR` | `/cnb/buildpacks` | Path to buildpacks directory (see [Buildpacks Directory Layout](#buildpacks-directory-layout)) |
| `<exec-env>` | `CNB_EXEC_ENV` | `production` | Target execution environment. Standard values: "production", "test", "development". |
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@jabrown85 jabrown85 May 22, 2025

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We probably want CNB_EXEC_ENV in restorer as well. In order to do things like skip cache restore.

Extender also needs it I would think?

| `<group>` | `CNB_GROUP_PATH` | `<layers>/group.toml` | Path to group definition (see [`group.toml`](#grouptoml-toml)) |
| `<layers>` | `CNB_LAYERS_DIR` | `/layers` | Path to layers directory |
| `<log-level>` | `CNB_LOG_LEVEL` | `info` | Log Level |
Expand Down Expand Up @@ -988,6 +992,7 @@ Usage:
| Input | Environment Variable | Default Value | Description |
|------------------------------------|----------------------|---------------|-----------------------------------------------------------|
| `<app>` | `CNB_APP_DIR` | `/workspace` | Path to application directory |
| `<exec-env>` | `CNB_EXEC_ENV` | `production` | Target execution environment. Standard values: "production", "test", "development". |
| `<layers>` | `CNB_LAYERS_DIR` | `/layers` | Path to layer directory |
| `<process-type>` | | | `type` of process to launch |
| `<direct>` | | | Process execution strategy |
Expand All @@ -1004,7 +1009,11 @@ The launcher:
- **If** the final path element in `$0`, matches the type of any buildpack-provided process type
- `<process-type>` SHALL be the final path element in `$0`
- The lifecycle:
- MUST select the process with type equal to `<process-type>` from `<layers>/config/metadata.toml`
- MUST select the process with type equal to `<process-type>` from `<layers>/config/metadata.toml` that is eligible for the current execution environment
- **If** no process with the requested type is eligible for the current execution environment, the lifecycle MUST fail
- A process is considered eligible for the current execution environment if:
- It has no execution environment specified in `exec-env`, OR
- Its `exec-env` includes the value of `<exec-env>`
- MUST set `<working-dir>` to the value defined for the process in `<layers>/config/metadata.toml`, or to `<app>` if not defined
- **If** the buildpack that provided the process supports default process args
- `<direct>` SHALL be `true`
Expand Down Expand Up @@ -1328,6 +1337,7 @@ command = ["<command>"]
args = ["<arguments>"]
direct = false
working-dir = "<working directory>"
exec-env = ["<execution environment>"] # Optional. If not specified, applies to all execution environments

[[slices]]
paths = ["<app sub-path glob>"]
Expand Down Expand Up @@ -1448,7 +1458,8 @@ Where:
],
"direct": false,
"working-dir": "<working-dir>",
"buildpackID": "<buildpack ID>"
"buildpackID": "<buildpack ID>",
"exec-env": ["<execution environment>"] // Optional. If not specified, applies to all execution environments
}
],
"buildpacks": [
Expand Down Expand Up @@ -1498,6 +1509,7 @@ Where:
"config": {
"sha": "<config-layer-diffID>"
},
"exec-env": "<execution environment>",
"launcher": {
"sha": "<launcher-layer-diffID>"
},
Expand Down