Add go115 builder (#1)

* add stack
* add builder
* update test

Signed-off-by: laminar <[email protected]>

BUILD.bazel

@@ -0,0 +1,11 @@
+load("@bazel_gazelle//:def.bzl", "gazelle")
+
+# Google Cloud Platform Buildpacks
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+exports_files(["LICENSE"])
+
+# gazelle:prefix https://github.com/GoogleCloudPlatform/buildpacks
+gazelle(name = "gazelle")

CONTRIBUTING.md

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+# How to Contribute
+
+We'd love to accept your patches and contributions to this project. There are
+just a few small guidelines you need to follow.
+
+## Contributor License Agreement
+
+Contributions to this project must be accompanied by a Contributor License
+Agreement. You (or your employer) retain the copyright to your contribution;
+this simply gives us permission to use and redistribute your contributions as
+part of the project. Head over to <https://cla.developers.google.com/> to see
+your current agreements on file or to sign a new one.
+
+You generally only need to submit a CLA once, so if you've already submitted one
+(even if it was for a different project), you probably don't need to do it
+again.
+
+## Code reviews
+
+All submissions, including submissions by project members, require review. We
+use GitHub pull requests for this purpose. Consult
+[GitHub Help](https://help.github.com/articles/about-pull-requests/) for more
+information on using pull requests.
+
+## Community Guidelines
+
+This project follows
+[Google's Open Source Community Guidelines](https://opensource.google/conduct/).
+
+## Building Buildpacks
+
+The GCP Buildpacks project is implemented in Go and uses
+[Bazel](https://bazel.build/) as the build system. Throughout the document, all
+commands are relative to project root and `bazel` is interchangable
+with `blaze`.
+
+### Installing project dependencies
+
+Please follow the links below for installation instructions.
+
+* [Bazel](https://docs.bazel.build/install.html)
+* [Docker](https://store.docker.com/search?type=edition&offering=community)
+* [pack](https://buildpacks.io/docs/install-pack/)
+* [container-structure-test](https://github.com/GoogleContainerTools/container-structure-test#installation)
+
+Note: `docker`, `pack`, and `container-structure-test` must to be on `$PATH`
+as interpreted by Bazel, which may differ from system `$PATH`. When using
+Blaze, the programs or symlinks to them must be in `/usr/bin`.
+
+The following command verifies that all dependencies are installed correctly
+or prints further instructions:
+
+```bash
+bazel test --test_output=errors tools/checktools:main_test
+```
+
+### Builder overview
+
+Builder definitions and acceptance tests are located in the `builders`
+directory.
+
+* GCP
+  * Builders used in [Cloud Code](https://cloud.google.com/code)/[Cloud Run](https://cloud.google.com/run)/[Skaffold](https://github.com/GoogleContainerTools/skaffold)
+    and appropriate for the general use case, e.g. Kubernetes, local development.
+* GAE
+  * Builders used in [App Engine](https://cloud.google.com/appengine).
+* GCF
+  * Builders used in [Cloud Functions](https://cloud.google.com/functions).
+
+### gcpbuildpack package
+
+The `gcpbuildpack` package implements general functionality that is shared
+across buildpacks. In addition to the signature of the `build` and `detect`
+functions, the package includes the `Context` struct that implements functions
+to manipulate files and layers and to execute arbitrary commands.
+
+Each buildpack has a single `main.go` file that implements a `detectFn` and
+a `buildFn`:
+
+* `detectFn` is invoked through `/bin/detect`.
+  A buildpack must choose to participate in a build by returning a
+  `detect.OptIn` or one if its variants opt-out of the build by returning
+  `detect.OptOut` or one of its variants. If needed, it may also return an
+  error. See `pkg/gcpbuildpack/detect.go` for the full list of `Opt*` functions.
+
+* `buildFn` is invoked through `/bin/build`.
+  The responsibility of the build function is to create layers and populate them
+  with data using a combination of Go and shell commands.
+
+### Error attribution
+
+The `gcpbuildpack` package supports error attribution to differentiate between
+user and platform errors. Generally, any error that was triggered while
+processing user code, such as installing dependencies or compiling a program,
+should be attributed to the user. Errors that occur while manipulating files or
+directories or when performing actions the user has no control over should be
+attributed to the platform. Some errors may be ambiguous, such as downloading
+dependencies from a remote repository, and attributable to both the user
+(wrong dependency version) and the platform (network error). In these cases,
+errors should be attributed based on the **most likely** cause. It is much
+more likely that the dependencies file has an incorrect version, undeclared
+dependency, or an outdated lock file than it is for the network to be down.
+
+Some examples:
+* Reading package.json: PLATFORM (I/O error)
+* Unmarshalling package.json: USER (invalid package.json file)
+* Compiling a Go program: USER (syntax error, dependency not found, etc.)
+* Downloading Go modules: USER (module not found more likely than network issue)
+
+### Using gcp.WithUserAttribution()
+
+The `Context` struct provides convenience functions to execute arbitrary
+commands. When calling `Exec`, use the option `gcp.WithUserAttribution`
+for commands that depend on user input, such as downloading dependencies or
+compiling a program. It is also possible to split failure attribution and
+timing attribution, using `gcp.WithUserFailureAttribution`, or
+`gcp.WithUserTimingAttribution`. In the absence of these options, attribution
+is assigned to the system.
+In all cases, prefer using specialized functions when available on `Context`
+instead of `Exec`, for example `ctx.Symlink` instead of `ln -s`.
+
+### Compiling a buildpack
+
+```bash
+export runtime=nodejs
+export buildpack=npm
+bazel build "cmd/${runtime}/${buildpack}:${buildpack}.tgz"
+```
+
+This will produce a tgz archive containing `buildpack.toml`, the `/bin/build`
+and `/bin/detect` binaries, as well as any other files required by the
+buildpack.
+
+### Creating a builder
+
+To create a builder for a given product and runtime, first pull or build the
+stack images required by the builder:
+
+```bash
+# Optional, pull stack images required by the builder.
+bazel run tools:pull_images gcp base
+# Create a builder image tagged as <product>/<runtime>.
+bazel build builders/gcp/base:builder.image
+```
+
+You can also rebuild the gcp/base stack images:
+
+```bash
+# Optional, build stack images required by the builder.
+bazel run builders/gcp/base/stack:build
+```
+
+GAE and GCF stack images cannot be modified, to pull the latest stack images
+and create a builder:
+
+```bash
+export product=gae
+export runtime=nodejs12
+
+# Optional, pull stack images required by the builder.
+bazel run tools:pull_images "$product" "$runtime"
+# Create a builder image tagged as gcp/base.
+bazel build "builders/${product}/${runtime}:builder.image"
+```
+
+This will produce a builder image tagged as `<product>/<runtime>` in the local
+Docker daemon.
+
+### Updating Dependencies
+
+If you would like to update any project dependencies, please file a new issue.
+
+## Testing
+
+Each builder has a set of acceptance tests that validate the builder by
+building and running a set of applications. By default, the tests pull the
+latest stack images from GCR. Running all acceptance tests is CPU, memory,
+and network intensive, so we recommend only running tests for affected builders.
+
+To run acceptance tests for the `gcp/base` builder, use the following command:
+
+```bash
+bazel test builders/gcp/base/acceptance/...
+```
+
+or more generally:
+
+```bash
+export product=gae
+export runtime=nodejs12
+bazel test "builders/${product}/${runtime}/acceptance/..."
+```
+
+### Cleaning up Docker artifacts
+
+The acceptance tests attempt to clean up containers and images after they
+finish running, but there maybe some left-over data that can end up taking
+a significant amount of storage space.
+
+```bash
+# Remove all stopped containers.
+docker rm -f $(docker ps -a -q)
+# Remove all untagged images.
+docker rmi $(docker images --filter "dangling=true" -q --no-trunc)
+# Remove pack cache volumes.
+docker volume prune
+# Delete images older than 30 days.
+docker image prune --all --filter until=720h
+```
+
+## Common Problems
+
+### Testing builder with `pack build` fails
+
+Run `pack build ... -v` to produce more verbose debug output.
+
+### `bazel test` fails on macOS or Windows
+
+By default, `bazel` builds Go binaries for the current platform.  As GCP Buildpacks
+are targeted to Linux-based container images, our `.bazelrc` configures builds for
+the Linux AMD64 platform by default.
+
+To run tests on the local platform, override the `--plaforms` as
+follows:
+```sh
+bazel test --platforms="" pkg/...
+```