`Forgejo Actions` provides continuous integration driven from the files in the `.forgejo/workflows` directory of a repository. The syntax and semantic of the `workflow` files will be familiar to people used to [GitHub Actions](https://docs.github.com/en/actions) but **they are not and will never be identical**.
The following guide explains key **concepts** to help understand how `workflows` are interpreted, with a set of **examples** that can be copy/pasted and modified to fit particular use cases.
A repository, a user or an organization can hold secrets, a set of key/value pairs that are stored encrypted in the `Forgejo` database and revealed to the `workflows` as `${{ secrets.KEY }}`. They can be defined from the web interface:
The syntax and semantic of the YAML file describing a `workflow` are partially explained here. When an entry is missing the [GitHub Actions](https://docs.github.com/en/actions) documentation can help because there are similarities. But there also are significant differences that deserve testing.
Each `job` in a `workflow` must specify the kind of machine it needs to run its `steps` with `runs-on`. For instance `docker` in the following `workflow`:
The actual machine provided by the runner **entirely depends on how the `Forgejo runner` was registered** (see the [Forgejo Actions administrator guide](../../admin/actions) for more information).
By default the `docker` label will create a container from a [Node.js 16 Debian GNU/Linux bullseye image](https://hub.docker.com/_/node/tags?name=16-bullseye) and will run each `step` as root. Since an application container is used, the jobs will inherit the limitations imposed by the engine (Docker for instance). In particular they will not be able to run or install software that depends on `systemd`.
If the default image is unsuitable, a job can specify an alternate container image with `container:`, [as shown in this example](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/testdata/example-container/.forgejo/workflows/test.yml). For instance the following will ensure the job is run using [Alpine 3.18](https://hub.docker.com/_/alpine/tags?name=3.18).
The `runs-on: self-hosted` label will run the jobs in a [LXC](https://linuxcontainers.org/lxc/) container where software that rely on `systemd` can be installed. Nested containers can also be created recursively (see [the setup-forgejo integration tests](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/.forgejo/workflows/integration.yml) for an example).
`Services` are not supported for jobs that run on LXC.
Specifies the repository from which the `Action` will be cloned.
A relative `Action` such as `uses: actions/checkout@v3` will clone the repository at the URL composed by prepending the default actions URL which is https://code.forgejo.org/actions. It is the equivalent of providing the fully qualified URL `uses: https://code.forgejo.org/actions/checkout@v3`. In other words the following:
`Forgejo` itself does not run the `jobs`, it relies on the [Forgejo runner](https://code.forgejo.org/forgejo/runner) to do so. See the [Forgejo Actions administrator guide](../../admin/actions) for more information.
## Actions
An `Action` is a repository that contains the equivalent of a function in any programming language, with inputs and outputs as desccribed in the `action.yml` file at the root of the repository (see [this example](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/action.yml)).
One of the most commonly used action is [checkout](https://code.forgejo.org/actions/checkout#usage) which clones the repository that triggered a `workflow`. Another one is [setup-go](https://code.forgejo.org/actions/setup-go#usage) that will install Go.
Just as any other program of function, an `Action` has pre-requisites to successfully be installed and run. When looking at re-using an existing `Action`, this is an important consideration. For instance [setup-go](https://code.forgejo.org/actions/setup-go) depends on NodeJS during installation.
## Services
PostgreSQL, redis and other services can conveniently be run from container images with something similar to (see the [full example](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/testdata/example-service/.forgejo/workflows/test.yml)):
```yaml
services:
pgsql:
image: postgres:15
env:
POSTGRES_DB: test
POSTGRES_PASSWORD: postgres
ports:
- '5432:5432'
```
A container with the specified `image:` is run before the `job` starts and is terminated when it completes. The job can address the service using its name, in this case `pgsql`.
Each example is part of the [setup-forgejo](https://code.forgejo.org/actions/setup-forgejo/) action [test suite](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/testdata).
- [Echo](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/testdata/example-echo/.forgejo/workflows/test.yml) - a single step that prints one sentence.
- [PostgreSQL service](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/testdata/example-service/.forgejo/workflows/test.yml) - a PostgreSQL service and a connection to display the (empty) list of tables of the default database.
- [Choosing the image with `container`](https://code.forgejo.org/actions/setup-forgejo/src/branch/main/testdata/example-container/.forgejo/workflows/test.yml) - replacing the `runs-on: docker` image with the `alpine:3.18` image using `container:`.
