Umgebungsvariablen

Informationen zu Umgebungsvariablen

GitHub setzt Standard-Umgebungsvariablen, die für jeden Schritt in einem Workflow-Lauf verfügbar sind. Bei Umgebungsvariablen wird die Groß-/Kleinschreibung berücksichtigt. Befehle, die in Aktionen oder „Steps“ (Schritten) ausgeführt werden, können Umgebungsvariablen erstellen, lesen und ändern.

Um benutzerdefinierte Umgebungsvariablen festzulegen, musst Du die Variablen in der Workflow-Datei angeben. You can define environment variables for a step, job, or entire workflow using the jobs.<job_id>.steps[*].env, jobs.<job_id>.env, and env keywords. Weitere Informationen finden Sie unter „Workflow-Syntax für GitHub“.

jobs:
  weekday_job:
    runs-on: ubuntu-latest
    env:
      DAY_OF_WEEK: Mon
    steps:
      - name: "Hello world when it's Monday"
        if: ${{ env.DAY_OF_WEEK == 'Mon' }}
        run: echo "Hello $FIRST_NAME $middle_name $Last_Name, today is Monday!"
        env:
          FIRST_NAME: Mona
          middle_name: The
          Last_Name: Octocat

To use the value of an environment variable in a workflow file, you should use the env context. If you want to use the value of an environment variable inside a runner, you can use the runner operating system's normal method for reading environment variables.

If you use the workflow file's run key to read environment variables from within the runner operating system (as shown in the example above), the variable is substituted in the runner operating system after the job is sent to the runner. For other parts of a workflow file, you must use the env context to read environment variables; this is because workflow keys (such as if) require the variable to be substituted during workflow processing before it is sent to the runner.

You can also use the set-env workflow command to set an environment variable that the following steps in a job can use. The set-env command can be used directly by an action or as a shell command in a workflow file using the run keyword. Weitere Informationen findest Du unter „Workflow-Befehle für GitHub Actions“.

Standard-Umgebungsvariablen

Es wird dringend empfohlen, dass Aktionen Umgebungsvariablen verwenden, um auf das Dateisystem zuzugreifen, anstatt hartcodierte Dateipfade zu verwenden. GitHub legt Umgebungsvariablen für Aktionen fest, die in allen Runner-Umgebungen verwendet werden sollen.

Determining when to use default environment variables or contexts

GitHub Actions includes a collection of variables called contexts and a similar collection of variables called default environment variables. These variables are intended for use at different points in the workflow:

• Default environment variables: These variables exist only on the runner that is executing your job. For more information, see "Default environment variables."
• Contexts: You can use most contexts at any point in your workflow, including when default environment variables would be unavailable. For example, you can use contexts with expressions to perform initial processing before the job is routed to a runner for execution; this allows you to use a context with the conditional if keyword to determine whether a step should run. Once the job is running, you can also retrieve context variables from the runner that is executing the job, such as runner.os. For details of where you can use various contexts within a workflow, see "Context availability."

The following example demonstrates how these different types of environment variables can be used together in a job:

name: CI
on: push
jobs:
  prod-check:
    if: ${{ github.ref == 'refs/heads/main' }}
    runs-on: ubuntu-latest
    steps:
      - run: echo "Deploying to production server on branch $GITHUB_REF"

In this example, the if statement checks the github.ref context to determine the current branch name; if the name is refs/heads/main, then the subsequent steps are executed. The if check is processed by GitHub Actions, and the job is only sent to the runner if the result is true. Once the job is sent to the runner, the step is executed and refers to the $GITHUB_REF environment variable from the runner.

Namens-Konventionen für Umgebungsvariablen

When you set a custom environment variable, you cannot use any of the default environment variable names listed above with the prefix GITHUB_. If you attempt to override the value of one of these default environment variables, the assignment is ignored.

Alle neuen Umgebungsvariablen, die auf einen Speicherort im Dateisystem verweisen, müssen das Suffix _PATH erhalten. Die Standardvariablen HOME und GITHUB_WORKSPACE sind von dieser Konvention ausgenommen, da die Bezeichnungen „home“ und „workspace“ bereits einen Speicherort implizieren.