# Security - First Steps { #security-first-steps }

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

You could also use it to generate code automatically, for clients that communicate with your API. For example, frontend, mobile or IoT applications.

## Recap, step by step { #recap-step-by-step }

### Step 1: import `FastAPI` { #step-1-import-fastapi }

{* ../../docs_src/first_steps/tutorial001.py hl[1] *}

`FastAPI` is a Python class that provides all the functionality for your API.

                  "text": "N/A"
                }
              },
              "type": "special"
            }
          ],
          "thresholds": {
            "mode": "percentage",
            "steps": [
              {
                "color": "green",
                "value": null
              }
            ]
          },
          "unit": "dtdurations"
        },
        "overrides": []
      },

                  "text": "N/A"
                }
              },
              "type": "special"
            }
          ],
          "thresholds": {
            "mode": "absolute",
            "steps": [
              {
                "color": "green",
                "value": null
              },
              {
                "color": "red",
                "value": 80
              }
            ]

jobs:
  changes:
    runs-on: ubuntu-latest
    # Required permissions
    permissions:
      pull-requests: read
    # Set job outputs to values from filter step
    outputs:
      docs: ${{ steps.filter.outputs.docs }}
    steps:
    - uses: actions/checkout@v5
    # For pull requests it's not necessary to checkout the code but for the main branch it is
    - uses: dorny/paths-filter@v3
      id: filter

    maxParallelForks: String = "%maxParallelForks%",
    extraSteps: BuildSteps.() -> Unit = {}, // the steps after runner steps
    preSteps: BuildSteps.() -> Unit = {}, // the steps before runner steps
) {
    buildType.applyDefaultSettings(os, timeout = timeout, buildJvm = buildJvm, arch = arch)

    buildType.steps {
        preSteps()
    }

        "type": "prometheus",
        "uid": "${DS_PROMETHEUS}"
      },
      "fieldConfig": {
        "defaults": {
          "mappings": [],
          "thresholds": {
            "mode": "absolute",
            "steps": [
              {
                "color": "green",
                "value": null
              },
              {
                "color": "semi-dark-red",
                "value": 80
              }

        title: '${{ github.event.inputs.release_branch }} cherry-pick: ${{ steps.cherrypick.outputs.SHORTSHA }} "${{ steps.cherrypick.outputs.TITLE }}"'
        committer: TensorFlow Release Automation <******@****.***>
        token: ${{ secrets.JENKINS_TOKEN }}
        base: ${{ github.event.inputs.release_branch }}
        branch: ${{ github.event.inputs.release_branch }}-${{ steps.cherrypick.outputs.SHORTSHA }}
        reviewers: learning-to-play

        include:
          - os: windows-latest
            java: 21
            root-pom: pom.xml
    runs-on: ${{ matrix.os }}
    env:
      ROOT_POM: ${{ matrix.root-pom }}
    steps:
      # Cancel any previous runs for the same branch that are still running.
      - name: 'Cancel previous runs'
        uses: styfle/cancel-workflow-action@85880fa0301c86cca9da44039ee3bb12d3bedbfa # 0.12.1
        with:

      - run: ./gradlew compileAll -DdisableLocalCache=true ${{ steps.determine-sys-prop-args.outputs.sys-prop-args }}
      - uses: actions/upload-artifact@v4
        if: always()
        with:
          name: build-receipt.properties
          path: platforms/core-runtime/base-services/build/generated-resources/build-receipt/org/gradle/build-receipt.properties
    outputs:
      matrix: ${{ steps.setup-matrix.outputs.matrix }}