# Middleware { #middleware }

You can add middleware to **FastAPI** applications.

A "middleware" is a function that works with every **request** before it is processed by any specific *path operation*. And also with every **response** before returning it.

* It takes each **request** that comes to your application.
* It can then do something to that **request** or run any needed code.

				// Adjust the probability of healing.
				// This first removes lowest x from the mod check and makes it x times more likely.
				// So if duudc = 10 and we want heal check every 50 cycles, we check
				// if (cycle/10) % (50/10) == 0, which would make heal checks run once every 50 cycles,
				// if the objects are pre-selected as 1:10.
				folder.objectHealProbDiv = dataUsageUpdateDirCycles
			}
			f.updateCurrentPath(folder.name)

		},
		{
			val:   0.79,
			label: labels[2],
		},
	}
	ticker := time.NewTicker(1 * time.Millisecond)
	defer ticker.Stop()
	for _, obs := range observations {
		// Send observations once every 1ms, to simulate delay between
		// observations. This is to test the channel based
		// synchronization used internally.
		<-ticker.C
		ttfbHist.With(prometheus.Labels{"api": obs.label}).Observe(obs.val)
	}

name: Feedback

on:
  schedule:
    - cron: '0 * * * *' # every hour
  workflow_dispatch:

permissions: {}

jobs:
  feedback:
    permissions:
      issues: write
      pull-requests: write
    runs-on: ubuntu-latest
    steps:
      # Feedback loop: ask for something on PR/Issue and close if not provided or return to the queue on update.
      # https://github.com/gradle/issue-management-action/blob/main/src/feedback.ts

# variables in it, OR may be left empty if the user has already exported the
# relevant variables in their environment. Because of 'set -o allexport' above
# (which is equivalent to "set -a"), every variable in the file is exported
# for other files to use.
#
# Separately, if TFCI is set *and* there are also additional TFCI_ variables
# set in the shell environment, those variables will be restored after the

Then wrap the WSGI (e.g. Flask) app with the middleware.

And then mount that under a path.

{* ../../docs_src/wsgi/tutorial001.py hl[2:3,3] *}

## Check it { #check-it }

Now, every request under the path `/v1/` will be handled by the Flask application.

And the rest will be handled by **FastAPI**.

name: 'Requeue stale team-triage items'
on:
  schedule:
    # Execute every day at 00:05 to avoid conflicts with other workflows
    - cron: '5 0 * * *'

permissions: {}

jobs:
  requeue:
    permissions:
      issues: write
      pull-requests: write
    runs-on: ubuntu-latest
    steps:
      - uses: actions/stale@v10
        with:
          operations-per-run: 50
          remove-stale-when-updated: false

	}
	// Each Lock has m entries
	if len(l.lockMap) != len(rResources)+len(wResources)*m {
		t.Fatalf("lockmap len, got %d, want %d + %d", len(l.lockMap), len(rResources), len(wResources)*m)
	}
	// A UID is added for every resource
	if len(l.lockUID) != len(rResources)*2+len(wResources)*m {
		t.Fatalf("lockUID len, got %d, want %d + %d", len(l.lockUID), len(rResources)*2, len(wResources)*m)
	}
	// RUnlock once...

name: 'Close stale PRs'
on:
  schedule:
    # Execute every hour at xx:05 to avoid conflicts with other workflows
    - cron: '5 * * * *'

permissions: {}

jobs:
  stale:
    permissions:
      pull-requests: write

    runs-on: ubuntu-latest
    steps:
      - uses: actions/stale@v10
        with:
          operations-per-run: 50
          ascending: true
          exempt-all-milestones: true

In an advanced scenario where you know you need the dependency to be called at every step (possibly multiple times) in the same request instead of using the "cached" value, you can set the parameter `use_cache=False` when using `Depends`:

//// tab | Python 3.8+

```Python hl_lines="1"