# Flask + Redis HTTP Server

import { Tabs, TabsContent, TabsList, TabsTrigger } from "zudoku/ui/Tabs"

{/* vale off */}
{/* THIS FILE WAS AUTOGENERATED FROM THE PUBLIC EXAMPLE REPOSITORY. DO NOT EDIT THIS FILE DIRECTLY. */}


This guide explains how to create and deploy a [Flask](https://flask.palletsprojects.com/en/3.0.x/) app with a [Redis](https://redis.io/) database on Unikraft Cloud.
The example consists of two services: a Flask web server that increments a page view counter stored in Redis.

To run this example, follow these steps:

1. Install the CLI.
   Use the [unikraft CLI](/cli/unikraft) or the legacy [kraft CLI](https://unikraft.org/docs/cli/install).
   You need a [BuildKit](https://github.com/moby/buildkit) builder. The easiest way to get one is via [Docker](https://docs.docker.com/engine/install/).
   Alternatively, you can also directly set up and use BuildKit, see the [quick start](https://github.com/moby/buildkit#quick-start).

:::note
The unikraft CLI is the current standard, while kraft is the legacy version.
Choose one of the CLIs below and only run the commands associated with it for the rest of this guide.
:::

2. Clone the [`examples` repository](https://github.com/unikraft-cloud/examples) and `cd` into the `examples/httpserver-flask-redis` directory:

```bash
git clone https://github.com/unikraft-cloud/examples
cd examples/httpserver-flask-redis/
```

Make sure to log into Unikraft Cloud and pick a [metro](/platform/metros) close to you.
This guide uses `fra` (Frankfurt, 🇩🇪):

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft login
```

```bash title="kraft"
# Set Unikraft Cloud access token
export UKC_TOKEN=token
# Set metro to Frankfurt, DE
export UKC_METRO=fra
```

</CodeTabs>

### Deploy Redis

First, deploy the Redis instance.
Redis is an internal service (not publicly accessible), reached via the `redis.internal` domain:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft build redis/ --output <my-org>/redis:latest
unikraft run --scale-to-zero policy=idle,cooldown-time=1000,stateful=true --metro fra -m 256M --image <my-org>/redis:latest --domain redis.internal
```

```bash title="kraft"
kraft cloud deploy --scale-to-zero idle --scale-to-zero-stateful --scale-to-zero-cooldown 1s -M 256Mi --domain redis.internal redis/
```

</CodeTabs>

The output shows the Redis instance details:

<CodeTabs syncKey="cli">

```ansi title="unikraft"
metro:         fra
name:          redis-09p2q
uuid:          0355f93a-7b60-4ade-9359-b01671e812b3
state:         starting
image:         <my-org>/redis
resources:
  memory:      256MiB
  vcpus:       1
service:
  uuid:        19c050b2-b5c9-4e8e-9d25-a9053ff09270
  name:        damp-brook-xmmmwzwo
  domains:
  - fqdn:      redis.internal
networks:
- uuid:        97df34f7-63bc-4f02-a1b4-5ba07278de00
  private-ip:  10.0.0.41
  mac:         12:b0:0a:00:00:29
timestamps:
  created:     just now
scale-to-zero: policy=idle,stateful=true,cooldown-time=1s
```

```ansi title="kraft"
[●] Deployed successfully!
 │
 ├───────── name: redis-o9abw
 ├───────── uuid: 9dd4c7b5-7cc4-4b99-ac70-b10af54ef075
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: redis.internal
 ├──────── image: oci://unikraft.io/<my-org>/redis@sha256:3e35bc6c8048269741a0c0b4b165a10112736c48dbf869c76bb263a237502462
 ├─────── memory: 256 MiB
 ├────── service: sparkling-fire-rnd4o9kb
 ├─ private fqdn: redis-o9abw.internal
 └─── private ip: 10.0.0.41
```

</CodeTabs>

### Deploy Flask

Next, deploy the Flask web server.
It connects to Redis using the `REDIS_HOST` and `REDIS_PORT` environment variables:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft build flask/ --output <my-org>/flask:latest
unikraft run --scale-to-zero policy=on,cooldown-time=1000 --metro fra -p 443:8000/tls+http -m 512M --image <my-org>/flask:latest --env REDIS_HOST=redis.internal --env REDIS_PORT=6379
```

```bash title="kraft"
kraft cloud deploy --scale-to-zero on --scale-to-zero-cooldown 1s -p 443:8000/tls+http -M 512Mi flask/ --env REDIS_HOST=redis.internal --env REDIS_PORT=6379
```

</CodeTabs>

The output shows the Flask instance details:

<CodeTabs syncKey="cli">

```ansi title="unikraft"
metro:          fra
name:           flask-q62qa
uuid:           d081ec92-629b-45b3-8caf-059e0a87dffd
state:          starting
image:          <my-org>/flask
runtime:
  env:
    REDIS_HOST: redis.internal
    REDIS_PORT: 6379
resources:
  memory:       512MiB
  vcpus:        1
service:
  uuid:         ac1cd90e-a1fe-478c-8f58-8598fa80c494
  name:         hidden-silence-htyml3s2
  domains:
  - fqdn:       hidden-silence-htyml3s2.fra.unikraft.app
networks:
- uuid:         d2f3d024-3082-4e98-be22-f36df84263a1
  private-ip:   10.0.0.53
  mac:          12:b0:0a:00:00:35
timestamps:
  created:      just now
scale-to-zero:  policy=on,cooldown-time=1s
```

```ansi title="kraft"
[●] Deployed successfully!
 │
 ├───────── name: flask-a06h2
 ├───────── uuid: 431f67ed-1f18-4dc1-86db-68dac4edff51
 ├──────── metro: https://api.fra.unikraft.cloud/v1
 ├──────── state: starting
 ├─────── domain: https://withered-cherry-xfcrfp93.fra.unikraft.app
 ├──────── image: oci://unikraft.io/<my-org>/flask@sha256:3d29ca3a8a3d434f41acf7c8093435836dcbacca9190c51ec39dbb4ddf1ee45a
 ├─────── memory: 512 MiB
 ├────── service: withered-cherry-xfcrfp93
 ├─ private fqdn: flask-a06h2.internal
 └─── private ip: 10.0.0.53
```

</CodeTabs>

In this case, the Flask instance address is `https://withered-cherry-xfcrfp93.fra.unikraft.app`.
It's different for each run.

### Test the deployment

Use `curl` to query the Flask instance.
Each request increments the Redis counter:

```bash
curl https://withered-cherry-xfcrfp93.fra.unikraft.app
```

```text
This webpage has been viewed 1 time(s)
```

```bash
curl https://withered-cherry-xfcrfp93.fra.unikraft.app
```

```text
This webpage has been viewed 2 time(s)
```

You can list information about the instances by running:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances list
```

```bash title="kraft"
kraft cloud instance list
```

</CodeTabs>

### Clean up

When done, remove the instances:

<CodeTabs syncKey="cli">

```bash title="unikraft"
unikraft instances delete flask-q62qa
unikraft instances delete redis-09p2q
```

```bash title="kraft"
kraft cloud instance remove flask-a06h2
kraft cloud instance remove redis-o9abw
```

</CodeTabs>

## Learn more

Use the `--help` option for detailed information on using Unikraft Cloud:

```bash
kraft cloud --help
```

Or visit the [CLI Reference](/cli/overview).
{/* vale on */}