|
| 1 | +# Azure Web App with Azure CosmosDB for NoSQL API |
| 2 | + |
| 3 | +This sample demonstrates a Python Flask single-page web application called *Vacation Planner* hosted on an [Azure Web App](https://learn.microsoft.com/en-us/azure/app-service/overview). The app runs on an Azure App Service Plan and stores activity data in the `activities` container of the `sampledb` NoSQL database on an [Azure CosmosDB for NoSQL](https://learn.microsoft.com/en-us/azure/cosmos-db/distributed-nosql) account. |
| 4 | + |
| 5 | +## Architecture |
| 6 | + |
| 7 | +The following diagram illustrates the architecture of the solution: |
| 8 | + |
| 9 | + |
| 10 | + |
| 11 | +- **Azure Web App**: Hosts the Python Flask application |
| 12 | +- **Azure App Service Plan**: Provides compute resources for the web app |
| 13 | +- **Azure CosmosDB for NoSQL API**: Stores activity data in a CosmosDB container |
| 14 | + |
| 15 | +## Prerequisites |
| 16 | + |
| 17 | +- [Azure Subscription](https://azure.microsoft.com/free/) |
| 18 | +- [Azure CLI](https://learn.microsoft.com/en-us/cli/azure/install-azure-cli) |
| 19 | +- [Python 3.11+](https://www.python.org/downloads/) |
| 20 | +- [Flask](https://flask.palletsprojects.com/) |
| 21 | + |
| 22 | +## Deployment |
| 23 | + |
| 24 | +Set up the Azure emulator using the LocalStack for Azure Docker image. Before starting, ensure you have a valid `LOCALSTACK_AUTH_TOKEN` to access the Azure emulator. Refer to the [Auth Token guide](https://docs.localstack.cloud/getting-started/auth-token/?__hstc=108988063.8aad2b1a7229945859f4d9b9bb71e05d.1743148429561.1758793541854.1758810151462.32&__hssc=108988063.3.1758810151462&__hsfp=3945774529) to obtain your Auth Token and set it in the `LOCALSTACK_AUTH_TOKEN` environment variable. The Azure Docker image is available on the [LocalStack Docker Hub](https://hub.docker.com/r/localstack/localstack-azure-alpha). To pull the image, execute: |
| 25 | + |
| 26 | +```bash |
| 27 | +docker pull localstack/localstack-azure-alpha |
| 28 | +``` |
| 29 | + |
| 30 | +Start the LocalStack Azure emulator by running: |
| 31 | + |
| 32 | +```bash |
| 33 | +export LOCALSTACK_AUTH_TOKEN=<your_auth_token> |
| 34 | +IMAGE_NAME=localstack/localstack-azure-alpha localstack start |
| 35 | + ``` |
| 36 | + |
| 37 | +Deploy the application to LocalStack for Azure using: |
| 38 | + |
| 39 | +- [Azure CLI Deployment](./scripts/README.md) |
| 40 | + |
| 41 | +> **Note** |
| 42 | +> When you deploy the application to LocalStack for Azure for the first time, the initialization process involves downloading and building Docker images. This is a one-time operation—subsequent deployments will be significantly faster. Depending on your internet connection and system resources, this initial setup may take several minutes. |
| 43 | +
|
| 44 | +## Test |
| 45 | + |
| 46 | +1. Retrieve the port published and mapped to port 80 by the Docker container hosting the emulated Web App. |
| 47 | +2. Open a web browser and navigate to `http://localhost:<published-port>`. |
| 48 | +3. If the deployment was successful, you will see the following user interface for adding and removing activities: |
| 49 | + |
| 50 | + |
| 51 | + |
| 52 | +You can use the `call-web-app.sh` Bash script below to call the web app. The script demonstrates three methods for calling web apps: |
| 53 | + |
| 54 | +1. **Through the LocalStack for Azure emulator**: Call the web app via the emulator using its default host name. The emulator acts as a proxy to the web app. |
| 55 | +2. **Via localhost and host port mapped to the container's port**: Use `127.0.0.1` with the host port mapped to the container's port `80`. |
| 56 | +3. **Via container IP address**: Use the app container's IP address on port `80`. This technique is only available when accessing the web app from the Docker host machine. |
| 57 | +4. **Via Runtime Gateway**: Use the `{web_app_name}website.localhost.localstack.cloud:4566` URL to call the web app via the LocalStack runtime gateway. |
| 58 | + |
| 59 | +```bash |
| 60 | +#!/bin/bash |
| 61 | + |
| 62 | +get_docker_container_name_by_prefix() { |
| 63 | + local app_prefix="$1" |
| 64 | + local container_name |
| 65 | + |
| 66 | + # Check if Docker is running |
| 67 | + if ! docker info >/dev/null 2>&1; then |
| 68 | + echo "Error: Docker is not running" >&2 |
| 69 | + return 1 |
| 70 | + fi |
| 71 | + |
| 72 | + echo "Looking for containers with names starting with [$app_prefix]..." >&2 |
| 73 | + |
| 74 | + # Find the container using grep |
| 75 | + container_name=$(docker ps --format "{{.Names}}" | grep "^${app_prefix}" | head -1) |
| 76 | + |
| 77 | + if [ -z "$container_name" ]; then |
| 78 | + echo "Error: No running container found with name starting with [$app_prefix]" >&2 |
| 79 | + return 1 |
| 80 | + fi |
| 81 | + |
| 82 | + echo "Found matching container [$container_name]" >&2 |
| 83 | + echo "$container_name" |
| 84 | +} |
| 85 | + |
| 86 | +get_docker_container_ip_address_by_name() { |
| 87 | + local container_name="$1" |
| 88 | + local ip_address |
| 89 | + |
| 90 | + if [ -z "$container_name" ]; then |
| 91 | + echo "Error: Container name is required" >&2 |
| 92 | + return 1 |
| 93 | + fi |
| 94 | + |
| 95 | + # Get IP address |
| 96 | + ip_address=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$container_name") |
| 97 | + |
| 98 | + if [ -z "$ip_address" ]; then |
| 99 | + echo "Error: Container [$container_name] has no IP address assigned" >&2 |
| 100 | + return 1 |
| 101 | + fi |
| 102 | + |
| 103 | + echo "$ip_address" |
| 104 | +} |
| 105 | + |
| 106 | +get_docker_container_port_mapping() { |
| 107 | + local container_name="$1" |
| 108 | + local container_port="$2" |
| 109 | + local host_port |
| 110 | + |
| 111 | + if [ -z "$container_name" ] || [ -z "$container_port" ]; then |
| 112 | + echo "Error: Container name and container port are required" >&2 |
| 113 | + return 1 |
| 114 | + fi |
| 115 | + |
| 116 | + # Get host port mapping |
| 117 | + host_port=$(docker inspect -f "{{(index (index .NetworkSettings.Ports \"${container_port}/tcp\") 0).HostPort}}" "$container_name") |
| 118 | + |
| 119 | + if [ -z "$host_port" ]; then |
| 120 | + echo "Error: No host port mapping found for container [$container_name] port [$container_port]" >&2 |
| 121 | + return 1 |
| 122 | + fi |
| 123 | + |
| 124 | + echo "$host_port" |
| 125 | +} |
| 126 | + |
| 127 | +call_web_app() { |
| 128 | + # Get the web app name |
| 129 | + echo "Getting web app name..." |
| 130 | + web_app_name=$(azlocal webapp list --query '[0].name' --output tsv) |
| 131 | + |
| 132 | + if [ -n "$web_app_name" ]; then |
| 133 | + echo "Web app [$web_app_name] successfully retrieved." |
| 134 | + else |
| 135 | + echo "Error: No web app found" |
| 136 | + exit 1 |
| 137 | + fi |
| 138 | + |
| 139 | + # Get the resource group name |
| 140 | + echo "Getting resource group name for web app [$web_app_name]..." |
| 141 | + resource_group_name=$(azlocal webapp list --query '[0].resourceGroup' --output tsv) |
| 142 | + |
| 143 | + if [ -n "$resource_group_name" ]; then |
| 144 | + echo "Resource group [$resource_group_name] successfully retrieved." |
| 145 | + else |
| 146 | + echo "Error: No resource group found for web app [$web_app_name]" |
| 147 | + exit 1 |
| 148 | + fi |
| 149 | + |
| 150 | + # Get the the default host name of the web app |
| 151 | + echo "Getting the default host name of the web app [$web_app_name]..." |
| 152 | + app_host_name=$(azlocal webapp show \ |
| 153 | + --name "$web_app_name" \ |
| 154 | + --resource-group "$resource_group_name" \ |
| 155 | + --query 'defaultHostName' \ |
| 156 | + --output tsv) |
| 157 | + |
| 158 | + if [ -n "$app_host_name" ]; then |
| 159 | + echo "Web app default host name [$app_host_name] successfully retrieved." |
| 160 | + else |
| 161 | + echo "Error: No web app default host name found" |
| 162 | + exit 1 |
| 163 | + fi |
| 164 | + |
| 165 | + # Get the Docker container name |
| 166 | + echo "Finding container name with prefix [ls-$web_app_name]..." |
| 167 | + container_name=$(get_docker_container_name_by_prefix "ls-$web_app_name") |
| 168 | + |
| 169 | + if [ $? -eq 0 ] && [ -n "$container_name" ]; then |
| 170 | + echo "Container [$container_name] found successfully" |
| 171 | + else |
| 172 | + echo "Failed to get container name" |
| 173 | + exit 1 |
| 174 | + fi |
| 175 | + |
| 176 | + # Get the container IP address |
| 177 | + echo "Getting IP address for container [$container_name]..." |
| 178 | + container_ip=$(get_docker_container_ip_address_by_name "$container_name") |
| 179 | + |
| 180 | + if [ $? -eq 0 ] && [ -n "$container_ip" ]; then |
| 181 | + echo "IP address [$container_ip] retrieved successfully for container [$container_name]" |
| 182 | + else |
| 183 | + echo "Failed to get container IP address" |
| 184 | + exit 1 |
| 185 | + fi |
| 186 | + |
| 187 | + # Get the mapped host port for web app HTTP trigger (internal port 80) |
| 188 | + echo "Getting the host port mapped to internal port 80 in container [$container_name]..." |
| 189 | + host_port=$(get_docker_container_port_mapping "$container_name" "80") |
| 190 | + |
| 191 | + if [ $? -eq 0 ] && [ -n "$host_port" ]; then |
| 192 | + echo "Mapped host port [$host_port] retrieved successfully for container [$container_name]" |
| 193 | + else |
| 194 | + echo "Failed to get mapped host port for container [$container_name]" |
| 195 | + exit 1 |
| 196 | + fi |
| 197 | + |
| 198 | + # Retrieve LocalStack proxy port |
| 199 | + proxy_port=$(curl http://localhost:4566/_localstack/proxy -s | jq '.proxy_port') |
| 200 | + |
| 201 | + if [ -n "$proxy_port" ]; then |
| 202 | + # Call the web app via emulator proxy |
| 203 | + echo "Calling web app [$web_app_name] via emulator..." |
| 204 | + curl --proxy "http://localhost:$proxy_port/" -s "http://$app_host_name/" 1> /dev/null |
| 205 | + |
| 206 | + if [ $? == 0 ]; then |
| 207 | + echo "Web app call via emulator proxy port [$proxy_port] succeeded." |
| 208 | + else |
| 209 | + echo "Web app call via emulator proxy port [$proxy_port] failed." |
| 210 | + fi |
| 211 | + else |
| 212 | + echo "Failed to retrieve LocalStack proxy port" |
| 213 | + fi |
| 214 | + |
| 215 | + if [ -n "$container_ip" ]; then |
| 216 | + # Call the web app via the container IP address |
| 217 | + echo "Calling web app [$web_app_name] via container IP address [$container_ip]..." |
| 218 | + curl -s "http://$container_ip/" 1> /dev/null |
| 219 | + |
| 220 | + if [ $? == 0 ]; then |
| 221 | + echo "Web app call via container IP address [$container_ip] succeeded." |
| 222 | + else |
| 223 | + echo "Web app call via container IP address [$container_ip] failed." |
| 224 | + fi |
| 225 | + else |
| 226 | + echo "Failed to retrieve container IP address" |
| 227 | + fi |
| 228 | + |
| 229 | + if [ -n "$host_port" ]; then |
| 230 | + # Call the web app via the host port |
| 231 | + echo "Calling web app [$web_app_name] via host port [$host_port]..." |
| 232 | + curl -s "http://127.0.0.1:$host_port/" 1> /dev/null |
| 233 | + |
| 234 | + if [ $? == 0 ]; then |
| 235 | + echo "Web app call via host port [$host_port] succeeded." |
| 236 | + else |
| 237 | + echo "Web app call via host port [$host_port] failed." |
| 238 | + fi |
| 239 | + else |
| 240 | + echo "Failed to retrieve host port" |
| 241 | + fi |
| 242 | + |
| 243 | + gateway_port=4566 |
| 244 | + |
| 245 | + if [ -n "$gateway_port" ]; then |
| 246 | + # Call the web app via the runtime gateway |
| 247 | + echo "Calling web app [$web_app_name] via runtime gateway on port [$gateway_port]..." |
| 248 | + curl -s "http://${web_app_name}website.localhost.localstack.cloud:$gateway_port/" 1> /dev/null |
| 249 | + |
| 250 | + if [ $? == 0 ]; then |
| 251 | + echo "Web app call via runtime gateway on port [$gateway_port] succeeded." |
| 252 | + else |
| 253 | + echo "Web app call via runtime gateway on port [$gateway_port] failed." |
| 254 | + fi |
| 255 | + else |
| 256 | + echo "Failed to retrieve runtime gateway port" |
| 257 | + fi |
| 258 | +} |
| 259 | + |
| 260 | +call_web_app |
| 261 | +``` |
| 262 | + |
| 263 | +## CosmosDB Tooling |
| 264 | + |
| 265 | +You can utilize **CosmosDB Data Explorer** to explore and manage your CosmosDB databases and containers. Ensure you connect using `http://localhost:port` connection string, where `port` corresponds to the port published by the CosmosDB container on the host and mapped to the internal CosmosDB port `1234`. |
| 266 | + |
| 267 | + |
| 268 | + |
| 269 | +## References |
| 270 | + |
| 271 | +- [Azure Web Apps Documentation](https://learn.microsoft.com/en-us/azure/app-service/) |
| 272 | +- [Azure CosmosDB Documentation](https://learn.microsoft.com/en-us/azure/cosmos-db/) |
| 273 | +- [Quickstart: Python Flask on Azure](https://learn.microsoft.com/en-us/azure/app-service/quickstart-python?tabs=flask%2Cbrowser) |
| 274 | +- [Azure Identity Client Library for Python](https://learn.microsoft.com/en-us/python/api/overview/azure/identity-readme?view=azure-python) |
| 275 | +- [LocalStack for Azure](https://azure.localstack.cloud/) |
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