doc: add serverless example

  - production

```

#### hook scripts

#### AWS scripts

##### `aws-deploy.sh`

This script is executed by the template to perform the application(s) deployment based on `aws` CLI, and uses dynamic variables provided by the template.

This script is executed by the template to perform the application(s) deployment based on `aws` CLI, and uses [dynamic variables](#dynamic-variables) provided by the template (`${appname}` is used as the CloudFormation stack name).

It implements [dynamic environment URLs](#static-vs-dynamic-environment-urls), by generating the `environment_url.txt` file, containing

the dynamically generated url at the end of the deployment script.

```bash

#!/usr/bin/env bash

set -e # fail on error

echo "[aws-deploy] Deploying $appname..."

# disable AWS CLI pager

export AWS_PAGER=""

template_file=file://MyStack.template

# retrieve environment type ($env) from template

# retrieve $AWS_KEYPAIR_NAME from project secret variables

params_opts="--parameters ParameterKey=EnvType,ParameterValue=$env ParameterKey=KeyName,ParameterValue=$AWS_KEYPAIR_NAME"

if aws cloudformation describe-stacks --output text --no-cli-pager --stack-name "$appname" > /dev/null

if aws cloudformation describe-stacks --output text --stack-name "$appname" > /dev/null

then

  echo -e "Stack exists: update..."

  aws cloudformation update-stack --output text --no-cli-pager --stack-name "$appname" --template-body $template_file $parameters

  aws cloudformation update-stack --output text --stack-name "$appname" --template-body $template_file $parameters

  echo "Waiting for stack to be updated..."

  aws cloudformation wait stack-update-complete --stack-name "$appname"

else

  echo -e "Stack doesn't exist: create..."

  aws cloudformation create-stack --output text --no-cli-pager --stack-name "$appname" --template-body $template_file $parameters

  aws cloudformation create-stack --output text --stack-name "$appname" --template-body $template_file $parameters

  echo "Waiting for stack to be created..."

  aws cloudformation wait stack-create-complete --stack-name "$appname"

fi

# Retrieve outputs (use a Python script as jq is not installed in the AWS CLI Docker image)

desc_json=$(aws cloudformation describe-stacks --output json --no-cli-pager --stack-name "$appname")

webserver_url=$(echo "$desc_json" | python -c 'import json,sys;desc=json.load(sys.stdin);outputs=desc["Stacks"][0]["Outputs"];print filter(lambda o: o["OutputKey"] == "WebServerUrl", outputs)[0]["OutputValue"]')

# Retrieve outputs (use cloudformation query)

webserver_url=$(aws cloudformation describe-stacks --output text --stack-name "$appname" --query 'Stacks[0].Outputs[?OutputKey==`WebServerUrl`].OutputValue')

echo "Stack created/updated:"

echo " - WebServerUrl: $webserver_url"

```bash

#!/usr/bin/env bash

set -e # fail on error

echo "[aws-cleanup] Cleanup $appname..."

# disable AWS CLI pager

export AWS_PAGER=""

aws cloudformation delete-stack --stack-name "$appname"

```

### AWS Serverless

This chapter gives some implementation hints to implement continuous deployment of a Serverless application based on [Serverless Application Model](https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/).

It enables review, staging and production environments.

#### `.gitlab-ci.yml`

```yaml

include:

  # Include AWS template

  - project: 'to-be-continuous/aws'

    ref: '1.0.1'

    file: '/templates/gitlab-ci-aws.yml'

  ...

# Global variables

variables:

  # AWS

  # use an image with both aws and sam CLI

  AWS_CLI_IMAGE: "pahud/aws-sam-cli:latest"

  # AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY defined as secret CI/CD variable

  AWS_REVIEW_ENABLED: "true" # enable review env

  AWS_STAGING_ENABLED: "true" # enable staging env

  AWS_PROD_ENABLED: "true" # enable production env

  ...

# Pipeline steps

stages:

  - build

  - test

  - deploy

  - acceptance

  - publish

  - production

```

#### AWS scripts

##### `aws-deploy.sh`

This script is executed by the template to perform the application(s) deployment based on `sam`and `aws` CLI, and uses [dynamic variables](#dynamic-variables) provided by the template (`${appname}` is used as the SAM/CloudFormation stack name).

It implements [dynamic environment URLs](#static-vs-dynamic-environment-urls), by generating the `environment_url.txt` file, containing

the dynamically generated url at the end of the deployment script.

```bash

#!/usr/bin/env bash

set -e # fail on error

echo "[aws-deploy] Deploy $appname..."

# disable AWS CLI pager

export AWS_PAGER=""

# 1: build

sam build ${TRACE+--debug}

# 2: deploy (each environment is a separate stack)

# AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY defined as secret CI/CD variable

# AWS_DEFAULT_REGION and AWS_SAM_BUCKET defined as project CI/CD variable

sam deploy ${TRACE+--debug} \

  --stack-name "$appname" \

  --region "$AWS_DEFAULT_REGION" \

  --s3-bucket "$AWS_SAM_BUCKET" \

  --no-fail-on-empty-changeset \

  --no-confirm-changeset \

  --tags "ci-job-url=$CI_JOB_URL environment=$env"

# Retrieve outputs (use cloudformation query)

api_url=$(aws cloudformation describe-stacks --stack-name "$appname" --output text --query 'Stacks[0].Outputs[?OutputKey==`MyProjectApiUrl`].OutputValue')

echo "Stack created/updated:"

echo " - Api URL: $api_url"

# Finally set the dynamically generated WebServer Url

echo "$api_url" > environment_url.txt

```

##### `aws-cleanup.sh`

This script is executed by the template to perform the application(s) cleanup based on `aws` CLI (review env only).

```bash

#!/usr/bin/env bash

set -e # fail on error

echo "[aws-cleanup] Cleanup $appname..."

aws cloudformation delete-stack --stack-name "$appname" || echo "delete stack failed"

# disable AWS CLI pager

export AWS_PAGER=""

aws cloudformation delete-stack --stack-name "$appname"

```