DeployEx

Who supervises the supervisor (of your application)?

DeployEx is a lightweight tool designed for managing deployments in Elixir applications without relying on additional deployment tools like Docker or Kubernetes. Its primary goal is to utilize the mix release package for executing full deployments or hot-upgrades, depending on the package's content, while leveraging OTP distribution for monitoring and data extraction.

DeployEx acts as a central deployment runner, gathering crucial deployment data such as the current version and release package contents. The content of the release package enables it to run for a full deployment or a hot-upgrade. Meanwhile, on the development front, your CI/CD pipeline takes charge of crafting and updating packages for the target release. This integration ensures that DeployEx is always equipped with the latest packages, ready to facilitate deployments.

DeployEx is currently used by Calori Web Server and you can check its deployment.

Upon deployment, the following dashboard becomes available, offering access to logs for both DeployEx and monitored applications, along with an IEX terminal."

Features

• Monitors multiple Elixir application instances and automatically restarts them if they crash for any reason.
• Includes a backoff delay restart mechanism to prevent excessive restarts.
• Performs full deployments based solely on the release file generated by mix release.
• Supports hot code reloading for applications using the Jellyfish library.
• Supports the following cloud providers: Amazon Web Services (AWS) and Google Cloud Provisioning (GCP)
• Provides rollback functionality if a monitored app version remains unstable after a certain period.
• Rolled-back monitored app versions are ghosted, preventing their redeployment.
• Ensures all instances remain connected to the OTP distribution, including DeployEx itself.
• Supports OTP distribution with mutual TLS (mTLS) for secure monitoring of apps and DeployEx.
• Provides the ability to run pre-commans prior deployments for Database migrations or any other eval command.
• Provides a friendly UI that only authenticated users can access.
• Allows setting a previously configured version in the UI, enabling DeployEx to enforce deployment of a specific version.
• Supports individual application restarts via the UI.
• Allows access to current log files (stdout and stderr) for both monitored apps and DeployEx.
• Provides access to the IEx shell for monitored apps and DeployEx.
• Provides installer script to be used with ubuntu hosts.
• Provides status information per instance:
  • OTP connectivity
  • Version history
  • Last deployment status
  • Number of crash restarts
  • Number of forced restarts

Note

All examples and deployments in this project use NGINX as a reverse proxy and load balancer. However, DeployEx does not depend on NGINX; it is used here purely for convenience.

Next steps

• Add telemetry support for DeployEx to capture metrics and telemetry via OTP distribution.
• Integrate CPU utilization monitoring from the OTP distribution.
• Continuous improvement in UI design.

Getting Started

Running the application

You can kickstart the setup with the following commands, the default number of replicas is 3:

mix deps.get
iex --sname deployex --cookie cookie -S mix phx.server
[info] Initialising deployment server
[info] Running DeployexWeb.Endpoint with Bandit 1.5.7 at 127.0.0.1:5001 (http)
[info] Access DeployexWeb.Endpoint at http://localhost:5001
[watch] build finished, watching for changes...
Erlang/OTP 26 [erts-14.1.1] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1] [jit]

Interactive Elixir (1.16.0) - press Ctrl+C to exit (type h() ENTER for help)

Rebuilding...

Done in 390ms.
[error] Invalid version map at: /tmp/myphoenixapp/versions/myphoenixapp/local/current.json reason: enoent

Now you can visit localhost:5001 from your browser and enter the credentials for the admin user, username: admin password: deployex. You should expect the following dashboard:

Note

The error message in the CLI is due to no monitored app is available to be deployed. If you want to proceed for a local test, follow the steps at Running DeployEx and Monitored app locally. Also, it is important to note that the distribution will be required so this is the reason to add -sname deployex in the command

How DeployEx handles monitored application Version/Release

The DeployEx app expects a current.json file to be available, which contains version, hash information and any pre-command. This file is mandatory for full deployment and hot upgrades.

Version file (current.json)

Expected location in the release folder:

# production path
./{bucket}/versions/{monitored_app}/{env}/current.json
# local test path
/tmp/{monitored_app}/versions/{monitored_app}/{env}/current.json

Expected JSON format for current.json:

{
  "version": "1.0.0",
  "pre_commands": [ "eval MyApp.Migrator.create", "eval MyApp.Migrator.migrate" ], # optional field
  "hash": "local"
}

Once the file is captured, the deployment will start if no app is running or if the current app is running with a version that differs from the current.json file.

Release package

Expected location in the release folder:

# production path
./{bucket}/dist/{monitored_app}/{monitored_app}-{version}.tar.gz
# local test path
/tmp/{monitored_app}/dist/{monitored_app}/{monitored_app}-{version}.tar.gz

Production Information

Environment Variables

DeployEx application typically requires several environment variables to be defined for proper operation. Ensure that you have the following environment variables set when running in production where the ones that have a default value available are not required:

ENV NAME	EXAMPLE	SOURCE	DEFAULT	DESCRIPTION
DEPLOYEX_SECRET_KEY_BASE	42otsNl...Fpq3dIJ02	aws secrets	-/-	secret key used for encryption
DEPLOYEX_ERLANG_COOKIE	cookie	aws secrets	-/-	erlang cookie
DEPLOYEX_ADMIN_HASHED_PASSWORD	$2b$1...5PAYTZjNQ42ASi	aws secrets	-/-	Hashed admin password for authentication
DEPLOYEX_MONITORED_APP_NAME	myphoenixapp	system ENV	-/-	Monitored app name
DEPLOYEX_CLOUD_ENVIRONMENT	prod	system ENV	-/-	cloud env name
AWS_REGION	us-east2	system ENV	-/-	the aws region
GOOGLE_APPLICATION_CREDENTIALS	/path/to/file.json	system ENV	-/-	the google application credentials path
DEPLOYEX_PHX_HOST	example.com	system ENV	-/-	The hostname for your application
DEPLOYEX_PHX_PORT	5001	system ENV	5001	The port on which the application will run
DEPLOYEX_PHX_SERVER	true	system ENV	true	enable/disable server
DEPLOYEX_RELEASE_ADAPTER	s3 or gcp-storage	system ENV	-/-	release adapter type
DEPLOYEX_RELEASE_BUCKET	myphoenixapp-prod-distribution	system ENV	-/-	release distribution bucket name
DEPLOYEX_SECRETS_ADAPTER	aws or gcp	system ENV	-/-	release adapter type
DEPLOYEX_SECRETS_PATH	deployex-myphoenixapp-prod-secrets	system ENV	-/-	secret path to be retrieved from
DEPLOYEX_MONITORED_APP_PORT	4000	system ENV	4000	the initial port for starting the monitored apps
DEPLOYEX_MONITORED_REPLICAS	2	system ENV	3	Number of replicas to monitor
DEPLOYEX_DEPLOY_TIMEOUT_ROLLBACK_MS	600000	system ENV	600000	The maximum time allowed for attempting a deployment before considering the version as non-deployable and rolling back
DEPLOYEX_DEPLOY_SCHEDULE_INTERVAL_MS	5000	system ENV	5000	Periodic checking for new deployments

For local testing, these variables are not expected or set to default values.

Cloud Providers

DeployEx offers a comprehensive set of Terraform examples for programmatically deploying in AWS and GCP, including detailed step-by-step setup instructions:

• AWS deployment
• GCP deployment

Installation

If you intend to install DeployEx directly on an Ubuntu server, you can utilize the installer script provided in the release package. For an example of monitored app, please see the setup for the Calori Web Server - AWS/Calori Web Server - GCP. The installer script requires a JSON configuration file, an example of which can be found here. This JSON file can also export environment variables specific to the monitored applications.

Currently, the release and installation process supports Ubuntu versions 20.04 and 22.04. However, you have the option to manually compile and install DeployEx on your target system.

Pre-commands

Your application will likely require database commands, such as migrations. DeployEx handles these through pre-commands specified in current.json under the pre_commands field. These commands will be executed in the order they are listed, before the application starts. If a pre-command is needed and does not require changes to the application itself, using pre-commands in conjunction with hotupgrade is ideal to avoid unnecessary downtime.

Secrets Requirements

DeployEx uses Secret Manager (AWS or GCP) to fetch its secrets via the config provider. The following environment variable configuration is expected for Secret Manager:

DEPLOYEX_SECRETS_ADAPTER=gcp
DEPLOYEX_SECRETS_PATH=deployex-myapp-prod-secrets

Within the secrets, the following key-value pairs are required:

ENV NAME	EXAMPLE	DESCRIPTION
DEPLOYEX_SECRET_KEY_BASE	42otsNl...Fpq3dIJ02	mix phx.gen.secret
DEPLOYEX_ERLANG_COOKIE	my-cookie	erlang cookie
DEPLOYEX_ADMIN_HASHED_PASSWORD	$2b$1...5PAYTZjNQ42ASi	Bcrypt.hash_pwd_salt("my-pass")

Running DeployEx and Monitored app locally

For local testing, the root path used for distribution releases and versions is /tmp/{monitored_app}. Follow these steps:

Create the required release folders:

export monitored_app_name=myphoenixapp
mkdir -p /tmp/${monitored_app_name}/dist/${monitored_app_name}
mkdir -p /tmp/${monitored_app_name}/versions/${monitored_app_name}/local/

It is important to note that for local deployments, DeployEx will use the path /tmp/deployex for local storage. This means you can delete the entire folder to reset any local version, history, or configurations.

Creating an Elixir phoenix app (default name is myphoenixapp)

In this example, we create a brand new application using mix phx.new and added the library Jellyfish for testing hotupgrades.

mix local.hex
mix archive.install hex phx_new
mix phx.new myphoenixapp --no-ecto
cd myphoenixapp

Add env.sh.eex file in the release folder to configure the OTP distribution

vi rel/env.sh.eex
# Add the following lines:

#!/bin/sh
# Set a default Erlang cookie value if not provided by ENV VAR.
# This default is temporary; update it using AWS secrets and config provider.
[ -z ${RELEASE_COOKIE} ] && export RELEASE_COOKIE="cookie"
export RELEASE_DISTRIBUTION=sname
[ -z ${RELEASE_NODE_SUFFIX} ] && export RELEASE_NODE_SUFFIX=""
export RELEASE_NODE=<%= @release.name %>${RELEASE_NODE_SUFFIX}

# save the file :wq

The next steps are needed ONLY for Hot upgrades

Add Jellyfish library ONLY if the application will need hotupgrades

def deps do
  [
    {:jellyfish, "~> 0.1.3"}
  ]
end

You also need to add the following lines in the mix project

  def project do
    [
      ...
      compilers: Mix.compilers() ++ [:gen_appup, :appup],
      releases: [
        myphoenixapp: [
          steps: [:assemble, &Jellyfish.Releases.Copy.relfile/1, :tar]
        ]
      ],
      ...
    ]
  end

Open the config/prod.exs and replace the static manifest for a live reload

#config :myphoenixapp, MyphoenixappWeb.Endpoint,
#  cache_static_manifest: "priv/static/cache_manifest.json"
# Since the application is using the Hot upgrade, the manifest cannot be static
config :myphoenixapp, MyphoenixappWeb.Endpoint,
live_reload: [
  patterns: [
    ~r"priv/static/.*(js|css|png|jpeg|jpg|gif|svg)$",
    ~r"priv/gettext/.*(po)$"
  ]
]

Generate a release

Then you can compile and generate a release

mix deps.get
MIX_ENV=prod mix assets.deploy
MIX_ENV=prod mix release
...
No appups, nothing to move to the release
* assembling myphoenixapp-0.1.0 on MIX_ENV=prod
* using config/runtime.exs to configure the release at runtime
* hot-upgrade copying release file to /Users/testeves/Workspace/Esl/myphoenixapp/_build/prod/rel/myphoenixapp/releases/myphoenixapp-0.1.0.rel
* building /Users/testeves/Workspace/Esl/myphoenixapp/_build/prod/myphoenixapp-0.1.0.tar.gz

Move the release file to the distributed folder and updated the version:

export app_name=myphoenixapp
cp _build/prod/${app_name}-0.1.0.tar.gz /tmp/${app_name}/dist/${app_name}
echo "{\"version\":\"0.1.0\",\"pre_commands\": [],\"hash\":\"local\"}" | jq > /tmp/${app_name}/versions/${app_name}/local/current.json

Running DeployEx and deploy the app

Move back to the DeployEx project and run the command line with the required ENV vars.

NOTE: All env vars that are available for DeployEx will also be available to the monitored_app

export SECRET_KEY_BASE=e4CXwPpjrAJp9NbRobS8dXmOHfn0EBpFdhZlPmZo1y3N/BzW9Z/k7iP7FjMk+chi
export PHX_SERVER=true
export DATABASE_URL=ecto://postgres:postgres@localhost:5432/myphoenixapp_prod # In case your monitored add is using ecto
iex --sname deployex --cookie cookie -S mix phx.server
...

[info] Update is needed at instance: 1 from: <no current set> to: 0.1.0.
[warning] HOT UPGRADE version NOT DETECTED, full deployment required, result: []
[info] Full deploy instance: 1 deploy_ref: 32656.
[info] Initialising monitor server for instance: 1
[info] Ensure running requested for instance: 1 version: 0.1.0
[info]  # Identified executable: /tmp/deployex/varlib/service/myphoenixapp/1/current/bin/myphoenixapp
[info]  # Starting application
[info]  # Running instance: 1, monitoring pid = #PID<0.790.0>, OS process = 36891 deploy_ref: 32656.
[info]  # Application instance: 1 is running
[info]  # Moving to the next instance: 2
...
iex(deployex@hostname)1>

You should then visit the application and check it is running localhost:5001. Since you are not using mTLS, the dashboard should look like this:

Note that the OTP-Nodes are connected, but the mTLS is not supported. The mTLS can be enabled and it will be covered ahead. Leave this terminal running and open a new one to compile and release the monitored app.

Updating the application

Full deployment

In this scenario, the existing application will undergo termination, paving the way for the deployment of the new one. It's crucial to maintain the continuous operation of DeployEx throughout this process. Navigate to the myphoenixapp project and increment the version in the mix.exs file. Typically, during release execution, the CI/CD pipeline either generates the package from scratch or relies on the precompiled version, particularly for hot-upgrades. If you've incorporated the Jellyfish library and wish to exclusively create the full deployment package, for this test you must follow the steps:

1. Remove any previously generated files and generate a new release

cp myphoenixapp
rm -rf _build/prod
MIX_ENV=prod mix assets.deploy
MIX_ENV=prod mix release
...
Generated myphoenixapp app
No appups, nothing to move to the release
Check your digested files at "priv/static"
No appups, nothing to move to the release
* assembling myphoenixapp-0.1.1 on MIX_ENV=prod
* using config/runtime.exs to configure the release at runtime
* hot-upgrade copying release file to /Users/testeves/Workspace/Esl/myphoenixapp/_build/prod/rel/myphoenixapp/releases/myphoenixapp-0.1.1.rel
* building /Users/testeves/Workspace/Esl/myphoenixapp/_build/prod/myphoenixapp-0.1.1.tar.gz

2. Now, keep DeployEx running in another terminal and copy the release file to the distribution folder and proceed to update the version accordingly:

export app_name=myphoenixapp
cp _build/prod/${app_name}-0.1.1.tar.gz /tmp/${app_name}/dist/${app_name}
echo "{\"version\":\"0.1.1\",\"pre_commands\": [],\"hash\":\"local\"}" | jq > /tmp/${app_name}/versions/${app_name}/local/current.json

3. You should then see the following messages in the DeployEx terminal while updating the app:

[info] Update is needed at instance: 1 from: 0.1.0 to: 0.1.1.
[warning] HOT UPGRADE version NOT DETECTED, full deployment required, result: []
[info] Full deploy instance: 1 deploy_ref: 37406.
[info] Requested instance: 1 to stop application pid: #PID<0.790.0>
[warning] Remaining beam app removed for instance: 1
[info] Initialising monitor server for instance: 1
[info] Ensure running requested for instance: 1 version: 0.1.1
[info]  # Identified executable: /tmp/deployex/varlib/service/myphoenixapp/1/current/bin/myphoenixapp
[info]  # Starting application
[info]  # Running instance: 1, monitoring pid = #PID<0.843.0>, OS process = 37992 deploy_ref: 37406.
[info]  # Application instance: 1 is running
[info]  # Moving to the next instance: 2
...

Hot-upgrades

For this scenario, the project must first be compiled to the current version and subsequently compiled for the version it's expected to update to. The current.json file deployed includes the git hash representing the current application version. In this local testing phase, it suffices to compile for the previous version, such as 0.1.1, and the subsequent version, like 0.1.2, so the necessary files will be automatically populated.

1. Since the application is already compiled for 0.1.1, change the mix.exs to 0.1.2, apply any other changes if you want to test and execute the command:

MIX_ENV=prod mix assets.deploy
MIX_ENV=prod mix release
...
Generated myphoenixapp app
You can find your generated appups in rel/appups/myphoenixapp/ with the .appup extension
Check your digested files at "priv/static"
You can find your generated appups in rel/appups/myphoenixapp/ with the .appup extension
* assembling myphoenixapp-0.1.2 on MIX_ENV=prod
* using config/runtime.exs to configure the release at runtime
* hot-upgrade copying release file to /Users/testeves/Workspace/Esl/myphoenixapp/_build/prod/rel/myphoenixapp/releases/myphoenixapp-0.1.2.rel
* building /Users/testeves/Workspace/Esl/myphoenixapp/_build/prod/myphoenixapp-0.1.2.tar.gz

2. Now, copy the release file to the distribution folder and proceed to update the version accordingly:

export app_name=myphoenixapp
cp _build/prod/${app_name}-0.1.2.tar.gz /tmp/${app_name}/dist/${app_name}
echo "{\"version\":\"0.1.2\",\"pre_commands\": [],\"hash\":\"local\"}" | jq > /tmp/${app_name}/versions/${app_name}/local/current.json

You can then check that DeployEx had executed a hot upgrade in the application:

[info] Update is needed at instance: 1 from: 0.1.1 to: 0.1.2.
[warning] HOT UPGRADE version DETECTED, from: 0.1.1 to: 0.1.2
[info] Hot upgrade instance: 1 deploy_ref: 37406.
[info] Unpacked successfully: ~c"0.1.2"
[info] Installed Release: ~c"0.1.2"
[info] Made release permanent: 0.1.2
[info] Release upgrade executed with success at instance: 1 from: 0.1.1 to: 0.1.2
[info]  # Moving to the next instance: 2
...

you can check that the version and the deployment status has changed in the dashboard:

Enhancing OTP Distribution Security with mTLS

In order to improve security, mutual TLS (mTLS for short) can be employed to encrypt communication during OTP distribution. To implement this, follow these steps:

1. Generate the necessary certificates, DeployEx has a good examples of how to create self-signed tls certificates:

cd deployex
make tls-distribution-certs

2. Copy the generated certificates to the /tmp folder:

cp ca.crt /tmp
cp deployex.crt /tmp
cp deployex.key /tmp

3. Create the inet_tls.conf file with the appropriate paths, utilizing the command found in rel/env.sh.eex:

export DEPLOYEX_OTP_TLS_CERT_PATH=/tmp

test -f /tmp/inet_tls.conf || (umask 277
 cd /tmp
 cat >inet_tls.conf <<EOF
[
  {server, [
    {certfile, "${DEPLOYEX_OTP_TLS_CERT_PATH}/deployex.crt"},
    {keyfile, "${DEPLOYEX_OTP_TLS_CERT_PATH}/deployex.key"},
    {cacertfile, "${DEPLOYEX_OTP_TLS_CERT_PATH}/ca.crt"},
    {verify, verify_peer},
    {secure_renegotiate, true}
  ]},
  {client, [
    {certfile, "${DEPLOYEX_OTP_TLS_CERT_PATH}/deployex.crt"},
    {keyfile, "${DEPLOYEX_OTP_TLS_CERT_PATH}/deployex.key"},
    {cacertfile, "${DEPLOYEX_OTP_TLS_CERT_PATH}/ca.crt"},
    {verify, verify_peer},
    {secure_renegotiate, true},
    {server_name_indication, disable}
  ]}
].
EOF
)

4. Ensure that myphoenixapp also utilizes the same options and certificate by updating rel/env.sh.eex:

cd myphoenixapp
vi rel/env.sh.eex
# Add the following line
#!/bin/sh
export ELIXIR_ERL_OPTIONS="-proto_dist inet_tls -ssl_dist_optfile /tmp/inet_tls.conf"
# save the file :q

5. To enable mTLS for DeployEx, set the appropriate Erlang options before running the application in the terminal:

ELIXIR_ERL_OPTIONS="-proto_dist inet_tls -ssl_dist_optfile /tmp/inet_tls.conf -setcookie cookie" iex --sname deployex -S mix phx.server

After making these changes, create and publish a new version 0.1.3 for myphoenixapp and run the DeployEx with the command from item 5. After the deployment, you should see the follwoing dashboard:

[!ATTENTION] Ensure that the cookie is properly set

Throubleshooting

Accessing DeployEx logs

# production
tail -f /var/log/deployex/deployex-stdout.log
tail -f /var/log/deployex/deployex-stderr.log
# local test
# not available when running as dev env

Connecting to the DeployEx IEX CLI

export RELEASE_NODE_SUFFIX=""
export RELEASE_COOKIE=cookie
# production
/opt/deployex/bin/deployex remote
# local test
# not available when running as dev env

Accessing monitored app logs

export instance=1
export monitored_app_name=myphoenixapp
# production
tail -f /var/log/${monitored_app_name}/${monitored_app_name}-${instance}-stdout.log
tail -f /var/log/${monitored_app_name}/${monitored_app_name}-${instance}-stderr.log
# local test
tail -f /tmp/${monitored_app_name}/${monitored_app_name}/${monitored_app_name}-${instance}-stdout.log
tail -f /tmp/${monitored_app_name}/${monitored_app_name}/${monitored_app_name}-${instance}-stderr.log

Connecting to the monitored app IEX CLI

export instance=1
export monitored_app_name=myphoenixapp
export RELEASE_NODE_SUFFIX=-${instance}
export RELEASE_COOKIE=cookie
# production
/var/lib/deployex/service/${monitored_app_name}/${instance}/current/bin/${monitored_app_name} remote
# local test
/tmp/deployex/varlib/service/${monitored_app_name}/${instance}/current/bin/${monitored_app_name} remote

How DeployEx handles services

DeployEx operates by monitoring applications and versions using folders and files, treating the monitored app as a service:

# test environment
/tmp/deployex/varlib/service/${monitored_app}/${instance}/previous/${monitored_app}
/tmp/deployex/varlib/service/${monitored_app}/${instance}/new/${monitored_app}
/tmp/deployex/varlib/service/${monitored_app}/${instance}/current/${monitored_app}

# production environment
/var/lib/deployex/service/${monitored_app}/${instance}/previous/${monitored_app}
/var/lib/deployex/service/${monitored_app}/${instance}/new/${monitored_app}
/var/lib/deployex/service/${monitored_app}/${instance}/current/${monitored_app}

The deployment process involves several steps to ensure smooth transitions:

Full deployment

1. Download and Unpack the New Version: The new version of the application is downloaded and unpacked into the new service folder, ready for deployment.
2. Check if the release contain a hot-upgrade or full deployment: DeployEx will check the release file received and if it is a full deployment, goes to the step 3 .
3. Stop the Current Application: The currently running application instance is stopped to prepare for the new deployment.
4. Delete the Previous Service Folder: The previous service folder, containing the previous version of the application, is deleted to make space for the new version.
5. Move the Current Service: The current service folder, representing the current version of the application, is moved to the previous service folder. Simultaneously, the new service folder is moved to become the new current service folder.
6. Run pre_commands: Before starting the application, DeployEx will attempt to run any pre_commands (if set) using the current service folder.
7. Start the Application: Finally, the application is started using the version now residing in the current service folder, ensuring that the latest version is active and operational.

By following this process, DeployEx facilitates deployments, ensuring that applications are updated while minimizing downtime.

Hot-upgrades

For this scenario, there will be no moving files/folders since the target is to keep the current service folder updated. The sequence is:

1. Download and Unpack the New Version: The new version of the application is downloaded and unpacked into the new service folder, ready for deployment.
2. Check if the release contain a hot-upgrade or full deployment: DeployEx will check the release file received and if it is a hot-upgrade, goes to the step 3 .
3. Run pre_commands: Before executing the hot-upgrade, DeployEx will attempt to run any pre_commands (if set) using the new service folder.
4. Execute the Hotupgrade checks and verification DeployEx will try to run the hotupgrade sequence and if succeeds, it makes the changes permanent. In any case of failure, it tries to execute a full deployment with the same release file.

Getting involved

🗨️ Contact us: Feel free to contact me on Linkedin.

Copyright and License

Copyright (c) 2024, Thiago Esteves.

DeployEx source code is licensed under the MIT License.