Run Mendix in Cloud Foundry

The Mendix Buildpack for Cloud Foundry has two main phases:

compile: Fetch the JRE, Mendix Runtime, and nginx and bundle these together with the application model into a droplet. This is handled by bin/compile.
run: Start the various processes and run the application. python start.py is for orchestration, the JVM is for executing the Mendix Model, and nginx is used as reverse proxy including handling access restrictions.

The compile phase accepts archives in .mda format (Mendix Deployment Archive). There is experimental support for .mpk archives (Mendix Project Package). If an .mpk file is pushed, mxbuild is executed using Mono in the compile phase as well, the run phase stays the same.

There are specific guides for deploying Mendix apps to the Pivotal and IBM Bluemix Cloud Foundry platforms on our documentation page. This buildpack readme documents the more low-level details and CLI instructions.

Deploying using the CLI

Install cloud foundry command line

Install the Cloud Foundry command line executable. You can find this on the releases page. Set up the connection to your preferred Cloud Foundry environment with cf login and cf target.

Push your app

We push an mda (Mendix Deployment Archive) that was built by the Mendix Business Modeler to Cloud Foundry.

cf push <YOUR_APP> -b https://github.com/mendix/cf-mendix-buildpack -p <YOUR_MDA>.mda -t 180

We can also push a project directory. This will move the build process (using mxbuild) to Cloud Foundry:

cd <PROJECT DIR>; cf push -b https://github.com/mendix/cf-mendix-buildpack -t 180

Note that you might need to increase the startup timeout to prevent the database from being partially synchronized. This can be done either by specifying the -t 180 parameter like above, or by using the CF_STARTUP_TIMEOUT environment variable (in minutes) from the command line.

Also note that building the project in Cloud Foundry takes more time and requires enough memory in the compile step.

Configuring admin password

The first push generates a new app. In order to login to your application as admin you can set the password using the ADMIN_PASSWORD environment variable. Keep in mind that the admin password should comply with the policy you have set in the Mendix Modeler. For security reasons it is recommended to set this environment variable once to create the admin user, then remove the environment variable and restart the app. Finally log in to the app and change the password via the web interface. Similarly, the setting can be used to reset the password of an administrator.

cf set-env <YOUR_APP> ADMIN_PASSWORD "<YOURSECRETPASSWORD>"

Connecting a Database

You also need to connect a PostgreSQL, MySQL or any other Mendix supported database instance which allows at least 5 connections to the database. Find out which services are available in your Cloud Foundry foundation with the marketplace command.

cf marketplace

In our trial we found the service elephantsql which offered the free turtle plan. All you need to do is give it a name and bind it to your application.

cf create-service elephantsql turtle <SERVICE_NAME>

cf bind-service <YOUR_APP> <SERVICE_NAME>

Note that not all databases are automatically picked up by the buildpack. If cf push returns an error like Could not parse database credentials, you need to set the DATABASE_URL variable manually using the details included in the service.

Now we need to push the application once more.

cf push <YOUR_APP> -b https://github.com/mendix/cf-mendix-buildpack -p <YOUR_MDA>.mda

You can now log in to your application with the configured admin password.

Configuring Constants

The default values for constants will be used as defined in your project. However, you can override them with environment variables. You need to replace the dot with an underscore and prefix it with MX_. So a constant like Module.Constant with value ABC123 could be set like this:

cf set-env <YOUR_APP> MX_Module_Constant "ABC123"

After changing environment variables you need to restart your app. A full push is not necessary.

cf restart <YOUR_APP>

Configuring Scheduled Events

The scheduled events can be configured using environment variable SCHEDULED_EVENTS.

Possible values are ALL, NONE or a comma separated list of the scheduled events that you would like to enable. For example: ModuleA.ScheduledEvent,ModuleB.OtherScheduledEvent

When scaling to multiple instances, the scheduled events that are enabled via the settings above will only be executed on instance 0. The other instances will not execute scheduled events at all.

Configuring External Filestore

Mendix supports multiple external file stores: AWS S3 compatible file stores, Azure Storage and Swift, used in Bluemix Object Storage. All of these can be configured manually via Custom Runtime Settings, but S3, Azure Storage and Swift (Bluemix Object Storage) can be configured in easier ways:

Swift (Bluemix Object Storage) Settings

When deploying Mendix 6.7 or higher to Bluemix, you can simply create an Object Storage service and attach it to your app. No further configuration in necessary, you just need to restart your app. By default, a storage container will be created for you called mendix. If you want to use a different container name (for example if you are sharing the Object Storage service between multiple apps), you can configure the container name with the environment variable SWIFT_CONTAINER_NAME.

Azure Storage Service Settings

When deploying Mendix 6.7 or higher to CF on Azure with the Azure Service Broker, you can simply create an Azure Storage Service instance and attach it to your app. No further configuration in necessary, you just need to restart your app. By default, a storage container will be created for you called mendix. If you want to use a different container name (for example if you are sharing the Azure Storage service between multiple apps), you can configure the container name with the environment variable AZURE_CONTAINER_NAME.

S3 Settings

Mendix can use external file stores with an S3 compatible api. Use the following environment variables to enable this.

S3_ACCESS_KEY_ID: credentials access key
S3_SECRET_ACCESS_KEY: credentials secret
S3_BUCKET_NAME: bucket name

The following environment variables are optional:

S3_PERFORM_DELETES: set to false to never delete items from the filestore. This is useful when you use a highly redundant service without a separate backup mechanism, such as AWS S3.
S3_KEY_SUFFIX: if your bucket is multi-tenant you can append a string after each object name, you can restrict IAM users to objects with this suffix.
S3_ENDPOINT: for S3 itself this is not needed, for S3 compatible object stores set the domain on which the object store is available.
S3_USE_V2_AUTH: use Signature Version 2 Signing Process, this is useful for connecting to S3 compatible object stores like Riak-CS, or Ceph.
S3_USE_SSE: if set to true this will enable Server Side Encryption in S3, available from Mendix 6.0

Configuring the Java heap size

The Java heap size is configured automatically based on best practices. You can tweak this to your needs by using another environment variable in which case it is used directly.

cf set-env <YOUR_APP> HEAP_SIZE 512M

Configuring the Java version

The default Java version is 8 for Mendix 5.18 and higher. If you want to force Java 7 or 8, you can set the environment variable JAVA_VERSION to 7 or 8.

cf set-env <YOUR_APP> JAVA_VERSION 8

Configuring Custom Runtime Settings

To configure any of the advanced Custom Runtime Settings you can use setting name prefixed with MXRUNTIME_ as an environment variable.

For example, to configure the ConnectionPoolingMinIdle setting to value 10, you can set the following environment variable:

cf set-env <YOUR_APP> MXRUNTIME_ConnectionPoolingMinIdle 10

If the setting contains a dot . you can use an underscore _ in the environment variable. So to set com.mendix.storage.s3.EndPoint to foo you can use:

cf set-env <YOUR_APP> MXRUNTIME_com_mendix_storage_s3_EndPoint foo

Configuring HTTP headers

To prevent clickjacking, the X-Frame-Options header can be configured. See this Mozilla page for all supported options. This can be configured via het X_FRAME_OPTIONS environment variable. For example:

cf set-env <YOUR_APP> X_FRAME_OPTIONS SAMEORIGIN

or:

cf set-env <YOUR_APP> X_FRAME_OPTIONS "ALLOW-FROM https://example.com/"

Horizontal Scaling

There are two ways for horizontal scaling in Mendix. In Mendix 5.15+ you can use sticky sessions. Mendix 7 brings this even further by no longer requiring a state store. See below on how to activate these settings, based on the Mendix version you use.

Things to keep in mind when scaling horizontally

When you make changes to your domain model, the Mendix Runtime will need to synchronize data model changes with the database on startup. This will only happen on instance 0. The other instances will wait until the database is fully synchronized. This is determined via the CF_INSTANCE_INDEX environment variable. This is a built-in variable in Cloud Foundry, you do not need to set it yourself. If the environment variable is not present (this is the case older Cloud Foundry versions) every instance will attempt to synchronize the database. A warning containing the text CF_INSTANCE_INDEX environment variable not found will be printed in the log.

Scheduled events will also only be executed on instance 0, see the section Configuring Scheduled Events.

In all horizontal scaling scenarios, extra care needs to be taken when programming Java actions. Examples of things to be avoided are:

relying on singleton variables to keep global application state
relying on scheduled events to make changes in memory, scheduled events will only run on the primary instance

Enabling Sticky Sessions (Mendix 5.15+)

If you want to enable sticky sessions, the only change that is needed is to set the environment variable ENABLE_STICKY_SESSIONS to true. This will replace the Mendix session cookie name from XASSESSIONID to JSESSIONID which will trigger sticky session detection in the Cloud Foundry http router. Watch out: custom login code might break if it still injects the XASSESSIONID cookie.

When using sticky sessions, clients need to support http cookies. Webservice integrations typically don't do this, so each request can end up on a different instance.

With sticky sessions there is an increase in resiliency. If one instance crashes, only 1/n-th of the users will be affected. These users will lose their session state and will have to sign in again.

Configuring Clustering for Mendix 7

Mendix 7 makes it easier to scale out. The absence of the need for a state store results in the fact that nothing needs to be configured for running Mendix 7 in clustering mode. Based on the CF_INSTANCE_INDEX variable, the runtime starts either in leader or slave mode. The leader mode will do the database synchronization activities (when necessary), while the slaves will automatically wait until that is finished.

NOTE: The previously documented setting CLUSTER_ENABLED and the REDIS related settings for Mendix 6 will have no effect anymore in Mendix 7 and are ignored.

Offline buildpack settings

If you are running Cloud Foundry without a connection to the Internet, you should specify an on-premises web server that hosts Mendix Runtime files and other buildpack resources. You can set the endpoint with the following environment variable:

BLOBSTORE: https://my-intranet-webserver.my-company.com/mendix/

The preferred way to set up this on-premises web server is as a transparent proxy to https://cdn.mendix.com/. This prevents manual work by system administrators every time a new Mendix version is released.

Alternatively you can make the required mendix runtime files mendix-VERSION.tar.gz available under BLOBSTORE/runtime/. The original files can be downloaded from https://cdn.mendix.com/. You should also make the Java version available on:

BLOBSTORE/mx-buildpack/jre-8-linux-x64.tar.gz
BLOBSTORE/mx-buildpack/jdk-8-linux-x64.tar.gz

And for Mendix < 6.6:

BLOBSTORE/mx-buildpack/jre-8u51-linux-x64.tar.gz
BLOBSTORE/mx-buildpack/jdk-8u51-linux-x64.tar.gz

Certificate Management

To import Certificate Authorities (CAs) into the Java truststore, use the CERTIFICATE_AUTHORITIES environment variable.

The contents of this variable should be a concatenated string containing a the additional CAs in PEM format that are trusted. Example:

Please note, these are two internal Mendix CAs which you should not actually add to your trust store.

Monitoring Tools

New Relic

To enable New Relic, simply bind a New Relic service to this app and settings will be picked up automatically. Afterwards you have to restage your application to enable the New Relic agent.

AppDynamics

To enable AppDynamics, configure the following environment variables:

APPDYNAMICS_CONTROLLER_PORT
APPDYNAMICS_CONTROLLER_SSL_ENABLED
APPDYNAMICS_CONTROLLER_HOST_NAME
APPDYNAMICS_AGENT_APPLICATION_NAME
APPDYNAMICS_AGENT_ACCOUNT_NAME
APPDYNAMICS_AGENT_ACCOUNT_ACCESS_KEY
APPDYNAMICS_AGENT_NODE_NAME *
APPDYNAMICS_AGENT_TIER_NAME

* The APPDYNAMICS_AGENT_NODE_NAME environment variable will be appended with the value of the CF_INSTANCE_ID variable. If you use my-app for APPDYNAMICS_AGENT_NODE_NAME, the AppDynamics agent will be configured as my-app-0 for instance 0 and my-app-1 for instance 1, etc.

If you have any environment variable that starts with APPDYNAMICS_, the AppDynamics Java Agent will be configured for your application. At the moment only agent version 4.3.5.7 is available. After configuring these environment variables, restage your app for the agent to be enabled.

Please note that AppDynamics requires Mendix 6.2 or higher.

Data Snapshots

If you want to enable initializing your database and files from an existing data snapshot included in the MDA, set the environment variable USE_DATA_SNAPSHOT to true. Please note: this only works when the database is completely empty. If there are any Mendix tables defined in the database already, the Runtime will refuse the overwrite it. So, if you have ever started an app before setting this environment variable (thereby initializing the database), you will not be able to import a data snapshot.

License Activation

To activate a license on your application you need license credentials. These credentials can be obtained by contacting Mendix Support.

cf set-env <YOUR_APP> LICENSE_ID <UUID>
cf set-env <YOUR_APP> LICENSE_KEY <LicenseKey>

An example UUID is aab8a0a1-1370-467e-918d-3a243b0ae160 and LicenseKey is a very long base64 string. The app needs to be restarted for the license to be effective.

Logging and Debugging

To debug the code of the buildpack itself, set the BUILDPACK_XTRACE environment variable to true.

App log levels

From Mendix 6 onwards it is possible to configure log levels using environment variables. This allows getting a better insight in the behavior of your Mendix app. Configuring environment variables happens by adding one or more environment variables starting with the name LOGGING_CONFIG (the part of the name after that is not relevant and only used to distinguish between multiple entries if necessary). Its value should be valid JSON, in the format:

{
  "LOGNODE": "LEVEL"
}

You can see the available Log Nodes in your application in the Mendix Modeler. The level should be one of:

CRITICAL
ERROR
WARNING
INFO
DEBUG
TRACE

Example:

cf set-env <YOUR_APP> LOGGING_CONFIG '{ "<LOG NODE VALUE>": "DEBUG"}'

Rate-limiting of log output

The buildpack has the ability to rate-limit the amount of log lines from the Mendix Runtime. This can be useful for apps that misbehave and cause problems for other users in a multi-tenant environment. Rate-limiting is done in log lines per second. Extra lines are dropped and the number of dropped messages is printed on stderr.

Example (1000 loglines/second):

cf set-env <YOUR_APP> LOG_RATELIMIT '1000'

Enabling the Mendix Debugger

You can enable the Mendix Debugger by setting a DEBUGGER_PASSWORD environment variable. This will enable and open up the debugger for the lifetime of this process and is to be used with caution. The debugger is reachable on https://DOMAIN/debugger/. You can follow the second half of this How To to connect with the Mendix Business Modeler. To stop the debugger, unset the environment variable and restart the application.

Buildpack Version Pinning

If you use the cf push commands as described above, you will always use the latest version of the buildpack, i.e. the most recent commit to the master branch. We recommend this for the majority of use cases, as you will always have the latest features and fixes.

However, if you need to exercise a high degree of control over your deployments, it is possible to pin a specific version of the buildpack. This will prevent you from being affected by bugs that are inadvertently introduced, but you will need to set up a procedure to regularly move to new versions of the buildpack.

To push with a specific version of the buildpack, append #<tag> to the buildpack URL in your cf push command like so:

cf push <YOUR_APP> -b https://github.com/mendix/cf-mendix-buildpack#v1.9.2 -p <YOUR_MDA>.mda -t 180

You can find the list of available tags here: https://github.com/mendix/cf-mendix-buildpack/tags

Contributing

Make sure your code complies with pep8 and that no pyflakes errors/warnings are present.

Rebase your git history in such a way that each commit makes one consistent change. Don't include separate "fixup" commits later on.

For new code changes going live, the version has to bumped at the top of start.py, and a new tag with that version number needs to be pushed to github.

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