A microservice in PIPEFORCE is an application which runs inside a (Docker) container which in term runs inside the PIPEFORCE (Kubernetes) cluster. Such a microservice can communicate with other microservices inside the same namespace via messaging and REST. A namespace can “host” many such microservices:
PIPEFORCE offers a lot of toolings to develop, deploy and monitor your microservices in your namesace. This is called the Microservices Framework.
Microservice or App?
In general, you have three main possibilities to write a business application:
Using low code inside an app.
Using a microservice.
Combining both approaches.
Depending on the requirements you should select the right approach for your implementation.
In the table below you can see the pros and cons:
App & Low Code, Pipelines
Easy to learn. No deep developer skills required. Very fast results possible. No compilation and build steps required. Huge set of out-of-the-box toolings like forms, lists, reports and utils available. Based on many pre-defined standards which can simplify maintenance and upgrading.
Limited to its main purposes. Requires a deployment process.
For data mappings and transformations, workflows and system integrations. Building frontend apps with forms, listings and basic reports.
Very flexible: You can use any programming language and libraries of your choice and you can develop any business complexity you like.
Requires developer skills and somebody who reviews and manages the architecture of the microservice. Requires a build and deployment process.
For complex business logics, running mainly as background services.
It's also possible to combine apps and microservices in order to implement a single business solution:
Typically a microservice is a relatively small application which has the responsibility about a concrete and well-defined part of an overall business process. How you slice the microservices depends on your requirements.
So before you start, you should be very clear, which parts should go into which microservices and which not at all.
In our experience, Python is often a very good choice for a microservice language. Since it has the best trade-off between complexity and flexibility. But as always, it depends on your concrete requirements.
Once a microservice has been developed, it must be wrapped inside a (Docker) image in order to be able to deploy it into PIPEFORCE. The deployment cycle of a microservice in PIPEFORCE is always an 4-step task:
Build a (Docker) container image from the sources of your microservice.
Upload the container image to a container registry which is supported by PIPEFORCE.
Deploy the image from this registry into your PIPEFORCE namespace by using the command service.start.
Step 2-4 are typically automated by using a CI/CD tool like Jenkins, CircleCI, Travis or similar.
Furthermore, we suggest managing your source code using GitHub and connect your CI/CD tool, so it starts to build, test and deploy automatically every time, a new push to GitHub happened (or on other triggers like merging or tagging).
Also see these commands to manage the deployment of your services:
Every time a service is started using the service.start command, also some implicit variables will be automatically passed to this container and can be accessed via the environment variables inside the container.
These implicit variables are:
The domain name used for the PIPEFORCE instance. For example customer.pipeforce.net.
The cluster internal host name of the hub service in order to connect to.
The cluster internal host port in order to connect to.
The cluster internal url of the hub service in order to connect via REST for example.
The default dead letter queue used for RabbitMQ messaging.
The default messaging exchange used for RabbitMQ messaging.
The default messaging topic used for RabbitMQ messaging. It is usually the same as the default exchange.
The messaging host to connect to in order to register a RabbitMQ listener. See below in documentation how to optionally pass messaging username and password as a secret if required. They aren’t provided by default.
The messaging host to connect to in order to register a RabbitMQ listener.
The namespace of the instance this services runs inside.
The external url to the PIPEFORCE webui portal in order to refer to from inside a microservice.
The name of this custom service inside PIPEFORCE.
The staging mode, this namespace is running in. Usually one of DEV, QA or PROD.
Additionally to these default environment variables, you can also add your custom ones by using the parameter env on the command service.start:
In case you would like to set secret values to environment variables, you should create such secrets in the secret store inside PIPEFORCE and refer to them, using the custom uri prefix $uri:secret:. For example:
On startup of the service, the secret with name MY_SECRET will be read from the secret store and passed to the container as environment variable MY_SECRET_ENV. This way it is not required to store the secret in code.
Since the secret is stored in the environment variable in plain text, make sure to pass secrets only along to trustworthy microservices which belong to your stack!
You can also define a default value for a secret. In case the secret could not be found in the secret store, the given default value will be used and passed as ENV variable value instead:
The preferred way each microservice inside PIPEFORCE can communicate with each other is by using messaging.
As message broker RabbitMQ is used by default.
If you're using one of our microservice templates, setting up a library to connect to RabbitMQ and creating the default channels and bindings is typically already done for you, or there is a best practise to do so.
How to connect a Microservice with the message broker?
In case you have deployed your microservice using the command service.start, then these environment variables will be automatically provided inside your microservice and can be used to connect to the RabbitMQ message broker:
PIPEFORCE_MESSAGING_HOST = The cluster-internal hostname of the messaging service.
PIPEFORCE_MESSAGING_PORT = The cluster-internal port of the messaging service.
Note: This these values can change at any time, so do not use them as fixed value.
Additionally to these variables, you need to set the PIPEFORCE_MESSAGING_USERNAME and PIPEFORCE_MESSAGING_PASSWORD along with your service.start command using the custom uri prefix $uri:secret. Here is how to do it:
Create a new secret in your secret store with name pipeforce-messaging-username and type secret-text and set the RabbitMQ username you would like to use to connect.
Create a new secret in your secret store with name pipeforce-messaging-password and type secret-text and set the RabbitMQ password you would like to use to connect.
Start your container using these env variables pointing to the secret store. Example:
This way, the sensitive values will be passed to your container without the requirement to store them into code or refer from external systems.
In case you're using one of the custom service templates from PIPEFORCE, messaging will be automatically setup for you using the ENV variables mentioned before.
In case you're using your own framework, how to setup your client in order to connect, depends on your programming language the RabbitMQ client. See the official documentation: https://www.rabbitmq.com/devtools.html
The next step is to create the queues required by your service. See the Default Queue Naming guide below.
Now create a binding between your queues, the default topic pipeforce.hub.default.topic and the routing key pattern of messages your service is interested in.
Also remember to setup the dead leader queue in order to not lose any message as mentioned below.
PIEPFORCE automatically creates a default topic exchange on startup with this name: pipeforce.hub.default.topic.
PIPEFORCE core services are configured in a way that any event which happens there or is sent using the event.send command is also send to this default topic.
In case a microservice wants to listen to a certain type of message with a given routing key, it needs to create a binding between the topic pipeforce.hub.default.topic and the queue you want to “feed” this message into.
How to set these arguments in your microservice depends on your selected programming language and the RabbitMQ client implementation you're using. See documentation for details: https://www.rabbitmq.com/dlx.html
In case you're using Java + Spring as microservice language for example, it could look like this:
Here you can find the default message keys, PIPEFORCE will use for internal events and send messages with these keys to the default topic pipeforce.hub.default.topic. You can subscribe to these keys using a binding between your queue and this default topic.
You can also describe to multiple keys using the * and # patterns. For example in order to listen to all property events, you could subscribe to the key pattern property.*.
In case a new public link for a delivery was created.
In case a public link for a delivery has been deleted.
In case the attachments of a delivery have been deleted.
In case the deletion of the attachments have been failed.
In case hub has context has been started is ready to accept requests but right before the startup phase.
In case hub context is about to start. Note: This event is not send to the topic queue since at the time of this, the RabbitMQ connector is not setup yet. This event is just for internal use in hub. Its mentioned here just for completeness reasons.
In case hub setup has been finished.
In case the hub setup is about to be started. This is right after the context has been started but before the setup has been fully finished.
In case a potential bruteforce attach has been detected by IAM.
In case a login using IAM has been failed.
In case a property in the property store has been copied. See PropertyCopiedEvent.java for implementation details.
In case a property in the property store has been created. See PropertyCreatedEvent.java for implementation details.
In case a property in the property store has been deleted. See PropertyDeletedEvent.java for implementation details.
In case a property in the property store has been moved. See PropertyMovedEvent.java for implementation details.
In case a property in the property store has been moved. See PropertyUpdatedEvent.java for implementation details.
A new usagelog entry was created in the property store. See UsageLogCreatedEvent.java for implementation details.
In case a webhook call has been occurred. The <name_of_webhook> depends on the setup. You can use the pattern webhook.# to listen to all webhooks.
Depends on key param of command event.send.
Furthermore whenever the command event.send is called, the payload of this event is also forwarded to the default hub topic using the key param of this command as the messaging key and the body as the payload of the message.