Allow users define custom port-mappings for port forwarding

[kadel]

/kind user-story

User Story

As an odo user, I want to be able to define a mapping for port-forwarding So that I can have predictable port numbers; this is useful when developing multi-component applications.

example:

cd frontend
odo dev

cd ../backend
odo dev

configure the frontend to use port 20002 (odo dev for backed was started second)

I stop everything, next day I want to continue working but this time I start odo dev session for backend before frontend. Now I have to keep in mind to reconfigure the frontend to use a different port.

A slightly better experience would be to have

cd frontend
odo dev

cd ../backend
odo dev --port-forward 8888:8000

Now no matter what order I run commands, I will get backed on localhost:8888.

An even better experience would be for odo to remember custom port mappings so next time I can just do odo dev. This is something that we can look into as second stage.

Acceptance Criteria

• Users should be able to define custom port mapping using flags provided to odo dev command using --port-forward flag. Flag accepts argument in <localPort>:<containerPort>
• port-forward can be defined as multiple times (for multiple ports)
• if multiple containers have the same port and the command should fail and guide the user to specify container name --port-forward <localPort>:<containerName>:<containerPort>
• --address <ipaddress> flag should allow specifying on which local address the port will be listening
• Validate if the containerPort is a valid endpoint(?)
• Handle dedicatedPod (is it handled currently?) (not handled in the Devfile library: Support dedicatedPod field on container components #6786)
• Cannot use --random-port and --port-forward together.
• Validate that a local port is not defined more than once

allowed formats for --port-forward

8080:80 - local port 8080 listening only on localhost, container port 80
8080:mycontainer:80 - local port 8080 listening only on localhost, container port 80 on container called mycontainer

/kind user-story

[rm3l]

Grooming (2023-03-23)

• Separate flag for listening host

[valaparthvi]

Can user also provide <hostip>:<localPort>:<containerName>:<containerPort>?

Should we allow :<containerPort>? Technically it is still valid, and a random port would be assigned, so I think it should be accepted.

We do not accept it atm, if there is a user requirement to do so, we can change it later. [Grooming Call March 30 '23]

[valaparthvi]

This issue will be fixed in 3 parts to avoid larger PR size:

• Implement for Kubernetes (Allow users to define custom port-mappings for port forwarding [Kubernetes] #6704)
• Implement for Podman
• Implement --address flag (might create a separate issue for this).

[valaparthvi]

What port range should we accept? Currently it accepts any value between 1 to 65535. Should we increase the lower limit to 1024?

[rm3l]

What port range should we accept? Currently it accepts any value between 1 to 65535. Should we increase the lower limit to 1024?

I think we should not prevent that.
A user might want to run odo dev as root to expose an application via a privileged port.. And it is even possible to grant a binary like odo the system capability to open privileged ports while still running with the privileges of a regular user.
I think we should make sure an appropriate error is returned when setting up port forwarding if the user does not have permission open privileged ports.