fix(kuma-dp): Fix envoy binary not found

[tharun208]

Check for envoy path and throw an error if not found during initializing envoy
Updated tests

Fix Envoy Binary Not Found

When envoy is not found Kuma-dp stops.

Full changelog

• Checked for envoy path and if present creates an envoy instance.
• Updated tests.

Issues resolved

Fix #686

[subnetmarco]

We need to implement two checks here:

1. One to determine if envoy exists. If not then return an error that says something like could not find the "envoy" executable in your path
2. One to return an error if running envoy fails for whatever reason (we have this here in this PR)
3. And we could even add a check to determine that the version of envoy that we found (envoy --version) is compatible with the current version of Kuma.

For the last step, we will need to have a list of version ranges that we support (ie from 1.12 to 1.14) so that we can support minor releases that are being created in the meanwhile by Envoy without having to update Kuma. I will let @jakubdyszkiewicz chime in for this.

[tharun208]

1. could not find the "envoy" executable in your pat

We need to implement two checks here:

1. One to determine if envoy exists. If not then return an error that says something like could not find the "envoy" executable in your path
2. One to return an error if running envoy fails for whatever reason (we have this here in this PR)
3. And we could even add a check to determine that the version of envoy that we found (envoy --version) is compatible with the current version of Kuma.

For the last step, we will need to have a list of version ranges that we support (ie from 1.12 to 1.14) so that we can support minor releases that are being created in the meanwhile by Envoy without having to update Kuma. I will let @jakubdyszkiewicz chime in for this.

1. I added the envoy exists check and the error message.
2. Running envoy fails is already present.

[tharun208]

1. could not find the "envoy" executable in your pat

We need to implement two checks here:

1. One to determine if envoy exists. If not then return an error that says something like could not find the "envoy" executable in your path
2. One to return an error if running envoy fails for whatever reason (we have this here in this PR)
3. And we could even add a check to determine that the version of envoy that we found (envoy --version) is compatible with the current version of Kuma.

For the last step, we will need to have a list of version ranges that we support (ie from 1.12 to 1.14) so that we can support minor releases that are being created in the meanwhile by Envoy without having to update Kuma. I will let @jakubdyszkiewicz chime in for this.

Hi Marco,

1. I added the envoy not exists check and the error message.
2. Running envoy fail check is already present.

[jakubdyszkiewicz]

And we could even add a check to determine that the version of envoy that we found (envoy --version) is compatible with the current version of Kuma.

For the last step, we will need to have a list of version ranges that we support (ie from 1.12 to 1.14) so that we can support minor releases that are being created in the meanwhile by Envoy without having to update Kuma. I will let @jakubdyszkiewicz chime in for this.

I am hesitant about this step @subnetmarco
It is very much a use case to use your custom Envoy distro with Kuma. The version name then could be anything. Additionally, I'd allow users to experiment with new versions of Envoy, especially if this is a minor security release.

If we want to do it, we should only validate major version so in case of 1.12.1 we let 1.12.*. Additionally, there should be a flag to skip this validation.

[tharun208]

And we could even add a check to determine that the version of envoy that we found (envoy --version) is compatible with the current version of Kuma.
For the last step, we will need to have a list of version ranges that we support (ie from 1.12 to 1.14) so that we can support minor releases that are being created in the meanwhile by Envoy without having to update Kuma. I will let @jakubdyszkiewicz chime in for this.

I am hesitant about this step @subnetmarco
It is very much a use case to use your custom Envoy distro with Kuma. The version name then could be anything. Additionally, I'd allow users to experiment with new versions of Envoy, especially if this is a minor security release.

If we want to do it, we should only validate major version so in case of 1.12.1 we let 1.12.*. Additionally, there should be a flag to skip this validation.

@subnetmarco are we going to add this check?

[subnetmarco]

Okay then we can skip the Envoy version range validation for now, but I added another comment to my review that needs to be addressed.

[lobkovilya]

Just small insignificant comments, overall looks good!

[lobkovilya]

@tharun208 Great! Thank you for your contribution!